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   27497篇
  免费   325篇
  2023年   42篇
  2022年   32篇
  2021年   60篇
  2020年   138篇
  2019年   141篇
  2018年   3627篇
  2017年   2957篇
  2016年   2436篇
  2015年   366篇
  2014年   238篇
  2013年   861篇
  2012年   882篇
  2011年   2715篇
  2010年   2687篇
  2009年   1692篇
  2008年   1963篇
  2007年   2452篇
  2006年   326篇
  2005年   480篇
  2004年   443篇
  2003年   397篇
  2002年   317篇
  2001年   170篇
  2000年   183篇
  1999年   160篇
  1998年   159篇
  1997年   129篇
  1996年   130篇
  1995年   104篇
  1994年   118篇
  1993年   90篇
  1992年   92篇
  1991年   65篇
  1990年   86篇
  1989年   54篇
  1988年   47篇
  1987年   67篇
  1986年   58篇
  1985年   62篇
  1984年   58篇
  1983年   78篇
  1982年   81篇
  1981年   61篇
  1980年   56篇
  1979年   71篇
  1978年   67篇
  1977年   51篇
  1976年   55篇
  1975年   35篇
  1974年   29篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
Suicides among older adults in the United States and Canada in the last decade have accounted for an increasing share of all suicides. In both countries the use of firearms among older adults has steadily increased. Despite these trends, little is known about the extent to which crisis centers are prepared to prevent elder suicide. A survey of AAS-listed crisis prevention centers examined the training, knowledge, and current practices relevant to elder suicide among personnel in 321 crisis prevention centers in both countries. Results revealed insufficient training, a lack of familiarity with recent suicide trends, and limited outreach to older adults.  相似文献   
24.
25.
26.
27.
A taxonomy of part-whole or meronymic relations is developed to explain the ordinary English-speaker's use of the term “part of” and its cognates. The resulting classification yields six types of meronymic relations: 1. component-integral object (pedal-bike), 2. member-collection (ship-fleet), 3. portion-mass (slice-pie), 4. stuff-object (steel-car), 5. feature-activity (paying-shopping), and 6. place-area (Everglades-Florida). Meronymic relations ore further distinguished from other inclusion relations, such as spatial inclusion, and class inclusion, and from several other semantic relations: attribution, attachment, and ownership. This taxonomy is then used to explain cases of apparent intransitivity in merological syllogisms, and standard form syllogisms whose premises express different inclusion relations. The data suggest that intransitivities arise due to equivocations between different types of semantic relations. These results are then explained by means of the relation element theory which accounts for the character and behavior of semantic relations in terms of more primitive relational elements. The inferential phenomena observed are then explained by means of a single principle of element matching.  相似文献   
28.
29.
30.
This paper reports the operation of robust attentional bias to the top and right during perception of small, single geometric forms. Same/different judgements of successively presented standard and comparison forms are faster when local differences are located at top and right rather than in other regions of the forms. The bias persists when form size is reduced to approximately one degree of visual angle, and it is unaffected by saccadic eye movements and by instructions to attend to other reliably differentiating regions of the forms. Results lend support in various degrees to two of the possible explanations of the bias: (1) a static, skewed distribution of attentional resources around eye fixation; and (2) biased, covert scanning that commences invariably at the top and right of stim ulus forms. Origins of the bias in terms of possible left-hemispheric capacity for constructing representations of visual stimuli from parts, as well as in terms of reading experience and prevailing optic flow during locomotion through space are considered. Recent investigations of conditions under which the bias can be maintained or reduced are mentioned.  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