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   158688篇
  免费   7371篇
  国内免费   155篇
  2021年   1481篇
  2020年   2770篇
  2019年   3434篇
  2018年   3381篇
  2017年   3805篇
  2016年   4506篇
  2015年   3912篇
  2014年   4778篇
  2013年   23392篇
  2012年   4084篇
  2011年   3019篇
  2010年   3654篇
  2009年   4652篇
  2008年   3332篇
  2007年   2839篇
  2006年   3585篇
  2005年   3592篇
  2004年   3118篇
  2003年   2766篇
  2002年   2541篇
  2001年   2635篇
  2000年   2476篇
  1999年   2711篇
  1998年   2751篇
  1997年   2606篇
  1996年   2542篇
  1995年   2367篇
  1994年   2334篇
  1993年   2290篇
  1992年   2240篇
  1991年   2103篇
  1990年   1942篇
  1989年   1902篇
  1988年   1865篇
  1987年   1912篇
  1986年   1889篇
  1985年   2118篇
  1984年   2308篇
  1983年   2135篇
  1982年   2302篇
  1981年   2272篇
  1980年   2116篇
  1979年   1942篇
  1978年   2050篇
  1977年   2046篇
  1976年   1826篇
  1975年   1799篇
  1974年   1803篇
  1973年   1643篇
  1972年   1283篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
172.
173.
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   
174.
175.
176.
177.
178.
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   
179.
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   
180.
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