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   129966篇
  免费   1937篇
  国内免费   242篇
教育   89979篇
科学研究   13920篇
各国文化   2039篇
体育   10397篇
综合类   195篇
文化理论   1124篇
信息传播   14491篇
  2021年   1000篇
  2020年   1733篇
  2019年   2677篇
  2018年   3384篇
  2017年   3632篇
  2016年   3630篇
  2015年   2392篇
  2014年   3251篇
  2013年   27683篇
  2012年   2628篇
  2011年   3137篇
  2010年   2522篇
  2009年   2706篇
  2008年   2636篇
  2007年   2404篇
  2006年   2565篇
  2005年   2569篇
  2004年   3220篇
  2003年   2489篇
  2002年   2327篇
  2001年   2279篇
  2000年   1911篇
  1999年   1782篇
  1998年   1506篇
  1997年   1557篇
  1996年   1711篇
  1995年   1478篇
  1994年   1480篇
  1993年   1484篇
  1992年   1627篇
  1991年   1531篇
  1990年   1519篇
  1989年   1479篇
  1988年   1328篇
  1987年   1244篇
  1986年   1270篇
  1985年   1542篇
  1984年   1376篇
  1983年   1348篇
  1982年   1285篇
  1981年   1199篇
  1980年   1188篇
  1979年   1348篇
  1978年   1247篇
  1977年   1149篇
  1976年   1049篇
  1975年   848篇
  1974年   863篇
  1973年   819篇
  1971年   676篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
The behavior of narcotics-addicted and nonaddicted newborns on the first 2 days of life was assessed with the Brazelton Neonatal Behavioral Assessment Scale. In addition to classic signs of narcotics abstinence, addicted infants were less able to be maintained in an alert state and less able to orient to auditory and visual stimuli. These deficits were especially pronounced at 48 hours of age. Addicted infants were as capable of self-quieting and responding to soothing intervention as normal neonates, although they were substantially more irritable. These characteristics and addicted infants' greater resistance to cuddling are discussed in terms of their potential impact on early infant-care-giver interaction.  相似文献   
993.
A study of seriation was conducted from the perspective of Gibson's theory of perceptual development. Kindergarten children who evidenced little seriation of height or brightness were assigned to either 1 of 3 perceptual training conditions or to a fourth, control condition. Training consisted of nonreinforced same-different judgments to wooden dowels varying in height, or in brightness, or simultaneously in height and brightness. The theoretical rationale for this training was that it would facilitate perception of the stimulus dimension(s) on which the dowels differed. It was found that perceptual training did facilitate seriation, particularly if both the height and brightness dimensions varied simultaneously in training.  相似文献   
994.
995.
996.
997.
A mathematical theory is developed for an imagined device termed a “junctor”. A junctor could be used to interconnect two n-terminal networks giving rise to another n-terminal network. Actually a junctor is itself a simple network with three banks of n-terminals internally connected in some fashion by perfectly conducting wires. Adjacency matrices are formulated to analyze various junctors and their current flows. The main problem treated concerns conditions which would ensure that the junctor operation is associative.  相似文献   
998.
The functional integral representation for the space-time Hopf characteristic functional associated with boundary-free incompressible fluid turbulence is evaluated accurately to order R-2, where R is the dimensionless Reynolds number in the theory. This work extends the results obtained previously for C-dominant turbulence to the regime of experimentally accessible large Reynolds numbers. We obtain a characteristic functional of non-Gaussian form as an asymptotically exact solution to the theory for large values of R. Two-point and three-point velocity correlation tensors of physical interest are derived from the characteristic functional.  相似文献   
999.
The principles of X-ray photoelectron spectroscopy are outlined. The application of this technique to the study of the electronic structure of metals, alloys and compounds is illustrated using data in Ag, β-brass, ReO3 and VO2. In the latter a major change in the density of states is observed on passing through the metal-insulator transition.  相似文献   
1000.
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