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   52589篇
  免费   2110篇
  国内免费   16篇
  54715篇
  2019年   604篇
  2018年   798篇
  2017年   774篇
  2016年   883篇
  2015年   635篇
  2014年   782篇
  2013年   3757篇
  2012年   1455篇
  2011年   1481篇
  2010年   921篇
  2009年   908篇
  2008年   1319篇
  2007年   1343篇
  2006年   1198篇
  2005年   1100篇
  2004年   1080篇
  2003年   975篇
  2002年   989篇
  2001年   1629篇
  2000年   1624篇
  1999年   1164篇
  1998年   580篇
  1997年   485篇
  1996年   483篇
  1992年   1075篇
  1991年   1033篇
  1990年   1053篇
  1989年   938篇
  1988年   926篇
  1987年   863篇
  1986年   912篇
  1985年   992篇
  1984年   751篇
  1983年   722篇
  1982年   510篇
  1981年   487篇
  1979年   893篇
  1978年   616篇
  1977年   550篇
  1976年   537篇
  1975年   763篇
  1974年   871篇
  1973年   930篇
  1972年   797篇
  1971年   745篇
  1970年   709篇
  1969年   720篇
  1968年   948篇
  1967年   856篇
  1966年   765篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
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   
992.
Eye position and visual attention influence perceived auditory direction   总被引:2,自引:0,他引:2  
The singular and joint effects of eccentric visual fixation and peripheral visual attention upon the perceived auditory median plane (PAMP) of the head were examined in four subjects. They positioned a hidden, horizontally-moving sound source to the perceived median plane of the head, while fixating a light 20 degrees or 45 degrees to the right or left of the actual median plane, and attending to another light in peripheral vision. Analysis by multiple linear regression yielded a model for each subject which indicated the nature and weighting of those factors contributing to variance reduction in PAMP judgments. Three subjects showed a strong linear attention effect, resulting in shifts of the PAMP away from the locus of attention. Similarly, a strong linear fixation effect was discovered in two subjects, a weak effect in another, and a nonlinear, inverse fixation effect in the last. Additional factors were noted for some subjects. Possible explanations of the observed effects were discussed. The study indicates that both visual attention and visual fixation are critical factors in experiments on auditory space perception although inter-individual differences do exist in the nature and strength of the effects.  相似文献   
993.
994.
995.
996.
The present study based on the indirect Clausen-test using NTA and PHA as antigens contributed to therapy control and possibly prognosis assessment rather than to immunological differential diagnosis.  相似文献   
997.
998.
Is there a cell-biological alphabet for simple forms of learning?   总被引:5,自引:0,他引:5  
  相似文献   
999.
Programs,language understanding,and searle   总被引:1,自引:0,他引:1  
  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