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   19612篇
  免费   142篇
  国内免费   7篇
教育   14851篇
科学研究   1678篇
各国文化   161篇
体育   1017篇
综合类   3篇
文化理论   504篇
信息传播   1547篇
  2022年   49篇
  2021年   75篇
  2020年   150篇
  2019年   216篇
  2018年   2405篇
  2017年   2332篇
  2016年   1824篇
  2015年   323篇
  2014年   348篇
  2013年   1907篇
  2012年   437篇
  2011年   900篇
  2010年   1018篇
  2009年   598篇
  2008年   897篇
  2007年   1334篇
  2006年   274篇
  2005年   573篇
  2004年   588篇
  2003年   536篇
  2002年   288篇
  2001年   137篇
  2000年   136篇
  1999年   118篇
  1998年   111篇
  1997年   130篇
  1996年   121篇
  1995年   128篇
  1994年   119篇
  1993年   93篇
  1992年   111篇
  1991年   113篇
  1990年   101篇
  1989年   91篇
  1988年   84篇
  1987年   71篇
  1986年   66篇
  1985年   73篇
  1984年   62篇
  1983年   76篇
  1982年   74篇
  1981年   78篇
  1980年   83篇
  1979年   75篇
  1978年   54篇
  1977年   44篇
  1976年   53篇
  1975年   38篇
  1974年   34篇
  1973年   25篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
12.
Measuring Search Engine Quality   总被引:12,自引:3,他引:9  
The effectiveness of twenty public search engines is evaluated using TREC-inspired methods and a set of 54 queries taken from real Web search logs. The World Wide Web is taken as the test collection and a combination of crawler and text retrieval system is evaluated. The engines are compared on a range of measures derivable from binary relevance judgments of the first seven live results returned. Statistical testing reveals a significant difference between engines and high intercorrelations between measures. Surprisingly, given the dynamic nature of the Web and the time elapsed, there is also a high correlation between results of this study and a previous study by Gordon and Pathak. For nearly all engines, there is a gradual decline in precision at increasing cutoff after some initial fluctuation. Performance of the engines as a group is found to be inferior to the group of participants in the TREC-8 Large Web task, although the best engines approach the median of those systems. Shortcomings of current Web search evaluation methodology are identified and recommendations are made for future improvements. In particular, the present study and its predecessors deal with queries which are assumed to derive from a need to find a selection of documents relevant to a topic. By contrast, real Web search reflects a range of other information need types which require different judging and different measures.  相似文献   
13.
This paper addresses the need to recognize the importance, and the challenges, of preserving the hugely expanding record of medicine today for historians of the future. We are faced not only with an increase in traditional publishing formats, but also with the rapid growth in electronic communications. Two celebrated medical cases, one from the late seventeenth century and one from the late twentieth, are used to illustrate the differences and the difficulties. The need for active and effective professional collaboration is stressed; libraries should work together to address these issues.  相似文献   
14.
15.
16.
17.
The UK Film Council established a Research and Statistics Unit in order to gather data relating to film to inform the development of UK Film Council strategy and to provide an information service to the industry, government, the arts and cultural sector and the wider research community. The Research and Statistics Unit draws data from both official and unofficial sources and commissions its own special-purpose studies to gather information relevant to the strategic objectives of the Council. Key tasks are the measurement of the size of the market for film and the various elements of the film value chain, the performance of films supported by the UK Film Council and the performance of UK films in general. Special-purpose research projects currently include a detailed survey of the film production workforce, a study of the economic impact of the UK screen industries and studies of the social impact of local cinemas and the experience of Black- and Minority-led film production companies. A range of industry and official partners are collaborating in these studies. The Research and Statistics Unit also provides statistical and policy analysis relating to the wider policy environment of UK film, including issues such as the future of film tax incentives. This analysis has been developed within the HM Treasury ‘Green Book’ framework with particular reference to understanding market failure in relation to film. Central to the market failure argument is the cultural value of film in both its qualitative and its quantitative aspects. UK Film Council research is placed in the context of the literature on hedonic pricing and contingent valuation. The industrial challenges of increasing cultural value are discussed. Finally, consideration is given to the potential of film to contribute directly to ‘public value’.  相似文献   
18.
19.
20.
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