The North China Plain(NCP)frequently experiences ozone pollution events,which are generally related to cross-border transport at multiple scales.However,current methods of calculating ozone transport are insufficient ...The North China Plain(NCP)frequently experiences ozone pollution events,which are generally related to cross-border transport at multiple scales.However,current methods of calculating ozone transport are insufficient to account for ozone transport at different altitudes.To further understand the characteristics of ozone transport,we applied theWeather Research and Forecasting(WRF)model and the Comprehensive Air Quality Model with Extensions(CAMx)based on flux calculation method.The results showed that the simulated flux calculation method was suitable for revealing the evolutionary trend of ozone fluxes.Monthly inflows,outflows,and total net fluxes ranged from-32985.45 to 37361.46 t/d and indicated strong transport and significant spatial and temporal variations of ozone in the urban boundary segments.Vertical distribution analysis of the net ozone fluxes demonstrated that the net fluxes varied with the altitude,and the altitude at which the corresponding peaks were located had a strong correlation with the neighborhood and season.It was noteworthy that there were three main transport directions throughout the year,namely northwest-southeast(NW-SE),southeast-northwest(SE-NW),and southwestnortheast(SW-NE).Additionally,the ozone flux was mainly affected by temperature,wind speed,and ozone concentration,with the correlation coefficient varying by season and altitude,up to 0.78.Moreover,the correlation analysis of ozone flux and wind direction in each city further verified the accuracy of the transport direction.This paper can provide scientific and technological support for the study of ozone generation mechanisms and the solution of urban/interregional ozone pollution problems.展开更多
Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads ...Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads and shock wave propagation process in semi-enclosed structures at various altitude environment is key research focus in the fields of explosion shock and fluid dynamics.The effect of altitude on the propagation of shock waves in tunnels was investigated by conducting explosion test and numerical simulation.Based on the experimental and numerical simulation results,a prediction model for the attenuation of the peak overpressure of tunnel shock waves at different altitudes was established.The results showed that the peak overpressure decreased at the same measurement points in the tunnel entrance under the high altitude condition.In contrast,an increase in altitude accelerated the propagation speed of the shock wave in the tunnel.The average error between the peak shock wave overpressure obtained using the overpressure prediction formula and the measured test data was less than15%,the average error between the propagation velocity of shock waves predicted values and the test data is less than 10%.The method can effectively predict the overpressure attenuation of blast wave in tunnel at various altitudes.展开更多
Hypersonic magnetohydrodynamic(MHD)control effectively enhances the aerothermal environment of aerospace vehicles,demonstrating considerable potential in plasma flow regulation and aerodynamic optimiza-tion.As aerospa...Hypersonic magnetohydrodynamic(MHD)control effectively enhances the aerothermal environment of aerospace vehicles,demonstrating considerable potential in plasma flow regulation and aerodynamic optimiza-tion.As aerospace vehicles progress toward mid-low-altitude hypersonic regimes,their external aerothermal conditions become increasingly severe.This study addresses the challenges of complex aerodynamic force/heat environments and the difficulties in MHD control numerical simulations for hypersonic vehicles at mid-low al-titudes.On the basis of the perfect gas model and the low magnetic Reynolds number assumption,we conduct numerical simulations of MHD control under mid-low altitudes,high-Mach-number conditions.The findings reveal the following:(1)the low magnetic Reynolds number assumption is valid and computationally accurate,as corroborated by a comparative analysis with the literature;(2)in the mid-low altitude hypersonic regime,magnetic fields significantly suppress the shock standoffdistance and reduce the surface heat flux.Both the mag-netically controlled shock wave and the thermal protection exhibit nonlinear variations with the Mach number,increasing and then decreasing as the Mach number increases.The optimal Mach number for shock wave control is 13,whereas optimal thermal protection is achieved at Mach 15.At an altitude of 40 km,the optimal magne-tohydrodynamic Mach range spans 13-17,achieving a maximum heat flux attenuation of 28.81%.Additionally,the effects of magnetic shock wave control correlate approximately exponentially with altitude within certain parameters,whereas the efficacy of thermal protection behaves linearly with altitude variations.展开更多
[Objectives]To analyze the differences in medicinal component contents of Magnolia officinalis across different altitude gradients and explore their causes.[Methods]In this experiment,M.officinalis trees aged 15-20 ye...[Objectives]To analyze the differences in medicinal component contents of Magnolia officinalis across different altitude gradients and explore their causes.[Methods]In this experiment,M.officinalis trees aged 15-20 years growing at four altitudes(1301,1444,1573,and 1643 m)were selected as experimental materials.Leaf traits,soil physicochemical properties,and medicinal component contents were investigated,and the relationships among leaf traits,soil physicochemical properties,and medicinal components were analyzed.[Results]With increasing altitude,the specific leaf area(SLA)of M.officinalis significantly increased,while stomatal density,vein density,leaf thickness,and mesophyll tissue thickness decreased.Soil total nitrogen(TN),total phosphorus(TP),total potassium(TK),available nitrogen(AN),and organic matter contents(OM)decreased significantly with altitude,whereas available potassium(AK)showed the opposite trend.The contents of medicinal components magnolol and honokiol in M.officinalis also significantly decreased with altitude.Correlation analysis revealed that,in addition to altitude,soil physicochemical properties(pH,TP,OM)and leaf traits(leaf thickness,palisade tissue thickness,SLA)were significantly correlated with magnolol and honokiol contents.[Conclusions]M.officinalis at lower altitudes exhibited better growth and higher magnolol and honokiol contents,which may be attributed to higher soil nutrient availability in low-altitude regions.This study provides guidance for selecting cultivation sites and optimizing planting patterns for M.officinalis.展开更多
By the method of gradient pattern analysis, twenty plots were set at altitudes of 700-2600 m with an interval of 100 m on the northern slope of the Changbai Mountain. The dissimilarity of respective sub-plots in the s...By the method of gradient pattern analysis, twenty plots were set at altitudes of 700-2600 m with an interval of 100 m on the northern slope of the Changbai Mountain. The dissimilarity of respective sub-plots in the same community was measured and the complexity of plant communities at different altitudes was analyzed. The result from binary data of tree species in canopy tree indicated that the sub-plots in the communities, except subalpine Betula ermanii forest, showed comparatively high dissimilarity in species composition. Especially, the dissimilarity index (0.7) of broadleaved/Korean pine forest at low altitudes was obviously higher than other communities. The differences are not obvious between communities referring to dark coniferous forest. Comparatively, the dissimilarity in sub-plots of the communities at altitude of 1400 m was slightly higher than that of other communities, which reflected the complexity of tree species compositions of transitory-type communities. For subalpine Betula ermanii forest, tree species composition was simple and showed a high similarity between sub-plots. The results derived from binary data of shrub showed that the dissimilarity index of shrub species in broadleaved/Korean pine forest at low altitudes was higher than that in other communities, but the divergence tendency wasn抰 so obvious as that of arbor species. The dissimilarity derived from binary data of herb and all plant species at different altitudes showed greatly close tendency, and the differences in herb and all plant species between sub-plots were the greatest for the communities of broad-leaved-Korean pine forest and alpine tundra zone..展开更多
[Objective] By investigating of change rule rice starch RVA profile properties and the influence of cold tolerance on rice quality,the aim was to provide scientific references to the breeding of new cold-tolerant japo...[Objective] By investigating of change rule rice starch RVA profile properties and the influence of cold tolerance on rice quality,the aim was to provide scientific references to the breeding of new cold-tolerant japonica rice varieties with high quality in the Yunnan plateau.[Method] Four cold-tolerant and five cold-sensitive japonica rice cultivars were grown at three locations with different altitudes in Yunnan plateau to investigate rice starch RVA profile characteristics.[Result] The results showed that with increasing altitude,the setback viscosity in cold-sensitive cultivars increased significantly,while the peak viscosity and breakdown viscosity decreased significantly.However,the peak viscosity and breakdown viscosity in cold-tolerant cultivars initially decreased and then gradually increased with rising altitude,whereas the setback viscosity initially increased and then decreased.[Conclusion] The starch RVA parameters of cold-tolerant cultivars were less sensitive to different environments than those of cold-sensitive cultivars.Cooking and eating quality of cold-tolerant cultivars had relatively stable trends with rising altitude,whereas cooking and eating quality of cold-sensitive cultivars had a trend toward inferior.展开更多
Twenty plots were investigated on northern slope of Changbai Mountain at an attitude interval of 100 m (from 700 to 2600 m). The species co-possession between plant communities at different altitudes was analyzed by J...Twenty plots were investigated on northern slope of Changbai Mountain at an attitude interval of 100 m (from 700 to 2600 m). The species co-possession between plant communities at different altitudes was analyzed by Jaccard index. The analytical results showed that the co-possession calculated according to species in different layers or all species between adjacent communities was higher than that between disjunct communities. The co-possessions between adjacent communities calculated by species in different layers had comparability and dissimilarity. If the two adjacent communities belong to different types of vegetation, then their co-possession was lower. The peak values and valley values of species co-possession between communities along elevation gradient just matched vegetation gradient patterns, and species subrogation of shrubs had more obvious rule on northern slope of Changbai Mountain. Co-possessions between communities with same altitude difference were much similar, and it decreased as the increase of elevation difference, which showed that species compositions in different layers of the communities were highly related.展开更多
In this study, the relationship between major meteorological factors and tobacco chemical components in different altitudes of Yongde County, Lincang Region of Yunnan Province was studied using correlation analysis an...In this study, the relationship between major meteorological factors and tobacco chemical components in different altitudes of Yongde County, Lincang Region of Yunnan Province was studied using correlation analysis and path analysis methods.The results showed that there was a difference on meteorological factors in different altitudes, causing different impacts on chemical components of flue-cured tobacco; contents of nicotine and total nitrogen decreased with the rising of altitude, conversely, total sugar and reducing sugar contents increased with the rising trend of altitude, and the differences on the contents of potassium （K） and chlorine（CI）, and the ratio of K to CI in different altitudes were not significant, at the altitude of 1 250-1 450 m, each chemical component indicator was better. The correlation between main meteorological factors and conventional chemical components of tobacco leaves was as follows： contents of reducing sugar and total sugar increased with the increase of rainfall and relative humidity, and decreased with the increase of sunshine duration; nicotine content increased with the increase of accumulated temperature and sunshine duration; total nitrogen （N） content increased with the increase of daily mean temperature and accumulated temperature; sugar-alkali ratio increased with the increase of rainfall. Path analysis showed that the direct effect of sunshine duration on reducing sugar and total sugar of tobacco leaves was faint, but the indirect effect was obvious; meanwhile, the direct and indirect effects of it on nicotine and total N were the greatest.展开更多
Populations living at high altitudes （HAs）, particularly in the Peruvian Andes, are characterized by a mixture of subjects with erythrocytosis （16 g dl-1〈haemoglobin （Hb）≤21 gdl-1） and others with excessive er...Populations living at high altitudes （HAs）, particularly in the Peruvian Andes, are characterized by a mixture of subjects with erythrocytosis （16 g dl-1〈haemoglobin （Hb）≤21 gdl-1） and others with excessive erythrocytosis （EE） （Hb〉21 g dl-1）. Elevated haemoglobin values （EE） are associated with chronic mountain sickness, a condition reflecting the lack of adaptation to HA. According to current data, native men from regions of HA are not adequately adapted to live at such altitudes if they have elevated serum testosterone levels. This seems to be due to an increased conversion of dehydroepiandrosterone sulphate （DH EAS） to testosterone. Men with erythrocytosis at HAs show higher serum androstenedione levels and a lower testosterone/androstenedione ratio than men with EE, suggesting reduced 17beta-hydroxysteroid dehydrogenase （17beta-HSD） activity. Lower 17beta-HSD activity via A4-steroid production in men with erythrocytosis at HA may protect against elevated serum testosterone levels, thus preventing EE. The higher conversion of DHEAS to testosterone in subjects with EE indicates increased 17beta-HSD activity via the A5-pathway. Currently, there are various situations in which people live （human biodiversity） with low or high haemoglobin levels at HA. Antiquity could be an important adaptation component for life at HA, and testosterone seems to participate in this process.展开更多
[Objective] The aim of this study is to investigate species diversity of alpine vegetation in different altitudes of Daban mountain. [Method] Plant communities were surveyed in three different altitudes （3 025 m,3 40...[Objective] The aim of this study is to investigate species diversity of alpine vegetation in different altitudes of Daban mountain. [Method] Plant communities were surveyed in three different altitudes （3 025 m,3 405 m,3 813 m） of Daban mountain,the eastern Qilian,and the richness or diversity index of vegetation in three different altitudes was comparatively analyzed. [Result] The species richness decreased with the gradual increase of altitude,and species diversity of plant communities was relatively lower in medium altitude. Furthermore,community similarity also decreased with the increase of altitude,and β diversity of communities had a significant change. [Conclusion] Environmental factor change caused by different altitudes and human disturbance are important reasons for the change of species distribution pattern in different altitudes.展开更多
[Objective] This study aimed to meet the demand of farmers for highyielding, high-quality, wide-adaptability and multi-resistant new maize cultivars, and to make food production grow continuously. [Method] Comparative...[Objective] This study aimed to meet the demand of farmers for highyielding, high-quality, wide-adaptability and multi-resistant new maize cultivars, and to make food production grow continuously. [Method] Comparative test of new maize cultivars was conducted at different altitudes in 2015, and the yield, main economic characters, agronomic traits, growth period and resistance of maize cultivars were analyzed. [Result] Ruidan 26 and Yongrui 16 can be cultivated in the areas below the altitude of 2 200 m; Huaxingdan 88 can be cultivated in the areas below the altitude of 1 750 m; the other new maize cultivars still need to be tested further. [Cenclusion] The research results can be applied in this area and other similar areas, which will effectively promote the upgrading of maize cultivars and improve the yield per unit area.展开更多
[Objectives]To optimize the extraction technology of total flavonoids from Pueraria lobata( Willd.) Ohwi. [Methods]The ultraviolet-visible spectrophotometry was used to determine the content of total flavonoids in Pue...[Objectives]To optimize the extraction technology of total flavonoids from Pueraria lobata( Willd.) Ohwi. [Methods]The ultraviolet-visible spectrophotometry was used to determine the content of total flavonoids in Pueraria lobata( Willd.) Ohwi. With the puerarin as index,the reflux extraction and single factor test were employed to investigate the effects of temperature,time,ethanol concentration and solid-liquid ratio on the content of total flavonoids in Pueraria lobata( Willd.) Ohwi,respectively. Under the optimal extraction technology,the content of total flavonoids in Pueraria lobata( Willd.) Ohwi at different altitudes was determined.[Results] The optimum extraction process was as follows: 70%ethanol; solid-liquid ratio of 1∶ 30; 1 h reflux extraction. Under these conditions,the extraction rate of flavonoids in Pueraria lobata( Willd.) Ohwi was 11. 48%,the total flavonoids content of different kudzu parts was in the order of roots > stems > leaves,and the total flavonoids content of the sample at about an altitude of 1000 m was significantly higher than at the altitudes of 1400 m and 1700 m.[Conclusions]It was suggested that the Pueraria lobata( Willd.) Ohwi should not be cultivated as medicinal plant in too high mountains,and the stems and leaves of Pueraria lobata( Willd.) Ohwi could be used as raw materials for extracting total flavonoids.展开更多
Glaciers in the Yarlung Zangbo Downstream Basin(YZDB)are sensitive to global climate change.The equilibrium-line altitude(ELA)is a key indicator of glacial development.Current models for simulating the meteorological ...Glaciers in the Yarlung Zangbo Downstream Basin(YZDB)are sensitive to global climate change.The equilibrium-line altitude(ELA)is a key indicator of glacial development.Current models for simulating the meteorological ELA underestimate the extent of glacial advance during the Last Glacial Maximum(LGM)in the YZDB and cannot explain the large-scale glacial extension compared with the Yarlung Zangbo Midstream Basin(YZMB).In this study,the distribution of ELA in the LGM is reconstructed using high-resolution 80-km ECHAM5 simulations and empirical relationships between temperature and precipitation.Changes in ELA between the LGM and pre-industrial era(PI)are compared.Our simulated ELA closely fits the published field data.In the YZDB,simulated LGM ELAs range from ca.3500 m to over 4900 m,representing declines of ca.300–950 m.The ECHAM5 simulations better reflect the complex topographic features than most coarse-resolution climate models,and the ELA distribution is controlled by the spatial arrangement of river valley systems and mountain ranges and their impact on precipitation.Compared with the PI era,most of the monsoon precipitation in the LGM was concentrated in the YZDB,which is the main driver of glacial extension and the differential response of the downstream and midstream basins.展开更多
Flood land, with abundant light, heat, and water resource, is an important potential land resource to resolve the situation of the limited arable land in mountain areas in Xiaojiang Valley, Dongchuan, Yunnan. It will ...Flood land, with abundant light, heat, and water resource, is an important potential land resource to resolve the situation of the limited arable land in mountain areas in Xiaojiang Valley, Dongchuan, Yunnan. It will have a great significance on the development of local characteristic agriculture and the settlement of poor moun- tain immigrants that how to develop and protect the flood land in a scientific, effec- tive and sustainable way. In this paper, flood land of Xiaojiang Valley is divided into three zones （higher zone is 1 600-1 300 m, medium zone is 1 300-1 000 m, low- er zone is 1 000-700 m） according to different elevations. Through field survey, in situ measurement, sampling analysis and ＂3S＂ technology, the area and soil nutri- ent characteristics of flood land at different altitudes are tested and analyzed sys- tematically. And also according to the climatic characteristics in different elevations of flood land, the research analyzed and investigated the growing conditions of flood land in different elevations in Xiaojiang Valley, and then discussed how to develop and cultivate reasonably and effectively in flood land. All the work is intended to provide beneficial reference for the development and cultivation of flood land in mountain areas.展开更多
In this study, 22 leaf samples of 22 Lilieae species were collected in six Province at 90 - 3740 m to study the variations of leaf characteristics with altitude change. The Qualitative character of leaf epidermis and ...In this study, 22 leaf samples of 22 Lilieae species were collected in six Province at 90 - 3740 m to study the variations of leaf characteristics with altitude change. The Qualitative character of leaf epidermis and two stomatal indexes, viz. stomatal area (SA), stomatal index (SI), were analyzed in laboratory. The results show that: 1) the shape of the leaf epidermis cells and the pattern of the anticlinal walls provide some useful taxonomic information to distinguish the genus, however, none of the stable traits are exclusive to a genus;2) there are significant or even very significant linear correlations between the two indexes and altitude, of which SA exhibit a negative correlation with altitude (r<sup>2</sup> = 0.294, p = 0.009), while SI exhibit a positive correlation with altitude (r<sup>2</sup> = -0.254, p = 0.017). As a result, the pattern of leaf cells and anticlinal walls is influenced by genetic factors, while the stomatal area and stomatal index are influenced by environmental factors. Members of the tribe Lilieae have a relatively stable elevation range, which is related to their long-term adaptation to the local environment in the structure of their leaf epidermis.展开更多
The active ingredients of Camellia japonica flowers(CJF)at high and low altitudes,as well as their skin care efficacy were compared.The dried red CJF at high and low altitudes were ultrasonically extracted with 70%eth...The active ingredients of Camellia japonica flowers(CJF)at high and low altitudes,as well as their skin care efficacy were compared.The dried red CJF at high and low altitudes were ultrasonically extracted with 70%ethanol,and these extracts were concentrated and then diluted to a constant volume.The content of total flavonoids,total polyphenols and total proteins was tested and analyzed.In addition,DPPH free radical scavenging,inhibition of the formation of advanced glycation end products,and inhibitory activity against elastase was measured to compare their skin care efficacy in anti-oxidation,anti-glycation,anti-wrinkling and firming.The results showed that,based on the dry weight of CJF,the content of total flavonoids and total proteins of the CJF at high altitude was approximately 1.5 times of the CJF at low altitude,while the content of total polyphenols was approximately 2.4 times that of the CJF at low altitude.The skin care efficacy of CJF at high altitude was significantly better than that of the CJF at low altitude.This work could provide theoretical basis for the selection and application of Camellia japonica flowers in the field of cosmetics.展开更多
This study analyzed the trends in extreme high temperature in Southwest China based on the observed daily maximum temperature and average temperature data from 410 Chinese stations recently released by the China Meteo...This study analyzed the trends in extreme high temperature in Southwest China based on the observed daily maximum temperature and average temperature data from 410 Chinese stations recently released by the China Meteorological Administration.The authors found that the trends in extreme high temperature at different altitudes of Southwest China exhibit staged variations during a recent 50-year period(1961–2014).The trends in mean temperature and maximum temperature also exhibit phase variation.All temperature-related variables increase gently during the period 1975–94,whereas they increase dramatically during the recent period of 1995–2014,with a rate that is approximately two to ten times more than that during 1975–94.In addition,the trends in mean temperature,maximum temperature,and the frequency of extreme high temperature in the low altitudes transit from negative to positive in the two periods,while they increase dramatically in the mid-and high-altitude areas during 1995–2014,the well-known global warming hiatus period.In particular,the maximum temperature increases much faster than that of average temperature.This result implies that the regional temperature trend could be apparently different from the global mean temperature change.展开更多
There are great differences in the distribution characteristics of shock waves produced by ammunition explosions at different altitudes.At present,there are many studies on plain explosion shock waves,but there are fe...There are great differences in the distribution characteristics of shock waves produced by ammunition explosions at different altitudes.At present,there are many studies on plain explosion shock waves,but there are few studies on the distribution characteristics of plateau explosion shock waves,and there is still a lack of complete analysis and evaluation methods.This paper compares and analyzes shock wave overpressure data at different altitudes,obtains the attenuation effect of different altitudes on the shock wave propagation process and proposes a calculation formula for shock wave overpressure considering the effect of altitude.The data analysis results show that at the same TNT equivalent and the same distance from the measuring point,the shock wave overpressure at high altitude is lower than that at low altitude.With the increase in the explosion center distance of the measuring point,the peak attenuation rate of the shock wave overpressure at high altitudes is smaller than that at low altitudes,and the peak attenuation rate of the shock wave overpressure at high altitudes gradually intensifies with increasing proportional distance.The average error between the shock wave overpressure and measured shock wave overpressure in a high-altitude environment obtained by using the above calculation formula is 11.1389%.Therefore,this method can effectively predict explosion shock wave overpressure in plateau environments and provides an effective calculation method for practical engineering tests.展开更多
Cultivated chrysanthemum(Chrysanthemum morifolium Ramat.)is an economically important ornamental plant species grown worldwide.However,the origin of the genus Chrysanthemum remains unclear.This study was conducted in ...Cultivated chrysanthemum(Chrysanthemum morifolium Ramat.)is an economically important ornamental plant species grown worldwide.However,the origin of the genus Chrysanthemum remains unclear.This study was conducted in the Hengduan Mountains,Yunnan Province.We took advantage of a special geographic region where the southernmost species of Ajania and the highest altitude population of Chrysanthemum indicum coexist to investigate their evolutionary origins.Diversity analysis of 9 populations of 5 species that came from 3 genera was carried out based on morphological traits and SRAP markers.Furthermore,topographical and ecological analyses and surveys of the vegetation communities in the plots were carried out for correlation analysis,and past data were used to reconstruct the ancient topography and vegetation to estimate the migration path and divergence time.We found that Chrysanthemum and Ajania were closely related based on the smooth transition states among marginal female florets and their common pollination system.The genetic relationship between Phaeostigma and Chrysanthemum was relatively distant,and Ajania was between them.Low light intensity and relatively humid habitats may be driving the elongation and evolution of marginal female florets.We found that Chrysanthemum and related genera were largely restricted to stony topographies at an altitude of~3000 m.a.s.l.and in specialized alpine coniferous(Pinus)and broadleaved(Quercus)mixed forest marginal communities.These stony topographies have become ecological islands of refuge for these species in the current interglacial period.The Hengduan Mountains play a key role in the evolution,divergence,and survival of Chrysanthemum and its allies.展开更多
基金supported by the National Natural Science Foundation of China(No.52200120)the R&D Program of Beijing Municipal Education Commission(No.KM202310011003)。
文摘The North China Plain(NCP)frequently experiences ozone pollution events,which are generally related to cross-border transport at multiple scales.However,current methods of calculating ozone transport are insufficient to account for ozone transport at different altitudes.To further understand the characteristics of ozone transport,we applied theWeather Research and Forecasting(WRF)model and the Comprehensive Air Quality Model with Extensions(CAMx)based on flux calculation method.The results showed that the simulated flux calculation method was suitable for revealing the evolutionary trend of ozone fluxes.Monthly inflows,outflows,and total net fluxes ranged from-32985.45 to 37361.46 t/d and indicated strong transport and significant spatial and temporal variations of ozone in the urban boundary segments.Vertical distribution analysis of the net ozone fluxes demonstrated that the net fluxes varied with the altitude,and the altitude at which the corresponding peaks were located had a strong correlation with the neighborhood and season.It was noteworthy that there were three main transport directions throughout the year,namely northwest-southeast(NW-SE),southeast-northwest(SE-NW),and southwestnortheast(SW-NE).Additionally,the ozone flux was mainly affected by temperature,wind speed,and ozone concentration,with the correlation coefficient varying by season and altitude,up to 0.78.Moreover,the correlation analysis of ozone flux and wind direction in each city further verified the accuracy of the transport direction.This paper can provide scientific and technological support for the study of ozone generation mechanisms and the solution of urban/interregional ozone pollution problems.
基金financially supported by National Natural Science Foundation of China(Grant Nos.52378401,52278504)the Fundamental Research Funds for the Central Universities(Grant No.30922010918)。
文摘Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads and shock wave propagation process in semi-enclosed structures at various altitude environment is key research focus in the fields of explosion shock and fluid dynamics.The effect of altitude on the propagation of shock waves in tunnels was investigated by conducting explosion test and numerical simulation.Based on the experimental and numerical simulation results,a prediction model for the attenuation of the peak overpressure of tunnel shock waves at different altitudes was established.The results showed that the peak overpressure decreased at the same measurement points in the tunnel entrance under the high altitude condition.In contrast,an increase in altitude accelerated the propagation speed of the shock wave in the tunnel.The average error between the peak shock wave overpressure obtained using the overpressure prediction formula and the measured test data was less than15%,the average error between the propagation velocity of shock waves predicted values and the test data is less than 10%.The method can effectively predict the overpressure attenuation of blast wave in tunnel at various altitudes.
基金the results of the research project funded by National Numerical Wind Tunnel Project of China.
文摘Hypersonic magnetohydrodynamic(MHD)control effectively enhances the aerothermal environment of aerospace vehicles,demonstrating considerable potential in plasma flow regulation and aerodynamic optimiza-tion.As aerospace vehicles progress toward mid-low-altitude hypersonic regimes,their external aerothermal conditions become increasingly severe.This study addresses the challenges of complex aerodynamic force/heat environments and the difficulties in MHD control numerical simulations for hypersonic vehicles at mid-low al-titudes.On the basis of the perfect gas model and the low magnetic Reynolds number assumption,we conduct numerical simulations of MHD control under mid-low altitudes,high-Mach-number conditions.The findings reveal the following:(1)the low magnetic Reynolds number assumption is valid and computationally accurate,as corroborated by a comparative analysis with the literature;(2)in the mid-low altitude hypersonic regime,magnetic fields significantly suppress the shock standoffdistance and reduce the surface heat flux.Both the mag-netically controlled shock wave and the thermal protection exhibit nonlinear variations with the Mach number,increasing and then decreasing as the Mach number increases.The optimal Mach number for shock wave control is 13,whereas optimal thermal protection is achieved at Mach 15.At an altitude of 40 km,the optimal magne-tohydrodynamic Mach range spans 13-17,achieving a maximum heat flux attenuation of 28.81%.Additionally,the effects of magnetic shock wave control correlate approximately exponentially with altitude within certain parameters,whereas the efficacy of thermal protection behaves linearly with altitude variations.
基金Supported by National Key Research and Development Program of China in 2018(2018YFC1708005)the Southwest Minzu University Research Startup Funds(RQD2023020).
文摘[Objectives]To analyze the differences in medicinal component contents of Magnolia officinalis across different altitude gradients and explore their causes.[Methods]In this experiment,M.officinalis trees aged 15-20 years growing at four altitudes(1301,1444,1573,and 1643 m)were selected as experimental materials.Leaf traits,soil physicochemical properties,and medicinal component contents were investigated,and the relationships among leaf traits,soil physicochemical properties,and medicinal components were analyzed.[Results]With increasing altitude,the specific leaf area(SLA)of M.officinalis significantly increased,while stomatal density,vein density,leaf thickness,and mesophyll tissue thickness decreased.Soil total nitrogen(TN),total phosphorus(TP),total potassium(TK),available nitrogen(AN),and organic matter contents(OM)decreased significantly with altitude,whereas available potassium(AK)showed the opposite trend.The contents of medicinal components magnolol and honokiol in M.officinalis also significantly decreased with altitude.Correlation analysis revealed that,in addition to altitude,soil physicochemical properties(pH,TP,OM)and leaf traits(leaf thickness,palisade tissue thickness,SLA)were significantly correlated with magnolol and honokiol contents.[Conclusions]M.officinalis at lower altitudes exhibited better growth and higher magnolol and honokiol contents,which may be attributed to higher soil nutrient availability in low-altitude regions.This study provides guidance for selecting cultivation sites and optimizing planting patterns for M.officinalis.
基金supported by the Chinese Academy of Science(grand KZCX2-406)founded by Chinese Science of Academy undred People’Project.
文摘By the method of gradient pattern analysis, twenty plots were set at altitudes of 700-2600 m with an interval of 100 m on the northern slope of the Changbai Mountain. The dissimilarity of respective sub-plots in the same community was measured and the complexity of plant communities at different altitudes was analyzed. The result from binary data of tree species in canopy tree indicated that the sub-plots in the communities, except subalpine Betula ermanii forest, showed comparatively high dissimilarity in species composition. Especially, the dissimilarity index (0.7) of broadleaved/Korean pine forest at low altitudes was obviously higher than other communities. The differences are not obvious between communities referring to dark coniferous forest. Comparatively, the dissimilarity in sub-plots of the communities at altitude of 1400 m was slightly higher than that of other communities, which reflected the complexity of tree species compositions of transitory-type communities. For subalpine Betula ermanii forest, tree species composition was simple and showed a high similarity between sub-plots. The results derived from binary data of shrub showed that the dissimilarity index of shrub species in broadleaved/Korean pine forest at low altitudes was higher than that in other communities, but the divergence tendency wasn抰 so obvious as that of arbor species. The dissimilarity derived from binary data of herb and all plant species at different altitudes showed greatly close tendency, and the differences in herb and all plant species between sub-plots were the greatest for the communities of broad-leaved-Korean pine forest and alpine tundra zone..
基金Supported the Key Technologies R&D Program of Yunnan(2010BB002)the National High-tech R & D Program of China(2010AA10Z104 )+2 种基金International Cooperation Programs betweenChina and Korea (YK 2007-2010)Young and Middle-aged Academic Technology Leader Backup Talents Project (2009CI058 )Training Programme for Young and Middle-aged Talents of Technology Innovation by Yunnan (2008PY089)~~
文摘[Objective] By investigating of change rule rice starch RVA profile properties and the influence of cold tolerance on rice quality,the aim was to provide scientific references to the breeding of new cold-tolerant japonica rice varieties with high quality in the Yunnan plateau.[Method] Four cold-tolerant and five cold-sensitive japonica rice cultivars were grown at three locations with different altitudes in Yunnan plateau to investigate rice starch RVA profile characteristics.[Result] The results showed that with increasing altitude,the setback viscosity in cold-sensitive cultivars increased significantly,while the peak viscosity and breakdown viscosity decreased significantly.However,the peak viscosity and breakdown viscosity in cold-tolerant cultivars initially decreased and then gradually increased with rising altitude,whereas the setback viscosity initially increased and then decreased.[Conclusion] The starch RVA parameters of cold-tolerant cultivars were less sensitive to different environments than those of cold-sensitive cultivars.Cooking and eating quality of cold-tolerant cultivars had relatively stable trends with rising altitude,whereas cooking and eating quality of cold-sensitive cultivars had a trend toward inferior.
基金the Chinese Academy of Science (a grant KZCX2-406), National Natural Science Foundation of China (NSFC39970123), and Changbai Mo
文摘Twenty plots were investigated on northern slope of Changbai Mountain at an attitude interval of 100 m (from 700 to 2600 m). The species co-possession between plant communities at different altitudes was analyzed by Jaccard index. The analytical results showed that the co-possession calculated according to species in different layers or all species between adjacent communities was higher than that between disjunct communities. The co-possessions between adjacent communities calculated by species in different layers had comparability and dissimilarity. If the two adjacent communities belong to different types of vegetation, then their co-possession was lower. The peak values and valley values of species co-possession between communities along elevation gradient just matched vegetation gradient patterns, and species subrogation of shrubs had more obvious rule on northern slope of Changbai Mountain. Co-possessions between communities with same altitude difference were much similar, and it decreased as the increase of elevation difference, which showed that species compositions in different layers of the communities were highly related.
文摘In this study, the relationship between major meteorological factors and tobacco chemical components in different altitudes of Yongde County, Lincang Region of Yunnan Province was studied using correlation analysis and path analysis methods.The results showed that there was a difference on meteorological factors in different altitudes, causing different impacts on chemical components of flue-cured tobacco; contents of nicotine and total nitrogen decreased with the rising of altitude, conversely, total sugar and reducing sugar contents increased with the rising trend of altitude, and the differences on the contents of potassium （K） and chlorine（CI）, and the ratio of K to CI in different altitudes were not significant, at the altitude of 1 250-1 450 m, each chemical component indicator was better. The correlation between main meteorological factors and conventional chemical components of tobacco leaves was as follows： contents of reducing sugar and total sugar increased with the increase of rainfall and relative humidity, and decreased with the increase of sunshine duration; nicotine content increased with the increase of accumulated temperature and sunshine duration; total nitrogen （N） content increased with the increase of daily mean temperature and accumulated temperature; sugar-alkali ratio increased with the increase of rainfall. Path analysis showed that the direct effect of sunshine duration on reducing sugar and total sugar of tobacco leaves was faint, but the indirect effect was obvious; meanwhile, the direct and indirect effects of it on nicotine and total N were the greatest.
文摘Populations living at high altitudes （HAs）, particularly in the Peruvian Andes, are characterized by a mixture of subjects with erythrocytosis （16 g dl-1〈haemoglobin （Hb）≤21 gdl-1） and others with excessive erythrocytosis （EE） （Hb〉21 g dl-1）. Elevated haemoglobin values （EE） are associated with chronic mountain sickness, a condition reflecting the lack of adaptation to HA. According to current data, native men from regions of HA are not adequately adapted to live at such altitudes if they have elevated serum testosterone levels. This seems to be due to an increased conversion of dehydroepiandrosterone sulphate （DH EAS） to testosterone. Men with erythrocytosis at HAs show higher serum androstenedione levels and a lower testosterone/androstenedione ratio than men with EE, suggesting reduced 17beta-hydroxysteroid dehydrogenase （17beta-HSD） activity. Lower 17beta-HSD activity via A4-steroid production in men with erythrocytosis at HA may protect against elevated serum testosterone levels, thus preventing EE. The higher conversion of DHEAS to testosterone in subjects with EE indicates increased 17beta-HSD activity via the A5-pathway. Currently, there are various situations in which people live （human biodiversity） with low or high haemoglobin levels at HA. Antiquity could be an important adaptation component for life at HA, and testosterone seems to participate in this process.
基金Supported by National Sci-tech Support Plan (2007BAC03A08-5)National Natural Science Foundation ( N0. 30570300, 30590381-02)The Third Period of 211 Project of Innovation Personnel Training for Postgraduate Education in Minzu University of China(0212110309090209)~~
文摘[Objective] The aim of this study is to investigate species diversity of alpine vegetation in different altitudes of Daban mountain. [Method] Plant communities were surveyed in three different altitudes （3 025 m,3 405 m,3 813 m） of Daban mountain,the eastern Qilian,and the richness or diversity index of vegetation in three different altitudes was comparatively analyzed. [Result] The species richness decreased with the gradual increase of altitude,and species diversity of plant communities was relatively lower in medium altitude. Furthermore,community similarity also decreased with the increase of altitude,and β diversity of communities had a significant change. [Conclusion] Environmental factor change caused by different altitudes and human disturbance are important reasons for the change of species distribution pattern in different altitudes.
基金Supported by Modern Agriculture(Maize)Industrial Technology System of Yunnan Province[YNKZ(2009)53,YCN(2009)171]~~
文摘[Objective] This study aimed to meet the demand of farmers for highyielding, high-quality, wide-adaptability and multi-resistant new maize cultivars, and to make food production grow continuously. [Method] Comparative test of new maize cultivars was conducted at different altitudes in 2015, and the yield, main economic characters, agronomic traits, growth period and resistance of maize cultivars were analyzed. [Result] Ruidan 26 and Yongrui 16 can be cultivated in the areas below the altitude of 2 200 m; Huaxingdan 88 can be cultivated in the areas below the altitude of 1 750 m; the other new maize cultivars still need to be tested further. [Cenclusion] The research results can be applied in this area and other similar areas, which will effectively promote the upgrading of maize cultivars and improve the yield per unit area.
基金Supported by Sichuan Science and Technology Support Program(2014SZ-0131)
文摘[Objectives]To optimize the extraction technology of total flavonoids from Pueraria lobata( Willd.) Ohwi. [Methods]The ultraviolet-visible spectrophotometry was used to determine the content of total flavonoids in Pueraria lobata( Willd.) Ohwi. With the puerarin as index,the reflux extraction and single factor test were employed to investigate the effects of temperature,time,ethanol concentration and solid-liquid ratio on the content of total flavonoids in Pueraria lobata( Willd.) Ohwi,respectively. Under the optimal extraction technology,the content of total flavonoids in Pueraria lobata( Willd.) Ohwi at different altitudes was determined.[Results] The optimum extraction process was as follows: 70%ethanol; solid-liquid ratio of 1∶ 30; 1 h reflux extraction. Under these conditions,the extraction rate of flavonoids in Pueraria lobata( Willd.) Ohwi was 11. 48%,the total flavonoids content of different kudzu parts was in the order of roots > stems > leaves,and the total flavonoids content of the sample at about an altitude of 1000 m was significantly higher than at the altitudes of 1400 m and 1700 m.[Conclusions]It was suggested that the Pueraria lobata( Willd.) Ohwi should not be cultivated as medicinal plant in too high mountains,and the stems and leaves of Pueraria lobata( Willd.) Ohwi could be used as raw materials for extracting total flavonoids.
基金The Second Tibetan Plateau Scientific Expedition and Research Program(STEP),No.2019QZKK0902Key Research and Development Program of Xizang Autonomous Region,No.XZ202301ZY0039GNational Natural Science Foundation of China,No.42305178,No.91747207,No.41790434。
文摘Glaciers in the Yarlung Zangbo Downstream Basin(YZDB)are sensitive to global climate change.The equilibrium-line altitude(ELA)is a key indicator of glacial development.Current models for simulating the meteorological ELA underestimate the extent of glacial advance during the Last Glacial Maximum(LGM)in the YZDB and cannot explain the large-scale glacial extension compared with the Yarlung Zangbo Midstream Basin(YZMB).In this study,the distribution of ELA in the LGM is reconstructed using high-resolution 80-km ECHAM5 simulations and empirical relationships between temperature and precipitation.Changes in ELA between the LGM and pre-industrial era(PI)are compared.Our simulated ELA closely fits the published field data.In the YZDB,simulated LGM ELAs range from ca.3500 m to over 4900 m,representing declines of ca.300–950 m.The ECHAM5 simulations better reflect the complex topographic features than most coarse-resolution climate models,and the ELA distribution is controlled by the spatial arrangement of river valley systems and mountain ranges and their impact on precipitation.Compared with the PI era,most of the monsoon precipitation in the LGM was concentrated in the YZDB,which is the main driver of glacial extension and the differential response of the downstream and midstream basins.
基金Supported by National Technology R&D Program(0BAC06B02)~~
文摘Flood land, with abundant light, heat, and water resource, is an important potential land resource to resolve the situation of the limited arable land in mountain areas in Xiaojiang Valley, Dongchuan, Yunnan. It will have a great significance on the development of local characteristic agriculture and the settlement of poor moun- tain immigrants that how to develop and protect the flood land in a scientific, effec- tive and sustainable way. In this paper, flood land of Xiaojiang Valley is divided into three zones （higher zone is 1 600-1 300 m, medium zone is 1 300-1 000 m, low- er zone is 1 000-700 m） according to different elevations. Through field survey, in situ measurement, sampling analysis and ＂3S＂ technology, the area and soil nutri- ent characteristics of flood land at different altitudes are tested and analyzed sys- tematically. And also according to the climatic characteristics in different elevations of flood land, the research analyzed and investigated the growing conditions of flood land in different elevations in Xiaojiang Valley, and then discussed how to develop and cultivate reasonably and effectively in flood land. All the work is intended to provide beneficial reference for the development and cultivation of flood land in mountain areas.
文摘In this study, 22 leaf samples of 22 Lilieae species were collected in six Province at 90 - 3740 m to study the variations of leaf characteristics with altitude change. The Qualitative character of leaf epidermis and two stomatal indexes, viz. stomatal area (SA), stomatal index (SI), were analyzed in laboratory. The results show that: 1) the shape of the leaf epidermis cells and the pattern of the anticlinal walls provide some useful taxonomic information to distinguish the genus, however, none of the stable traits are exclusive to a genus;2) there are significant or even very significant linear correlations between the two indexes and altitude, of which SA exhibit a negative correlation with altitude (r<sup>2</sup> = 0.294, p = 0.009), while SI exhibit a positive correlation with altitude (r<sup>2</sup> = -0.254, p = 0.017). As a result, the pattern of leaf cells and anticlinal walls is influenced by genetic factors, while the stomatal area and stomatal index are influenced by environmental factors. Members of the tribe Lilieae have a relatively stable elevation range, which is related to their long-term adaptation to the local environment in the structure of their leaf epidermis.
文摘The active ingredients of Camellia japonica flowers(CJF)at high and low altitudes,as well as their skin care efficacy were compared.The dried red CJF at high and low altitudes were ultrasonically extracted with 70%ethanol,and these extracts were concentrated and then diluted to a constant volume.The content of total flavonoids,total polyphenols and total proteins was tested and analyzed.In addition,DPPH free radical scavenging,inhibition of the formation of advanced glycation end products,and inhibitory activity against elastase was measured to compare their skin care efficacy in anti-oxidation,anti-glycation,anti-wrinkling and firming.The results showed that,based on the dry weight of CJF,the content of total flavonoids and total proteins of the CJF at high altitude was approximately 1.5 times of the CJF at low altitude,while the content of total polyphenols was approximately 2.4 times that of the CJF at low altitude.The skin care efficacy of CJF at high altitude was significantly better than that of the CJF at low altitude.This work could provide theoretical basis for the selection and application of Camellia japonica flowers in the field of cosmetics.
基金supported by the National Natural Science Foundation of China grant numbers 41722504 and 41975116the Youth Innovation Promotion Association of the Chinese Academy of Sciences grant number 2016074。
文摘This study analyzed the trends in extreme high temperature in Southwest China based on the observed daily maximum temperature and average temperature data from 410 Chinese stations recently released by the China Meteorological Administration.The authors found that the trends in extreme high temperature at different altitudes of Southwest China exhibit staged variations during a recent 50-year period(1961–2014).The trends in mean temperature and maximum temperature also exhibit phase variation.All temperature-related variables increase gently during the period 1975–94,whereas they increase dramatically during the recent period of 1995–2014,with a rate that is approximately two to ten times more than that during 1975–94.In addition,the trends in mean temperature,maximum temperature,and the frequency of extreme high temperature in the low altitudes transit from negative to positive in the two periods,while they increase dramatically in the mid-and high-altitude areas during 1995–2014,the well-known global warming hiatus period.In particular,the maximum temperature increases much faster than that of average temperature.This result implies that the regional temperature trend could be apparently different from the global mean temperature change.
文摘There are great differences in the distribution characteristics of shock waves produced by ammunition explosions at different altitudes.At present,there are many studies on plain explosion shock waves,but there are few studies on the distribution characteristics of plateau explosion shock waves,and there is still a lack of complete analysis and evaluation methods.This paper compares and analyzes shock wave overpressure data at different altitudes,obtains the attenuation effect of different altitudes on the shock wave propagation process and proposes a calculation formula for shock wave overpressure considering the effect of altitude.The data analysis results show that at the same TNT equivalent and the same distance from the measuring point,the shock wave overpressure at high altitude is lower than that at low altitude.With the increase in the explosion center distance of the measuring point,the peak attenuation rate of the shock wave overpressure at high altitudes is smaller than that at low altitudes,and the peak attenuation rate of the shock wave overpressure at high altitudes gradually intensifies with increasing proportional distance.The average error between the shock wave overpressure and measured shock wave overpressure in a high-altitude environment obtained by using the above calculation formula is 11.1389%.Therefore,this method can effectively predict explosion shock wave overpressure in plateau environments and provides an effective calculation method for practical engineering tests.
基金funded by the National Key Research and Development Program of China(2019YFD1001501)the National Natural Science Foundation of China(31730081,31870306)+1 种基金the Youth Program of Science and Technology Department of Yunnan Province(2016FD070)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institution.
文摘Cultivated chrysanthemum(Chrysanthemum morifolium Ramat.)is an economically important ornamental plant species grown worldwide.However,the origin of the genus Chrysanthemum remains unclear.This study was conducted in the Hengduan Mountains,Yunnan Province.We took advantage of a special geographic region where the southernmost species of Ajania and the highest altitude population of Chrysanthemum indicum coexist to investigate their evolutionary origins.Diversity analysis of 9 populations of 5 species that came from 3 genera was carried out based on morphological traits and SRAP markers.Furthermore,topographical and ecological analyses and surveys of the vegetation communities in the plots were carried out for correlation analysis,and past data were used to reconstruct the ancient topography and vegetation to estimate the migration path and divergence time.We found that Chrysanthemum and Ajania were closely related based on the smooth transition states among marginal female florets and their common pollination system.The genetic relationship between Phaeostigma and Chrysanthemum was relatively distant,and Ajania was between them.Low light intensity and relatively humid habitats may be driving the elongation and evolution of marginal female florets.We found that Chrysanthemum and related genera were largely restricted to stony topographies at an altitude of~3000 m.a.s.l.and in specialized alpine coniferous(Pinus)and broadleaved(Quercus)mixed forest marginal communities.These stony topographies have become ecological islands of refuge for these species in the current interglacial period.The Hengduan Mountains play a key role in the evolution,divergence,and survival of Chrysanthemum and its allies.
