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基于2003~2013年中国277个地级及以上城市统计数据,运用空间面板计量模型实证分析产业发展模式、城市规模对城市经济绩效的协同影响,估计城市规模约束下专业化和多样化的边际收益、与城市专业化或多样化经济相适应的最优城市规模,以及专业化经济的空间溢出范围.研究发现:(1)随着城市规模的扩大,城市产业发展模式应由专业化向多样化转变,多样化对经济效率提升的门槛规模是129万人;(2)随着城市规模扩大,经济绩效呈现倒U型结构,而城市规模增大的边际收益随专业化向多样化转变和多样化水平的提高而增加;(3)专业化具有显著的跨区域空间外部性,空间溢出效应在100千米和400千米时较大. 相似文献
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本文以长三角城市群为例,采用空间杜宾模型实证分析了生产性服务业专业化集聚与多样化集聚对城镇化的作用。研究发现：生产性服务业集聚显著促进城镇化发展。其中专业化集聚对城镇化的解释力更强且具有显著的空间溢出作用,多样化集聚在本地发挥集聚效应,但未对邻近地区形成扩散效应。生产性服务业专业化集聚与多样化集聚的作用路径存在异质性,专业化集聚通过降低交易成本、发展非农产业及人力资本的联动作用促进城镇化发展,多样化集聚通过优化产业结构及劳动力结构推动城镇化进程。本文从生产性服务业角度出发,为推进新型城镇化提供了新的研究视角。 相似文献
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《中国科技论坛》2015,(3)
本文基于2003—2012年中国285个地级及以上城市的统计数据,运用空间计量模型实证研究了产业集聚对城市全要素生产率影响的空间溢出效应。研究结论表明:中国城市全要素生产率的空间相关性呈逐年增强的趋势,其溢出效应在0~950千米范围内呈现先升后降的"倒U型"曲线过程,波峰出现在500千米左右;制造业集聚对城市全要素生产率的影响显著为负,生产性服务业集聚和市场潜能有利于城市全要素生产率的提升;从集聚外部性效应来看,MAR外部性和Porter外部性对城市全要素生产率存在显著负向影响,Jacobs外部性有利于城市全要素生产率的提升,这意味着制造业集聚所带来的负影响主要是由MAR外部性和Porter外部性所主导。 相似文献
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生产性服务业集聚对工业效率提升的空间外溢效应 《科学学研究》2017,35(3):364-371
本文从生产性服务业集聚的内在机制出发,分析了生产性服务业集聚提升工业效率以及产生空间外溢效应的理论机制。在此基础上,利用中国285个地级及以上城市2003-2013年的统计数据,采用空间杜宾模型实证分析了生产性服务业集聚对工业效率提升的空间外溢效应。研究结论表明：生产性服务业集聚不仅可以提升本地区的工业效率,还能通过空间外溢效应提升周围地区的工业效率,而且这种空间外溢效应存在一定的区域边界。从生产性服务业集聚的外部性效应来看,专业化集聚和多样化集聚对不同规模等级城市工业效率提升的影响存在显著差异。 相似文献
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基于科技服务业空间集聚对企业创新效率的影响机理,利用2005—2014年中国省级高技术产业面板数据,运用空间杜宾模型实证检验了科技服务业空间集聚对企业创新效率的空间溢出效应.研究表明: 中国科技服务业空间集聚与企业创新效率均存在全域范围内的空间相关性,并且其局域性的空间集群特征尤为明显;科技服务业空间集聚显著提升了中国高技术企业创新效率,科技服务业空间集聚每增长1〖WTB3〗%〖WTBZ〗,高技术企业创新效率将提升0.24%;相邻地区的科技服务业空间集聚对本地区高技术企业创新效率存在显著的空间溢出效应,如果忽略这种影响,会低估科技服务业空间集聚对高技术企业创新效率的提升作用.文章最后给出了相应的政策建议. 相似文献
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服务业集聚与城市技术进步 《科学学研究》2017,35(2):230-239
本文从新经济地理学角度,利用2003～2013年我国277个城市面板数据,构建空间杜宾模型,通过距离衰减、经济距离和逆距离平方三种空间权重矩阵,检验了服务业及细分服务业集聚对于本地和临近城市技术进步的影响。三种空间权重矩阵一致表明：(1)生产性服务业、公共服务业集聚显著促进了本地区城市技术进步,而消费性服务业集聚抑制了技术进步;从地区层面来看,生产性服务业、公共服务业集聚对东部、中部、西部技术进步的集聚效应呈U型结构。(2）在空间溢出效应上,西部地区生产性和公共服务业集聚对临近城市技术进步显示了显著的空间溢出效应,但全国层面、东部地区和中部地区在正向溢出和集聚阴影的共同作用下,空间溢出效应不明显。 相似文献
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生产性服务业集聚对绿色经济效率的影响研究 《科学学研究》2022,40(11):1968-1978
作为制造业转型升级的重要动力,生产性服务业已经成为推动我国经济高质量发展的重要引擎。本文选取2005-2018年中国278个城市面板数据,实证检验了生产性服务业集聚对城市绿色经济效率提升的机理。研究结果表明：（1）生产性服务业集聚对城市绿色经济效率有显著促进作用,且存在空间溢出效应,但直接效应更大;（2）生产性服务业集聚可以通过工业生产率、知识存量和市场环境三条路径影响城市绿色经济效率,但存在异质性;（3）知识存量和市场环境两种中介效应均存在双重门槛,且两者在调节生产性服务业集聚作用绿色经济效率中表现出“由抑制到促进,由微弱到增强”的阶梯性特征。文章不仅检验了生产性服务业集聚在影响城市绿色经济效率中具体的影响路径;同时,也证实了门槛效应和空间效应的存在。 相似文献
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Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
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A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
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Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
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Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
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Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献
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Milton Mueller 《The Information Society》2001,17(3):151-163
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP. 相似文献
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Prof. Raymond C.K. Chen a neuropsychologist with the CAS Institute of Psychology has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology. 相似文献
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《中国科学院院刊(英文版)》2014,(3)
<正>In Xishuangbanna,one of China’s most biodiverse regions,landscape has changed dramatically during the past three decades due to the conversion of tropical rainforest to rubber plantations.In steep areas,terraces are often constructed before planting rubber trees,which causes two important changes in the soil:the destabilization of soil in the bench terraces and the increased vulnerability of unvegetated riser faces to erosion.Few studies have documented the nature and intensity of erosion on bench terraces.Prof.LIU Wenjie and his colleagues from the Xishuangbanna Tropical Botanical Garden(XTBG)conducted a study in Menglun County(21°5′39″N,101°15′55″E),Xishuangbanna to evaluate the influence 相似文献
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Chinese Scientists Use Earth Observation Technologies to Study and Protect Wild Camels 总被引：1，自引：0，他引：1
《中国科学院院刊(英文版)》2014,(3):267-268
<正>Chinese scientists plan to apply Earth Observation technologies to protect the critically endangered wild camels(Camelus ferus).With the help of remote sensing,satellite positioning,geographical information system and wireless sensors networks,they will be able to access the distribution and population of the wild camels and protect their habitats.The project will be carried out by the International Research Center for Wild Camel Conservation,which was jointly established earlier this year by the Institute of Remote Sensing and Digital Earth(RADI)of the Chinese 相似文献
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WANG Sijia 《中国科学院院刊(英文版)》2014,(2):192-194
<正>The Paul Gerson Unna Research Group on Dermatogenomics was founded in October 2012 at the Partner Institute for Computational Biology.The ultimate goal of the group is to understand the biology of skin and skin appendages. 相似文献