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   53327篇
  免费   2228篇
  国内免费   21篇
  2020年   543篇
  2019年   600篇
  2018年   848篇
  2017年   841篇
  2016年   935篇
  2015年   707篇
  2014年   821篇
  2013年   3761篇
  2012年   1589篇
  2011年   1512篇
  2010年   972篇
  2009年   926篇
  2008年   1378篇
  2007年   1375篇
  2006年   1192篇
  2005年   1157篇
  2004年   1061篇
  2003年   956篇
  2002年   1001篇
  2001年   1813篇
  2000年   1770篇
  1999年   1290篇
  1998年   565篇
  1997年   500篇
  1996年   501篇
  1992年   1185篇
  1991年   1079篇
  1990年   1123篇
  1989年   967篇
  1988年   958篇
  1987年   915篇
  1986年   922篇
  1985年   1000篇
  1984年   801篇
  1983年   724篇
  1982年   516篇
  1979年   873篇
  1978年   586篇
  1977年   553篇
  1976年   532篇
  1975年   745篇
  1974年   870篇
  1973年   899篇
  1972年   766篇
  1971年   735篇
  1970年   684篇
  1969年   713篇
  1968年   935篇
  1967年   818篇
  1966年   723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.
陈莲笙道长生于1917年10月25日,上海市人.历任中国道教协会副会长,中国道教协会顾问,上海市道教协会会长.上海市道教协会名誉会长,上海城隍庙住持,上海道学院院长,<上海道教>杂志主编,上海市宗教学会理事,上海市政协第七届委员,上海市政协第八、九届常委等职.  相似文献   
45.
46.
Previous work on children's intuitive knowledge about the natural world has documented their difficulty in acquiring an overarching concept of biological life that includes plants as well as humans and non‐human animals. It has also suggested that the acquisition of fundamental biological concepts like alive and die may be influenced by the language used to describe them, as evidenced by differences between English‐ and Indonesian‐speaking children's performance in tasks involving these concepts. Here, we examine one particularly important source of linguistic information available to children during this acquisition process: everyday conversations with their parents. We take a cross‐linguistic approach in analysing the evidence available to English‐ and Indonesian‐speaking children as they acquire meanings for words corresponding to the concepts alive and die . Our analysis illustrates that young children acquiring English and Indonesian are faced with distinct problems, but that parental input in both languages does little to support the acquisition of broad, inclusive biological concepts.  相似文献   
47.
This paper examines college students' attributions about suicide as a function of gender and context (athletic vs. relationship failure). Results indicated that male athletes who suicided were considered more emotionally well-adjusted compared to males who suicided because of a relationship failure and all females. Male and female athletes who suicided were seen as more competent and less distressed compared to those who suffered a failed relationship. Females were also seen as more distressed compared to males. These results are discussed in terms of a positive bias toward athletes in our society as well as gender stereotypes. Implications of these findings as well as methodological limitations are discussed.  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