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   38588篇
  免费   1388篇
  国内免费   13篇
  2019年   413篇
  2018年   612篇
  2017年   549篇
  2016年   633篇
  2015年   463篇
  2014年   551篇
  2013年   3710篇
  2012年   960篇
  2011年   974篇
  2010年   647篇
  2009年   610篇
  2008年   927篇
  2007年   841篇
  2006年   796篇
  2005年   687篇
  2004年   677篇
  2003年   689篇
  2002年   658篇
  2001年   1207篇
  2000年   1162篇
  1999年   907篇
  1998年   422篇
  1996年   542篇
  1995年   509篇
  1994年   504篇
  1993年   472篇
  1992年   929篇
  1991年   828篇
  1990年   837篇
  1989年   734篇
  1988年   738篇
  1987年   725篇
  1986年   720篇
  1985年   716篇
  1984年   626篇
  1983年   535篇
  1982年   422篇
  1981年   431篇
  1979年   583篇
  1978年   444篇
  1975年   540篇
  1974年   536篇
  1973年   597篇
  1972年   566篇
  1971年   507篇
  1970年   446篇
  1969年   426篇
  1968年   537篇
  1967年   455篇
  1966年   443篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
An electronic apparatus using infrared beams for monitoring the movements of individual bees under dark conditions is described. The searching behavior of workers in an arena was monitored over 2-h periods. Mean ambulatory velocity for one bee over a distance of 100 mm was 45.6±1.51 mm/sec (n=45). Thigmokinesis and temporal activity patterns are illustrated.  相似文献   
43.
44.
Extensive empirical evidence confirms a depressed entitlement effect wherein women pay themselves less than men for comparable work and believe the allocation fair. The present study tests the hypothesis that status subordination linked to being female underlies at least some of this effect. A 2 × 3 design crossed 180 undergraduates' gender with a control condition, which successfully established the depressed entitlement effect, and two experimental conditions. In one, women's status was enhanced through legitimation of women's task abilities; in the other, both women's and men's status was enhanced by adding educational credentials relevant to task ability. Follow-up analyses of the significant interaction revealed that the gap in self-pay demonstrated in the control condition disappeared when women's status was enhanced such that higher-status women's self-pay equaled that of men and exceeded that of control women. Although these findings confirm that status plays a role in producing depressed entitlement in self-pay, ancillary analyses of participants' perceptions point to the persistence of shifting standards and men's resistance to status threats.  相似文献   
45.
46.
47.
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   
48.
49.
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   
50.
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