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Purification Effects of Aquatic Vegetations on Lake Wetland Water Environment and Analysis of the Influencing Factors in Hongze Lake 被引量:3
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作者 赵洪波 吴睿 卡林 《Agricultural Science & Technology》 CAS 2012年第1期211-216,共6页
[Objective] To study the purification effect of plant community on wetland water environment in Hongze Lake, and to provide references to the ecological restoration of this area. [Methed] The typical lakeside zone of ... [Objective] To study the purification effect of plant community on wetland water environment in Hongze Lake, and to provide references to the ecological restoration of this area. [Methed] The typical lakeside zone of Hongze Lake Wetland National Nature Reserve was taken as the study area. Through the field survey based on environmental characteristics of aquatic areas and non-aquatic areas, combined with laboratory test, the content changes of nutrients (N and P), COD (chemical oxygen demand) and SD (transparency) levels in the water body of lake wetland were measured; the purification effect of the lake wetland ecosystem in the growth process of aquatic vegetation was quantitatively analyzed, and possible influ- encing factors were discussed. [Result] Aquatic vegetation could remove the TN, TP, COD, Chla in wetland water environment and had obvious effects on the changes of SD content. Competition between aquatic plants can inhibit the growth of algae and relieve the eutrophication of water body. [Conclusion] This study provided theoretical basis for ecological restoration and enhancement of self-purification capability in the lakeside zone of Hongze Lake. 展开更多
关键词 Aquatic vegetation Water environment Purification effect Influencing factors
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Impact of Tourism Interference on Vegetations in Xijing Mountain
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作者 杨少华 侯平 《Journal of Landscape Research》 2010年第12期32-36,40,共6页
[Objective] Taking Xijing Mountain for example,this study investigates characteristics of roadside plant communities and width changes of trampled vegetations by the tourist road,analyzes influence of tourism activiti... [Objective] Taking Xijing Mountain for example,this study investigates characteristics of roadside plant communities and width changes of trampled vegetations by the tourist road,analyzes influence of tourism activities on environment.[Method] Characteristics of roadside plant communities are studied by applying species diversity index,coverage and other such indexes;from the bottom to the top of Xijing Mountain,investigation objects are selected along the tourist road to measure the trampled width of vegetations.[Result] Characteristics of plant communities,trampled vegetations are both closely related to the design of tourist road.[Conclusion] Suggestions are proposed for the design of tourist road. 展开更多
关键词 Plant community characteristics WIDTH of trampled vegetations Design of TOURIST ROAD
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Echocardiographic predictors and associated outcomes of multiple vegetations in infective endocarditis:A pilot study
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作者 Ajay Kumar Mishra Kannu Bansal +6 位作者 Ibragim Al-Seykal Pradnya B Bhattad Anu Anna George Anil Jha Nitish Sharma Jennifer Sargent Mark J Kranis 《World Journal of Cardiology》 2024年第6期318-328,共11页
BACKGROUND Infective endocarditis(IE)is a life-threatening infection with an annual mortality of 40%.Embolic events reported in up to 80%of patients.Vegetations of>10 mm size are associated with increased embolic e... BACKGROUND Infective endocarditis(IE)is a life-threatening infection with an annual mortality of 40%.Embolic events reported in up to 80%of patients.Vegetations of>10 mm size are associated with increased embolic events and poor prognosis.There is a paucity of literature on the association of multiple vegetations with outcome.AIM To study the echocardiographic(ECHO)features and outcomes associated with the presence of multiple vegetations.METHODS In this retrospective,single-center,cohort study patients diagnosed with IE were recruited from June 2017 to June 2019.A total of 84 patients were diagnosed to have IE,of whom 67 with vegetation were identified.Baseline demographic,clinical,laboratory,and ECHO parameters were reviewed.Outcomes that were studied included recurrent admission,embolic phenomenon,and mortality.RESULTS Twenty-three(34%)patients were noted to have multiple vegetations,13(56.5%)were male and 10(43.5%)were female.The mean age of these patients was 50.Eight(35%)had a prior episode of IE.ECHO features of moderate to severe valvular regurgitation[odds ratio(OR)=4],presence of pacemaker lead(OR=4.8),impaired left ventricle(LV)relaxation(OR=4),and elevated pulmonary artery systolic pressure(PASP)(OR=2.2)are associated with higher odds of multiple vegetations.Of these moderate to severe valvular regurgitation(P=0.028),pacemaker lead(P=0.039)and impaired relaxation(P=0.028)were statistically significant.These patients were noted to have an increased association of recurrent admissions(OR=3.6),recurrent bacteremia(OR=2.4),embolic phenomenon(OR=2.5),intensive care unit stay(OR=2.8),hypotension(OR=2.1),surgical intervention(OR=2.8)and device removal(OR=4.8).Of this device removal(P=0.039)and recurrent admissions(P=0.017)were statistically significant.CONCLUSION This study highlights the associations of ECHO predictors and outcomes in patients with IE having multiple vegetations.ECHO features of moderate to severe regurgitation,presence of pacemaker lead,impaired LV relaxation,and elevated PASP and outcomes including recurrent admissions and device removal were found to be associated with multiple vegetations. 展开更多
关键词 ENDOCARDITIS ECHOCARDIOGRAPHY vegetations PREDICTORS OUTCOME
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A Fractal Method of Estimating Soil Structure Changes Under Different Vegetations on Ziwuling Mountains of the Loess Plateau,China 被引量:14
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作者 ZHAO Shi-wei SU Jing +3 位作者 YANG Yong-hui LIU Na-na WU Jin-shui SHANGGUAN Zhou-ping 《Agricultural Sciences in China》 CAS CSCD 2006年第7期530-538,共9页
Fractal method is a new method to estimate soil structure. It has been shown to be a useful tool in studies related to physical properties of soil as well as erosion and other hydrological processes. Fractal dimension... Fractal method is a new method to estimate soil structure. It has been shown to be a useful tool in studies related to physical properties of soil as well as erosion and other hydrological processes. Fractal dimension was used to study the soil structure in soil at different stages of vegetative succession on the Ziwuling Mountains. The land use and vegetation types included cultivated land, abandoned land, grassland, two types of shrub land, and three types of forests. The grassland, shrub land, and forested areas represented a continuum in vegetative succession that had occurred naturally, as the land was abandoned in 1862. Disturbed and undisturbed soil samples were collected from ten vegetation types from depths of 0-10, 10-20, and 20-30 cm on the Ziwuling Mountains, at a site with an elevation of about 1 500 m. Particle size distribution was determined by the pipette method and aggregate size distribution was determined by wet sieving. The results were used to calculate the particle and aggregate fractal dimension. The results showed that particle and aggregate fractal dimensions varied between vegetation types. There was a positive correlation between the particle fractal dimension and the weight of particles with diameter 〈 0.001 mm, but no relationship between particle fractal dimension and the other particle size classes. Particle fractal dimension was lower in vegetated soils compared to cropland and there was no consistent relationship between fractal dimension and vegetation type. Aggregate fractal dimension was positively correlated with the weight of 〉 0.25 mm aggregates. Aggregate fractal dimension was lower in vegetated soils compared with cropland. In contrast to particle fractal dimension, aggregate fractal dimension described changes in soil structure associated with vegetative succession. The results of this study indicate that aggregate fractal dimension is more effective in describing soil structure and function compared with particle fractal dimension. 展开更多
关键词 soil fractal dimension soil particle soil aggregate vegetation type Ziwuling Mountains
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Sensitivity analyses of different vegetations responding to climate change in inland river basin of China 被引量:8
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作者 Hou Peng Wang Qiao +3 位作者 Cao Guangzhen Wang Changzuo Zhan Zhiming Yang Bingfeng 《Journal of Geographical Sciences》 SCIE CSCD 2012年第3期387-406,共20页
Terrestrial ecosystem and climate system are closely related to each other. Faced with the unavoidable global climate change, it is important to investigate terrestrial ecosystem responding to climate change. In inlan... Terrestrial ecosystem and climate system are closely related to each other. Faced with the unavoidable global climate change, it is important to investigate terrestrial ecosystem responding to climate change. In inland river basin of arid and semi-arid regions in China, sensitivity difference of vegetation responding to climate change from 1998 to 2007 was analyzed in this paper. (1) Differences in the global spatio-temporal distribution of vegetation and climate are obvious. The vegetation change shows a slight degradation in this whole region. Degradation is more obvious in densely vegetated areas. Temperature shows a general downward trend with a linear trend coefficient of -1.1467. Conversely, precipitation shows an increasing trend with a linear trend coefficient of 0.3896. (2) About the central tendency response, there are similar features in spatial distribution of both NDVI responding to precipitation (NDVI-P) and NDVI responding to AI (NDVI-AI), which are contrary to that of NDVI responding to air temperature (NDVI-T). Typical sensitivity region of NDVI-P and NDVI-AI mainly covers the northern temperate arid steppe and the northern temperate desert steppe. NDVI-T typical sensitivity region mainly covers the northern temperate desert steppe. (3) Regarding the fluctuation amplitude response, NDVI-T is dominated by the lower sensitivity, typical regions of the warm temperate shrubby, selui-shrubby, bare extreme dry desert, and northern temperate meadow steppe in the east and temperate semi-shrubby, dwarf arboreous desert in the north are high response. (4) Fluctuation amplitude responses between NDVI-P and NDVI-AI present a similar spatial distribution. The typical sensitivity region mainly covers the northern temperate desert steppe. There are various linear change trend responses of NDVI-T, NDVI-P and NDVI-AI. As to the NDVI-T and NDVI-AI, which are influenced by the boundary effect of semi-arid and semi-humid climate zones, there is less correlation of their linear change tendency along the border. There is stronger correlation in other regions, especially in the NDVI-T in the northern temperate desert steppe and NDVI-AI in the warm temperate shrubby, selui-shrubby, bare, extreme and dry desert. 展开更多
关键词 VEGETATION CLIMATE satellite images sensitivity analyses inland river basin China
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Fractions and Bioavailability of Soil Inorganic Phosphorus in the Loess Plateau of China under Different Vegetations 被引量:6
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作者 WEI Xiaorong SHAO Mingan +2 位作者 SHAO Hongbo GAO Jianlun XU Gang 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2011年第1期263-270,共8页
Plants play an important role in soil phosphorus nutrition. However, the effect of plants on phosphorus nutrition in soils of the Loess Plateau of China is not well understood. This study was conducted to reveal the r... Plants play an important role in soil phosphorus nutrition. However, the effect of plants on phosphorus nutrition in soils of the Loess Plateau of China is not well understood. This study was conducted to reveal the relationships between plants and phosphorus' fractions and availability in the Loess Plateau of China. Twenty-two plant communities were surveyed and soil samples under different plant canopies were collected for the determination of soil properties and inorganic phosphorus fractionation. The results showed that Leguminosae and Lilaceae reduced pH and increased organic matter, cation exchange capacity, total and Olsen phosphorus in soils under their canopies, while Labiatae and Rosaceae increased pH and decreased organic matter, cation exchange capacity, total and Olsen phosphorus in soils under their canopies. The contents of Ca2P, CasP, AI-P and Fe-P were highly related with soil Oisen phosphorus. They were all higher in soils under Leguminosae and Lilaceae and lower in softs under Labiatae and Rosaceae. The results of this study indicate that Leguminosae and Lilaceae improved phosphorus nutrition in soils, yet Labiatae and Rosaceae impeded the improvement of phosphorus nutrition in soils under their canopies, which will be of more help to instruct vegetation restoration in the region and provide information for soil development. 展开更多
关键词 BIOAVAILABILITY FRACTION inorganic phosphorus VEGETATION soil development Loess Plateau
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Velocity distribution of flow with submerged flexible vegetations based on mixing-length approach 被引量:2
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作者 槐文信 韩杰 +3 位作者 曾玉红 安翔 钱忠东 Yu-lu LIU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2009年第3期343-351,共9页
By choosing a PVC slice to simulate flexible vegetation, we carried out experiments in an open channel with submerged flexible vegetation. A 3D acoustic Doppler velocimeter (micro ADV) was used to measure local flow... By choosing a PVC slice to simulate flexible vegetation, we carried out experiments in an open channel with submerged flexible vegetation. A 3D acoustic Doppler velocimeter (micro ADV) was used to measure local flow velocities and Reynolds stress. The results show that hydraulic characteristics in non-vegetation and vegetation layers are totally different. In a region above the vegetation, Reynolds stress distribution is linear, and the measured velocity profile is a classical logarithmic one. Based on the concept of new-riverbed, the river compression parameter representing the impact of vegetation on river is given, and a new assumption of mixing length expression is made. The formula for time-averaged velocity derived from the expression requires less parameters and simple calculation, and is useful in applications. 展开更多
关键词 flexible vegetation PVC slice micro ADV mixing-length approach streamwise velocity distribution Reynolds stress river compression parameter
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Modelling analysis embodies drastic transition among global potential natural vegetations in face of changing climate
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作者 Zhengchao Ren Lei Liu +1 位作者 Fang Yin Xiaoni Liu 《Forest Ecosystems》 SCIE CSCD 2024年第2期184-192,共9页
Potential natural vegetation(PNV)is a valuable reference for ecosystem renovation and has garnered increasing attention worldwide.However,there is limited knowledge on the spatio-temporal distributions,transitional pr... Potential natural vegetation(PNV)is a valuable reference for ecosystem renovation and has garnered increasing attention worldwide.However,there is limited knowledge on the spatio-temporal distributions,transitional processes,and underlying mechanisms of global natural vegetation,particularly in the case of ongoing climate warming.In this study,we visualize the spatio-temporal pattern and inter-transition procedure of global PNV,analyse the shifting distances and directions of global PNV under the influence of climatic disturbance,and explore the mechanisms of global PNV in response to temperature and precipitation fluctuations.To achieve this,we utilize meteorological data,mainly temperature and precipitation,from six phases:the Last Inter-Glacial(LIG),the Last Glacial Maximum(LGM),the Mid Holocene(MH),the Present Day(PD),2030(20212040)and 2090(2081–2100),and employ a widely-accepted comprehensive and sequential classification sy–stem(CSCS)for global PNV classification.We find that the spatial patterns of five PNV groups(forest,shrubland,savanna,grassland and tundra)generally align with their respective ecotopes,although their distributions have shifted due to fluctuating temperature and precipitation.Notably,we observe an unexpected transition between tundra and savanna despite their geographical distance.The shifts in distance and direction of five PNV groups are mainly driven by temperature and precipitation,although there is heterogeneity among these shifts for each group.Indeed,the heterogeneity observed among different global PNV groups suggests that they may possess varying capacities to adjust to and withstand the impacts of changing climate.The spatio-temporal distributions,mutual transitions and shift tendencies of global PNV and its underlying mechanism in face of changing climate,as revealed in this study,can significantly contribute to the development of strategies for mitigating warming and promoting re-vegetation in degraded regions worldwide. 展开更多
关键词 Potential natural vegetation Global warming Vegetation classification Predicted model CSCS
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Floral Diversity of Abandoned Mansions and the Influence of Soil Properties on These Unique Vegetations
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作者 Md. Tahidul Islam Md. Mahadiy Hasan +2 位作者 Md. Ashikur Rahman Laskar Subroto K. Das Tania Sultana 《American Journal of Plant Sciences》 2021年第10期1559-1600,共42页
Abandoned land and mansions are always a matter of curiosity to the human beings. They are treated as haunted places in many societies. In the present research, three decrepit abandoned mansions from the southern Bang... Abandoned land and mansions are always a matter of curiosity to the human beings. They are treated as haunted places in many societies. In the present research, three decrepit abandoned mansions from the southern Bangladesh were investigated to measure their floral diversity, physico-chemical properties of soil and the soil-plant interrelationship which is responsible for the diversification of wild flora within the regions. From Shannon and Simpson diversity indexes, it can be deducted that the floral diversity within the abandoned mansions ha</span><span style="font-family:"">s</span><span style="font-family:""> a<span style="color:red;"> </span>positive relationship with their territory size. The high values of Marg<span>alef’s and Menhinick’s species richness indexes confirmed that these areas are a rich source of a large number of plant species. A great variation in soil physico-chemical properties has been observed during the analysis. Soil organic matter, nitrogen, phosphorus, potassium & moisture contents were varied significantly from one quadrat to another in every site. Biplot analysis showed that the distribution of plant species in abandoned mansions </span></span><span style="font-family:"">is</span><span style="font-family:""> primarily determined by the organic matter, pH, moisture and potassium contents of soil. As t</span><span style="font-family:"">hese factors were present in versatile distribution within the studied regions, a great number of plants can grow in the same area simultaneously. So these areas should be protected from human intervention to proce</span><span style="font-family:"">ss</span><span style="font-family:""> natural selection and in situ conservation of plant species. 展开更多
关键词 Floral Diversity Abandoned Area Soil Properties VEGETATION
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A random walk simulation of scalar mixing in flows through submerged vegetations 被引量:14
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作者 梁东方 WU Xuefei 《Journal of Hydrodynamics》 SCIE EI CSCD 2014年第3期343-350,共8页
The scalar transport phenomena in vertical two-dimensional flows are studied using the random walk method. The established Lagrangian model is first applied to study the idealized longitudinal dispersion in open chann... The scalar transport phenomena in vertical two-dimensional flows are studied using the random walk method. The established Lagrangian model is first applied to study the idealized longitudinal dispersion in open channels, before being used to investigate the scalar mixing characteristics of the flows through submerged vegetations. The longitudinal dispersion coefficients of the fully-developed boundary layer flows, with and without vegetations, are calculated based on the positions of the particles. A convenient way of incorporating the effects of vegetations is proposed, where all the flow parameters are regarded to be continually distributed over the depth. The simulation results show high accuracy of the developed random walk method, and indicate that the new method of accounting for the vegetation effects is appropriate for all the test cases considered. The predicted longitudinal dispersion coefficients agree well with the measurements. The merit of the new method is highlighted by its simplicity and efficiency in comparison with the conventional method that assumes the discontinuous distribution of the flow parameters over the depth. 展开更多
关键词 random walk longitudinal dispersion submerged vegetations scalar mixing
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Differential Vegetation Feedback on the Global Land Monsoon System during the Mid-Holocene and Last Interglacial
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作者 Zhenqian WANG Qiong ZHANG +1 位作者 Jie CHEN Zixuan HAN 《Advances in Atmospheric Sciences》 2026年第1期103-119,共17页
This study investigates the impact of vegetation-climate feedback on the global land monsoon system during the Last Interglacial(LIG,127000 years BP)and the mid-Holocene(MH,6000 years BP)using the earth system model E... This study investigates the impact of vegetation-climate feedback on the global land monsoon system during the Last Interglacial(LIG,127000 years BP)and the mid-Holocene(MH,6000 years BP)using the earth system model EC-Earth3.Our findings indicate that vegetation changes significantly influence the global monsoon area and precipitation patterns,especially in the North African and Indian monsoon regions.The North African monsoon region experienced the most substantial increase in vegetation during both the LIG and MH,resulting in significant increases in monsoonal precipitation by 9.8%and 6.0%,respectively.The vegetation feedback also intensified the Saharan Heat Low,strengthened monsoonal flows,and enhanced precipitation over the North African monsoon region.In contrast,the Indian monsoon region exhibited divergent responses to vegetation changes.During the LIG,precipitation in the Indian monsoon region decreased by 2.2%,while it increased by 1.6%during the MH.These differences highlight the complex and region-specific impacts of vegetation feedback on monsoon systems.Overall,this study demonstrates that vegetation feedback exerts distinct influences on the global monsoon during the MH and LIG.These findings highlight the importance of considering vegetation-climate feedback in understanding past monsoon variability and in predicting future climate change impacts on monsoon systems. 展开更多
关键词 Last Interglacial MID-HOLOCENE global land monsoon vegetation feedback
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Optimizing a multimedia model to assess the differential roles of crops and natural vegetation in the fate of PAHs
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作者 Chao Su Danfeng Zheng +7 位作者 Wenlei Chen Kifayatullah Khan Hong Zhang Shuai Song Ruoyu Liang Xiaoyu Zhang Yong Liu Xianghui Cao 《Journal of Environmental Sciences》 2026年第1期413-423,共11页
Vegetation plays an important role in the environmental transport behavior of organic pollutants,however,the different roles of crops and natural vegetation have been ignored in most previous studies.In this study,we ... Vegetation plays an important role in the environmental transport behavior of organic pollutants,however,the different roles of crops and natural vegetation have been ignored in most previous studies.In this study,we developed the BETR-Urban-Rural-Veg model to quantitatively evaluate the influences of both natural vegetation and crops on the multimedia transport processes of Phenanthrene(PHE)and Benzo(a)pyrene(BaP)in mainland of China.The geographic distribution of polycyclic aromatic hydrocarbon(PAH)emissions and concentrations were consistent,displaying higher levels in northern China while lower levels in southern China.Under seasonal simulations,for both natural vegetation and crops,PAH concentrations in winter and spring were 1.5 to 27-fold higher than in summer and autumn,especially for PHE.Owing to the higher leaf area index(LAI)of natural vegetation and harvesting of crops,the filter and sequestration effect of natural vegetation was stronger than crops,while the seasonal changes of PAH concentrations in crops were more significant than natural vegetation.Temperature,precipitation rates and LAI might have important influences on seasonal concentrations and overall persistence of PAHs.PHE was more sensitive to the impacts of seasonal environmental parameters.Under different landscape scenarios,average annual PAH concentrations in natural vegetation were always a little higher than those in crops,and the overall persistence of BaP was greatly affected increasing by 15.15%-16.47%.This improved model provides a useful tool for environmental management.The results of this study are expected to support land use plans and decision-making in China's mainland. 展开更多
关键词 Multimedia fate model Natural vegetation CROPS Seasonal variabilities Landscape scenarios
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Primary Systemic Amyloidosis Presenting as Skin Vegetations:A Case Report
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作者 Meng-Hua Li Li-Ming Wu 《International Journal of Dermatology and Venereology》 2022年第3期178-180,共3页
Introduction:Primary systemic amyloidosis is characterized by clonal plasma cell disorder,and its signs and symptoms are various and complex,damage to the skin and mucous membrane is often more likely to attract atten... Introduction:Primary systemic amyloidosis is characterized by clonal plasma cell disorder,and its signs and symptoms are various and complex,damage to the skin and mucous membrane is often more likely to attract attention.Here we reported a case of a 61-year-old male patient who presented with topical mucocutaneous lesion,as well unusual skin vegetations.Case presentation:A 61-year-old man was hospitalized due to repeated burning sensation on his back,multiple ecchymosis,and skin vegetations.Through a series of examinations(mainly including skin histopathology,bone marrow cytology,bone marrow flow cytometry,immunofixation electrophoresis),Primary systemic amyloidosis was diagnosed,but multiple myeloma could not be diagnosed.Subsequently,he received chemotherapy.In the half-year follow-up,there was no significant change in his symptoms and signs.Discussion:In this case,in addition to the typical skin damage of primary amyloidosis,the multiple skin vegetations in the buttocks,abdomen,and arms are particularly noteworthy.According to the histopathology and Immunohistochemistry of the skin vegetation,we infer that the formation mechanism of these skin vegetation is lymphatic obstruction caused by amyloid,which leads to lymphatic dilatation,lymph leakage,and dermal edema.Conclusion:Primary systemic amyloidosis is a rare disease,which is often difficult to diagnose.We should be alert to those atypical skin features so as not to delay diagnosis. 展开更多
关键词 primary systemic amyloidosis skin vegetations case report
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Effects of vegetations on the removal of contaminants in aquatic environments: A review 被引量:25
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作者 王超 郑莎莎 +1 位作者 王沛芳 钱进 《Journal of Hydrodynamics》 SCIE EI CSCD 2014年第4期497-511,共15页
This paper reviews the removal of contaminants including nutrients, metals and organic pollutants by vegetations in aquatic environments. The removal efficiencies are considered with respect to 16, 19 and 14 kinds of ... This paper reviews the removal of contaminants including nutrients, metals and organic pollutants by vegetations in aquatic environments. The removal efficiencies are considered with respect to 16, 19 and 14 kinds of different aquatic plants, respectively in three tables. Due to different characteristics, the removal effects of plants on contaminants from the overlying water differ greatly. The vegetation can improve the water quality mainly through two ways: (1) to adsorb and absorb pollutants from water, (2) to prevent pollutants from releasing from sediment. The contaminant removal mechanisms of vegetations and related physical, chemical and biological effects are discussed. The effects of vegetations on the contaminant removal are found to depend on the environmental conditions, the number and the type of plants, the nature and the chemical structure of the pollutants. In addition, the contaminant release and reoaoval by vegetations under hydrodynamic conditions is specially addressed. Further research directions are suggested. 展开更多
关键词 VEGETATION NUTRIENT metal organic pollutant REMOVAL hydrodynamic condition
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Flow characteristics of the wind-driven current with submerged and emergent flexible vegetations in shallow lakes 被引量:3
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作者 王超 范秀磊 +2 位作者 王沛芳 侯俊 钱进 《Journal of Hydrodynamics》 SCIE EI CSCD 2016年第5期746-756,共11页
A pneumatic annular flume is designed to simulate the current induced by the wind acting on the water surface in shallow lakes and the experiments are conducted to investigate the influence of submerged and emergent f... A pneumatic annular flume is designed to simulate the current induced by the wind acting on the water surface in shallow lakes and the experiments are conducted to investigate the influence of submerged and emergent flexible vegetations of different densities on the flow characteristics (e.g., the flow velocity, the turbulence intensity, the vegetal drag coefficient CD and the equivalent roughness coefficient nb ) at different wind speeds. Vallisneria natans (K natans ) and Acorus calamus (A. calamus) widely distributed in Taihu Lake are selected in this study. It is indicated that the vertical distribution profiles are in logarithmic- curves, The stream-wise velocity rapidly decreases with the increasing vegetation density. The flow at the lower layer of the vegeta- tion sees compensation current characteristics when the vegetation density is the largest. The turbulence intensity in the flume without vegetation is the highest at the free surface and it is near the canopy top for the flume with V. natans. The turbulence intensity near the bottom in the flume with vegetation is smaller than that in the flume without vegetation. A. calamus exerts much larger resistance to the flow than V. natans. The variations of CD and nb caused by the vegetation density and the wind speed are also discussed. 展开更多
关键词 velocity profile turbulence intensity flow resistance aquatic vegetation wind-driven current
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Numerical investigation of the dynamics of flexible vegetations in turbulent open-channel flows 被引量:3
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作者 Dong Xu Jia-ning Liu +1 位作者 Yun-feng Wu Chun-ning Ji 《Journal of Hydrodynamics》 SCIE EI CSCD 2022年第4期681-699,共19页
Aquatic vegetations widely exist in natural rivers and play an essential role in the evolution of the water environment and ecosystem by changing the river’s hydrodynamic characteristics and transporting sediments an... Aquatic vegetations widely exist in natural rivers and play an essential role in the evolution of the water environment and ecosystem by changing the river’s hydrodynamic characteristics and transporting sediments and nutrition.In reality,most aquatic vegetations are highly flexible,which invalidates the“rigid-cylinder”assumption widely adopted in many literatures.To explore the dynamics of submerged flexible vegetation in open-channel flows and its feedback to turbulent flow structures,numerical simulations are carried out using an in-house fluid-structure interaction(FSI)solver.In the simulations,the geometry of vegetation plants is grid-resolved,the turbulent flow is simulated using the large eddy simulation(LES),the dynamics of the flexible plants are solved using the vector form intrinsic finite element(VFIFE)method,and the turbulent flow and the plants are two-way coupled using the immersed boundary(IB)method.The dynamic responses of the flexible vegetation with different plant flexibility,spacing,and submergence are investigated.Simulation results show that flexible plants are subjected to complex flow-induced vibrations(FIVs)rather than static bending.The FIV involves both streamwise and cross-flow motions driven by the small-scale vortex shedding around the plants and the large-scale Kelvin-Helmholtz(K-H)vortices developed in the vegetation canopy layer.The vegetations exhibit pulsive wave motion of different patterns in relatively long and narrow open channels.Compared with the open-channel flows with static plants with equivalent bending deformation,the dynamic responses of flexible plants may increase the turbulent Reynolds stress of the open-channel flow by 70%–100%and increase the invasion depth of the K-H vortices by 30%–50%. 展开更多
关键词 Flexible vegetation dynamic responses flow-induced vibration(FIV) fluid-structure interaction(FSI)
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Impact of marshy area reclamation by various vegetations on soil-nematode community structure in Dachigam National Park
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作者 Humira Nesar Shahid Afzal +1 位作者 Zarrin Imran Wasim Ahmad 《Soil Ecology Letters》 CSCD 2023年第3期123-133,共11页
Marshy areas are ecologically important and sensitive areas which are under immense pressure,such as reclamation by various terrestrial vegetations.However,how these vegetation types disrupt the stability of nematode ... Marshy areas are ecologically important and sensitive areas which are under immense pressure,such as reclamation by various terrestrial vegetations.However,how these vegetation types disrupt the stability of nematode community is scarce.The present study determined how the soil nematode community responded to shifting environmental states by using nematode abundances,nematode indices and metabolic footprints as indicators.In this context,we selected three types of reclaimed vegetation around a marshy land(MR)in Dachigam National Park,Kashmir,which includes grassland(GL),forest(FR)and cropland(CL)to investigate the soil nematode community.Acrobeloides,Plectus,Eudorylaimus,and Aphelenchus proved more sensitive to reclamation effect.Results revealed decrease in total nematode and bacterivore abundance.Reclamation reduced diversity in CL,whereas no effect was observed in the GL and FR as compared to MR.Channel index indicated shift from fungal decomposition to bacterial decomposition pathway in GL.The nematode faunal profile depicted grassland(GL)as the most structured ecosystem compared to MR,FR,and CL.Our results suggest that vegetation type regulates the structure,function,and stability of the soil food web,which has significant implications for managing the vegetation cover in a sustainable manner in the Dachigam National Park. 展开更多
关键词 nematodes DIVERSITY VEGETATION HABITAT RECLAMATION
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松嫩平原玉米秸秆遥感估算及其保护性耕作潜力分析
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作者 卓开锃 杨凤芸 杜嘉 《地理科学》 北大核心 2025年第9期2096-2106,共11页
本研究基于Google Earth Engine(GEE)平台,结合Sentinel-2时间序列遥感影像、气温、辐射数据以及文献中的收获指数,应用改进的Vegetation Photosynthesis Model(VPM)对松嫩平原的秸秆产量进行了估算。遥感影像用于提取植被生长和水分状... 本研究基于Google Earth Engine(GEE)平台,结合Sentinel-2时间序列遥感影像、气温、辐射数据以及文献中的收获指数,应用改进的Vegetation Photosynthesis Model(VPM)对松嫩平原的秸秆产量进行了估算。遥感影像用于提取植被生长和水分状况,温度与辐射数据则用于模拟模型中的生物物理过程。模型验证方面,研究通过实测数据和县级统计数据对遥感估算结果进行了验证。在此基础上,依据保护性耕作的定义和实施条件,结合估算的秸秆产量和气候数据,分析了松嫩平原的保护性耕作潜力。研究结果表明,2022年秸秆估算产量与县级统计数据的相关系数R^(2)为0.93,均方根误差(RMSE)为17.52万t;实测与估算的秸秆产量相关系数R^(2)为0.62,RMSE为936.4 kg/hm^(2),改进的VPM模型在秸秆产量估算中的准确性较好。基于气候和秸秆产量条件,松嫩平原有94.93%的区域适宜进行保护性耕作。研究证实了VPM模型在玉米(Zea mays)秸秆产量估算中的有效性,并对松嫩平原的保护性耕作潜力进行了评估。研究可为秸秆资源的综合利用与区域保护性耕作的实施提供科学数据支持,为农业可持续发展提供理论依据。 展开更多
关键词 Vegetation Photosynthesis Model(VPM) Sentinel-2 秸秆产量 保护性耕作潜力
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Quantitative Analysis of the Fatty Acid Compositions of Different Oils and Associations with Antioxidant Capacity and Oxidative Stability 被引量:1
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作者 LIU Junchen SUN Xiaoman +3 位作者 ZHANG Huirong SHAO Haofan LING Xiao LI Li 《现代食品科技》 北大核心 2025年第4期305-315,共11页
Fatty acids are the main constituents of vegetable oils.To determine the fatty acid compositions of small trade vegetable oils and some less well studied beneficial vegetable oils,and investigate their relationships w... Fatty acids are the main constituents of vegetable oils.To determine the fatty acid compositions of small trade vegetable oils and some less well studied beneficial vegetable oils,and investigate their relationships with antioxidant activity and oxidative stability,gas chromatography-mass spectrometry was performed to characterize the associated fatty acid profiles.The antioxidant activity of vegetable oils,based on their DPPH-scavenging capacity(expressed as IC_(50) values),was used to assess their impact on human health,and their oxidative stability was characterized by performing lipid oxidation analysis to determine the oxidative induction time of fats and oils.In addition,correlation analyses were performed to examine associations between the fatty acid composition of the oils and DPPH-scavenging capacity and oxidative stability.The results revealed that among the assessed oils,coffee seed oil has the highest saturated fatty acid content(355.10 mg/g),whereas Garddenia jaminoides oil has the highest unsaturated fatty acid content(844.84 mg/g).Coffee seed oil was also found have the lowest DPPH IC_(50) value(2.30 mg/mL)and the longest oxidation induction time(17.09 h).Correlation analysis revealed a significant linear relationship(P<0.05)between oxidative stability and unsaturated fatty acid content,with lower contents tending to be associated with better oxidative stability.The findings of this study provide reference data for the screening of functional edible vegetable oils. 展开更多
关键词 gas chromatography-mass spectrometry vegetable oil fatty acid composition oxidative stability antioxidant capacity
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High-Priority Actions to Improve Carbon Sequestration Potential for Mining Ecological Restoration in China 被引量:3
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作者 Fu Chen Yanfeng Zhu +3 位作者 Yinli Bi Yongjun Yang Jing Ma Suping Peng 《Engineering》 2025年第4期16-21,共6页
1.Introduction Changes in land use are key factors promoting global climate change,and the side effects of mining activity that destroy the soil,vegetation,and biodiversity lead to imbalanced carbon cycling in terrest... 1.Introduction Changes in land use are key factors promoting global climate change,and the side effects of mining activity that destroy the soil,vegetation,and biodiversity lead to imbalanced carbon cycling in terrestrial ecosystems. 展开更多
关键词 biodiversity impairment land use changes soil destruction global climate changeand mining activity land use vegetation loss imbalanced carbon cycling
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