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   67084篇
  免费   2570篇
  国内免费   18篇
  2019年   806篇
  2018年   1124篇
  2017年   1096篇
  2016年   1171篇
  2015年   844篇
  2014年   1059篇
  2013年   5817篇
  2012年   1844篇
  2011年   1940篇
  2010年   1195篇
  2009年   1191篇
  2008年   1768篇
  2007年   1674篇
  2006年   1578篇
  2005年   1357篇
  2004年   1323篇
  2003年   1295篇
  2002年   1296篇
  2001年   2034篇
  2000年   1910篇
  1999年   1473篇
  1998年   752篇
  1996年   773篇
  1995年   733篇
  1994年   716篇
  1992年   1354篇
  1991年   1265篇
  1990年   1227篇
  1989年   1187篇
  1988年   1172篇
  1987年   1111篇
  1986年   1150篇
  1985年   1178篇
  1984年   1002篇
  1983年   888篇
  1982年   730篇
  1981年   725篇
  1979年   1024篇
  1978年   769篇
  1976年   699篇
  1975年   917篇
  1974年   952篇
  1973年   1023篇
  1972年   915篇
  1971年   816篇
  1970年   772篇
  1969年   775篇
  1968年   948篇
  1967年   829篇
  1966年   811篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
Reducing STDs and HIV/AIDS incidence requires campaigns designed to change knowledge, attitudes, and practices of risky sexual behavior. In China, a significant obstacle to such changes is the stigma associated with these diseases. Thus 1 campaign intervention strategy is to train credible community leaders to discuss these issues in everyday social venues. This study tested the effectiveness of such an approach on reducing HIV/AIDS stigma, across 2 years, from a sample of over 4,500 market vendors, in 3 conditions. Results showed an increasing growth in market communication about intervention messages, and concomitant declines in stigmatizing attitudes, across time, with the greatest changes in community popular opinion leaders, significant changes in intervention nonopinion leaders, and little change in the control markets.  相似文献   
73.
74.
The ability to make egocentric distance estimates of a single point source of light, seen in darkness and without the cues of changing size and luminance, was investigated in sixteen observers. The attenuation required to maintain constant luminance, when the target was viewed from different distances, was shown to follow the inverse square law providing the angle subtended by the light was less than 20 s arc. Distance changes were also simulated by means of a split mirror which produced vergence cues, or by test lenses to provide accommodation cues. Over the range 0.5 to 9.2 m distance estimates were surprisingly accurate, although there was some overestimation of near and underestimation of far distances. Most observers made good judgements when only convergence cues were varied, whereas no observers made consistently good judgements when only accommodation cues were varied. The difficulties are discussed in terms of the accommodation-convergence link. When distance was simulated by changing convergence and accommodation cues, estimates were not as good as when real distance was changed. Since good estimates were made with brief target exposures, these judgements were not based on subsequent convergence or accommodation changes. It is suggested that the metric or reference against which the apparently absolute judgements were made was the efferent demand signal associated with a 'resting' position of convergence in darkness.  相似文献   
75.
76.
77.
78.
79.
80.
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