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   57184篇
  免费   2252篇
  国内免费   21篇
  59457篇
  2020年   625篇
  2019年   664篇
  2018年   1063篇
  2017年   969篇
  2016年   1043篇
  2015年   690篇
  2014年   912篇
  2013年   5069篇
  2012年   1606篇
  2011年   1677篇
  2010年   1013篇
  2009年   1010篇
  2008年   1545篇
  2007年   1395篇
  2006年   1302篇
  2005年   1094篇
  2004年   1036篇
  2003年   1059篇
  2002年   985篇
  2001年   1822篇
  2000年   1787篇
  1999年   1348篇
  1998年   595篇
  1996年   653篇
  1995年   631篇
  1994年   599篇
  1993年   598篇
  1992年   1305篇
  1991年   1153篇
  1990年   1190篇
  1989年   1045篇
  1988年   1029篇
  1987年   997篇
  1986年   1016篇
  1985年   1051篇
  1984年   887篇
  1983年   740篇
  1982年   582篇
  1979年   853篇
  1978年   651篇
  1975年   778篇
  1974年   824篇
  1973年   894篇
  1972年   798篇
  1971年   708篇
  1970年   612篇
  1969年   618篇
  1968年   783篇
  1967年   667篇
  1966年   684篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Loneliness in relation to depression and self-esteem   总被引:1,自引:0,他引:1  
  相似文献   
992.
993.
994.
995.
996.
Reaction and movement times in men of different ages: a population study   总被引:5,自引:0,他引:5  
Tests of psychomotor and motor speed at different levels of complexity were studied in random samples of men aged 31 to 35, 51 to 55, and 71 to 75 yr. The study was performed as a part of a larger research project on health and functional aging. Analyses indicated significantly slower responses among older men at all levels of test complexity (maximal knee extension velocity, tapping rate, simple and choice reaction and movement times). There were marked differences both between the youngest and the middle-aged groups and between the middle-aged and the oldest groups. Within the age groups high psychomotor and motor speed were associated with a favourable functioning of certain senses (vibration sensitivity and postural balance), with a high isometric muscular force, and with a high directly assessed aerobic capacity. The most important covariants of the speed functions within the age groups were, however, cognitive performance, length of education, and perceived health.  相似文献   
997.
Aerobic exercise which resulted in a significant improvement in cardiovascular functioning had no more effect on psychological mood states than did the placebo control of participation in nonaerobic recreational games or no exercise and sport at all (N = 430 college students). Beta-endorphin levels with the 41 depressed subjects were not a biochemical link that might explain the possible influence of physical activity on depression.  相似文献   
998.
The purpose of this study was to gather evidence on the validity of the Vando R-A Scale, a paper-and-pencil measure of perceptual reactance. The Vando R-A Scale and Petrie's kinesthetic aftereffect measure of perceptual reactance were administered to 46 participants drawn from university undergraduates. The Vando R-A Scale was not a valid measure of perceptual reactance. The continued use of the Vando R-A Scale as an alternate measure of perceptual reactance is contraindicated.  相似文献   
999.
For 40 males who smoked 20 cigarettes a day titratable acidity of the urine was significantly correlated with nicotine/cotinine excretion at several sample intervals, as was urinary pH, but not urinary acidity and daily cigarette consumption or serum COHB.  相似文献   
1000.
The parallel-lines illusion provides a prototypical example of visual-size assimilation, where the size of a test element is phenomenally skewed towards (or "averaged with") that of a context element. Most assimilation theories predict that distortion should decrease with spatial separation between context and test lengths. However, there is some disagreement about the nature of the function relating sizes of context and test elements and magnitude of assimilation. The present study tests the limits of assimilation in the parallel-lines configurations by observing the effects of a wide range of context/test size ratios, repeated over two disparate levels of spatial separation. The results replicate and extend 1979 findings by Brigell and Uhlarik, confirming that assimilation rises to a peak at midrange size ratios, only to decrease continuously as the ratios become more extreme. The functions were nonmonotonic and similar in shape for both levels of spatial separation, with an over-all decrease in distortion for configurations with the larger separation.  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