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   122605篇
  免费   1845篇
  国内免费   233篇
教育   85313篇
科学研究   13447篇
各国文化   1975篇
体育   9438篇
综合类   171篇
文化理论   1054篇
信息传播   13285篇
  2021年   939篇
  2020年   1640篇
  2019年   2550篇
  2018年   3055篇
  2017年   3297篇
  2016年   3365篇
  2015年   2292篇
  2014年   3169篇
  2013年   27184篇
  2012年   2346篇
  2011年   2694篇
  2010年   2307篇
  2009年   2595篇
  2008年   2348篇
  2007年   2092篇
  2006年   2337篇
  2005年   2333篇
  2004年   3015篇
  2003年   2330篇
  2002年   2147篇
  2001年   2009篇
  2000年   1692篇
  1999年   1567篇
  1998年   1449篇
  1997年   1521篇
  1996年   1698篇
  1995年   1459篇
  1994年   1469篇
  1993年   1467篇
  1992年   1501篇
  1991年   1420篇
  1990年   1413篇
  1989年   1347篇
  1988年   1190篇
  1987年   1138篇
  1986年   1173篇
  1985年   1427篇
  1984年   1284篇
  1983年   1293篇
  1982年   1269篇
  1981年   1180篇
  1980年   1163篇
  1979年   1288篇
  1978年   1215篇
  1977年   1120篇
  1976年   1004篇
  1975年   822篇
  1974年   821篇
  1973年   785篇
  1971年   651篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
921.
922.
923.
924.
The effects of salience on 4- and 6-year-old children's ability to classify multiplicatively was investigated. A rank-ordered salience hierachy consisting of 3 dimensions was first assessed for each S. Several weeks later half the Ss of each age group were presented with a series of 9 3 times 3 matrix problems consisting of values from 2 dimensions ranked high in salience. The remaining half received identically structured matrices consisting of values from 1 highly salient dimension and of others from a dimension ranked low in salience. The goal in each problem was to select that compound stimulus from a set of alternatives that appropriately filled an empty cell in the matrix. Prior to the matrix problems, half the Ss in each matrix condition received sensitization training designed to increase the salience of the relevant dimensions in the matrix problems. The results showed that the pre-assessed salience of the relevant dimensions affected matrix solution in that more accurate performance was associated with those problems with both relevant dimensions relatively high in salience than those with one high and one low. Although the older Ss solved more problems, the evidence for coordination in the younger Ss was clear. No effects of sensitization training were found.  相似文献   
925.
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   
926.
927.
928.
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   
929.
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   
930.
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   
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