检索结果-南通市图书馆

Persistent greening against drying in northeast Asian semiarid grasslands:Asymmetrical responses of direct and legacy effects to intensified drought

引用

Advances in Climate Change Research 2024年第1期15卷 9-20页

作者： yu-Tong MA Hai-shan CHEN Yao-ming SONG Bo-Tao ZHOU shan-Lei SUN Xin-Guan DU yue SUN Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China School of Atmospheric Sciences Nanjing University of Information Science and TechnologyNanjing 210044China

Despite experiencing a decadal shift towards drought conditions at the end of the 2Oth century,semiarid grasslands in northeast Asia(NEA)exhibited an evident greening trend from 1982 to ***,the mechanism behind this phenomenon remains ***,we analysed the interdecadal changes in vegetation response to drought on the basis of the standardised precipitation evapotranspiration index(SPEI)and Global Inventory Modelling and Mapping Studies LAI4g datasets,with an emphasis on the differences between direct and legacy effects(as measured by resilience),to explore the mechanism of persistent grassland *** revealed that during the post-drought shift period(2000-2020),the sudden decrease in the water content of the intermediate soil layer triggered an intensified vegetation response to ***,although direct effects and resilience were amplified,they exhibited asymmetric *** was stronger than direct effects,and this difference increased with increasing drought(drought recovery)*** combined effects may account for persistent greening against intensified drying in the semiarid grasslands in *** the projected exacerbation of future droughts,this study holds notable importance for comprehending the long-term change dynamics of dryland ecosystems.

关键词： Semiarid grassland Drought decadal shift Direct effect Legacy effect(resilience) Northeast Asia

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

不同来流条件下急弯段环流结构演化过程研究

引用

工程力学 2025年第1期42卷 259-272页

作者：胡呈维余明辉渠庚长江科学院河流研究所武汉430010 长江科学院水利部长江中下游河湖治理与防洪重点实验室武汉430010 武汉大学水资源与水电工程科学国家重点实验室武汉430072

弯道环流是弯道水流运动的典型特征之一，一直以来都是众多学者关注的重点。弯道环流主要分为两类：第一类由水流经过弯道时受到的径向压差力差而引起，流速较大;第二类主要由紊流各向异性引起，尽管流速很小，但其与弯道岸坡冲刷过程... 详细信息

弯道环流是弯道水流运动的典型特征之一，一直以来都是众多学者关注的重点。弯道环流主要分为两类：第一类由水流经过弯道时受到的径向压差力差而引起，流速较大;第二类主要由紊流各向异性引起，尽管流速很小，但其与弯道岸坡冲刷过程密切相关。然而当前成果较少关注第二类弯道环流发展演化过程。因此，该文采用弯道水槽试验与数值模拟方法得到的高精度三维流速数据，研究弯道环流结构的变化规律及其动力特性，特别是第二类弯道环流的发展变化。研究结果表明：对于高雷诺数的急弯水流，由于紊动各向异性特征明显，弯道水流常会出现多个环流;对于纵向流速，当水流流经弯顶断面后，纵向流速沿垂向的分布已经明显偏离对数流速分布;当水流经过弯顶断面后，纵向流速沿着垂线存在着显著的均匀化趋势;当弗劳德数较大时，大尺寸涡体在不断分解中，使得原来的各向异性影响越来越小，凹岸附近的小尺寸环流趋近于各向同性状态，造成凹岸小环流逐渐微弱并最后消失;急弯段中环流与纵向水流互馈作用十分显著，弯道环流将对断面内的动量进行重分配，携带某些高速流体到断面内的其他区域，因此，在出现弯道环流的区域其纵向流速也一般比较小。

关键词：弯曲型河流急弯河段弯道环流水槽试验数值模拟

来源：博看期刊评论

在线全文

博看期刊

学校读者我要写书评

暂无评论

Microstructure evolution and mechanical properties of high-boron steel with different ratios of boron and carbon

引用

China Foundry 2022年第2期19卷 169-176页

作者： ming-chen Ma Chao-qing Luo Si-min Chen Hong-qun Tang shan-shan Hu yu-mei Zhou Jian-lin Liang Guangxi Key Laboratory of Processing for Nonferrous Metals and Featured Materials Center of Ecological Collaborative Innovation for Aluminium Industry in GuangxiSchool of ResourcesEnvironment and MaterialsGuangxi UniversityNanning 530004China School of Mechanical Engineering Guangxi UniversityNanning 530004China School of Mechatronic Engineering Guangdong Polytechnic Normal UniversityGuangzhou 510665China

Boron and carbon contents are the main factors influencing the properties of high-boron *** this study,experimental samples with different boron-to-carbon ratios(%B/%C)were *** microstructures of the different samples were observed,and their hardness,bending strength,and impact toughness were *** show that the main microstructures in the investigated high-boron steel samples are the eutectic Fe_(2)B structure with a fishbone shape and the ternary peritectic Fe_(3)(C,B)structure with a chrysanthemum *** the boron content is 2.5wt.%and the carbon content is 0.43wt.%(i.e.,%B/%C=5.82),the overall mechanical properties of the alloy are the *** alloy's hardness,bending strength and impact toughness reach their maximums,which are 67.3 HRC,1,267.36 MPa and 6.19 J·cm^(-2),*** optimized alloy is compared with conventional materials exhibiting excellent wear resistance(namely,high-manganese steel and high-chromium cast iron)through two-body and three-body abrasion *** wear resistance of this high-boron steelinvestigated in this work is found to be superior to those of the more common materials.

关键词： high-boron steel boron and carbon contents wear resistance microstructure mechanical properties

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Quantum Algorithm for Boolean Equation Solving and Quantum Algebraic Attack on Cryptosystems

引用

Journal of Systems Science & Complexity 2022年第1期35卷 373-412页

作者： CHEN yu-Ao GAO Xiao-shan Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

This paper presents a quantum algorithm to decide whether a Boolean equation system F has a solution and to compute one if F does have solutions with any given success *** runtime complexity of the algorithm is polynomial in the size of F and the condition number of certain Macaulay matrix associated with *** a consequence,the authors give a polynomial-time quantum algorithm for solving Boolean equation systems if their condition numbers are polynomial in the size of *** authors apply the proposed quantum algorithm to the cryptanalysis of several important cryptosystems:The stream cipher Trivum,the block cipher AES,the hash function SHA-3/Keccak,the multivariate public key cryptosystems,and show that they are secure under quantum algebraic attack only if the corresponding condition numbers are *** leads to a new criterion for designing such cryptosystems which are safe against the attack of quantum computers:The corresponding condition number.

关键词： Block cipher AES Boolean equation solving condition number hash function SHA3/Keccak HHL algorithm MPKC polynomial system solving quantum algorithm stream cipher Trivum

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Inhibitory effect of antisense vascular endothelial growth factor RNA on the profile of hepatocellular carcinoma cell line in vitro and in vivo

引用

World Journal of Gastroenterology 2006年第7期12卷 1140-1143页

作者： Ji-Hui Hao ming yu Hui-Kai Li yu-Rong Shi Qiang Li Xi-shan Hao Department of Abdominal Surgery Tianjin Cancer Hospital Tianjin 300060 China Public Health College Tianjin Medical UniversityTianjin 300070 China

AIM： To evaluate the effect of antisense vascular endothelial growth factor （VEGF） RNA （PCMV-FGEV） transfection on the profile of hepatocellular carcinoma （HCC） SMMC-7721 cells in vitro and in vivo.METHODS： SMMC-7721 cells were transfected with PCMV-FGEV antisense, PCMV-VEGF sense and empty vector plasmid encapsulated by lipofectamine as antisense group, sense group and control group respectively. The positive cell clones were selected with G418. The stable transfection and expression of VEGF in the cells were determined by RT-PCR and immunohistochemistry. Cell proliferation was observed by Mnassay. FACS analysis was used to determine the effect of PCMV-FGEV transfection on cell apoptosis. The growth of transfected cells in vivo was also observed in nude mice.RESULTS： VEGF expression was reduced in SMMC-7721 transfected with PCMV-FGEV, which was confirmed by RT-PCR and immunohistochemistry. No effect of PCMV- FGEV transfection was found on cell proliferation and cell apoptosis of SMMC-7721 in vitro. The growth of cells transfected with PCMV-FGEV was slow in nude mice and accompanied with obvious apoptosis. The latent time of tumors in the antisense group was 25.0 ：l： 1.8 d, which was longer than that in sense and control groups （F= 19.455, P〈 0.01）. The average tumor weight in antisense group （0.96 g±0.28 g） was the smallest among the three groups （F= 21.501, P〈 0.01）.CONCLUSION： The expression of VEGF can be inhibited by antisense PCMV-FGEV. Antisense PCMV-FGEV has no effect on cell proliferation and apoptosis of SMMC-7721 in vitro but can inhibit tumor growth and induce cell apoptosis in vivo.

关键词： Antisense RNA Vascular endothelial growth factor Gene expression Hepatocellular carcinoma Transfection

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

生物炭过滤对沼液超滤膜分离的膜污染减缓效应

引用

水处理技术 2025年第1期51卷 40-46页

作者：周珊郑展望宋成芳余兵浙江农林大学环境与资源学院碳中和学院浙江杭州311300

采用猪粪生物炭过滤进行预处理,考察了猪粪生物炭过滤对沼液超滤时膜通量的影响,同时监测分析其对透过液的基本水质指标、超滤污染膜的表面微观形态和膜污染物组成的影响。结果显示预处理组比对照组的膜通量提高了12%,猪粪炭过滤可去除2... 详细信息

采用猪粪生物炭过滤进行预处理,考察了猪粪生物炭过滤对沼液超滤时膜通量的影响,同时监测分析其对透过液的基本水质指标、超滤污染膜的表面微观形态和膜污染物组成的影响。结果显示预处理组比对照组的膜通量提高了12%,猪粪炭过滤可去除21.64%的悬浮物,生物炭和超滤膜联合使用,膜透过液中的悬浮物、化学需氧量、氨氮、全氮、全磷、总有机碳的去除率均有所提高,分别为28.49%、17.71%、18.26%、24.97%、13.53%,悬浮物浓度为62.76 mg/L。扫描电镜图显示污染膜表面的污垢粗糙松散,而对照组的污染膜表面滤饼层更密实。对照组污染膜清洗液中UV254的值和TOC浓度均大于预处理组污染膜,无机离子浓度也大于预处理组污染膜清洗液。研究结果说明由于猪粪生物炭过滤预处理吸附截留了沼液中的污染物和生物炭颗粒对膜污染物结构组成的影响作用,有效的减缓了沼液超滤膜分离过程中的膜污染发生。

关键词：沼液猪粪炭超滤膜膜通量膜污染

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

sp^(3)-like defect structure of hetero graphene-carbon nanotubes for promoting carrier transfer and stability

引用

Journal of Energy Chemistry 2021年第6期30卷 189-197,I0005页

作者： shan-shan Fan Ling Shen yuan Dong Ge Tian Si-ming Wu Gang-Gang Chang Christoph Janiak Ping Wei Jin-Song Wu Xiao-yu Yang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing and School of Materials Science&EngineeringWuhan University of TechnologyWuhan 430070HubeiChina School of Chemistry Chemical Engineering and Life ScienceWuhan University of TechnologyWuhan 430070HubeiChina Institut für Anorganische Chemie und Strukturchemie Heinrich-Heine-Universität Düsseldorf40204 DüsseldorfGermany NRC(Nanostructure Research Centre) Wuhan University of TechnologyWuhan 430070HubeiChina Department of Engineering and Applied Sciences Harvard University CambridgeMA 02138United States

Three-dimensional(3 D) hybrid of nanocarbons is a very promising way to the high-performance design of electrocatalysis ***,sp^(3)-like defect structure,a combination of high strength and conduction of graphene and carbon nanotubes(CNTs) is rarely ***,3 D neural-like hybrids of graphene(from reduced graphene oxide) and carbon nanotubes(CNTs) have been integrated via sp^(3)-like defect structure by a hydrothermal *** sp^(3)-like defect structure endows 3 D nanocarbon hybrids with an enhanced carrier transfer,high structural stability,and electrocatalytic *** neural-like structure is shown to demonstrate a cascade effect of charges and significant performances regarding bio-electrocatalysis and lithium-sulfur energy *** concept and mechanism of "sp^(3)-like defect structure" are proposed at an atomic/nanoscale to clarify the generation of rational structure as well as the cascade electron transfer.

关键词： Graphene Carbon nanotubes sp^(3)-like defect structure Bio-electrocatalysis Lithium-sulfur batteries

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Remarks on g-functions on H^n

引用

Acta Mathematica Sinica,English Series 2007年第1期23卷 7-16页

作者： ming Ju LIU shan Zhen LU LMIB and Department of Mathematics Beihang University Beijing 100083 P. R. China Department of Mathematics Beijing Normal University Beijing 100875 P. R. China

In this paper, the authors study some properties of Littlewood-Paley g-functions gψ（f）,Lusin area functions Sψ,α（f） and Littlewood-Paley gψ^＊,λ（f） functions defined on H^n, where α,λ 〉 0 and ψ, f are s... 详细信息

关键词： Square integrable function Weight Herz spaces

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Evolutionary Pattern and Effect of Administrative Division Adjustment During Urbanization of China:Empirical Analysis on Multiple Scales

引用

Chinese Geographical Science 2018年第5期28卷 758-772页

作者： yu Hu DENG yu XU shan Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Science Key Laboratory of Regional Sustainable Development Modeling Chinese Academy of Science

The adjustment of administrative divisions is one of the important factors guiding China's urbanization, which has profound economic and social effects for regional development. In this paper, we comprehensively describe the process of the adjustment of administrative divisions at provincial and municipal levels in China and summarize the effects on the basic structure and patterns of the spatial development. We quantitatively assess the effects on fields such as urbanization and social economy through the use of multidimensional scaling. The results show that: 1) Upgrading county to municipality(or city-governed district) is the main way of adjusting the administrative divisions. It is also an important factor in the spatial differentiation of interprovincial urbanization. China's population urbanization can be divided into four patterns including interprovincial migration, provincial migration, natural growth, and growth caused by the adjustment of administrative divisions, which is also the main reason for the increased Chinese urbanization rate at the provincial level. 2) Taking the city of Beijing as an example, we generalize five adjustment patterns made to administrative divisions: the set-up of sub-districts, the set-up of regional offices, the upgrading of townships to sub-districts, the upgrading of townships to towns, and the set-up of towns and the addition of new regional offices. We summarize the municipal urban spatial structure, including the sub-district office area in the central urban area, the regional office area in the new urban area, the mixed area of villages, towns, and sub-district offices in the suburb area, and the township area in the outer suburb area. 3) The adjustment of administrative divisions triggers a significant circulative accumulation effect, resulting in the spatial locking of population and industrial agglomeration. It affects the evolution of the urban spatial form and plays an important role in shaping the urban spatial st

关键词： administrative division adjustment evolutionary structure effect evaluation multidimensional scaling urbanization China

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effect of Ni addition on microstructure and mechanical properties of Al–Mg–Si–Cu–Zn alloys with a high Mg/Si ratio

引用

International Journal of Minerals,Metallurgy and Materials 2019年第6期26卷 740-751页

作者： Gao-jie Li ming-xing Guo yu Wang Cai-hui Zheng Ji-shan Zhang Lin-zhong Zhuang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing

The effect of adding 0.03wt%Ni on the microstructure and mechanical properties of Al–Mg–Si–Cu–Zn alloys was systematically *** results reveal that the number density of spherical Fe-rich phases within grains increases with the addition of Ni,accompanied by the formation of Q(Al3Mg9Si7Cu2)precipitates around the spherical Fe-rich ***,Ni addition is beneficial to reducing the grain size in the as-cast *** the homogenization process,Q phases could be completely dissolved and the grain size could remain basically ***,compared with the Ni-free alloy,the Fe-rich phase in the Ni-containing alloy is more likely to undergo the phase transformation and further form more spherical particles during homogenization *** thermomechanical processing,the distribution of Fe-rich phases in the Ni-containing alloy was further greatly improved and directly resulted in a greater formability than that of the Ni-free ***,a reasonable Ni addition positively affected the microstructure and formability of the alloys.

关键词： Al-Mg-Si-Cu-Zn alloy Ni addition Fe-rich phase phase transformation formability

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：