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   61830篇
  免费   2642篇
  国内免费   25篇
  2021年   541篇
  2020年   848篇
  2019年   956篇
  2018年   1474篇
  2017年   1459篇
  2016年   1480篇
  2015年   1031篇
  2014年   1234篇
  2013年   5615篇
  2012年   2349篇
  2011年   2353篇
  2010年   1456篇
  2009年   1368篇
  2008年   2028篇
  2007年   1918篇
  2006年   1747篇
  2005年   1460篇
  2004年   1421篇
  2003年   1362篇
  2002年   1297篇
  2001年   1973篇
  2000年   1871篇
  1999年   1395篇
  1998年   641篇
  1997年   553篇
  1996年   628篇
  1995年   569篇
  1994年   565篇
  1993年   548篇
  1992年   1140篇
  1991年   1035篇
  1990年   1017篇
  1989年   980篇
  1988年   953篇
  1987年   880篇
  1986年   866篇
  1985年   918篇
  1984年   745篇
  1983年   637篇
  1979年   770篇
  1978年   572篇
  1975年   608篇
  1974年   692篇
  1973年   716篇
  1972年   616篇
  1971年   575篇
  1970年   491篇
  1968年   628篇
  1967年   536篇
  1966年   518篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
Some of the advantages of LISP and some of its unsavory reputation are discussed. Some LISP programs in a variety of areas (chemistry, medicine, question answering, natural language, mathematics, airline tariffs, etc.) are briefly described.  相似文献   
133.
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   
134.
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   
135.
This research reports a first attempt to study adaptation to laterally displacing prisms in human infants of ages six to ten months. Twenty infants were tested over four days under conditions similar to those used in adult adaptation studies. Evidence was found of vigorous adaptation when infants were exposed to base-right prisms under conditions of active exposure. Detailed consideration is given to the conditions and methods of studying adaptation in infants and implications for adult studies.  相似文献   
136.
137.
138.
139.
140.
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