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   37077篇
  免费   1537篇
  国内免费   11篇
  2020年   382篇
  2019年   542篇
  2018年   711篇
  2017年   724篇
  2016年   731篇
  2015年   519篇
  2014年   674篇
  2013年   2860篇
  2012年   1178篇
  2011年   1261篇
  2010年   746篇
  2009年   745篇
  2008年   1074篇
  2007年   1047篇
  2006年   979篇
  2005年   885篇
  2004年   849篇
  2003年   788篇
  2002年   823篇
  2001年   1107篇
  2000年   1009篇
  1999年   786篇
  1998年   430篇
  1997年   348篇
  1996年   345篇
  1992年   597篇
  1991年   585篇
  1990年   566篇
  1989年   578篇
  1988年   565篇
  1987年   532篇
  1986年   563篇
  1985年   606篇
  1984年   487篇
  1983年   460篇
  1982年   392篇
  1981年   370篇
  1979年   557篇
  1978年   412篇
  1976年   382篇
  1975年   461篇
  1974年   511篇
  1973年   532篇
  1972年   433篇
  1971年   407篇
  1970年   408篇
  1969年   431篇
  1968年   517篇
  1967年   461篇
  1966年   453篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
A growing literature has observed a significant reduction in pain sensitivity among hypertensive animals and humans. It is uncertain whether a reduced sensitivity to pain can be observed in nonnotensive individuals who go on to develop high blood pressure. Blood pressure (BP) was reassessed in one hundred fifteen 19-year-old boys initially tested at age 14, when they were also presented with a pain stimulus (mechanical finger pressure). Hierarchical regression analyses indicated that information regarding pain tolerance improved prediction of changes in systolic and diastolic blood pressure beyond that afforded by differences in BP at age 14, parental history of hypertension, and body mass index. These analyses suggest that pain sensitivity may be associated with physiological processes involved in the development of sustained high blood pressure.  相似文献   
42.
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   
43.
The country‐of‐origin effect is a topic central to the field of international marketing. Country of origin has been found to exert a particularly potent effect on consumer evaluation in situations where there is a strong link between a country and a particular product category. The present study provides further insight into how this particular effect can be understood. Drawing on a novel conceptualization of how country image and product categories interact, this study tested the relative evaluative relevance of product category with respect to estimates of brand equity across a variety of product categories. The findings suggest that facets of a country's image that are more closely related to the evaluation situation exert a greater influence on the evaluation of brands. This result encourages scholars as well as practitioners to re‐evaluate which situations might cause the country of origin effect to hold managerial relevance and paves the way for new paths toward a more comprehensive understanding of the effect. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
44.
45.
46.
47.
In the first part I discuss the thesis, advanced by John Broome, that intentions are normatively required by all-things-considered judgments about what one ought to do. I endorse this thesis, but remain sceptical about Broome's programme of grounding the correctness of reasoning in formal relations between contents of mental states. After discussing objections to the thesis, I concentrate in the second part on the relation between rational action and rational intention. I distinguish between content-related and attitude-related reasons for propositional attitudes like believing, wanting, and intending something. The former appeal to features of the content of the propositional attitude they are reasons for, the latter would be reasons for a propositional attitude because of features of the propositional attitude as a whole, for example the feature of its being beneficial to believe or to want that p . I try to show that the common philosophical reaction to attitude-related reasons, namely to claim that they are merely content-related reasons in disguise, is mistaken. In its most extreme form such a reaction would fail to respect the first-person character of reasoning which manifests itself in, among other things, the fact that a Moore-sentence and its analogue for intentions cannot be a conclusion of reasoning. In the third part I argue that there are attitude-related reasons for intentions, and, in showing how they influence practical deliberation, I find that their existence can be rendered compatible with the thesis that it is rational to intend to do what one thinks one ought to do.  相似文献   
48.
A series of stereograms are presented which demonstrate that texture boundaries can strongly influence the perception of discontinuities between neighbouring three-dimensional (3-D) surfaces portrayed by means of stereo cues. In these demonstration figures, no stereo information is available in the immediate vicinity of the boundary between the two 3-D stereo surfaces because all texture in that region is removed in one eye's view. On the other hand, various forms of texture boundary information are provided in the resulting monocular region. This stimulus paradigm is used to explore the question: what influence does texture boundary information have on the nature of the perceived 3-D surface that is interpolated between two stimulus regions which carry stereo cues? It is shown that if a clear-cut texture boundary is present in the monocular region then this is used by the human visual system to fix the perceived location of 3-D crease and step surface discontinuities between the stereo regions. Collett (1985) explored this issue with a similar methodology and reported weak and unreliable assistance from monocular texture boundaries in helping shape 3-D stereo surface discontinuities. The strong and robust phenomena demonstrated here seem to rely on two main differences between the present stimuli and those of Collett. In the present stimuli, figurally continuous textures containing strong texture boundaries are used, together with a technique for minimising the complications, including binocular rivalry, that arise from the borders of the stimulus regions present in only one half of each stereogram.  相似文献   
49.
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