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   112993篇
  免费   4637篇
  国内免费   39篇
  2020年   1187篇
  2019年   1502篇
  2018年   2054篇
  2017年   2108篇
  2016年   2231篇
  2015年   1597篇
  2014年   1935篇
  2013年   9228篇
  2012年   3567篇
  2011年   3724篇
  2010年   2296篇
  2009年   2326篇
  2008年   3238篇
  2007年   3257篇
  2006年   3019篇
  2005年   2600篇
  2004年   2530篇
  2003年   2401篇
  2002年   2418篇
  2001年   3488篇
  2000年   3397篇
  1999年   2556篇
  1998年   1311篇
  1997年   1158篇
  1996年   1193篇
  1995年   1081篇
  1993年   1060篇
  1992年   2152篇
  1991年   2029篇
  1990年   2042篇
  1989年   1889篇
  1988年   1839篇
  1987年   1739篇
  1986年   1795篇
  1985年   1851篇
  1984年   1572篇
  1983年   1419篇
  1982年   1065篇
  1979年   1655篇
  1978年   1255篇
  1975年   1351篇
  1974年   1517篇
  1973年   1627篇
  1972年   1355篇
  1971年   1274篇
  1970年   1116篇
  1969年   1164篇
  1968年   1458篇
  1967年   1333篇
  1966年   1188篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
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   
102.
103.
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   
104.
105.
106.
107.
108.
109.
110.
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