Subjects: Library Science，Information Science >> Library Science submitted time 2023-08-27 Cooperative journals: 《图书情报工作》
Abstract： [Purpose/significance] The article reveals the academic contributions and evolution features of major countries of library and information science since 2002 on the dimensions of outputs of papers, citations and research topics, in the hope of providing a reference for the subject construction and related researchers tracking research topics and frontiers.[Method/process] Based on 86 core journals in the last 15 years of library and information science in Web of Science, the article used research methods including bibliometrics, scientific knowledge maps and econometric models, utilized data analysis tools including TDA, Ucinet and VOSviewer. The article gave an in-depth analysis of the academic contribution of major countries of library and information science from the following perspectives:academic papers amount, citation features and theme features. Meanwhile, the article built a metrological model to examine the impact of spatial distance and academic ability on academic cooperation among major countries.[Result/conclusion] The United States has a strong scientific research strength in the field of library and information science, China has the fastest growth of academic contribution, Netherlands, Finland and Belgium all excel in quoted rate indicators. The research topics mainly focus on the eight thematic areas of libraries, information retrieval, internet, knowledge management, social networks, metrology, user study and research methods. Britain, Spain, China and the United States have the most extensive research topics. Spatial distance and academic capabilities have a significant impact on academic cooperation among countries.
Subjects: Library Science，Information Science >> Library Science submitted time 2023-08-27 Cooperative journals: 《图书情报工作》
Abstract： [Purpose/significance] Under the background of big data, the research of scientific data management has important theoretical and practical significance.[Method/process] Based on WoS and Google Scholar databases, the paper utilized Citespace, Ucinet, TDA and other analysis tools to explore the evolution of scientific data management research in international academic community.[Result/conclusion] The paper fully revealed the history, current situation and development direction of scientific data management research from four aspects including time distribution map, spatial distribution map, thematic evolution map and knowledge base map. Furthermore, the paper put forward relevant proposals according to the domestic research status quo.
Subjects: Dynamic and Electric Engineering >> Electrical Engineering submitted time 2019-03-05 Cooperative journals: 《电气工程学报》
Abstract：基于三电平逆变器的感应电机直接转矩控制无速度传感器系统存在着逆变 器结构复杂、元器件使用较多、基于转子磁链定向的无速度传感器算法使磁链计算复 杂、磁链观测环节不精确等问题。为解决上述问题，对三电平逆变器的拓扑结构进行 简化，针对直接转矩控制的特点，采用基于定子磁链的无速度传感器算法，并与改进 的磁链观测器相结合，进行速度观测，构建了改进拓扑结构、改进磁链观测算法的感 应电机直接转矩控制无速度传感器系统。通过仿真实验验证了上述改进方法在减少开 关器件损耗的同时，可提高磁链观测精度，使转速估算更精确。
Subjects: Biology >> Zoology submitted time 2018-12-24 Cooperative journals: 《动物营养学报》
Abstract：猪肠道微生物区系的建立是一个非常复杂的过程。微生物与宿主之间在长期的进化与演变过程中形成了一种相互依赖、相互制约的微生态平衡。肠道微生物在宿主动物的生长发育、器官功能、营养代谢、机体免疫等方面发挥了重要作用。微生物区系的形成与动态平衡受到内部和外部多种因素的影响与制约，特别是不同营养素（碳水化合物、蛋白质、脂肪等）对猪肠道微生物菌群的组成具有重要影响。本文着重探讨了猪肠道微生物区系的形成特点和主要营养素对其调控的影响。
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