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   6066篇
  免费   176篇
  国内免费   3篇
  6245篇
  2018年   110篇
  2017年   88篇
  2016年   83篇
  2015年   67篇
  2014年   75篇
  2013年   451篇
  2012年   172篇
  2011年   165篇
  2010年   86篇
  2009年   99篇
  2008年   139篇
  2007年   155篇
  2006年   132篇
  2005年   128篇
  2004年   124篇
  2003年   103篇
  2002年   118篇
  2001年   217篇
  2000年   206篇
  1999年   143篇
  1998年   59篇
  1997年   54篇
  1996年   65篇
  1993年   58篇
  1992年   121篇
  1991年   122篇
  1990年   121篇
  1989年   100篇
  1988年   95篇
  1987年   101篇
  1986年   112篇
  1985年   113篇
  1984年   102篇
  1983年   87篇
  1981年   55篇
  1979年   98篇
  1978年   74篇
  1977年   67篇
  1976年   57篇
  1975年   67篇
  1974年   93篇
  1973年   102篇
  1972年   74篇
  1971年   71篇
  1970年   82篇
  1969年   75篇
  1968年   106篇
  1967年   82篇
  1966年   93篇
  1958年   62篇
排序方式: 共有6245条查询结果,搜索用时 9 毫秒
211.
The long-term effects of infantile malnutrition on information processing were studied in squirrel monkeys. From 2 through 8 weeks of age, four low-calorie infants were fed reduced amounts of a high protein diet, limiting their mean body weight gain to 23% of that of four well-fed controls, with all of this gain occurring during the first 2 weeks on the low-calorie diet. Thereafter, both groups received the standard diet ad libitum. At 68 weeks of age, incidental learning was tested by introducing shape cues that were redundant to the solution of a previously learned, two-choice, color discrimination. Removal of the color cues showed that the low-calorie monkeys had learned significantly less about the shape cues than had the controls. The basis for this incidental learning failure was then examined with an embedded-figures dicrimination, to measure attentional ability, and a novel stimulus substitution task, to measure curiosity. The groups did not differ in detecting embedded figures, but the low-calorie monkeys were significantly less likely than controls to select or handle novel stimuli that had been substituted for previously learned discriminative cues. It was concluded that undernutrition in infancy may induce a long-term strategy of only learning information which leads to an immediate reward, while suppressing the acquisition of information due to intrinsic curiosity.  相似文献   
212.
This study examined the questions of whether employment and educational tests demonstrate either differential validity or test unfairness to Hispanic Americans relative to the majority group. Relevant data from 19 published and unpublished studies formed the basis of the review and analysis. Results for employment tests, based on a very large amount of data, indicated that differential validity occurs no more frequently than would be expected on the basis of chance plus the operation of various statistical artifacts. The frequencies of slope and intercept differences between Hispanic and majority regressions were also within the chance range. A similar pattern of results obtained for the more limited amount of data available on educational tests. Taken together, the results provide strong evidence that tests are neither differentially valid for, nor unfair to, Hispanics. These findings are consistent with the results of previous studies of test validity and fairness for blacks.  相似文献   
213.
This article takes up methodological issues of the kind raised by Jan Smedslund in earlier issues of this journal, concerning the status of psychological enquiry as a discipline. Arguments are presented which aim to show that Smedslund has failed to establish the thesis that all generally valid theoretical statements in psychology are explications of conceptual relationships embedded in ordinary language, i.e., analytic statements. Some specific examples of what Smedslund takes to be "ordinary language theorems" are examined. Doubts are expressed concerning the validity of the proof procedure Smedslund employs in the "demonstration" of a number of his alleged theorems. Finally, it is argued that the results produced by the situation-bound and culture-bound empirical research of the psychologist need not be viewed as "arbitrary" in Smedslund's sense of that term.  相似文献   
214.
LetN. be the set of all natural numbers (except zero), and letD n * = {kNk|n} ∪ {0} wherek¦n if and only ifn=k.x f or somex∈N. Then, an ordered setD n * = 〈D n * , ? n , wherex? ny iffx¦y for anyx, y∈D n * , can easily be seen to be a pseudo-boolean algebra. In [5], V.A. Jankov has proved that the class of algebras {D n * n∈B}, whereB =,{kN∶ ? \(\mathop \exists \limits_{n \in N} \) (n > 1 ≧n 2 k)is finitely axiomatizable. The present paper aims at showing that the class of all algebras {D n * n∈B} is also finitely axiomatizable. First, we prove that an intermediate logic defined as follows: $$LD = Cn(INT \cup \{ p_3 \vee [p_3 \to (p_1 \to p_2 ) \vee (p_2 \to p_1 )]\} )$$ finitely approximatizable. Then, defining, after Kripke, a model as a non-empty ordered setH = 〈K, ?〉, and making use of the set of formulas true in this model, we show that any finite strongly compact pseudo-boolean algebra ? is identical with. the set of formulas true in the Kripke modelH B = 〈P(?), ?〉 (whereP(?) stands for the family of all prime filters in the algebra ?). Furthermore, the concept of a structure of divisors is defined, and the structure is shown to beH D n * = 〈P (D n * ), ?〉for anyn∈N. Finally, it is proved that for any strongly compact pseudo-boolean algebraU satisfying the axiomp 3∨ [p 3→(p1→p2)∨(p2→p1)] there is a structure of divisorsD * n such that it is possible to define a strong homomorphism froomiH D n * ontoH D U . Exploiting, among others, this property, it turns out to be relatively easy to show that \(LD = \mathop \cap \limits_{n \in N} E(\mathfrak{D}_n^* )\) .  相似文献   
215.
An information processing system for a psychiatric emergency room is described. Several studies are presented that show the utility of the system. In the first study, variables involved in diagnosis are explicated. The second study attempts to determine the characteristics that distinguish recidivists from nonrecidivists at an emergency room. The third study attempts to find patient variables related to success in short-term treatment programs. The final study is aimed at discovering whether there are psychopathological effects related to the use of inhalants. Together, these studies show the potential of a mental health information system for learning more about the nature of mental disorders and their treatment.  相似文献   
216.
It has been assumed that certain stimulus transformations lead directly to depth effects, that is, that such transformations are the necessary and sufficient conditions for kinetically generated depth perception. An alternative is to view such perception as the preferred solution to the problem posed by the transforming stimulus as to what even in the world is producing that transformation. In several experiments it is shown that when other solutions are supportable by the stimulus, those same transformations will no longer lead to depth perception. These other solutions become preferred on the basis of rejection of certain coincidental features of the stimulus that otherwise would have to be accepted were the kinetic depth solution to be maintained. The findings are interpreted as challenging any theory that perception is simply the direct result of stimulation or of extraction of stimulus information and as supporting the Helmkoltzian rule of perception as a construction of the most reasonable representation.  相似文献   
217.
Recent literature has suggested there is a causal link between malnutrition and impaired cognitive development. From a selective review of this literature it is concluded that owing to methodological imperfections in many of these studies the presence or absence of such a link cannot be established, even if randomized experiments were to be carried out. It is argued that compensatory experiments, even though they are not as logically compelling as experiments where proper nutrition is withheld, are ethically justifiable and more useful strategically since they may suggest ways of improving the cognitive development of currently affected children, especially if a variety of compensatory treatments is implemented. A reanalysis of such an experiment was conducted to determine whether the nutritional or educational component of the treatment was responsible for the observed gains in cognitive development. The reanalysis indicated that after four years of treatment there was no association between cognitive and nutritional status. The results were discussed in relation to previous research. Some of the social implications of the results were also discussed.  相似文献   
218.
219.
Three experiments examined the influence of videotaped classroom events on the academic performance and study behavior of reading-disabled and normally reading children in grades 1 through 6. In experiments 1 and 2a an experimenter-controlled presentation of these distractors resulted in performance decrements, the magnitude of which was greater for higher difficulty tasks. The distractor effects were similar for the two groups in this condition. However, when the children themselves were allowed to control their degree of exposure to the same distractors in experiment 2b, the reading-disabled children were less likely to act to escape the distraction. Results are discussed in terms of children's metacognitive awareness of distraction, and implications for the classroom are considered.  相似文献   
220.
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