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   53401篇
  免费   2152篇
  国内免费   31篇
  2020年   619篇
  2019年   786篇
  2018年   1136篇
  2017年   1103篇
  2016年   1155篇
  2015年   773篇
  2014年   959篇
  2013年   4672篇
  2012年   1703篇
  2011年   1874篇
  2010年   1082篇
  2009年   1097篇
  2008年   1679篇
  2007年   1665篇
  2006年   1460篇
  2005年   1320篇
  2004年   1302篇
  2003年   1166篇
  2002年   1204篇
  2001年   1771篇
  2000年   1667篇
  1999年   1285篇
  1998年   681篇
  1997年   578篇
  1996年   529篇
  1995年   530篇
  1994年   505篇
  1993年   525篇
  1992年   1017篇
  1991年   962篇
  1990年   947篇
  1989年   859篇
  1988年   826篇
  1987年   811篇
  1986年   813篇
  1985年   863篇
  1984年   678篇
  1983年   584篇
  1982年   478篇
  1979年   666篇
  1978年   493篇
  1976年   456篇
  1975年   597篇
  1974年   629篇
  1973年   610篇
  1972年   548篇
  1971年   483篇
  1968年   546篇
  1967年   545篇
  1966年   480篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
We examined the effects of acute psychological stress on lymphocyte proliferation and circulating levels of interleukin-1 and -2. Healthy men were exposed to two viewings of a gruesome surgery film and were asked to recall details of the film twice during a 30-min period. These subjects were compared to a nonstress control group. Lymphocyte proliferation to the mitogen concanavalin A (Con A; 5 micrograms/ml) was decreased during and after exposure to the stressor when compared to the control group. This decrease was more pronounced in subjects exhibiting greater blood pressure reactivity while viewing the film than in subjects showing smaller blood pressure responses. None of the other immunological measures was significantly affected by the stressor. Cortisol was not correlated with lymphocyte responsiveness. Possible explanations for these results and implications for further research are discussed.  相似文献   
122.
Cardiovascular reactivity to video game and mental arithmetic stressors was compared among three groups of men: aerobically trained mild hypertensives, untrained mild hypertensives, and a comparison group of untrained normotensives. Relative to the untrained hypertensives, the trained hypertensives reacted to the video game with marginally smaller systolic blood pressure and diastolic blood pressure, but there were no significant differences between these groups in reactivity during the mental arithmetic task. Comparisons between each hypertensive group and the normotensive group showed that blood pressure (BP) reactivity of normotensives during the video game was generally similar to that of trained hypertensives but smaller than that of untrained hypertensives. These results indicate that aerobic training, which has been found to reduce resting BP in mild hypertensives, may also exert a favorable impact in reducing cardiovascular reactivity of hypertensives during some stressful situations.  相似文献   
123.
This study examines the effects of certain communication variables (member integration, boundary communication, environmental uncertainty, and system autonomy) on organizational effectiveness. While often discussed in the literature, these variables have not been precisely defined. As a result, a multiple indicator model using maximum likelihood estimates for each variable was created. Interviews with managers from 82 different organizations from a variety of industries are used to test the model. The results suggest that member integration and environmental uncertainty, when the latter is mediated by boundary communication, provide an excellent predictor of organizational effectiveness (R= .64). The results are discussed in light of the proposed theory along with implications for future research using intertypical sampling methods and LISREL analysis.  相似文献   
124.
125.
126.
127.
128.
Typical word-association procedures result in verbal response hierarchies for a specific stimulus word. The problem of assessing corresponding stimulus hierarchies is discussed Three approaches are entertained: obtaining associations to all of the words in the dictionary, clerical cross-indexing of existing response-hierarchy data, and obtaining backward associations which are then used in forward association. A comparison of data obtainable by the last two methods is presented.  相似文献   
129.
130.
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