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   184241篇
  免费   8163篇
  国内免费   163篇
  2020年   2798篇
  2019年   3476篇
  2018年   3741篇
  2017年   4166篇
  2016年   4795篇
  2015年   3951篇
  2014年   4825篇
  2013年   23584篇
  2012年   5129篇
  2011年   4377篇
  2010年   4122篇
  2009年   4922篇
  2008年   4536篇
  2007年   4135篇
  2006年   4541篇
  2005年   4456篇
  2004年   3968篇
  2003年   3564篇
  2002年   3408篇
  2001年   3816篇
  2000年   3616篇
  1999年   3473篇
  1998年   2905篇
  1997年   2723篇
  1996年   2613篇
  1995年   2464篇
  1994年   2425篇
  1993年   2363篇
  1992年   2821篇
  1991年   2674篇
  1990年   2537篇
  1989年   2415篇
  1988年   2367篇
  1987年   2359篇
  1986年   2360篇
  1985年   2602篇
  1984年   2614篇
  1983年   2391篇
  1982年   2420篇
  1981年   2386篇
  1980年   2234篇
  1979年   2320篇
  1978年   2245篇
  1977年   2185篇
  1976年   2006篇
  1975年   2117篇
  1974年   2164篇
  1973年   2011篇
  1972年   1618篇
  1971年   1547篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
181.
182.
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   
183.
184.
185.
186.
187.
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   
188.
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   
189.
190.
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