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   27935篇
  免费   424篇
  国内免费   5篇
  28364篇
  2023年   93篇
  2022年   120篇
  2021年   154篇
  2020年   204篇
  2019年   245篇
  2018年   3721篇
  2017年   3058篇
  2016年   2513篇
  2015年   429篇
  2014年   334篇
  2013年   1117篇
  2012年   1113篇
  2011年   2860篇
  2010年   2782篇
  2009年   1672篇
  2008年   2080篇
  2007年   2488篇
  2006年   339篇
  2005年   545篇
  2004年   401篇
  2003年   340篇
  2002年   258篇
  2001年   141篇
  2000年   178篇
  1999年   96篇
  1998年   74篇
  1997年   56篇
  1996年   53篇
  1995年   36篇
  1994年   22篇
  1993年   39篇
  1992年   53篇
  1991年   49篇
  1990年   65篇
  1989年   45篇
  1988年   51篇
  1987年   39篇
  1986年   34篇
  1985年   32篇
  1984年   42篇
  1983年   33篇
  1979年   27篇
  1978年   23篇
  1977年   16篇
  1976年   21篇
  1974年   20篇
  1973年   18篇
  1971年   17篇
  1969年   16篇
  1968年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
241.
Four experiments tested the effects of information about a proxy's related attributes and maximal effort in social comparisons of ability. In Study 1, a proxy's prior performance at maximal effort exerted systematic effects on participants' personal performance predictions for a novel task. When information about the proxy's effort was ambiguous (Study 2). information about related attribute similarity was used in the formulation of performance predictions. In Studies 3 and 4, 2-way interaction terms revealed that participants used related attribute information in generating performance predictions when the proxy's maximum effort was unknown. However, related attribute information was disregarded when proxy's maximum effort was unambiguous. Results were consistent with the proxy comparison model of ability self-evaluation (L. Wheeler, R. Martin, & J. Suls, 1997).  相似文献   
242.
Using a new polynomial regression criterion, the authors investigated empirically the short-term reliability of infants' visual habituation measures. Twenty-one 5-month-old infants were tested twice with a 1-day interval. Results revealed many reliable habituation measures, a reliable reaction to novelty measure, and a new reliable measure of interest. The 2nd-order polynomial regression criterion probably produced this improvement because it uses all of the available looking time data.  相似文献   
243.
Two predictions derived from Markovits and Barrouillet's (2001) developmental model of conditional reasoning were tested in a study in which 72 twelve-year-olds, 80 fifteen-year-olds, and 104 adults received a paper-and-pencil test of conditional reasoning with causal premises ("if cause P then effect Q"). First, we predicted that conditional premises would induce more correct uncertainty responses to the Affirmation of the consequent and Denial of the antecedent forms when the antecedent term is weakly associated to the consequent than when the two are strongly associated and that this effect would decrease with age. Second, uncertainty responding to the Denial of the antecedent form ("P is not true") should be easier when the formulation of the minor premise invites retrieval of alternate antecedents ("if something other than P is true"). The results were consistent with the hypotheses and indicate the importance of retrieval processes in understanding developmental patterns in conditional reasoning with familiar premises.  相似文献   
244.
245.
Empathy: Its ultimate and proximate bases   总被引:22,自引:0,他引:22  
Preston SD  de Waal FB 《The Behavioral and brain sciences》2002,25(1):1-20; discussion 20-71
  相似文献   
246.
Relationships between frequency of computer use or ability to use the computer effectively with the tendency to construct and process visual mental images were investigated by administering a computer-use questionnaire and a visualization questionnaire to a sample of 185 Italian and Spanish undergraduates. Analysis did not support associations between either (a) frequent computer use of any kind or (b) high competence in using the computer for various purposes and spontaneous use of imagery.  相似文献   
247.
We introduce non-associative linear logic, which may be seen as the classical version of the non-associative Lambek calculus. We define its sequent calculus, its theory of proof-nets, for which we give a correctness criterion and a sequentialization theorem, and we show proof search in it is polynomial.  相似文献   
248.
Gutiérrez  G.  de Guzmán  I. P.  Martínez  J.  Ojeda-Aciego  M.  Valverde  A. 《Studia Logica》2002,72(1):85-112
The tree-based data structure of -tree for propositional formulas is introduced in an improved and optimised form. The -trees allow a compact representation for negation normal forms as well as for a number of reduction strategies in order to consider only those occurrences of literals which are relevant for the satisfiability of the input formula. These reduction strategies are divided into two subsets (meaning- and satisfiability-preserving transformations) and can be used to decrease the size of a negation normal form A at (at most) quadratic cost. The reduction strategies are aimed at decreasing the number of required branchings and, therefore, these strategies allow to limit the size of the search space for the SAT problem.  相似文献   
249.
Neuronal changes in normal human aging and Alzheimer's disease   总被引:8,自引:0,他引:8  
This article discusses age-related changes in brain weight, total number of cortical neurons, cortical dendrites, spine, and synapse density. The conclusion is that the present outlook is less grim than it was 30 years ago. Age-related reduction appears to be specific to brain region and cortical layer rather than a general feature. In addition, we describe a different pattern of changes that occur in Alzheimer's disease patients. This review concludes that the association cortices in particular are affected in aging and Alzheimer's disease and that the primary visual and somatosensory cortices are relatively spared.  相似文献   
250.
The primary purpose of the study was to identify event-based prospective-memory tasks that provide sensitive and reliable tools for assessing effects of normal aging in prospective-memory performance. Four prospective-memory tasks were selected from the literature or were newly developed, with the tasks differing on various dimensions that, for theoretical reasons or based on previous evidence, might determine task sensitivity to age effects on prospective-memory performance: perceptual saliency of prospective target events, frequency of occurrence of prospective target events, complexity of prospective-memory instructions, and provision of feedback after prospective-memory errors. Two of the four tasks yielded large and robust age effects on prospective-memory performance. Correlational analyses suggested that these age effects on prospective-memory performance were mediated, at least in part, by a reduced ability of older adults to maintain prospective intentions in a highly activated state and not by age effects on basic mental speed alone.  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