检索结果-南通市图书馆

β-diversity Patterns of Plant Community in Fragmented Habitat in a Degenerated Meadow in Songnen Plain,China

Chinese Geographical Science 2009年第4期19卷 375-381页

作者： HAN Dayong LI Haiyan yang yunfei Key Laboratory for Vegetation Ecology of Ministry of Education Institute of Grassland Science Northeast Normal University Changchun 130024 China

A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 2007. These islands were classified as large, medium, and small scales on the basis of the island area （100-1000m2, large island; 50-100m2, middle island; 10-50m2, small island）. Each scale of the investigation involved eight islands. The responses ofβ-diversity patterns of plant taxon to the habitat fragmentation at local community and metacommunity levels were analyzed on different scales of 24 isolated islands. The results indicated that at the local community level, there were 57 species belonging to 20 families and 49 genera in large islands, 49 species belonging to 16 families and 40 genera in middle islands, and 27 species belonging to eight families and 23 genera in small islands, β-diversity indexes for species, genus and family in large, middle, and small islands varied greatly, and the highest value of the indexes was not noted in the largest island. However, the average of the data obtained at the three scales showed that across large islands, Whittaker indexes were low and Bray-Curtis similarity indexes were high, while across small islands, Whittaker indexes were high and Bray-Curtis similarity indexes were low. At the metacommunity level, Whittaker indexes for species and genus showed a great significantly negative double logarithmic correlation （p〈0.01） with the island area, whereas the Bray-Curtis indexes for species, genus and family showed a great significantly positive double logarithmic correlation （p〈0.01） with the island area. At both local community and metacommunity levels, tumovers of species and genus could respond more sensitively to spatial changes of plant diversity patterns than that of family. Hence, the species and the genus could be used for the analysis offl-diversity patterns of plant community.

关键词： habitat fragmentation local community metacommunity plant taxon β-diversity

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

Growth and production characters of elymus cylindricus in different shortening heading time

引用

Phyton-International Journal of Experimental Botany 2019年第1期88卷 55-61页

作者： Chengcheng Li Chan Zhou yunfei yang Key Laboratory of Vegetation Ecology Ministry of EducationInstitute of Grassland ScienceNortheast Normal UniversityChangchunChina School of Life Science Liaoning UniversityShenyangChina

Ramet modules in a certain population differ in terms of functions,which accounts for different contributions of the same *** heading time brings about different contributions of such *** heading one after another were treated as a continuum in respective cohorts of Elymus cylindricus aged *** reproductive ramets that head earlier were marked with tags every four days during the whole heading stage from the beginning to the end,after which all the labeled ramets at the maturity period were *** results showed that,the height and biomass of ramets,the length and biomass of inflorescences,percentage of inflorescence length to ramet height,percentage of inflorescence biomass to ramet biomass,the number and biomass of seeds,seed-setting rate,and percentage of seed biomass to ramet biomass declined with the increasing intensity of heading time shortening as displayed with linear or quadratic *** characteristics weakened remarkably when shortened heading time added up to 17 *** biomass distribution in relation to inflorescence and seed maintain a stable rate at the early heading stage and dwindled quickly at the near-end stage,but the biomass of ramets remain constant throughout the entire heading *** ramets with earlier heading time make greater contribution to the survival of population than the shortened heading time in this species of bunchgrass.

关键词： Perennial herb Allocation strategy Phenotypic plasticity Irregular heading Ramet reproduction

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

Hydrogel-based composites beyond the porous architectures for electromagnetic interference shielding

引用

Nano Research 2022年第10期15卷 9614-9630页

作者： yunfei yang Mingrui Han Wei Liu Na Wu Jiurong Liu Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials School of Materials Science and EngineeringShandong UniversityJinan 250061China State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China Shenzhen research institute of Shandong University Shenzhen 518052China Department of Chemistry and Applied Biosciences ETH ZurichZurich CH-8093Switzerland

With the rapid development of the electronic industry and wireless communication technology,electromagnetic interference(EMI)or pollution has been increasingly *** not only severely endangers the normal operation of electronic equipment but also threatens human ***,it is urgent to develop high-performance EMI shielding *** advent of hydrogel-based materials has given EMI shields a novel *** combined with conductive functional materials have good mechanical flexibility,fatigue durability,and even high stretchability,which are beneficial for a wide range of applications,especially in EMI shielding and some flexible functional ***,the current progress of hydrogel-based EMI shields was reviewed,in the meanwhile,some novel studies about pore structure design that we believe will help advance the development of hydrogel-based EMI shielding materials were also *** the outlook,we suggested some promising development directions for the hydrogel-based EMI shields,by which we hope to provide a reference for designing hydrogels with excellent EMI shielding performance and multifunctionalities.

关键词： electromagnetic interference(EMI)shielding porous hydrogels structural design composites

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

The inconsistency of documentation:a study of online C standard library documents

引用

Cybersecurity 2022年第4期5卷 117-131页

作者： Ruishi Li yunfei yang Jinghua Liu Peiwei Hu Guozhu Meng KLois Institute oflnformation EngineeringChinese Academy of SciencesBejingChina School of Cyber Security University of Chinese Academy of SciencesBeijingChina.

The C standard libraries are basic function libraries standardized by the C *** usually refer to their APl documentation provided by third-party ***,these documents are not necessarily complete or accurate,especially for constraint sentences of APl usage,which are called Security Specifications(SSs).SS issues can prevent programmers from following obligatory constraints,which results in APl misuse *** work studying SS issues could only find certain types of inaccurate SSs through checking the compliance between APl usage and existing ***,we propose a novel approach SSeeker for quickly discovering missing and inaccurate SSs through the inconsistency of semantically similar *** specifically,SSeeker first completes broken sentences and discovers SSs from them by judging their constraint *** SSeeker puts semantically similar SSs from different sources into a group,which can be used to discover missing or inaccurate *** the help of SSeeker,we investigated 4 popular online third-party C standard library documents,studied their conformity with the C99 standard,analyzed their APls and SSs,and discovered 92 prototype issues,15 web page issues,and 96 SS issues.

关键词： Documentation issues Security specification Standard library

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

Simultaneous Detection of Flare-related Decaying and Decayless Kink Oscillations Using Jerk-aware Motion Magnification

引用

Research in Astronomy and Astrophysics 2022年第11期22卷 130-136页

作者： Xiaowei Guo Bo Liang Song Feng Wei Dai yunfei yang Faculty of Information Engineering and Automation Kunming University of Science and TechnologyKunming 650500China

Kink oscillations of coronal loops are often influenced by external events and this results in various changes of the *** the changes can provide valuable information for understanding kink *** observation focuses on a flare region acquired by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory spacecraft on 2016 March *** are a bunch of arched loops and an open loop near the ***,their oscillations show very low *** we used the jerk-aware motion method to magnify the weak *** found that before the flare onset at 02:59 UT,there were some large loops above the arched loops being raised *** properties of the weak oscillations show clear *** the one hand,the oscillations in the arched loops were decayless initially,but both their amplitude and period increased after 02:30 UT and before the flare *** enhanced,the oscillations decayed with *** the other hand,the oscillations in the open loop were nearly constant before and after 02:30 UT,but their period *** means that the changes in periods and amplitudes of oscillations are likely associated with the loops raised before the flare.

关键词： Sun:corona Sun:oscillations Sun:flares waves

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

Recent progress of efficient utilization of titanium-bearing blast furnace slag

引用

International Journal of Minerals,Metallurgy and Materials 2022年第1期29卷 22-31页

作者： Yongfeng Cai Ningning Song yunfei yang Lingmin Sun Peng Hu Jinshu Wang Key Laboratory of Advanced Functional Materials Ministry of EducationFaculty of Materials and ManufactureBeijing University of TechnologyBeijing 100124China

Titanium-bearing blast furnace slag(BFS)has valuable compositions and potential environmental ***,developing efficient and green approaches to utilize BFS is highly desired for resource economization and environmental *** the past decades,many attempts have been adopted to reuse BFS efficiently,and significant advances in understanding the fundamental features and the development of efficient approaches have been *** review provides a comprehensive overview of the latest progress on the efficient utilization of BFS and discusses the mechanism and characteristics of various approaches,along with their application *** particular,the extraction and enrichment of titanium-bearing phases from BFS are highlighted because of the high availability of titanium *** systemic and comprehensive review may benefit the design of new and green utilization routes with high efficiency and low cost.

关键词： titanium-bearing blast furnace slag utilization approach enrichment process extracting titanium mechanism

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

Quality Model and Metrics of Ontology for Semantic Descriptions of Web Services

引用

Tsinghua Science and Technology 2017年第3期22卷 254-272页

作者： Hong Zhu Dongmei Liu Ian Bayley Arantza Aldea yunfei yang Ying Chen Department of Computing and Communication Technologies Oxford Brookes University School of Computer Science and Engineering Nanjing University of Science and Technology

An ontology is a conceptualisation of domain knowledge. It is employed in semantic web services technologies to describe the meanings of services so that they can be dynamically searched for and composed according to their meanings. It is essential for dynamic service discovery, composition, and invocation. Whether an ontology is well constructed has a tremendous impact on the accuracy of the semantic description of a web service, the complexity of the semantic definitions, the efficiency of processing messages passed between services, and the precision and recall rates of service retrieval from service registrations. However, measuring the quality of an ontology remains an open problem. Works on the evaluation of ontologies do exist, but they are not in the context of semantic web services. This paper addresses this problem by proposing a quality model of ontology and defining a set of metrics that enables the quality of an ontology to be measured objectively and quantitatively in the context of semantic descriptions of web services. These metrics cover the contents, presentation, and usage aspects of ontologies. The paper also presents a tool that implements these metrics and reports a case study on five real-life examples of web services.

关键词： semantic web services ontology quality model ontology evaluation ontology metrics

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

Tree‑Inspired Structurally Graded Aerogel with Synergistic Water,Salt,and Thermal Transport for High‑Salinity Solar‑Powered Evaporation

引用

Nano-Micro Letters 2024年第11期16卷 19-37页

作者： Xiaomeng Zhao Heng Zhang Kit‑Ying Chan Xinyue Huang yunfei yang Xi Shen Department of Aeronautical and Aviation Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARPeople’s Republic of China Research Institute for Sports Science and Technology The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARPeople’s Republic of China Research Institute for Advanced Manufacturing The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARPeople’s Republic of China

Solar-powered interfacial evaporation is an energy-efficient solution for water *** requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient ***,downward salt ion transport is also desired to prevent salt ***,achieving simultaneously fast water uptake,downward salt transport,and heat localization is challenging due to highly coupled water,mass,and thermal ***,we develop a structurally graded aerogel inspired by tree transport systems to collectively optimize water,salt,and thermal *** arched aerogel features root-like,fan-shaped microchannels for rapid water uptake and downward salt diffusion,and horizontally aligned pores near the surface for heat localization through maximizing solar absorption and minimizing conductive heat *** structural characteristics gave rise to consistent evaporation rates of 2.09 kg m^(-2) h^(-1) under one-sun illumination in a 3.5 wt%NaCl solution for 7 days without *** in a high-salinity solution of 20 wt%NaCl,the evaporation rates maintained stable at 1.94 kg m^(-2) h^(-1) for 8 h without salt crystal *** work offers a novel microstructural design to address the complex interplay of water,salt,and thermal transport.

关键词： Composite aerogel Graded structure Solar-powered evaporation Thermal insulation Salt rejection

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

Labor protection,information disclosure and analyst forecasts:Evidence from China's Labor Contract Law

引用

China Journal of Accounting Research 2022年第3期15卷 5-27页

作者： Xiaojia Zheng yunfei yang Yanyan Shen School of International Trade and Economics University of International Business and EconomicsBeijingChina100029 School of Business Renmin University of ChinaBeijingChina100872

Labor protection increases employees’stability and strengthens their monitoring role,improving firms’information environment and increasing analysts’earnings forecast *** the implementation of China’s Labor Contract Law as a quasi-natural experiment,we find that labor protection significantly improves analyst *** positive impact is stronger when agency problems are weaker,board independence is greater,corporate reputation is better and industry competition is more *** labor protection significantly reduces firms’business risk and accrual-based earnings management,decreases stock price synchronicity and increases market pricing *** findings of significant impacts of China’s Labor Contract Law on analysts’forecasting behaviors offer important guidance for promoting the development of the Chinese capital market and policy making in labor protection.

关键词： Labor protection Analyst forecasts Information disclosure China’s Labor Contract Law

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

A review on scandia doped tungsten matrix scandate cathode

引用

Tungsten 2019年第1期1卷 91-100页

作者： Jinshu Wang yunfei yang Yiman Wang Wei Liu Meiling Zhou Tieyong Zuo College of Material Science and Engineering Key Laboratory of Advanced Functional MaterialsEducation Ministry of ChinaBeijing University of TechnologyBeijing 100124China

As the cathode with the highest electron emission capability in the thermionic cathode,the scandate cathode has attracted more and more attention in recent years,especially the scandia doped tungsten matrix scandate *** studies show that scandia doped tungsten matrix scandate cathodes with submicron microstructures exhibit excellent emission capacity,and the pulse emission current density in the space-charge region can be over 35 A cm^(−2) at 850°*** the direct current(DC)condition with temperature compensation,the emission current density could reach 25 A cm^(−2) at 850°*** device lifetime is over 3700 h after operating at 950°C_(b) with the DC loading of 40 A cm^(−2).The emission mechanism of the scandate cathode including the effect of the surface structure and composition on the work function of the cathode are systematically reviewed.

关键词： Scandate cathode Tungsten Electron emission Microstructure Surface analysis

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

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：