The rhizosphere bacteria play crucial roles in plant health and growth as they are involved in assimilating nutrients and resisting adverse conditions such as nutrient stress,drought,and wind erosion.Agriophyllum squa...The rhizosphere bacteria play crucial roles in plant health and growth as they are involved in assimilating nutrients and resisting adverse conditions such as nutrient stress,drought,and wind erosion.Agriophyllum squarrosum(L.)Moq.is a pioneer plant used in sand fixation due to its strong resistance to drought and wind erosion.However,the bacterial community characteristics and ecological function in the rhizosphere of A.squarrosum are poorly understood.In this study,soil samples were collected from different developmental stages(seedling stage,vegetative stage,reproductive stage,and withering stage)of A.squarrosum.Illumina Miseq sequencing was used to detect differences in soil bacterial abundance.The Phylogenetic Investigation of Communities by Reconstruction of Unobserved States(PICRUSt)program was used to predict bacterial functions,and the relationships among bacteria,functional populations,and soil nutrients were examined using a heatmap analysis.The results showed that the Shannon and Sobs indices of rhizosphere bacteria were significantly higher during the reproductive stage than during the other stages.Pantoea sp.(7.03%)was the dominant genus during the seedling stage;Arthrobacter sp.was the dominant genus during the vegetative(13.94%),reproductive(7.57%),and withering(12.30%)stages.The relative abundances of Chloroflexi,Acidobacteria,and Gemmatimonadetes were significantly high during the reproductive stage.According to the PICRUSt analysis,membrane transport,signal transduction,and environmental adaptation of the bacterial functional population occurred during the seedling stage.Carbohydrate metabolism increased during the vegetative stage,while energy metabolism,lipid metabolism,and biosynthesis of other secondary metabolites of the bacterial functional population significantly increased during the reproductive stage.The abundances of bacterial communities,functional genes,and soil nutrients were synergistically altered during various developmental stages.Our findings suggest that the developmental stages of A.squarrosum play a significant role in defining the composition and structure of bacterial communities in the rhizosphere.The results will provide a basis for better prediction and understanding of soil bacterial metabolic potential and functions of A.squarrosum rhizosphere in sandy areas.展开更多
The gastrointestinal tract is essential for food digestion,nutrient absorption,waste elimination,and microbial defense.Single-cell transcriptome profiling of the intestinal tract has greatly enriched our understanding...The gastrointestinal tract is essential for food digestion,nutrient absorption,waste elimination,and microbial defense.Single-cell transcriptome profiling of the intestinal tract has greatly enriched our understanding of cellular diversity,functional heterogeneity,and their importance in intestinal tract development and disease.Although such profiling has been extensively conducted in humans and mice,the single-cell gene expression landscape of the pig cecum remains unexplored.Here,single-cell RNA sequencing was performed on 45572 cells obtained from seven cecal samples in pigs at four different developmental stages(days(D)30,42,150,and 730).Analysis revealed 12 major cell types and 38 subtypes,as well as their distinctive genes,transcription factors,and regulons,many of which were conserved in humans.An increase in the relative proportions of CD8^(+)T and Granzyme A(low expression)natural killer T cells(GZMA^(low)NKT)cells and a decrease in the relative proportions of epithelial stem cells,Tregs,RHEX^(+)T cells,and plasmacytoid dendritic cells(pDCs)were noted across the developmental stages.Moreover,the post-weaning period exhibited an up-regulation in mitochondrial genes,COX2 and ND2,as well as genes involved in immune activation in multiple cell types.Cell-cell crosstalk analysis indicated that IBP6^(+)fibroblasts were the main signal senders at D30,whereas IBP6^(−)fibroblasts assumed this role at the other stages.NKT cells established interactions with epithelial cells and IBP6^(+)fibroblasts in the D730 cecum through mediation of GZMA-F2RL1/F2RL2 pairs.This study provides valuable insights into cellular heterogeneity and function in the pig cecum at different development stages.展开更多
Spike development directly affects the yield and quality of rice. We describe an algorithm for automatically identifying multiple developmental stages of rice spikes(AI-MDSRS) that transforms the automatic identificat...Spike development directly affects the yield and quality of rice. We describe an algorithm for automatically identifying multiple developmental stages of rice spikes(AI-MDSRS) that transforms the automatic identification of multiple developmental stages of rice spikes into the detection of rice spikes of diverse maturity levels. The scales vary greatly in different growth and development stages because rice spikes are dense and small, posing challenges for their effective and accurate detection. We describe a rice spike detection model based on an improved faster regions with convolutional neural network(Faster R-CNN).The model incorporates the following optimization strategies: first, Inception_Res Net-v2 replaces VGG16 as a feature extraction network;second, a feature pyramid network(FPN) replaces single-scale feature maps to fuse with region proposal network(RPN);third, region of interest(Ro I) alignment replaces Ro I pooling, and distance-intersection over union(DIo U) is used as a standard for non-maximum suppression(NMS). The performance of the proposed model was compared with that of the original Faster R-CNN and YOLOv4 models. The mean average precision(m AP) of the rice spike detection model was92.47%, a substantial improvement on the original Faster R-CNN model(with 40.96% m AP) and 3.4%higher than that of the YOLOv4 model, experimentally indicating that the model is more accurate and reliable. The identification results of the model for the heading–flowering, milky maturity, and full maturity stages were within two days of the results of manual observation, fully meeting the needs of agricultural activities.展开更多
Although scientists have performed many studies on crescent （barchan） dunes in the Taklimakan Desert,few studies reported the changes in grain size at different development stages of crescent dunes.In order to evalu...Although scientists have performed many studies on crescent （barchan） dunes in the Taklimakan Desert,few studies reported the changes in grain size at different development stages of crescent dunes.In order to evaluate the changing trends of surface sediment grain size with dune development,we investigated the grain size characteristics at four developmental stages （oval sand pile,shield dune,incipient crescent dune and mature crescent dune） of crescent dunes by measuring the morphology of sand dune and observing the near-surface wind regime.The dunes have developed in a wide inter-dune corridor between high compound longitudinal ridges in China＇s Taklimakan Desert.The surface sediments at four developmental stages of the crescent dunes were primarily composed of fine sands,followed by very fine and medium sands.Mean grain sizes ranged from 2.8 to 3.1 φ,with a unimodal distribution.The sands were moderately well-sorted,their distribution varied from platykurtic to very platykurtic,and symmetrical or skewed towards the fine particles.From oval sand piles through shield and incipient crescent dunes to mature crescent dunes,incipient grain size gradually increased,particles became finer,sorting became better,kurtosis and skewness increased.Grain sizes on the surface layer became coarser upwards from the toe of the windward slope and then became finer towards the bottom of the leeward slope.We found that the coarsest particles at different positions at the four developmental stages were different.The coarsest particles were distributed at the top of the oval sand piles and shield dunes,versus at the middle of the windward slope of the incipient and mature crescent dunes.Correlations between the mean grain size and other grain size parameters showed that as mean grain size became finer,sorting became better and kurtosis became wider,but skewness changed only slightly.In addition,grain size variation in the surface sediments correlated with the movement speed of the dunes in the study area.In the open ground among tall-complex longitudinal ridges in the hinterland of the Taklimakan Desert where aeolian environment is characterized by comparatively strong wind and unsaturated sand flow,faster dune movement corresponded to coarser grain size.展开更多
The purpose of this article is twofold.First,it explores the order of the development of nominal and verbal gender of Amharic,which is one of the Ethio-Semitic languages.Second,it provides empirical evidence for the t...The purpose of this article is twofold.First,it explores the order of the development of nominal and verbal gender of Amharic,which is one of the Ethio-Semitic languages.Second,it provides empirical evidence for the typological plausibility of processability theory(PT).In fact,PT has been tested in typologically different languages(e.g.,English,Italian,and Japan);however,it does not have any validation from Ethiopian languages in general and Ethio-Semitic languages in particular yet.Relevant data was collected from sixteen respondents via picture description tasks,short storytelling,interviews,story re-telling,and spot the difference tasks.Distributional analysis was conducted for the analysis,and the point of emergence of target structures was determined using the emergence criteria.Accordingly,the result shows that the development of gender assignment is compatible with processability theory’s predictions in that lexical procedure precedes phrasal procedure,which is followed by S-procedure.Moreover,the masculine gender emerged earlier than its feminine counterpart at all developmental stages.However,subject agreement markers in pro-drop context emerged at stage two preceding subject verb agreement.This finding is against processability theory’s claim that suggests subject agreement markers only emerge at stage four of the processability hierarchy disregarding their stages of development in pro-drop context in particular.展开更多
The photosynthetic activities between two main developmental stages, colony and hormogonium, of the edible cyanobacterium Nostoc sphaeroides Kutzing, were compared. Hormogonia have a higher content of chlorophyll than...The photosynthetic activities between two main developmental stages, colony and hormogonium, of the edible cyanobacterium Nostoc sphaeroides Kutzing, were compared. Hormogonia have a higher content of chlorophyll than that of colonies. It showed that the ratios of phycocyain （PC）, allophycocyain （APC） and phycoerythrocyanin （PEC） in hormogonia and colonies were different. The room temperature chlorophyll fluorescence, 77 K chlorophyll fluorescence, measurements of PSⅠand PS Ⅱ activities all showed that colony has higher photosynthetic competence than hormogonia. Hormogonia had a higher respiration rate than colony, while their maximum photosynthetic oxygen evolution rates were very close. The responses of hormogonia and colonies to high light illuminations also were different. Both of their oxygen evolution rates decreased quickly with the prolonged high light illumination, but hormogonia can keep relatively higher PSⅡ activity （Fv/Fm） than that of colonies. The results suggested that colony was photosynthetically more competent than hormogonia, while the ability of hormogonia to tolerate high light illumination was higher than that of colony.展开更多
BACKGROUND: Under the normal circumstance, there exist some synapses with inactive functions in central nervous system (CNS), but these functions are activated following nerve injury. At the early stage of brain injur...BACKGROUND: Under the normal circumstance, there exist some synapses with inactive functions in central nervous system (CNS), but these functions are activated following nerve injury. At the early stage of brain injury, the abnormal functions of brain are varied, and they have very strong plasticity and are corrected easily. OBJECTIVE: To observe the changes of neuronal morphology in hippocampal CA1 region and memory function in newborn rats with hypoxic-ischemic encephalopathy(HIE) from ischemia 6 hours to adult. DESIGN: Completely randomized grouping, controlled experiment. SETTING: Taian Health Center for Women and Children; Taishan Medical College. MATERIALS: Altogether 120 seven-day-old Wistar rats, of clean grade, were provided by the Experimental Animal Center, Shandong University of Traditional Chinese Medicine. Synaptophysin (SYN) polyclonal antibody was provided by Maixin Biological Company, Fuzhou. METHODS: This experiment was carried out in the Laboratory of Morphology, Taishan Medical College between October 2000 and December 2003. ① The newborn rats were randomly divided into 2 groups: model group and control group, 60 rats in each group. Five rats were chosen from each group at postoperative 6 hours, 24 hours, 72 hours, 7 days, 2 weeks and 3 weeks separately for immunohistochemical staining. Fifteen newborn rats were chosen from each group at postoperative 4 weeks and 2 months separately for testing memory ability (After test, 5 rats from each group were sacrificed and used for immunohistochemical staining)② The right common carotid artery of newborn rats of model group was ligated under the anesthetized status. After two hours of incubation, the rats were placed for 2 hours in a container filled with nitrogen oxygen atmosphere containing 0.08 volume fraction of oxygen, thus, HIE models were created; As for the newborn rats in the control group, only blood vessels were isolated, and they were not ligated and hypoxia-treated. ③ Thalamencephal tissue sections of newborn rats of two groups were performed DAB developing and haematoxylin slight staining. Cells with normal nucleous in 250 μm-long granular layer which started from hippocampal CA1 region were counted with image analysis system under high-fold optical microscope (×600), and the thickness of granular layer was measured. The absorbance (A) of positive reactant of SYN in immunohistochemically-stained CA1 region was measured. Learning and memory ability were measured with step through test 3 times successively. ④ t test and paired t test were used for comparing intergroup and intragroup difference of measurement data respectively, and Chi-square for comparing the difference of enumeration data. MAIN OUTCOME MEASURES: Comparison of cytological changes in hippocampal CA1 region and memory ability at different postoperative time points between two groups. RESULTS: Totally 120 newborn rats were involved in the result analysis. ① Cell morphological changes in hippocampal CA1 region: In the control group, with aging, perikaryon, nucleus and nucleolus in cortex of parietal lobe were significantly increased, Nissl body was compacted, the amount of neurons was declined, but the A of SYN positive reactant was relatively increased. In the model group, at postoperative each time point, neurons were seriously shrunk and dark-stained, nucleus was contracted, chromatin was condensed, nucleolus was unclear, even cells disappeared, especially the cells in 6 hours and 24 hours groups. The amount of neurons with normal morphology in hippocampal CA1 region and granular layer thickness in the model group at postoperative each time point were significantly less or smaller than those in the control group at postoperative 6 hours respectively (t =3.002-1.254, P < 0.01). The A value of SYN positive reactant at postoperative 2, 3 and 4 weeks was significantly higher than that at previous time point (t =2.011-2.716,P < 0.05-0.01). ② Test results of learning and memory ability: In the first test, there was no significant difference in the ratio of rats which kept memory ability between two groups (P > 0.05); In the third test, the ratio of rats which kept memory ability in the model group was significantly lower than that in the control group at postoperative 4 weeks and 2 months[53%(8/15),100%(15/15);60%(9/15),93%(14/15),χ 2=2.863,2.901,P < 0.01]. CONCLUSION: The destroyed hippocampal structure induces the decrease of learning and memory ability of developmental rats. Early interference can increase the quality of neurons and also promote functional development of the nervous system.展开更多
Nanoparticles are widely observed in the natural shear zone and experimental slip faults, which can lubricate the fault and significantly reduce the friction coefficient during seismic slip. But it is still not clear ...Nanoparticles are widely observed in the natural shear zone and experimental slip faults, which can lubricate the fault and significantly reduce the friction coefficient during seismic slip. But it is still not clear how the nanoparticles develop during the process of sliding. Clarifying the development stage of nanoparticles in a fault zone is critical to understanding the formation mechanisms of nanoparticles and the mechanism of fault weakening from a nanoperspective. In this study, four types of nanoparticles were found in the Indosinian Xiaomei shear zone, including spherical nanoparticles, rod-like nanograins and their aggregations. Ultramicroscopic analyses indicate that polished patches are highly smooth and composed of tightly packed spherical nanoparticles and well orientated rod-like nanograins during slip at high velocities. Meanwhile, the dome nanoparticles were formed by the calcite thermal decomposition due to frictional heat during highspeed sliding. The polygonal grooves are possibly related to high temperature(>900℃) grain boundary sliding deformation mechanisms. However, the porous and rough surfaces are accompanied by a series of holes and parallel "scratches" during a subsequent low-velocity stage. To ascertain the chemical composition of these nanoparticles, the energy dispersive spectrometer(EDS) test were conducted. The results suggest that materials rich in Fe, MgO and wollastonite are likely to form the rod-like nanograins, while materials rich in SiO2 are likely to form the spherical nanoparticles.展开更多
The Yemaomian landslide,the largest near-dam accumulation landslide in the Three Gorges Reservoir area,is situated 17 km upstream of the Three Gorges Dam.Nearly 20 years of monitoring data indicate that the landslide ...The Yemaomian landslide,the largest near-dam accumulation landslide in the Three Gorges Reservoir area,is situated 17 km upstream of the Three Gorges Dam.Nearly 20 years of monitoring data indicate that the landslide has been undergoing slow deformation with a low deformation rate and magnitude.This paper applies a stepwise linear regression method and a mechanical model of hydrodynamics triggering to deeply explore the relationship between geological conditions,external factors,and deformation characteristics.Based on the stage transition characteristics of external triggering factors,the deformation evolution process of the landslide since the reservoir impoundment is divided into three stages:(1)June 2003-September 2006,the landslide was reactivated by the significant rise in reservoir water levels,in a retrogressive mode;(2)October 2006-September 2018,the deformation mode shifted from retrogressive mode to creep deformation as a whole,primarily due to the degradation effect on the landslide mass caused by immersion in reservoir water.(3)October 2018-February 2024,a further significant reduction in the overall deformation rate and the impact of seasonal rainfall on landslide deformation surpassed that of reservoir water level fluctuations.The main component of landslide deformation is convergent creep,and extreme rainfall will be an important triggering factor for the local instability.Identifying the deformation evolution stages and determining the dominant external influencing factors at each stage is crucial for landslide research,and this paper provides an effective research paradigm for this purpose.展开更多
The early life stages of marine organisms are pivotal in shaping community dynamics and resource availability.In this study,we focused on Portunus trituberculatus,a crustacean integral to China's fisheries economy...The early life stages of marine organisms are pivotal in shaping community dynamics and resource availability.In this study,we focused on Portunus trituberculatus,a crustacean integral to China's fisheries economy,and examined the effect of sea surface temperature(SST)in its critical early life stages on subsequent yields.To analyze the correlation between SST in different larval stages and the corresponding yield of P.trituberculatus,we simulated the transport and distribution of larvae from 2014 to 2022 by employing circulation models and Lagrangian particle tracking experiments(LPTE).In the five years(2014,2015,2016,2019,and 2020),particles were transported in a northwestern direction and moved in the direction of low SST.The distribution of particles in the megalopa stage(M stage)were located in the region of the lower temperature.In 2017,2018,and 2021,the particles were transported in a northeastern direction but they did not move with the gradient of low SST in these years,and the particles in the last M stage were located in the region where the SST was at the peak of the time period.In 2022,the distribution was observed for most of the particles in the southwestern part of Zhejiang coast,a small part of them were transported in the northwestern direction and a small amount of particles was distributed offshore along the northern area of the Zhejiang coast.The correlations between the SST at each stage of larvae with the corresponding year's yield showed that the yield of P.trituberculatus decreased significantly(R=-0.772,P=0.015)with increasing SST at the M stage.This study preliminarily explains the correlation between SST at the larval stage and the yield of P.trituberculatus and provides essential information for scientific stock enhancement in the future.展开更多
Land plants in natural soil form intimate relationships with the diverse root bacterial microbiota. A growing body of evidence shows that these microbes are important for plant growth and health. Root microbiota compo...Land plants in natural soil form intimate relationships with the diverse root bacterial microbiota. A growing body of evidence shows that these microbes are important for plant growth and health. Root microbiota composition has been widely studied in several model plants and crops; however, little is known about how root microbiota vary throughout the plant's life cycle under field conditions. We performed longitudinal dense sampling in field trials to track the time-series shift of the root microbiota from two representative rice cultivars in two separate locations in China. We found that the rice root microbiota varied dramatically during the vegetative stages and stabilized from the beginning of the reproductive stage, after which the root microbiota underwent relatively minor changes until rice ripening. Notably, both rice genotype and geographical location influenced the patterns of root microbiota shift that occurred during plant growth. The relative abundance of Deltaproteobacteria in roots significantly increased overtime throughout the entire life cycle of rice, while that of Betaproteobacteria, Firmicutes, and Gammaproteobacteria decreased. By a machine learning approach, we identified biomarker taxa and established a model to correlate root microbiota with rice resident time in the field(e.g., Nitrospira accumulated from 5 weeks/tillering in field-grown rice). Our work provides insights into the process of rice root microbiota establishment.展开更多
Heracleum dissectum Ledeb.(HD)with high edible and medicinal values is distributed in Northeast Asia.To provide a reference for selecting appropriate parts and periods to harvest HD,the nutrient contents in different ...Heracleum dissectum Ledeb.(HD)with high edible and medicinal values is distributed in Northeast Asia.To provide a reference for selecting appropriate parts and periods to harvest HD,the nutrient contents in different parts of HD at three growth stages were determined.The nutrients being determined are essential nutrients closely related to human needs,and the crude protein content of HD was 3.58‒28.43 g•100 g^(-1)DW(dry weight),sugar content was 2.33‒30.92 g•100 g^(-1)DW,and soluble dietary fiber content was 9.71‒26.09 g•100 g^(-1)DW.Crude protein was mainly distributed in leaf blades and inflorescences,sugar was primarily found in roots,and dietary fiber was predominantly located in leaves.From the leaf development stage to the flowering stage and then to the late seed harvest stage,the content of moisture,crude protein and soluble sugar first decreased and then increased.In contrast,the content of dietary fiber and crude fat first increased and then decreased.展开更多
As important mechanisms of regional strategy and policy, prefecture-level regions have played an increasingly significant role in the development of China＇s economy. However, little research has grasped the essence o...As important mechanisms of regional strategy and policy, prefecture-level regions have played an increasingly significant role in the development of China＇s economy. However, little research has grasped the essence of the economic development stage and the spatio-temporal evolution process at the prefecture level; this may lead to biased policies and their ineffective implementations. Based on Chenery＇s economic development theory, this paper identifies China＇s economic development stages at both national and prefectural levels. Both the Global Moran I index and the Getis-Ord Gi＊ index are employed to investigate the spatio-temporal evolution of China＇s economic development from 1990 to 2010. Major conclusions can be drawn as follows. （1） China＇s economic development is generally in the state of agglomeration. It entered the Primary Production Stage in 1990, and the Middle Industrialized Stage in 2010, with a ＇balanced-unbalanced-gradually rebalanced＇ pattern in the process. （2） China＇s rapid economic growth experienced a spatial shift from the coastal areas to the the inland areas. Most advanced cities in mid-western China can be roughly categorized into regional hub cities and resource-dependent cities. （3） Hot spots in China＇s economy moved northward and westward. The interactions between cities and prefectures became weaker in Eastern China, while cities and prefectures in Central and Western China were still at the stage of individual development, with limited effect on the surrounding cities. （4） While the overall growth rate of China＇s economy has gradually slowed down during the past two decades, the growth rate of cities and prefectures in Central and Western China was much faster than those in coastal areas. （5） Areas rich in resources, such as Xinjiang and Inner Mongolia, have become the new hot spots of economic growth in recent years. For these regions, however, more attention needs to be paid to their unbalanced industrial structures and the lagging social development against the backdrop of the rapid economic growth, driven predominantly by the exploitation of resources.展开更多
Threshold is a limit and marginal point when a qualitative change takes place. Since threshold principle was firstly used in landform research by S.A.Schumm in the 1970s, the quantitative research on watershed landfor...Threshold is a limit and marginal point when a qualitative change takes place. Since threshold principle was firstly used in landform research by S.A.Schumm in the 1970s, the quantitative research on watershed landform development stage has come true. Davis proposed a three-stage model on landform evolution: young, mature and old stages. Thereafter Strahler quantified this model by hypsometric analysis method. The authors thought that the material movement stage cannot be expressed by hypsometric method in watershed landform at development stage, because of the uncertainty on stage delimitation. To meet this shortcoming, this paper presents an integral erosion value method. A clear delimitation on landform development stage in the Loess Plateau region has been tested by this method. The result shows that gullied loessial hilly area is at the mature stage, and gullied loessial tableland area is at the young stage. It is estimated that from the point of erosion related sediment yield, natural erosion accounts for 70% of the total erosion amount, and artificial accelerating erosion is 30%. Therefore soil and water conservation is very crucial for the Loess Plateau.展开更多
The continuous growth of recoverable reserves in a waterflooding oilfield has a significant impact on the patterns of production evolution. A new production evolution model is established by improving the Weng Cycle m...The continuous growth of recoverable reserves in a waterflooding oilfield has a significant impact on the patterns of production evolution. A new production evolution model is established by improving the Weng Cycle model. With the new model, the statistical correspondence between the production decline stage and the reserve-production imbalance is clarified,and the correlation of water cut with the recovery percent of recoverable reserves is discussed, providing quantitative basis of reservoir engineering for dividing development stages of oilfield and defining mature oilfields. According to the statistics of oilfields in eastern China, the time point corresponding to the reserve-production balance coefficient dropping to less than 1dramatically is well correlated the beginning point of production decline, thus the time when the reserve-production balance coefficient drops dramatically can be taken as the initiation point of production decline stage. The research results show that the water cut and the recovery percent of recoverable reserves have a good statistical match in the high water cut stage, and it is more rational to take both the start point of production decline stage and the water cut of 90%(or the recovery percent of recoverable reserves of 80%) as the critical criteria for defining a mature oilfield. Five production evolution patterns can be summarized as follows: growth–peak plateau–stepped decline, growth–stepped stabilizing–stepped decline, growth–stepped stabilizing–rapid decline, growth–peak plateau–rapid decline, and growth–continuous decline.展开更多
There is a growing concern over the presence of high concentrations of nitrate in orally consumed herbal remedies. Since nitrate accumulation in the plant body can vary with spatial location in plant and plant develop...There is a growing concern over the presence of high concentrations of nitrate in orally consumed herbal remedies. Since nitrate accumulation in the plant body can vary with spatial location in plant and plant development and temporally with photoperiod, understanding the relations between these factors and nitrate contents in the consumed herbs are vital for the development of agrotechnical strategies for nitrate avoidance. Therefore, the distribution profiles of nitrate content and nitrate reductase （NR） activity were analyzed in 14 accessions of Andrographis paniculata （Burm.f.） Wall. ex Nees., a medicinal plant widely used as a component of many herbal teas and medicinal infusions. Significant variation in nitrate accumulation in the plant was observed between the accessions, and most contained nitrate levels beyond the safety limit recommended according to the European Commission＇s Scientific Committee on Food. Nitrate content increased with plant development and leaf age, and that in leaf segment was higher in the middle of the leaf than at its tip or base; the nitrate concentration in plant organ followed the order of petiole 〉 leaf 〉 stem, and it was lower at mid-day than in the early morning or evening. Gradients of NR activity were negatively correlated with nitrate content in all studied temporal and spatial profiles. Identification of the characteristic spatial and developmental profiles of nitrate accumulation and NR activity in A. paniculata can guide the development of harvest strategies, aiming at minimizing nitrate contents in the consumed herbal tissue.展开更多
Agriculture is a basic industry related to national economy and people’s livelihood,and is also the cornerstone of national economic development. European Union(EU) is the second largest exporter of agricultural prod...Agriculture is a basic industry related to national economy and people’s livelihood,and is also the cornerstone of national economic development. European Union(EU) is the second largest exporter of agricultural products in the world,and its agricultural production change has international influence. In this paper,starting from two angles of EU agricultural development scale and target,development stage of its agricultural production is explored,and development and evolution causes of EU agriculture are analyzed: efficiency and benefit targets cause change of EU agricultural management model; change of agricultural product supply-demand pattern leads the evolution of EU agricultural development idea; the reflection of agricultural development target impels the transformation of EU agricultural development. On this basis,the below conclusions are obtained: agricultural development could evolve according to the changes of economic and social conditions; it is a necessary requirement of promoting internal market stability and international market harmony to actively use agricultural support policies adapting to agricultural development at each stage; it is an important measurement of impelling agricultural modernization process to promote innovation of agricultural management model and development of market integration; it is an inevitable road of realizing sustainable development of agriculture to develop ecological agriculture and emphasize equal development of agriculture and countryside. On this basis,it could provide the reference for agricultural development of China based on EU agricultural development experience.展开更多
This paper constructs the index system of the regional division of the development stage of China's wind power resources,including the index of energy,the index of wind energy endowments and other indices.Based on...This paper constructs the index system of the regional division of the development stage of China's wind power resources,including the index of energy,the index of wind energy endowments and other indices.Based on principal component analysis and layered clustering analysis of these indices,and combined with the conceptual function of the development and utilization stage of the wind power,this paper divides the development and utilization stage of the wind power into four stages taking province as the basic yardstick:optimization growth stage,the rapid growth stage,the slow growth stage and the initial growth stage.In addition,this paper briefly discusses the basic strategy that should be adopted in each development stage of wind power resources.展开更多
China has basically succeeded in its quantitative catch-up with advanced economies and has now entered into a new stage of economic development focused on the greater efficiency of resource allocation. In order to ach...China has basically succeeded in its quantitative catch-up with advanced economies and has now entered into a new stage of economic development focused on the greater efficiency of resource allocation. In order to achieve the objectives of the 13th Five-Year Plan for National Economic and Social Development, efforts must be made to reform the ＂petty-farmer＂ economic mode of production while promoting specialization, modernization, and economies of scale. The restructuring and upgrade of the manufacturing sector should be focused on existing industries and the development of high-end industries while maintaining China＇s comparative advantage in narrowing technology gaps with advanced economies. The goal should be to transform China from a large industrial manufacturer into a competitive one. Technological innovation should be based on demand, supported by projects, carried out by firms through the social division of labor, and work to increase the capacity of la^e enterprises to integrate the results of innovation. Materialized labor consumption and logistical costs must be reduced, and the quality and level of urbanization must be increased. To assist productivity development, urban citizenship should be granted to rural migrant workers. In addition, the urbanization of those who remain in the countryside should be promoted in order for rural populations to enjoy the benefits of industrially robust, technologically modern and ecologically sound civilization.展开更多
基金supported by the Natural Science Foundation Project of Inner Mongolia Autonomous Region(2024LHMS03017)Research Capacity Enhancement“Unveiling and Leading”Project of Inner Mongolia Forestry Science Research Institute(2024NLTS03).
文摘The rhizosphere bacteria play crucial roles in plant health and growth as they are involved in assimilating nutrients and resisting adverse conditions such as nutrient stress,drought,and wind erosion.Agriophyllum squarrosum(L.)Moq.is a pioneer plant used in sand fixation due to its strong resistance to drought and wind erosion.However,the bacterial community characteristics and ecological function in the rhizosphere of A.squarrosum are poorly understood.In this study,soil samples were collected from different developmental stages(seedling stage,vegetative stage,reproductive stage,and withering stage)of A.squarrosum.Illumina Miseq sequencing was used to detect differences in soil bacterial abundance.The Phylogenetic Investigation of Communities by Reconstruction of Unobserved States(PICRUSt)program was used to predict bacterial functions,and the relationships among bacteria,functional populations,and soil nutrients were examined using a heatmap analysis.The results showed that the Shannon and Sobs indices of rhizosphere bacteria were significantly higher during the reproductive stage than during the other stages.Pantoea sp.(7.03%)was the dominant genus during the seedling stage;Arthrobacter sp.was the dominant genus during the vegetative(13.94%),reproductive(7.57%),and withering(12.30%)stages.The relative abundances of Chloroflexi,Acidobacteria,and Gemmatimonadetes were significantly high during the reproductive stage.According to the PICRUSt analysis,membrane transport,signal transduction,and environmental adaptation of the bacterial functional population occurred during the seedling stage.Carbohydrate metabolism increased during the vegetative stage,while energy metabolism,lipid metabolism,and biosynthesis of other secondary metabolites of the bacterial functional population significantly increased during the reproductive stage.The abundances of bacterial communities,functional genes,and soil nutrients were synergistically altered during various developmental stages.Our findings suggest that the developmental stages of A.squarrosum play a significant role in defining the composition and structure of bacterial communities in the rhizosphere.The results will provide a basis for better prediction and understanding of soil bacterial metabolic potential and functions of A.squarrosum rhizosphere in sandy areas.
基金supported by the National Natural Science Foundation of China(31790410,32160781)。
文摘The gastrointestinal tract is essential for food digestion,nutrient absorption,waste elimination,and microbial defense.Single-cell transcriptome profiling of the intestinal tract has greatly enriched our understanding of cellular diversity,functional heterogeneity,and their importance in intestinal tract development and disease.Although such profiling has been extensively conducted in humans and mice,the single-cell gene expression landscape of the pig cecum remains unexplored.Here,single-cell RNA sequencing was performed on 45572 cells obtained from seven cecal samples in pigs at four different developmental stages(days(D)30,42,150,and 730).Analysis revealed 12 major cell types and 38 subtypes,as well as their distinctive genes,transcription factors,and regulons,many of which were conserved in humans.An increase in the relative proportions of CD8^(+)T and Granzyme A(low expression)natural killer T cells(GZMA^(low)NKT)cells and a decrease in the relative proportions of epithelial stem cells,Tregs,RHEX^(+)T cells,and plasmacytoid dendritic cells(pDCs)were noted across the developmental stages.Moreover,the post-weaning period exhibited an up-regulation in mitochondrial genes,COX2 and ND2,as well as genes involved in immune activation in multiple cell types.Cell-cell crosstalk analysis indicated that IBP6^(+)fibroblasts were the main signal senders at D30,whereas IBP6^(−)fibroblasts assumed this role at the other stages.NKT cells established interactions with epithelial cells and IBP6^(+)fibroblasts in the D730 cecum through mediation of GZMA-F2RL1/F2RL2 pairs.This study provides valuable insights into cellular heterogeneity and function in the pig cecum at different development stages.
基金supported by the Key-Area Research and Development Program of Guangdong Province (2019B020214005)Agricultural Research Project and Agricultural Technology Promotion Project of Guangdong (2021KJ383)。
文摘Spike development directly affects the yield and quality of rice. We describe an algorithm for automatically identifying multiple developmental stages of rice spikes(AI-MDSRS) that transforms the automatic identification of multiple developmental stages of rice spikes into the detection of rice spikes of diverse maturity levels. The scales vary greatly in different growth and development stages because rice spikes are dense and small, posing challenges for their effective and accurate detection. We describe a rice spike detection model based on an improved faster regions with convolutional neural network(Faster R-CNN).The model incorporates the following optimization strategies: first, Inception_Res Net-v2 replaces VGG16 as a feature extraction network;second, a feature pyramid network(FPN) replaces single-scale feature maps to fuse with region proposal network(RPN);third, region of interest(Ro I) alignment replaces Ro I pooling, and distance-intersection over union(DIo U) is used as a standard for non-maximum suppression(NMS). The performance of the proposed model was compared with that of the original Faster R-CNN and YOLOv4 models. The mean average precision(m AP) of the rice spike detection model was92.47%, a substantial improvement on the original Faster R-CNN model(with 40.96% m AP) and 3.4%higher than that of the YOLOv4 model, experimentally indicating that the model is more accurate and reliable. The identification results of the model for the heading–flowering, milky maturity, and full maturity stages were within two days of the results of manual observation, fully meeting the needs of agricultural activities.
基金supported by the National Natural Science Foundation of China (41571011,41330746)
文摘Although scientists have performed many studies on crescent （barchan） dunes in the Taklimakan Desert,few studies reported the changes in grain size at different development stages of crescent dunes.In order to evaluate the changing trends of surface sediment grain size with dune development,we investigated the grain size characteristics at four developmental stages （oval sand pile,shield dune,incipient crescent dune and mature crescent dune） of crescent dunes by measuring the morphology of sand dune and observing the near-surface wind regime.The dunes have developed in a wide inter-dune corridor between high compound longitudinal ridges in China＇s Taklimakan Desert.The surface sediments at four developmental stages of the crescent dunes were primarily composed of fine sands,followed by very fine and medium sands.Mean grain sizes ranged from 2.8 to 3.1 φ,with a unimodal distribution.The sands were moderately well-sorted,their distribution varied from platykurtic to very platykurtic,and symmetrical or skewed towards the fine particles.From oval sand piles through shield and incipient crescent dunes to mature crescent dunes,incipient grain size gradually increased,particles became finer,sorting became better,kurtosis and skewness increased.Grain sizes on the surface layer became coarser upwards from the toe of the windward slope and then became finer towards the bottom of the leeward slope.We found that the coarsest particles at different positions at the four developmental stages were different.The coarsest particles were distributed at the top of the oval sand piles and shield dunes,versus at the middle of the windward slope of the incipient and mature crescent dunes.Correlations between the mean grain size and other grain size parameters showed that as mean grain size became finer,sorting became better and kurtosis became wider,but skewness changed only slightly.In addition,grain size variation in the surface sediments correlated with the movement speed of the dunes in the study area.In the open ground among tall-complex longitudinal ridges in the hinterland of the Taklimakan Desert where aeolian environment is characterized by comparatively strong wind and unsaturated sand flow,faster dune movement corresponded to coarser grain size.
文摘The purpose of this article is twofold.First,it explores the order of the development of nominal and verbal gender of Amharic,which is one of the Ethio-Semitic languages.Second,it provides empirical evidence for the typological plausibility of processability theory(PT).In fact,PT has been tested in typologically different languages(e.g.,English,Italian,and Japan);however,it does not have any validation from Ethiopian languages in general and Ethio-Semitic languages in particular yet.Relevant data was collected from sixteen respondents via picture description tasks,short storytelling,interviews,story re-telling,and spot the difference tasks.Distributional analysis was conducted for the analysis,and the point of emergence of target structures was determined using the emergence criteria.Accordingly,the result shows that the development of gender assignment is compatible with processability theory’s predictions in that lexical procedure precedes phrasal procedure,which is followed by S-procedure.Moreover,the masculine gender emerged earlier than its feminine counterpart at all developmental stages.However,subject agreement markers in pro-drop context emerged at stage two preceding subject verb agreement.This finding is against processability theory’s claim that suggests subject agreement markers only emerge at stage four of the processability hierarchy disregarding their stages of development in pro-drop context in particular.
文摘The photosynthetic activities between two main developmental stages, colony and hormogonium, of the edible cyanobacterium Nostoc sphaeroides Kutzing, were compared. Hormogonia have a higher content of chlorophyll than that of colonies. It showed that the ratios of phycocyain （PC）, allophycocyain （APC） and phycoerythrocyanin （PEC） in hormogonia and colonies were different. The room temperature chlorophyll fluorescence, 77 K chlorophyll fluorescence, measurements of PSⅠand PS Ⅱ activities all showed that colony has higher photosynthetic competence than hormogonia. Hormogonia had a higher respiration rate than colony, while their maximum photosynthetic oxygen evolution rates were very close. The responses of hormogonia and colonies to high light illuminations also were different. Both of their oxygen evolution rates decreased quickly with the prolonged high light illumination, but hormogonia can keep relatively higher PSⅡ activity （Fv/Fm） than that of colonies. The results suggested that colony was photosynthetically more competent than hormogonia, while the ability of hormogonia to tolerate high light illumination was higher than that of colony.
基金the Grant from Family Planning Commission of Shandong Province,No.97-15
文摘BACKGROUND: Under the normal circumstance, there exist some synapses with inactive functions in central nervous system (CNS), but these functions are activated following nerve injury. At the early stage of brain injury, the abnormal functions of brain are varied, and they have very strong plasticity and are corrected easily. OBJECTIVE: To observe the changes of neuronal morphology in hippocampal CA1 region and memory function in newborn rats with hypoxic-ischemic encephalopathy(HIE) from ischemia 6 hours to adult. DESIGN: Completely randomized grouping, controlled experiment. SETTING: Taian Health Center for Women and Children; Taishan Medical College. MATERIALS: Altogether 120 seven-day-old Wistar rats, of clean grade, were provided by the Experimental Animal Center, Shandong University of Traditional Chinese Medicine. Synaptophysin (SYN) polyclonal antibody was provided by Maixin Biological Company, Fuzhou. METHODS: This experiment was carried out in the Laboratory of Morphology, Taishan Medical College between October 2000 and December 2003. ① The newborn rats were randomly divided into 2 groups: model group and control group, 60 rats in each group. Five rats were chosen from each group at postoperative 6 hours, 24 hours, 72 hours, 7 days, 2 weeks and 3 weeks separately for immunohistochemical staining. Fifteen newborn rats were chosen from each group at postoperative 4 weeks and 2 months separately for testing memory ability (After test, 5 rats from each group were sacrificed and used for immunohistochemical staining)② The right common carotid artery of newborn rats of model group was ligated under the anesthetized status. After two hours of incubation, the rats were placed for 2 hours in a container filled with nitrogen oxygen atmosphere containing 0.08 volume fraction of oxygen, thus, HIE models were created; As for the newborn rats in the control group, only blood vessels were isolated, and they were not ligated and hypoxia-treated. ③ Thalamencephal tissue sections of newborn rats of two groups were performed DAB developing and haematoxylin slight staining. Cells with normal nucleous in 250 μm-long granular layer which started from hippocampal CA1 region were counted with image analysis system under high-fold optical microscope (×600), and the thickness of granular layer was measured. The absorbance (A) of positive reactant of SYN in immunohistochemically-stained CA1 region was measured. Learning and memory ability were measured with step through test 3 times successively. ④ t test and paired t test were used for comparing intergroup and intragroup difference of measurement data respectively, and Chi-square for comparing the difference of enumeration data. MAIN OUTCOME MEASURES: Comparison of cytological changes in hippocampal CA1 region and memory ability at different postoperative time points between two groups. RESULTS: Totally 120 newborn rats were involved in the result analysis. ① Cell morphological changes in hippocampal CA1 region: In the control group, with aging, perikaryon, nucleus and nucleolus in cortex of parietal lobe were significantly increased, Nissl body was compacted, the amount of neurons was declined, but the A of SYN positive reactant was relatively increased. In the model group, at postoperative each time point, neurons were seriously shrunk and dark-stained, nucleus was contracted, chromatin was condensed, nucleolus was unclear, even cells disappeared, especially the cells in 6 hours and 24 hours groups. The amount of neurons with normal morphology in hippocampal CA1 region and granular layer thickness in the model group at postoperative each time point were significantly less or smaller than those in the control group at postoperative 6 hours respectively (t =3.002-1.254, P < 0.01). The A value of SYN positive reactant at postoperative 2, 3 and 4 weeks was significantly higher than that at previous time point (t =2.011-2.716,P < 0.05-0.01). ② Test results of learning and memory ability: In the first test, there was no significant difference in the ratio of rats which kept memory ability between two groups (P > 0.05); In the third test, the ratio of rats which kept memory ability in the model group was significantly lower than that in the control group at postoperative 4 weeks and 2 months[53%(8/15),100%(15/15);60%(9/15),93%(14/15),χ 2=2.863,2.901,P < 0.01]. CONCLUSION: The destroyed hippocampal structure induces the decrease of learning and memory ability of developmental rats. Early interference can increase the quality of neurons and also promote functional development of the nervous system.
基金the National Natural Science Foundation of China(Nos.41776072,41676048,U1701641,91328205)。
文摘Nanoparticles are widely observed in the natural shear zone and experimental slip faults, which can lubricate the fault and significantly reduce the friction coefficient during seismic slip. But it is still not clear how the nanoparticles develop during the process of sliding. Clarifying the development stage of nanoparticles in a fault zone is critical to understanding the formation mechanisms of nanoparticles and the mechanism of fault weakening from a nanoperspective. In this study, four types of nanoparticles were found in the Indosinian Xiaomei shear zone, including spherical nanoparticles, rod-like nanograins and their aggregations. Ultramicroscopic analyses indicate that polished patches are highly smooth and composed of tightly packed spherical nanoparticles and well orientated rod-like nanograins during slip at high velocities. Meanwhile, the dome nanoparticles were formed by the calcite thermal decomposition due to frictional heat during highspeed sliding. The polygonal grooves are possibly related to high temperature(>900℃) grain boundary sliding deformation mechanisms. However, the porous and rough surfaces are accompanied by a series of holes and parallel "scratches" during a subsequent low-velocity stage. To ascertain the chemical composition of these nanoparticles, the energy dispersive spectrometer(EDS) test were conducted. The results suggest that materials rich in Fe, MgO and wollastonite are likely to form the rod-like nanograins, while materials rich in SiO2 are likely to form the spherical nanoparticles.
基金supported by the National Natural Science Foundation of China(Nos.U2340226,12072047,42277186)China Three Gorges Corporation under the contract of No.0799291(SXSN/5115)the Fundamental Research Funds for Central Public Welfare Research Institutes(CKSF20241014/YT,CKSF20241016/YT).
文摘The Yemaomian landslide,the largest near-dam accumulation landslide in the Three Gorges Reservoir area,is situated 17 km upstream of the Three Gorges Dam.Nearly 20 years of monitoring data indicate that the landslide has been undergoing slow deformation with a low deformation rate and magnitude.This paper applies a stepwise linear regression method and a mechanical model of hydrodynamics triggering to deeply explore the relationship between geological conditions,external factors,and deformation characteristics.Based on the stage transition characteristics of external triggering factors,the deformation evolution process of the landslide since the reservoir impoundment is divided into three stages:(1)June 2003-September 2006,the landslide was reactivated by the significant rise in reservoir water levels,in a retrogressive mode;(2)October 2006-September 2018,the deformation mode shifted from retrogressive mode to creep deformation as a whole,primarily due to the degradation effect on the landslide mass caused by immersion in reservoir water.(3)October 2018-February 2024,a further significant reduction in the overall deformation rate and the impact of seasonal rainfall on landslide deformation surpassed that of reservoir water level fluctuations.The main component of landslide deformation is convergent creep,and extreme rainfall will be an important triggering factor for the local instability.Identifying the deformation evolution stages and determining the dominant external influencing factors at each stage is crucial for landslide research,and this paper provides an effective research paradigm for this purpose.
基金Supported by the National Key Research and Development Program of China(No.2019YFD0901304)the Public Welfare Technology Application Research Project of Zhejiang(No.LGN21C190009)the Science and Technology Project of Zhoushan(No.2022C41003)。
文摘The early life stages of marine organisms are pivotal in shaping community dynamics and resource availability.In this study,we focused on Portunus trituberculatus,a crustacean integral to China's fisheries economy,and examined the effect of sea surface temperature(SST)in its critical early life stages on subsequent yields.To analyze the correlation between SST in different larval stages and the corresponding yield of P.trituberculatus,we simulated the transport and distribution of larvae from 2014 to 2022 by employing circulation models and Lagrangian particle tracking experiments(LPTE).In the five years(2014,2015,2016,2019,and 2020),particles were transported in a northwestern direction and moved in the direction of low SST.The distribution of particles in the megalopa stage(M stage)were located in the region of the lower temperature.In 2017,2018,and 2021,the particles were transported in a northeastern direction but they did not move with the gradient of low SST in these years,and the particles in the last M stage were located in the region where the SST was at the peak of the time period.In 2022,the distribution was observed for most of the particles in the southwestern part of Zhejiang coast,a small part of them were transported in the northwestern direction and a small amount of particles was distributed offshore along the northern area of the Zhejiang coast.The correlations between the SST at each stage of larvae with the corresponding year's yield showed that the yield of P.trituberculatus decreased significantly(R=-0.772,P=0.015)with increasing SST at the M stage.This study preliminarily explains the correlation between SST at the larval stage and the yield of P.trituberculatus and provides essential information for scientific stock enhancement in the future.
基金supported by the“Strategic Priority Research Program”of the Chinese Academy of Sciences(XDB11020700)CPSF-CAS Joint Foundation for Excellent Postdoctoral Fellows(2016LH00012)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(QYZDB-SSW-SMC021)the National Natural Science Foundation of China(31772400)
文摘Land plants in natural soil form intimate relationships with the diverse root bacterial microbiota. A growing body of evidence shows that these microbes are important for plant growth and health. Root microbiota composition has been widely studied in several model plants and crops; however, little is known about how root microbiota vary throughout the plant's life cycle under field conditions. We performed longitudinal dense sampling in field trials to track the time-series shift of the root microbiota from two representative rice cultivars in two separate locations in China. We found that the rice root microbiota varied dramatically during the vegetative stages and stabilized from the beginning of the reproductive stage, after which the root microbiota underwent relatively minor changes until rice ripening. Notably, both rice genotype and geographical location influenced the patterns of root microbiota shift that occurred during plant growth. The relative abundance of Deltaproteobacteria in roots significantly increased overtime throughout the entire life cycle of rice, while that of Betaproteobacteria, Firmicutes, and Gammaproteobacteria decreased. By a machine learning approach, we identified biomarker taxa and established a model to correlate root microbiota with rice resident time in the field(e.g., Nitrospira accumulated from 5 weeks/tillering in field-grown rice). Our work provides insights into the process of rice root microbiota establishment.
基金Supported by the Heilongjiang Provincial Natural Science Foundation of China(YQ2020C028)the Science and Technology Basic Resources Investigation Program of China(2019FY100503)+2 种基金the Science and Technology Development Project of Jilin Province(YDZJ202402007CXJD)the Key Special Project of the"Science and Technology Revitalization of Mongolia"Action(2022EEDSKJXM001)Shen-nong Talent Plan of the Ministry of Agriculture and Rural Affairs(SNYCQN138-2022)。
文摘Heracleum dissectum Ledeb.(HD)with high edible and medicinal values is distributed in Northeast Asia.To provide a reference for selecting appropriate parts and periods to harvest HD,the nutrient contents in different parts of HD at three growth stages were determined.The nutrients being determined are essential nutrients closely related to human needs,and the crude protein content of HD was 3.58‒28.43 g•100 g^(-1)DW(dry weight),sugar content was 2.33‒30.92 g•100 g^(-1)DW,and soluble dietary fiber content was 9.71‒26.09 g•100 g^(-1)DW.Crude protein was mainly distributed in leaf blades and inflorescences,sugar was primarily found in roots,and dietary fiber was predominantly located in leaves.From the leaf development stage to the flowering stage and then to the late seed harvest stage,the content of moisture,crude protein and soluble sugar first decreased and then increased.In contrast,the content of dietary fiber and crude fat first increased and then decreased.
基金National Natural Science Foundation of China, No.41171107
文摘As important mechanisms of regional strategy and policy, prefecture-level regions have played an increasingly significant role in the development of China＇s economy. However, little research has grasped the essence of the economic development stage and the spatio-temporal evolution process at the prefecture level; this may lead to biased policies and their ineffective implementations. Based on Chenery＇s economic development theory, this paper identifies China＇s economic development stages at both national and prefectural levels. Both the Global Moran I index and the Getis-Ord Gi＊ index are employed to investigate the spatio-temporal evolution of China＇s economic development from 1990 to 2010. Major conclusions can be drawn as follows. （1） China＇s economic development is generally in the state of agglomeration. It entered the Primary Production Stage in 1990, and the Middle Industrialized Stage in 2010, with a ＇balanced-unbalanced-gradually rebalanced＇ pattern in the process. （2） China＇s rapid economic growth experienced a spatial shift from the coastal areas to the the inland areas. Most advanced cities in mid-western China can be roughly categorized into regional hub cities and resource-dependent cities. （3） Hot spots in China＇s economy moved northward and westward. The interactions between cities and prefectures became weaker in Eastern China, while cities and prefectures in Central and Western China were still at the stage of individual development, with limited effect on the surrounding cities. （4） While the overall growth rate of China＇s economy has gradually slowed down during the past two decades, the growth rate of cities and prefectures in Central and Western China was much faster than those in coastal areas. （5） Areas rich in resources, such as Xinjiang and Inner Mongolia, have become the new hot spots of economic growth in recent years. For these regions, however, more attention needs to be paid to their unbalanced industrial structures and the lagging social development against the backdrop of the rapid economic growth, driven predominantly by the exploitation of resources.
文摘Threshold is a limit and marginal point when a qualitative change takes place. Since threshold principle was firstly used in landform research by S.A.Schumm in the 1970s, the quantitative research on watershed landform development stage has come true. Davis proposed a three-stage model on landform evolution: young, mature and old stages. Thereafter Strahler quantified this model by hypsometric analysis method. The authors thought that the material movement stage cannot be expressed by hypsometric method in watershed landform at development stage, because of the uncertainty on stage delimitation. To meet this shortcoming, this paper presents an integral erosion value method. A clear delimitation on landform development stage in the Loess Plateau region has been tested by this method. The result shows that gullied loessial hilly area is at the mature stage, and gullied loessial tableland area is at the young stage. It is estimated that from the point of erosion related sediment yield, natural erosion accounts for 70% of the total erosion amount, and artificial accelerating erosion is 30%. Therefore soil and water conservation is very crucial for the Loess Plateau.
基金Supported by the National Natural Science Foundation of China (72088101)。
文摘The continuous growth of recoverable reserves in a waterflooding oilfield has a significant impact on the patterns of production evolution. A new production evolution model is established by improving the Weng Cycle model. With the new model, the statistical correspondence between the production decline stage and the reserve-production imbalance is clarified,and the correlation of water cut with the recovery percent of recoverable reserves is discussed, providing quantitative basis of reservoir engineering for dividing development stages of oilfield and defining mature oilfields. According to the statistics of oilfields in eastern China, the time point corresponding to the reserve-production balance coefficient dropping to less than 1dramatically is well correlated the beginning point of production decline, thus the time when the reserve-production balance coefficient drops dramatically can be taken as the initiation point of production decline stage. The research results show that the water cut and the recovery percent of recoverable reserves have a good statistical match in the high water cut stage, and it is more rational to take both the start point of production decline stage and the water cut of 90%(or the recovery percent of recoverable reserves of 80%) as the critical criteria for defining a mature oilfield. Five production evolution patterns can be summarized as follows: growth–peak plateau–stepped decline, growth–stepped stabilizing–stepped decline, growth–stepped stabilizing–rapid decline, growth–peak plateau–rapid decline, and growth–continuous decline.
文摘There is a growing concern over the presence of high concentrations of nitrate in orally consumed herbal remedies. Since nitrate accumulation in the plant body can vary with spatial location in plant and plant development and temporally with photoperiod, understanding the relations between these factors and nitrate contents in the consumed herbs are vital for the development of agrotechnical strategies for nitrate avoidance. Therefore, the distribution profiles of nitrate content and nitrate reductase （NR） activity were analyzed in 14 accessions of Andrographis paniculata （Burm.f.） Wall. ex Nees., a medicinal plant widely used as a component of many herbal teas and medicinal infusions. Significant variation in nitrate accumulation in the plant was observed between the accessions, and most contained nitrate levels beyond the safety limit recommended according to the European Commission＇s Scientific Committee on Food. Nitrate content increased with plant development and leaf age, and that in leaf segment was higher in the middle of the leaf than at its tip or base; the nitrate concentration in plant organ followed the order of petiole 〉 leaf 〉 stem, and it was lower at mid-day than in the early morning or evening. Gradients of NR activity were negatively correlated with nitrate content in all studied temporal and spatial profiles. Identification of the characteristic spatial and developmental profiles of nitrate accumulation and NR activity in A. paniculata can guide the development of harvest strategies, aiming at minimizing nitrate contents in the consumed herbal tissue.
文摘Agriculture is a basic industry related to national economy and people’s livelihood,and is also the cornerstone of national economic development. European Union(EU) is the second largest exporter of agricultural products in the world,and its agricultural production change has international influence. In this paper,starting from two angles of EU agricultural development scale and target,development stage of its agricultural production is explored,and development and evolution causes of EU agriculture are analyzed: efficiency and benefit targets cause change of EU agricultural management model; change of agricultural product supply-demand pattern leads the evolution of EU agricultural development idea; the reflection of agricultural development target impels the transformation of EU agricultural development. On this basis,the below conclusions are obtained: agricultural development could evolve according to the changes of economic and social conditions; it is a necessary requirement of promoting internal market stability and international market harmony to actively use agricultural support policies adapting to agricultural development at each stage; it is an important measurement of impelling agricultural modernization process to promote innovation of agricultural management model and development of market integration; it is an inevitable road of realizing sustainable development of agriculture to develop ecological agriculture and emphasize equal development of agriculture and countryside. On this basis,it could provide the reference for agricultural development of China based on EU agricultural development experience.
基金National Basic Research and Development Program(973)(Grant no.2007CB210306)
文摘This paper constructs the index system of the regional division of the development stage of China's wind power resources,including the index of energy,the index of wind energy endowments and other indices.Based on principal component analysis and layered clustering analysis of these indices,and combined with the conceptual function of the development and utilization stage of the wind power,this paper divides the development and utilization stage of the wind power into four stages taking province as the basic yardstick:optimization growth stage,the rapid growth stage,the slow growth stage and the initial growth stage.In addition,this paper briefly discusses the basic strategy that should be adopted in each development stage of wind power resources.
文摘China has basically succeeded in its quantitative catch-up with advanced economies and has now entered into a new stage of economic development focused on the greater efficiency of resource allocation. In order to achieve the objectives of the 13th Five-Year Plan for National Economic and Social Development, efforts must be made to reform the ＂petty-farmer＂ economic mode of production while promoting specialization, modernization, and economies of scale. The restructuring and upgrade of the manufacturing sector should be focused on existing industries and the development of high-end industries while maintaining China＇s comparative advantage in narrowing technology gaps with advanced economies. The goal should be to transform China from a large industrial manufacturer into a competitive one. Technological innovation should be based on demand, supported by projects, carried out by firms through the social division of labor, and work to increase the capacity of la^e enterprises to integrate the results of innovation. Materialized labor consumption and logistical costs must be reduced, and the quality and level of urbanization must be increased. To assist productivity development, urban citizenship should be granted to rural migrant workers. In addition, the urbanization of those who remain in the countryside should be promoted in order for rural populations to enjoy the benefits of industrially robust, technologically modern and ecologically sound civilization.
