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   53647篇
  免费   1418篇
  国内免费   9篇
  2020年   333篇
  2019年   482篇
  2018年   3950篇
  2017年   3300篇
  2016年   2794篇
  2015年   642篇
  2014年   659篇
  2013年   2609篇
  2012年   1583篇
  2011年   3404篇
  2010年   3069篇
  2009年   2093篇
  2008年   2621篇
  2007年   3023篇
  2006年   911篇
  2005年   1002篇
  2004年   939篇
  2003年   813篇
  2002年   789篇
  2001年   1069篇
  2000年   995篇
  1999年   736篇
  1998年   410篇
  1997年   344篇
  1996年   320篇
  1992年   555篇
  1991年   559篇
  1990年   542篇
  1989年   547篇
  1988年   535篇
  1987年   497篇
  1986年   529篇
  1985年   580篇
  1984年   459篇
  1983年   438篇
  1982年   361篇
  1981年   343篇
  1979年   525篇
  1978年   380篇
  1976年   363篇
  1975年   436篇
  1974年   492篇
  1973年   512篇
  1972年   409篇
  1971年   384篇
  1970年   379篇
  1969年   413篇
  1968年   493篇
  1967年   421篇
  1966年   425篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
We discuss computational language analysis as it pertains to suicide prevention research, with an emphasis on providing non‐technologists with an understanding of key issues and, equally important, considering its relation to the broader enterprise of suicide prevention. Our emphasis here is on naturally occurring language in social media, motivated by its non‐intrusive ability to yield high‐value information that in the past has been largely unavailable to clinicians.  相似文献   
22.
As the complexity of the challenges presented by our interactions with our planet continues to grow, we must develop new modes of knowledge production. In these modes, distinctions between multidisciplinary and inter-disciplinary activities and processes have renewed importance. There are at least two distinct types of interdisciplinary activities distinguished by the disciplinary breadth they attempt to bridge. In the narrow case, reductionist processes reveal a common underlying principle or process which can serve as a Rosetta stone. In the broad case, no such common arbiter exists. Investigators must develop integrating vocabulary in the context of the full breadth of their work. His primary activities are the fostering of university-wide interdisciplinary research and curriculum programs focused on global change with the goal of developing Columbia into a world leader in issues related to global stewardship.  相似文献   
23.
24.
Convergent and divergent stereo mechanisms were compared in their ability to recover structure from motion. Contrary to a recent result reported by Richards and Lieberman, no difference in their performance was found; both mechanisms appeared equally capable of supporting the perception of good structure from motion. Possible reasons for the disparate results are discussed.  相似文献   
25.
26.
27.
Brain mapping studies using dynamic imaging methods demonstrate areas regional cerebral blood flow (rCBF) decreases, as well as areas where increases, during performance of various experimental tasks. Task holds for both sets of cerebral blood flow changes (CBF), providing the opportunity to investigate areas that become and “activated” in the experimental condition relative to control state. Such data yield the intriguing observation that in areas in emotional processing, such as the amygdala, the posteromedial cortex, and the ventral anterior cingulate cortex, although flow as expected during specific emotion-related tasks, flow decreases performance of some attentionally demanding, cognitive tasks. Conversely, in some of the areas that appear to subserve cognitive functions, as the dorsal anterior cingulate and the dorsolateral prefrontal cortices, increases while performing attentionally demanding cognitive tasks, but during some experimentally induced and pathological emotional Although the specific nature of such reciprocal patterns of regional remains unclear, they may reflect an important cross-modal interaction during mental operations. The possibility that neural activity is less in areas required in emotional processing during some higher cognitive processes holds implications for the mechanisms underlying interactions cognition and emotion. Furthermore, the possibility that neural in some cognitive-processing areas is suppressed during intense states suggests mechanisms by which extreme fear or severe may interfere with cognitive performance.  相似文献   
28.
29.
30.
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