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   67075篇
  免费   2719篇
  国内免费   20篇
  2020年   623篇
  2019年   791篇
  2018年   1080篇
  2017年   1108篇
  2016年   1164篇
  2015年   867篇
  2014年   1033篇
  2013年   4820篇
  2012年   1966篇
  2011年   2000篇
  2010年   1215篇
  2009年   1177篇
  2008年   1751篇
  2007年   1732篇
  2006年   1577篇
  2005年   1463篇
  2004年   1390篇
  2003年   1269篇
  2002年   1304篇
  2001年   2068篇
  2000年   1926篇
  1999年   1473篇
  1998年   732篇
  1997年   609篇
  1992年   1318篇
  1991年   1234篇
  1990年   1219篇
  1989年   1142篇
  1988年   1148篇
  1987年   1103篇
  1986年   1135篇
  1985年   1235篇
  1984年   956篇
  1983年   904篇
  1982年   687篇
  1981年   655篇
  1979年   1117篇
  1978年   754篇
  1977年   685篇
  1976年   719篇
  1975年   940篇
  1974年   1067篇
  1973年   1135篇
  1972年   954篇
  1971年   878篇
  1970年   880篇
  1969年   896篇
  1968年   1145篇
  1967年   1014篇
  1966年   938篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
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   
33.
34.
35.
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   
36.
37.
38.
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   
39.
Subjects in five experiments read nine-digit memory lists from a cathode ray tube for immediate recall. Reading aloud always produced a localized and reliable advantage for the last item, compared to reading silently. Two experiments on whispered and mouthed lists, with or without simultaneous broadband noise, falsified expectations derived from the theory of precategorical acoustic storage. Three additional experiments showed no enhancement of recency in the silent conditions when the digits were drawn or spelled gradually on the screen, a result that is inconsistent with the changing-state hypothesis. The classic auditory-visual modality effect is large and reliable, but still poorly understood.  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