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   18670篇
  免费   254篇
  国内免费   119篇
教育   12821篇
科学研究   2340篇
各国文化   163篇
体育   1632篇
综合类   13篇
文化理论   170篇
信息传播   1904篇
  2021年   141篇
  2020年   275篇
  2019年   405篇
  2018年   535篇
  2017年   478篇
  2016年   466篇
  2015年   301篇
  2014年   417篇
  2013年   3356篇
  2012年   373篇
  2011年   422篇
  2010年   311篇
  2009年   309篇
  2008年   322篇
  2007年   354篇
  2006年   356篇
  2005年   339篇
  2004年   321篇
  2003年   307篇
  2002年   280篇
  2001年   300篇
  2000年   321篇
  1999年   313篇
  1998年   189篇
  1997年   192篇
  1996年   219篇
  1995年   194篇
  1994年   161篇
  1993年   173篇
  1992年   244篇
  1991年   256篇
  1990年   262篇
  1989年   296篇
  1988年   247篇
  1987年   260篇
  1986年   246篇
  1985年   274篇
  1984年   250篇
  1983年   245篇
  1982年   196篇
  1981年   186篇
  1980年   177篇
  1979年   278篇
  1978年   223篇
  1977年   204篇
  1976年   172篇
  1975年   148篇
  1974年   171篇
  1973年   155篇
  1971年   133篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
32.
33.
34.
35.
36.
Quantum algorithms are a field of growing interest within the theoretical computer science as well as the physics community. Surprisingly, although the number of researchers working on the subject is ever-increasing, the number of quantum algorithms found so far is quite small. In fact, the task of designing new quantum algorithms has been proven to be extremely difficult. In this paper we give an overview of the known quantum algorithms and briefly describe the underlying ideas. Roughly, the algorithms presented are divided into hidden subgroup type algorithms and in amplitude amplification type algorithms. While the former deal with problems of group-theoretical nature and have the promise to yield strong separations of classical and quantum algorithms, the latter have been proved to be a prolific source of algorithms in which a polynomial speed-up as compared to classical algorithms can be achieved. We also discuss quantum algorithms which do not fall under these two categories and give a survey of techniques of general interest in quantum computing such as adiabatic computing, lower bounds for quantum algorithms, and quantum interactive proofs.  相似文献   
37.
Medicine has made increasing use of meta-analysis, largely as a quantitative procedure for combining results of clinical trials. Meta-analysis begins with a comprehensive review of the literature. The next step is a systematic analysis of the quality and content of each study. Finally, results are combined statistically and conclusions are drawn from this new overview of the data. This paper presents a brief historical perspective on the use of meta-analysis in medicine with emphasis on the medical library. The authors conclude that in the future, medical librarians will play a significant role in the application of this useful technique.  相似文献   
38.
Chaos theory, informational needs, and natural disasters   总被引:2,自引:0,他引:2  
This study applies chaos theory to a system-wide analysis of crisis communication in a natural disaster. Specifically, we analyze crisis communication during the 1997 Red River Valley flood in Minnesota and North Dakota. This flood, among the worst in modern American history, consumed entire metropolitan areas, displacing thousands of people. The conditions and decisions leading to the disaster, and the subsequent reactions are retraced. Communication related to river crest predictions (fractals), the shock at the magnitude of the crisis (cosmology episode), novel forms of reorganizing (self-organization), and agencies that aided in establishing a renewed order (strange attractors) are evaluated. Ultimately, we argue that preexisting sensemaking structures favoring rationalized, traditional views of a complex system led officials to make inappropriately unequivocal predictions and ultimately diminished the effectiveness of the region's crisis communication and planning.  相似文献   
39.
This investigation identifies demographic, media, and social correlates of verbally aggressive communication in adolescence. Mail surveys were completed and returned by 2,300 adolescents between the ages of 13 and 15. These adolescents were asked about the prevalence of verbal and physical aggression, the context in which it occurred, demographics, and the interpersonal and media influences in their lives. The results indicate that verbal aggression is widespread, that committing and experiencing verbal aggression is largely reciprocal, that there is a strong relationship between committing verbal and physical aggression, and that peer social influence and listening to violently oriented music are mildly related to verbal aggression in adolescents. These findings suggest more resources should be allocated to teaching adolescents to understand and control verbal aggression. Further, they provide important answers to many prevention and intervention programmatic questions, including context, content, and targeting concerns. Since the negative consequences of verbal aggression are severe and long lasting, decreasing this destructive communication behavior should significantly improve the lives of many adolescents. These and other practical implications are expanded upon and discussed.  相似文献   
40.
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