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Response of vegetation variation to climate change and human activities in the Shiyang River Basin of China during 2001-2022

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Journal of Arid Land 2024年第8期16卷 1044-1061页

作者： SUN Chao BAI Xuelian WANG Xinping ZHAO Wenzhi wei lemin Northwest Institute of Eco-Environment and Resources Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Gansu Provincial Academy of Water Sciences Lanzhou 730000China

Understanding the response of vegetation variation to climate change and human activities is critical for addressing future conflicts between humans and the environment,and maintaining ecosystem ***,we aimed to identify the determining factors of vegetation variation and explore the sensitivity of vegetation to temperature(SVT)and the sensitivity of vegetation to precipitation(SVP)in the Shiyang River Basin(SYRB)of China during *** climate data from climatic research unit(CRU),vegetation index data from Moderate Resolution Imaging Spectroradiometer(MODIS),and land use data from Landsat images were used to analyze the spatial-temporal changes in vegetation indices,climate,and land use in the SYRB and its sub-basins(i.e.,upstream,midstream,and downstream basins)during *** regression analysis and correlation analysis were used to explore the SVT and SVP,revealing the driving factors of vegetation *** increasing trends(P<0.05)were detected for the enhanced vegetation index(EVI)and normalized difference vegetation index(NDVI)in the SYRB during 2001-2022,with most regions(84%)experiencing significant variation in vegetation,and land use change was determined as the dominant factor of vegetation ***-significant decreasing trends were detected in the SVT and SVP of the SYRB during *** were spatial differences in vegetation variation,SVT,and *** NDVI and EVI exhibited increasing trends in the upstream,midstream,and downstream basins,the change slope in the downstream basin was lower than those in the upstream and midstream basins,the SVT in the upstream basin was higher than those in the midstream and downstream basins,and the SVP in the downstream basin was lower than those in the upstream and midstream *** and precipitation changes controlled vegetation variation in the upstream and midstream basins while human activities(land use change)dominated vegetation variation in the d

关键词： vegetation variation climate change land use change normalized difference vegetation index(NDVI) enhanced vegetation index(EVI) Shiyang River Basin

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Utilizing sediment grain size characteristics to assess the effectiveness of clay–sand barriers in reducing aeolian erosion in Minqin desert area,China

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Journal of Arid Land 2024年第5期16卷 668-684页

作者： SONG Dacheng ZHAO Wenzhi LI Guangyu wei lemin WANG Lide YANG Jingyi WU Hao MA Quanlin College of Forestry Gansu Agricultural UniversityLanzhou 730070China Gansu Hexi Corridor Forest Ecosystem National Research Station Gansu Desert Control Research InstituteLanzhou 730070China Linze Inland River Basin Research Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

The clay–sand barriers in Minqin desert area,China,represent a pioneering windbreak and sand fixation project with a venerable history of 60 ***,studies on evaluating the long-term effectiveness of clay–sand barriers against aeolian erosion,particularly from the perspective of surface sediment grain size,are limited and thus insufficient to ascertain the protective impact of these barriers on regional aeolian *** study focused on the surface sediments(topsoil of 0–3 cm depth)of clay–sand barriers in Minqin desert area to explain their erosion resistance from the perspective of surface sediment grain *** March 2023,six clay–sand barrier sampling plots with clay–sand barriers of different deployment durations(1,5,10,20,40,and 60 a)were selected as experimental plots,and one control sampling plot was set in an adjacent mobile sandy area without sand *** sediment samples were collected from the topsoil of each sampling plot in the study area in April 2023 and sediment grain size characteristics were *** indicated a predominance of fine and medium sands in the surface sediments of the study *** deployment of clay–sand barriers cultivated a fine quality in grain size composition of the regional surface sediments,increasing the average contents of very fine sand,silt,and clay by 30.82%,417.38%,and 381.52%,*** trend became markedly pronounced a decade after the deployment of clay–sand *** effectiveness of clay–sand barriers in erosion resistance was manifested through reduced wind velocity,the interception of sand flow,and the promotion of fine surface sediment *** particles such as medium,coarse,and very coarse sands predominantly accumulated on the external side of the barriers,while finer particles such as fine and very fine sands concentrated in the upwind(northwest)region of the *** contrast,the contents of finest particles such as silt and clay were higher in the downwind

关键词： clay-sand barriers sediment grain size grain size distribution aeolian erosion windbreak and sand fixation Minqin desert area

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术后发生重症肺栓塞的急诊导管及导丝碎栓治疗

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上海医学 2003年第11期26卷 834-835页

作者：王乐民魏林孙政育李晓光刘雅君同济大学附属同济医院心内科上海200065 哈尔滨医科大学第四临床医学院心内科

目的　探讨急诊导管、导丝治疗术后重症肺栓塞的可行性。方法　 6例术后发生急性重症肺栓塞患者均采用肺动脉造影及导管、导丝碎栓术。结果　 6例患者经造影证实其肺动脉内均有大块状血栓栓塞 ,经导管、导丝碎栓治疗后 ,5例患者痊愈。... 详细信息

目的　探讨急诊导管、导丝治疗术后重症肺栓塞的可行性。方法　 6例术后发生急性重症肺栓塞患者均采用肺动脉造影及导管、导丝碎栓术。结果　 6例患者经造影证实其肺动脉内均有大块状血栓栓塞 ,经导管、导丝碎栓治疗后 ,5例患者痊愈。结论　通过急诊肺动脉造影和直接导管介入治疗 ,可使术后大面积肺栓塞患者的血流动力学迅速得到改善。

关键词：术后并发症重症肺栓塞急诊导管碎栓术导丝碎栓术治疗血流动力学

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Vacuum ultraviolet photovoltaic arrays

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Photonics Research 2019年第1期7卷 98-102页

作者： wei ZHENG RICHENG LIN lemin JIA FENG HUANG State Key Laboratory of Optoelectronic Materials and Technologies School of Materials Sun Yat-sen University

As one of the ideal tools for monitoring the formation and evolution of solar storms, the vacuum ultraviolet(VUV) detector should have both a fast temporal response and an array structure that enables image ***, by combining a nontraditional graphene processing technique with traditional metal organic chemical vapor deposition epitaxy technology, we created hybrid heterostructure(HH) arrays of p-Gr/AlN/p-Si with VUV photovoltaic response capability and silicon integration potential. The HH arrays not only exhibit ultrafast temporal response(rise time of only 120 ns) and an extremely high I_(on)∕I_(off) ratio of 10~7, but also achieve the imaging demonstration of a VUV pattern for the first time. The HH technique provides a possible new path for the development of VUV imaging devices.

关键词： monitoring processing technique traditional metal

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祁连山自然保护区煤矿修复区地表节肢动物分布特征及其影响因素

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中国沙漠 2022年第6期42卷 165-175页

作者：罗维成赵文智刘继亮杨竟艺白雪莲魏乐民冯怡琳中国科学院西北生态环境资源研究院临泽内陆河流域研究站甘肃兰州730000 甘肃农业大学甘肃兰州730000 中国科学院大学北京100049 宁夏大学宁夏银川750021

恢复人工植被是祁连山自然保护区矿区废弃地修复的主要手段,经过近5年的修复,矿区废弃地修复区地上植被盖度明显提高,但关于作为评价土壤修复效果重要指标的土壤动物群落变化的认识还很有限。以祁连山自然保护区典型煤矿废弃地为研究对... 详细信息

恢复人工植被是祁连山自然保护区矿区废弃地修复的主要手段,经过近5年的修复,矿区废弃地修复区地上植被盖度明显提高,但关于作为评价土壤修复效果重要指标的土壤动物群落变化的认识还很有限。以祁连山自然保护区典型煤矿废弃地为研究对象,采用野外调查的方法对比研究了煤矿修复区和毗邻区(原始地貌)大型土壤动物分布特征及其影响因素。结果表明:(1)修复区植物丰富度、生物量、盖度及土壤粗砂、有机质、全氮含量均显著低于毗邻区(P0.05)。(2)修复区土壤动物活动密度和多样性均显著高于毗邻区,修复区和毗邻区土壤动物均以蝗科(12.7%和55.7%)和蚁科(14.4%和49.6%)为主;进房沟、水磨沟和柳树沟煤矿修复区及毗邻区土壤动物群落相似性分别为39.9%、52.9%和43.4%。(3)土壤有机质含量是影响煤矿修复区和对照区捕食性土壤动物群落变化的主要因子,而草本物种数和土壤粗砂含量是影响植食性土壤动物群落变化的主要因子。总之,人工修复后煤矿废弃地修复区土壤动物个体数均高于对照区,部分矿区修复生境类群丰富度及多样性已经超过了毗邻区,这表明蚂蚁、步甲和蝗虫等地表节肢动物对煤矿矿区覆土恢复植被和封禁等措施驱动的植被和土壤环境变化响应敏感。因此,还需要优化植被及土壤修复模式,提高土壤动物多样性及多功能性,使矿区废弃地生态环境能够得到快速修复。

关键词：祁连山自然保护区矿区修复地表节肢动物群落结构影响要素

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疏勒河流域土地利用变化对净初级生产力的影响

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生态科学 2021年第5期40卷 102-108页

作者：周妍妍郑续魏乐民郭建军岳东霞兰州大学资源环境学院兰州730000 中国科学院西北生态环境资源研究院沙漠与沙漠化重点实验室兰州730000

研究区域土地利用变化对植被净初级生产力(NPP)的影响,对厘清植被的生长状况及其和土地利用变化的关系,以及维持区域生态环境可持续发展具有重要意义。以中国西北干旱区疏勒河流域为例,基于土地利用数据和CASA模型计算的2001—2015年植... 详细信息

研究区域土地利用变化对植被净初级生产力(NPP)的影响,对厘清植被的生长状况及其和土地利用变化的关系,以及维持区域生态环境可持续发展具有重要意义。以中国西北干旱区疏勒河流域为例,基于土地利用数据和CASA模型计算的2001—2015年植被NPP数据,分析了疏勒河流域NPP的时空变化特征,探讨土地利用变化对植被NPP的影响。结果如下:2001—2015年,疏勒河流域NPP年总值整体上呈上升的趋势。NPP增加的区域占总面积的84.29%,上游山区和中下游绿洲区增加的最显著。NPP减少的区域占总面积的15.71%,主要分布于北部的肃北、敦煌的西部和南部及中下游绿洲的南北两侧。15年间土地利用的面积变化对NPP贡献率空间差异显著,但总体上对NPP总量增加起到促进作用,且耕地面积的变化对NPP总量的贡献率最大。

关键词：疏勒河流域土地利用净初级生产力时空变化

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8-nm narrowband photodetection in diamonds

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Opto-Electronic Science 2023年第7期2卷 1-11页

作者： lemin Jia Lu Cheng wei Zheng State Key Laboratory of Optoelectronic Materials and Technologies School of MaterialsSun Yat-sen UniversityShenzhen 518107China

Spectrally-selective photodetection plays a crucial role in various applications,including target imaging and environmental *** deep-ultraviolet(DUV)narrowband photodetection systems consist of broadband photodetectors and filters,which complicates the architecture and constrains imaging ***,we introduce an electronic-grade diamond single-crystal photodetector exhibiting an exceptionally narrow spectral response in the DUV range with a full width at half maximum of 8 *** examining diamond photodetectors with varying dislocation densities,we propose that mitigating the defect-induced trapping effect to achieve charge collection narrowing,assisted by free exciton radiative recombination,is an effective strategy for narrowband *** superior performance of this device is evidenced through the imaging of DUV light sources,showcasing its capability to differentiate between distinct light sources and monitor human-safe sterilization *** findings underscore the promising potential applications of electronicgrade diamond in narrowband photodetection and offer a valuable technique for identifying electronic-grade diamond.

关键词： narrowband photodetection electronic-grade diamond charge collection narrowing

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面向数字孪生流域的多尺度三维数据底板建设

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河南科技 2024年第10期51卷 10-15页

作者：高永红田帅帅陈乐旻范伟王芳李震黄河勘测规划设计研究院有限公司河南郑州450003

【目的】数据底板是数字孪生相关项目建设的第一要务,是数字孪生流域“四预”目标实现的“基石”。【方法】根据水利部智慧水利实施方案和流域信息化需求,提出了基于地理空间数据的多尺度三维数字底板建设方案思路,明确了三维场景数据... 详细信息

【目的】数据底板是数字孪生相关项目建设的第一要务,是数字孪生流域“四预”目标实现的“基石”。【方法】根据水利部智慧水利实施方案和流域信息化需求,提出了基于地理空间数据的多尺度三维数字底板建设方案思路,明确了三维场景数据底板构建的目标,提出了多来源、多尺度数字孪生底板数据构建的具体方式,阐明了底板建设过程中包括数据来源、数据获取、数据治理、数据融合的理论和方法。【结果】通过实践,细化了L1~L3级数据底板的建设内容和技术路线,提供了完整的数字孪生项目数据底板建设的思路和方法。【结论】通过三级数据底板建设与共享,构建了高精度、可视化场景,为智慧防汛、水资源管理与调配等业务化应用提供了强有力的数据支撑。

关键词：数字孪生数据底板可视化场景数据融合

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Laser tuning in AlN single crystals

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Science China Materials 2021年第11期64卷 2877-2882页

作者： Yanming Zhu wei Zheng Siqi Zhu Ying Ding lemin Jia Feng Huang State Key Laboratory of Optoelectronic Materials and Technologies School of MaterialsSun Yat-sen UniversityGuangzhou 510275China

In the fields of trace gas detection,electric field detection,visible optical communication,and beyond,laser tuning technology plays an increasingly important role,as shown in *** the miniaturization of optoelectronic devices,it is desirable to integrate a large number of lasers with different wavelengths into one chip[1].However,the dynamic wavelength allocation efficiency of fixedwavelength laser is quite low,which greatly limits the monolithic integration of optoelectronics ***,the development of laser wavelength tuning technology is urgent and crucial to the efficiency of optoelectronics[2–7].Raman scattering is a physical phenomenon that can be explained by mature normal form[8,9].However,most studies only pay attention to the fact that Raman spectrum is a non-destructive material characterization method with fingerprint identification characteristics,while its essential feature of inelastic scattering is always ignored[10].The natural frequency shift characteristics indicate the possibility of Raman scattering as a feasible method to realize laser wavelength tuning[11–13].

关键词：波长调谐测试结构动态波长分配偏振特性非线性光学效应拉曼散射激光调谐氮化铝

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Ultrawide-bandgap(6.14 eV)(AlGa))_(2)O_(3)/Ga_(2)O_(3)heterostructure designed by lattice matching strategy for highly sensitive vacuum ultraviolet photodetection

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Science China Materials 2021年第12期64卷 3027-3036页

作者： Yuqiang Li Dan Zhang lemin Jia Siqi Zhu Yanming Zhu wei Zheng Feng Huang State Key Laboratory of Optoelectronic Materials and Technologies School of MaterialsSun Yat-sen UniversityGuangzhou 510275China

One judiciously designed strategy of utilizing an ultrathin but conductive Ga_(2)O_(3):Si nanolayer to prepare(AlGa)_(2)O_(3)crystalline film is *** from the existence of Ga_(2)O_(3):Si nanolayer,a high-quality(Al_(0.68)Ga_(0.32))_(2)O_(3)sesquioxide film with 68 at.%aluminum was epitaxially grown on sapphire substrates,which was characterized by high-resolution transmission electron microscopy,X-ray photoelectron spectroscopy and X-ray *** bandgap was broadened to 6.14 eV,and a vacuum ultraviolet(VUV)(AlGa)_(2)O_(3)/Ga_(2)O_(3):Si photodetector was subsequently *** detector exhibits a pretty high on-off ratio of about 10^(3),an open-circuit voltage of 1.0 V and a responsivity of 8.1 mA W^(-1) at 0 V bias *** performances imply that the proposed strategy is valuable for improving the quality and also adjusting the bandgap of(AlGa)_(2)O_(3)sesquioxides,which is expected to facilitate their application in VUV photodetection.

关键词： (AlGa)_(2)O_(3) ultrawide bandgap vacuum ultraviolet photovoltaic detector

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