首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   12322篇
  免费   464篇
  国内免费   225篇
教育   8343篇
科学研究   2440篇
各国文化   51篇
体育   715篇
综合类   593篇
文化理论   38篇
信息传播   831篇
  2024年   16篇
  2023年   83篇
  2022年   220篇
  2021年   286篇
  2020年   344篇
  2019年   367篇
  2018年   372篇
  2017年   351篇
  2016年   371篇
  2015年   435篇
  2014年   734篇
  2013年   1148篇
  2012年   1014篇
  2011年   964篇
  2010年   713篇
  2009年   629篇
  2008年   731篇
  2007年   836篇
  2006年   725篇
  2005年   636篇
  2004年   533篇
  2003年   470篇
  2002年   349篇
  2001年   268篇
  2000年   167篇
  1999年   67篇
  1998年   51篇
  1997年   34篇
  1996年   22篇
  1995年   17篇
  1994年   15篇
  1993年   16篇
  1992年   10篇
  1991年   7篇
  1990年   2篇
  1989年   3篇
  1983年   1篇
  1979年   1篇
  1977年   1篇
  1976年   2篇
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
41.
Millions of Canadians residing in Canada's northern, isolated, rural, and remote communities do not have broadband Internet access. This situation has led to a national “broadband divide.” That is, the deployment of wireline broadband is very limited in Canada's northern, isolated, rural, and remote areas because of the significant expense of installation and maintenance of the wired infrastructure needed to reach dwellings in these locations.Terrestrial broadband wireless technology, on the other hand, does not entail the same kind of physical infrastructure. As a result, there are dramatic changes in how spatial considerations affect the provision of broadband Internet services (BIS) to areas beyond the urban zone. In particular, the spatial question is now focused on assessing the capacity for different technological solutions to reach profitable population bases, and brings to the forefront organizations that are developing non-line-of-sight (NLOS) technologies that would permit wireless Internet access over much greater distances than current solutions.We begin this paper by establishing the importance of broadband connectivity to Canada's northern, isolated, rural, and remote communities. This discussion comments on the role of the Government of Canada in the provision of broadband connectivity to residents of these communities, and outlines the current regulatory issues that govern wireless services and policy formulation.The second part of the paper illustrates the use of geographic information system (GIS) approaches in the study of wireless broadband planning and deployment. Case study findings suggest that GIS applications can make a significant contribution to the analysis of wireless deployment planning, to the understanding of the relationships between wireless signal sources and consumers, and to the spatial configuration of terrestrial wireless broadband networks. We conclude the paper by discussing how the GIS approach employed could be used to inform the public policy process with regard to increasing access to broadband Internet services in all regions of the country, and thereby providing the opportunity for all Canadians, regardless of location, to fully participate in the Information Society.  相似文献   
42.
Two-stage statistical language models for text database selection   总被引:2,自引:0,他引:2  
As the number and diversity of distributed Web databases on the Internet exponentially increase, it is difficult for user to know which databases are appropriate to search. Given database language models that describe the content of each database, database selection services can provide assistance in locating databases relevant to the information needs of users. In this paper, we propose a database selection approach based on statistical language modeling. The basic idea behind the approach is that, for databases that are categorized into a topic hierarchy, individual language models are estimated at different search stages, and then the databases are ranked by the similarity to the query according to the estimated language model. Two-stage smoothed language models are presented to circumvent inaccuracy due to word sparseness. Experimental results demonstrate that such a language modeling approach is competitive with current state-of-the-art database selection approaches.  相似文献   
43.
论网络信息政策   总被引:3,自引:0,他引:3  
提出网络信息政策的概念,分析网络信息政策的特点和类型,阐述网络信息政策环境和网络信息政策的功能与研究、方法等。  相似文献   
44.
提出了将支持向量机应用于文本自动分类的研究,与常用的K-最邻近法相比,无论是对训练数据集还是测试数据集均具有一定的优势,而且不同特征选择方法对支持向量机的影响要比K-最邻近法小。此外,从研究中的不同特征选择的评价函数来看,它们对分类有一定的影响,应用X2统计进行特征选择的分类正确率最高,其次是文本证据权,而期望交叉熵的效果最差,说明特征选择在文本自动分类中也是相当重要的。  相似文献   
45.
俄罗斯图书馆作为社会公共信息机构之一,在执行政府公共政策中发挥了重要作用。本文分析了政府公共政策进入图书馆的两条途径,原由以及作用等问题。  相似文献   
46.
师范院校图书馆读者文献资源需求调查与分析   总被引:10,自引:0,他引:10  
论文对读者获取文献信息能力及阅读需求等方面进行了调查与分析。  相似文献   
47.
The author, a professor at the University of Toronto, touches briefly on the extensive and rich archival literature that supports the teaching of macroappraisal, but notes that this is not the only educational material she offers her students when teaching appraisal theory. She discusses the usefulness to archivists of literature from the fields of ethnography, organizational knowing, records in history, personal documentary behaviour, memory, and communications, noting that the use of texts from these fields can encourage students to reflect on their own presumptions and to develop a taste for the wide reading and research that must support appraisal.  相似文献   
48.
[目的/意义]探究我国为实现促进大数据发展的政策目标而构建的政策工具选择体系结构,揭示大数据政策工具选择中存在的问题,为优化我国促进大数据发展政策工具选择提供建议。[方法/过程]构建由63项聚焦大数据发展的政策文本构成的政策样本集,运用内容分析法,对样本集中包含的政策工具进行编码。建立包含基础资源维度、技术维度和领域维度的政策工具选择三维分析框架,通过编码映射,建立其与政策工具编码的关联。从领域维度,使用层次聚类分析法,对样本政策文本进行聚类分析。[结果/结论]政策工具编码分析结果显示,我国大数据政策工具选择中存在缺乏长期规划,政策及政策工具协同不足,政策工具选择欠丰富;政策工具选择结构失衡;需求表达模糊,难以定位关键政策及政策工具等问题。应加强战略规划和发展理念指引,重视政策及政策工具协同,规避公共风险,构建需求驱动和问题导向的政策工具选择体系结构,创新设计与应用关键政策工具。  相似文献   
49.
Organizational communication scholars are increasingly called upon to use theoretical knowledge to address problematic processes in public institutions. This article reports a process improvement project focused on a university conflict of interest (COI) policy as an example of how scholars can engage theory to improve ongoing policy processes. The project team included communication scholars and research administration staff who designed, implemented, and evaluated the mixed-methods project guided by structurating activity theory. Baseline survey results were used to design the process improvement project. Results of the follow-up survey indicate that researchers who participated in some aspect of the process improvement project (i.e. attending a policy café, using the redesigned website, or reading the new Quick Reference Guide) reported higher levels of policy communication and knowledge and more positive attitudes toward the COI policy than researchers who had not engaged with process improvement efforts. We offer theoretical and practical implications of results for organizational communication scholars and practitioners.  相似文献   
50.
Air pollution is a critical environmental problem that has spurred great public concern in China. This study examines how issue salience, environmental value, risk perception, and affective response influence information seeking, objective knowledge, and policy support related to this issue. The recent release of a controversial environmental documentary on Chinese social media, Under the Dome, also prompted us to explore the impact of exposure to this documentary on Chinese social media users’ information seeking and policy support related to air pollution. Results showed that risk perception and negative affect influenced information seeking and policy support both directly and indirectly. Also, exposure to the documentary moderated the effects of key variables on information seeking and policy support. However, contrary to our expectations, no significant relationship was found between information seeking and objective knowledge. Theoretical and practical implications of these findings were discussed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号