The Chinese urban system is currently experiencing a fundamental shift, as it moves from a size-based hierarchy to a network-based system. Contemporary studies of city networks have tended to focus on economic interac...The Chinese urban system is currently experiencing a fundamental shift, as it moves from a size-based hierarchy to a network-based system. Contemporary studies of city networks have tended to focus on economic interactions without paying sufficient attention to the issue of knowledge flow. Using data on co-authored papers obtained from China Academic Journal Network Publishing Database （CAJNPD） during 2014-2016, this study explores several features of the scientific collaboration network between Chinese mainland cities. The study concludes that： （1） the spatial organization of scientific cooperation amongst Chinese cities is shifting from a jurisdiction-based hierarchical system to a networked system; and （2） several highly intra-connected city regions were found to exist in the network of knowledge, and such regions had more average internal linkages （14.21） than external linkages （8.69）, and higher average internal linkage degrees （14.43） than external linkage degrees （10.43）; and （3） differences existed in terms of inter-region connectivity between the Western, Eastern, and Central China regional networks （the average INCD of the three regional networks were 109.65, 95.81, and 71.88）. We suggest that China should engage in the development of regional and subregional scientific centers to achieve the goal of building an innovative country. Whilst findings reveal a high degree of concentration in those networks - a characteristic which reflects the hierarchical nature of China＇s urban economic structure - the actual spatial distribution of city networks of knowledge flow was found to be different from that of city networks based on economic outputs or population.展开更多
Solid phase extraction is widely used in sample pretreatment,concentration and analysis processes due to high selectivity and suitability for low concentration sample system.In this review,we systematically summarized...Solid phase extraction is widely used in sample pretreatment,concentration and analysis processes due to high selectivity and suitability for low concentration sample system.In this review,we systematically summarized and discussed the development trends of solid phase extraction by bibliometrics method.By analyzing papers output scale,the research and development direction of solid phase extraction technology is prospected.We also give an overview on current strategies of novel solid phase extraction from the separation medium and separation technology.The paper aims to describe the global research profile and the development trends of solid phase extraction,to help researchers to accurately grasp the research trend and to provide support for scientific research institutions to formulate scientific policies and strategic plans.Furthermore,the prospect of the development and application of solid phase extraction is also discussed.展开更多
基金National Natural Science Foundation of China,No.41571151,No.41590842,No.71433008
文摘The Chinese urban system is currently experiencing a fundamental shift, as it moves from a size-based hierarchy to a network-based system. Contemporary studies of city networks have tended to focus on economic interactions without paying sufficient attention to the issue of knowledge flow. Using data on co-authored papers obtained from China Academic Journal Network Publishing Database （CAJNPD） during 2014-2016, this study explores several features of the scientific collaboration network between Chinese mainland cities. The study concludes that： （1） the spatial organization of scientific cooperation amongst Chinese cities is shifting from a jurisdiction-based hierarchical system to a networked system; and （2） several highly intra-connected city regions were found to exist in the network of knowledge, and such regions had more average internal linkages （14.21） than external linkages （8.69）, and higher average internal linkage degrees （14.43） than external linkage degrees （10.43）; and （3） differences existed in terms of inter-region connectivity between the Western, Eastern, and Central China regional networks （the average INCD of the three regional networks were 109.65, 95.81, and 71.88）. We suggest that China should engage in the development of regional and subregional scientific centers to achieve the goal of building an innovative country. Whilst findings reveal a high degree of concentration in those networks - a characteristic which reflects the hierarchical nature of China＇s urban economic structure - the actual spatial distribution of city networks of knowledge flow was found to be different from that of city networks based on economic outputs or population.
基金financial support of the Natural Science Foundation of Beijing (2194086)the National Natural Science Foundation of China (Nos. 21922814, 21676273, 21961160745, 31961133019 and 21921005)
文摘Solid phase extraction is widely used in sample pretreatment,concentration and analysis processes due to high selectivity and suitability for low concentration sample system.In this review,we systematically summarized and discussed the development trends of solid phase extraction by bibliometrics method.By analyzing papers output scale,the research and development direction of solid phase extraction technology is prospected.We also give an overview on current strategies of novel solid phase extraction from the separation medium and separation technology.The paper aims to describe the global research profile and the development trends of solid phase extraction,to help researchers to accurately grasp the research trend and to provide support for scientific research institutions to formulate scientific policies and strategic plans.Furthermore,the prospect of the development and application of solid phase extraction is also discussed.
