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   200935篇
  免费   8676篇
  国内免费   156篇
  2020年   2809篇
  2019年   3464篇
  2018年   3887篇
  2017年   4268篇
  2016年   4861篇
  2015年   3955篇
  2014年   4818篇
  2013年   23518篇
  2012年   5564篇
  2011年   4926篇
  2010年   4299篇
  2009年   4987篇
  2008年   4923篇
  2007年   4503篇
  2006年   4819篇
  2005年   4690篇
  2004年   4230篇
  2003年   3791篇
  2002年   3604篇
  2001年   4674篇
  2000年   4423篇
  1999年   3974篇
  1998年   2954篇
  1997年   2745篇
  1996年   2673篇
  1995年   2498篇
  1994年   2454篇
  1993年   2420篇
  1992年   3335篇
  1991年   3140篇
  1990年   3016篇
  1989年   2859篇
  1988年   2817篇
  1987年   2753篇
  1986年   2801篇
  1985年   3083篇
  1984年   2908篇
  1983年   2649篇
  1982年   2492篇
  1981年   2450篇
  1980年   2274篇
  1979年   2698篇
  1978年   2418篇
  1977年   2325篇
  1976年   2181篇
  1975年   2414篇
  1974年   2571篇
  1973年   2499篇
  1972年   2059篇
  1968年   1956篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
192.
193.
Are different responses differentially associable with their consequences? An overshadowing design was used to try to answer this question for three responses previously studied in golden hamsters. In Experiment I, scrabbling was rapidly suppressed by electric shock punishment, and it overshadowed a tone which occurred between scrabbling and shock. In Experiment II, no evidence of response-shock association was obtained when open rearing was the punished response, and open rearing did not overshadow the tone. Punishment had some effect on face washing, but there was no statistically significant overshadowing with this response. These results are consistent with the idea that differences in punishment suppression among these three responses have an associative basis. They also demonstrate the usefulness of a novel paradigm for studying “preparedness” of response-reinforcer associations.  相似文献   
194.
195.
196.
197.
198.
199.
By roughly 6 years of age, children acquire the stereotype that men are more competent than women in science, technology, engineering, and mathematics (STEM), potentially leading to greater trust in scientific information provided by men. This study tested whether 3- to 8-year-old children differentially endorsed conflicting information about science and toys presented by male and female informants depicted as a ‘man’ and ‘woman’ (Exp1) or ‘scientists’ (Exp2). Children were expected to endorse toy testimony from gender-matched informants; thus, the key question concerned endorsement of science testimony. In Exp1 (N = 149), boys and girls showed a same-gender informant preference for toy testimony; however, girls endorsed the male informant's testimony more for science than for toys – but only when tested by a male experimenter. In Exp2 (N = 264), boys and girls showed a same-gender preference, irrespective of content. Findings suggest that STEM-related gender stereotypes might lead girls to trust scientific information presented by men over women in certain contexts.  相似文献   
200.
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   
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