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   49096篇
  免费   892篇
  国内免费   5篇
  49993篇
  2018年   603篇
  2017年   654篇
  2016年   718篇
  2015年   551篇
  2014年   656篇
  2013年   3464篇
  2012年   1166篇
  2011年   1238篇
  2010年   800篇
  2009年   787篇
  2008年   1170篇
  2007年   1059篇
  2006年   981篇
  2005年   909篇
  2004年   863篇
  2003年   882篇
  2002年   914篇
  2001年   1270篇
  2000年   1248篇
  1999年   930篇
  1998年   481篇
  1997年   489篇
  1996年   468篇
  1992年   903篇
  1991年   854篇
  1990年   864篇
  1989年   835篇
  1988年   797篇
  1987年   780篇
  1986年   842篇
  1985年   867篇
  1984年   737篇
  1983年   685篇
  1982年   501篇
  1981年   568篇
  1979年   805篇
  1978年   619篇
  1977年   546篇
  1976年   545篇
  1975年   708篇
  1974年   841篇
  1973年   887篇
  1972年   705篇
  1971年   721篇
  1970年   676篇
  1969年   710篇
  1968年   885篇
  1967年   812篇
  1966年   814篇
  1958年   467篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
331.
332.
This study was designed to determine possible differences in the cognitive, perceptual, and personal-social development of prematurely and maturely born 3-yr.-olds which might foreshadow later learning problems. The subjects were 40 prematurely born graduates of a neonatal intensive care unit (birth weight less than 2,500 gm, less than 37 wk. gestation) matched on the pair-level with full-term controls on sex, race, post-conceptual age, and socioeconomic background. All subjects were singletons and parity was matched at the group level. No differences were found between the groups on tests of higher mental processes including the General Cognitive, Verbal, Quantitative, and Memory Scales of the McCarthy Scales of Children's Abilities, and researcher-devised measures of problem-solving competence. No differences in parental reports of personal-social development were noted. Prematures did not perform as well as controls on perceptual performance tasks, and this difference was interpreted as reflecting relatively impaired visual-motor coordination.  相似文献   
333.
This annotated listing is of group reports pertaining to therapeutic strategies utilized with infants and young children who have cerebral palsy. The studies are organized by type of design used.  相似文献   
334.
This paper presents the results of an in-depth study of parameters characterizing sequenced saccadic eye movements for a group of dyslexic children and a comparative normal control group with ages in the range greater than 8.0 yr. and less than 13.0 yr. No parameters were statistically different for the two groups, which supports the findings of Brown, et al. and contradicts the findings of Pavlidis. Our results indicate that sequenced saccadic eye movements are not diagnostically useful for early detection of dyslexia.  相似文献   
335.
Previous research aimed at quantifying and reducing the decrements encountered in performing manual tasks in cold weather has not described the relationships between task characteristics and cold-induced impairments. The amount of decrement and, often times, the optimal means for reducing the decrement, appear to be task-specific. The research reported here is one in a series of studies formulated to explore those relationships. The strategy is to use tasks from the battery developed by Fleishman (1967) to measure the factorially 'pure' abilities needed to perform all manual tasks. 24 U.S. Marines performed this battery of nine tasks across a range of cold temperatures. To determine if the decrement due to wearing gloves might be less than the decrement due to cold hands as the air temperature decreased, performance on the battery of tasks was measured with and without gloves. Only three of the tasks (abilities) were affected by cold temperatures, and the amount of decrement increased as the air temperature decreased. Three tasks deteriorated due to wearing of gloves, two of those affected by cold and one other. Temperature affected performance independently of the glove effect. Half of the subjects did not complete bare-handed testing at -18 degrees C (approximately 20 min.), indicating this is the lower end of the temperature range in which bare-handed performance for more than a few minutes is practical.  相似文献   
336.
By 48 patients with Wilson's disease the brainstem acoustic evoked potentials were stated. There were 35 pathological findings (73%), 13 were normal (27%). The waves, determined by the middle and upper brainstem (Pons and Mesencephalon) showed most of all pathological changes. Those patients with forms of Wilson's disease called Pseudoskelerose and Pseudoparkinson showed the most pathological findings. But one could watch these findings by about 30% of patients in preclinical stage. This method can possibly be used for early detection of disorders of brainstem functions and in the same way it can be used for control of treatment by patients in preclinical stage.  相似文献   
337.
338.
339.
340.
Why 2 + 2 = 5 looks so wrong: On the odd-even rule in sum verification   总被引:1,自引:0,他引:1  
The odd-even status of a sum depends on the odd-even status of its addends. A sum must be odd if an odd number of its addends are odd; else it must be even. A proposed sum that violates the required odd-even status of the sum—that is, deviates from the correct sum, whether odd or even, by an odd value (e.g., splits of ±1, ±3, ±5)—can be rejected immediately as false. Subjects in the present study did indeed use the odd-even rule in sum verification, because they were as fast and accurate in rejecting a split of ±1 as one of ±2, and a split of ±3 as one of ±4, even though a larger split generally is easier to reject (symbolic distance effect), and splits of ±3 and ±4 were rejected faster and more accurately than those of ±1 and ±2. Performance on separate odd-even tasks indicated that the odd-even properties of numbers and sums are readily available for use by adults, and that persons who do well on such tasks are especially likely to use the odd-even rule in sum verification.  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