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   5476篇
  免费   81篇
  国内免费   20篇
教育   3786篇
科学研究   661篇
各国文化   34篇
体育   394篇
综合类   6篇
文化理论   35篇
信息传播   661篇
  2022年   42篇
  2021年   56篇
  2020年   91篇
  2019年   135篇
  2018年   177篇
  2017年   210篇
  2016年   168篇
  2015年   132篇
  2014年   172篇
  2013年   910篇
  2012年   140篇
  2011年   150篇
  2010年   134篇
  2009年   117篇
  2008年   129篇
  2007年   144篇
  2006年   113篇
  2005年   83篇
  2004年   97篇
  2003年   92篇
  2002年   69篇
  2001年   111篇
  2000年   146篇
  1999年   93篇
  1998年   77篇
  1997年   66篇
  1996年   67篇
  1995年   47篇
  1994年   49篇
  1993年   37篇
  1992年   80篇
  1991年   74篇
  1990年   63篇
  1989年   68篇
  1988年   81篇
  1987年   63篇
  1986年   81篇
  1985年   75篇
  1984年   59篇
  1983年   70篇
  1982年   55篇
  1981年   43篇
  1980年   32篇
  1979年   53篇
  1978年   50篇
  1977年   37篇
  1976年   45篇
  1975年   36篇
  1974年   37篇
  1973年   34篇
排序方式: 共有5577条查询结果,搜索用时 0 毫秒
11.
12.
13.
14.
15.
16.
This study is a social media analysis on the use of Twitter at Historically Black Colleges and University (HBCU) libraries. While information science researchers have begun examining how libraries use social media, the vast majority of these studies are situated at large flagship research-intensive universities. Additionally, there currently exist deficiencies in research on social media deployment at HBCU libraries. We leverage, the IBM Watson's analytic engine, to systemically examine over 23,000, tweets over an eighteen-month period, around a set of objective measures including propagation of retweets and sentiment to assess follower engagement. The analysis found little evidence of follower engagement with library generated content. However, we observed a substantial volume of library tweets coalesced around institutional boosterism, rather than library related phenomena. This non-library related content represented the vast majority of retweets, but paradoxically was propagated by non-followers. Additionally, tweets relating to institutional boosterism produced the most positive sentiment within the data.  相似文献   
17.
Although the USSR and the United States had a comparable number of employees in the field of scientific information, there was a substantial difference in funding, which resulted in a lack of information support for Soviet scientists. While 90% of the publications in the United States were available almost immediately after their release, in the USSR they were delayed by 1.5 to 2 years. Since the publication of the Abstracts Journal by VINITI (AJ), its content was consistently expanding and reached its peak in 1990 (1.5 million documents per year). The next quarter of a century was characterized by a decline in both the composition of the AJ and the time required for its document coverage. The steps for restructuring VINITI activities are discussed. The focus is made on improving the limited coverage of the Russian-language part of the global flow of scientific information by Western information systems.  相似文献   
18.
This study examined whether persuasive health messages embedded in shooter games have broad or targeted effects on players’ willingness to engage in risk behaviors (N = 145). Participants presented with in-game health messages discouraging alcohol-impaired driving of motor vehicles showed reduced willingness to drink alcohol and to operate both motor and nonmotor vehicles, compared to those in a no-message gaming control condition. There were no spillover effects on willingness to smoke cigarettes or marijuana, thus implying targeted persuasive effects. In addition, players experiencing high instead of low cognitive load showed decreased postexperiment willingness to drink and operate nonmotor vehicles, thus suggesting that playing a game under high cognitive load can influence players’ attitudes. The findings replicate previous research and further expand on knowledge-activation and thought-disruption mechanisms underlying the persuasiveness of health messages.  相似文献   
19.
20.
Although angiogenetic therapy using recombinant growth factors holds much hope for the treatment of ischaemic diseases, there are still many unanswered questions, including the method of administration, the correct dose of these factors, and the duration of the therapeutic approach. Exercise has also been suggested to induce neovascularizaiton in muscles. We evaluated the angiogenetic effects of the intramuscular administration of basic-fibroblast growth factor (b-FGF) and acidic-fibroblast growth factor (a-FGF) in rat heart, compared with rats who exercised daily. In conclusion, both the intramuscular administration of b-FGF and exercise increased significantly angiogenesis in the heart in contrast to the intramuscular administration of a-FGF, which was ineffective.  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