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   54973篇
  免费   2152篇
  国内免费   34篇
  57159篇
  2020年   588篇
  2019年   666篇
  2018年   904篇
  2017年   916篇
  2016年   1041篇
  2015年   740篇
  2014年   855篇
  2013年   4258篇
  2012年   1606篇
  2011年   1648篇
  2010年   998篇
  2009年   1067篇
  2008年   1462篇
  2007年   1387篇
  2006年   1237篇
  2005年   1111篇
  2004年   1058篇
  2003年   1019篇
  2002年   1061篇
  2001年   1640篇
  2000年   1615篇
  1999年   1178篇
  1998年   553篇
  1997年   519篇
  1992年   1027篇
  1991年   984篇
  1990年   956篇
  1989年   937篇
  1988年   892篇
  1987年   847篇
  1986年   882篇
  1985年   961篇
  1984年   794篇
  1983年   734篇
  1982年   551篇
  1981年   550篇
  1979年   855篇
  1978年   622篇
  1977年   561篇
  1976年   566篇
  1975年   735篇
  1974年   850篇
  1973年   899篇
  1972年   761篇
  1971年   716篇
  1970年   650篇
  1969年   694篇
  1968年   849篇
  1967年   782篇
  1966年   746篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Interference and facilitation in short-term memory for odors   总被引:2,自引:0,他引:2  
  相似文献   
962.
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   
963.
40 schizophrenic subjects, divided into paranoid/non-paranoid categories and 14 normal controls were presented a task which involved making "same-different" judgments during random presentations of a series of visual comparison stimuli with a standard which represented the midpoint of the stimulus continuum. Using Sternberg's Choice RT paradigm for studying the locus of cognitive deficit, difficulty at the response-selection stage was manipulated while holding other stages constant. It was predicted that paranoids would have shorter RTs at easy decision points and longer RTs at difficult decision points relative to non-paranoids. The directions of the differences were as predicted but did not attain statistical significance. Both schizophrenic groups, compared to normals, made significantly fewer "same" responses on those trials where the comparison and standard were most similar.  相似文献   
964.
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   
965.
A longitudinal study of the development of hand preference in 152 adopted and 120 nonadopted (control) infants measured in natural behavioral situations at both 12 and 24 mo. of age is reported. Significant developmental trends were observed for both increasing strength and direction of handedness. Less than 10% of the infants exhibited a clear preference at 12 mo. of age, whereas about 30% were lateralized at 24 mo., with more boys than girls being left-handed. In contrast, over 90% of the parents of these children (both biological and adoptive parents of the adopted children and parents of the nonadopted children) were lateralized. Perhaps because so few infants were lateralized at either age, parent-offspring resemblances were inconsistent and the number of significant parent/child correlations was about that expected on the basis of chance alone.  相似文献   
966.
In a previous experiment, Allen found no release from proactive inhibition using the Brown-Peterson procedure in a group who were shifted from recalling colors to recalling the names of colors. The lack of release suggests that colors and color names are encoded in similar ways. It was argued that the similarity of encoding might have been caused by the procedure of requiring the subjects to say out loud the names of the colors at the time of stimulus presentation and recall. In the present experiment, a procedure was devised that eliminated the need for verbalization of the colors. The same pattern of results was obtained, namely, release from proactive inhibition in the group shifted from recalling color names to colors but not in the group shifted in the opposite direction. It was concluded that if subjects encode colors as a verbal label, then this encoding strategy is not caused by the procedure of requiring the subjects to verbalize the colors.  相似文献   
967.
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   
968.
969.
970.
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