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   39033篇
  免费   805篇
  国内免费   4篇
  39842篇
  2020年   421篇
  2019年   508篇
  2018年   732篇
  2017年   632篇
  2016年   695篇
  2015年   474篇
  2014年   668篇
  2013年   2944篇
  2012年   1113篇
  2011年   1225篇
  2010年   684篇
  2009年   796篇
  2008年   1058篇
  2007年   1077篇
  2006年   1002篇
  2005年   865篇
  2004年   856篇
  2003年   815篇
  2002年   770篇
  2001年   1202篇
  2000年   1261篇
  1999年   906篇
  1998年   445篇
  1997年   374篇
  1996年   363篇
  1995年   348篇
  1992年   740篇
  1991年   676篇
  1990年   754篇
  1989年   662篇
  1988年   628篇
  1987年   578篇
  1986年   612篇
  1985年   680篇
  1984年   517篇
  1983年   485篇
  1982年   364篇
  1979年   558篇
  1978年   468篇
  1977年   348篇
  1975年   501篇
  1974年   569篇
  1973年   594篇
  1972年   484篇
  1971年   440篇
  1970年   357篇
  1969年   410篇
  1968年   511篇
  1967年   473篇
  1966年   470篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
In the first part of this article, I raisequestions about Dworkin's theory of theintrinsic value of life and about the adequacyof his proposal to understand abortion in termsof different ways of valuing life. In thesecond part of the article, I consider hisargument in ``The Philosophers' Brief on AssistedSuicide', which claims that the distinctionbetween killing and letting die is morallyirrelevant, the distinction between intendingand foreseeing death can be morally relevantbut is not always so. I argue that thekilling/letting die distinction can be relevantin the context of assisted suicide, but alsoshow when it is not. Then I consider why theintention/foresight distinction can be morallyirrelevant and conclude by presenting analternative argument for physician-assistedsuicide.  相似文献   
992.
In the present study we examined the effects of the specific NMDA receptor antagonist CPP on discrimination reversal learning in rabbits. We report two primary findings. First, the institution of NMDA receptor blockade had no effect on a learned discrimination. Second, after stimulus reversal, CPP treatment impaired acquisition of the discrimination reversal. This impairment manifested itself early in training as a retardation in acquisition of a CR to the new CS+ and late in training as an inability to suppress responsiveness to the new CS-. Given the comparability of the present results with previously published results for phenytoin-treated rabbits, we suggest that the effects of phenytoin on learning in this paradigm is at least in part mediated by its effects on NMDA receptors. We further suggest that these findings emphasize the need to better define the role of NMDA receptor activation and hippocampally-mediated circuits in a variety of associative learning paradigms.  相似文献   
993.
994.
Knapp  Deborah Erdos  Heshizer  Brian P. 《Sex roles》2001,44(3-4):109-128
In this study we employ a policy-capturing approach to identify those variables that appear to have a significant influence on the outcomes of defense requests for summary judgments in federal sexual harassment (SH) cases. The purpose of the study is to extend studies performed by D. E. Terpstra and D. D. Baker (1988, 1992) in light of evolving legislation and case law and address the criticisms of policy-capturing studies by M. V. Roehling (1993). Results of the analysis indicate that those variables that most influence case outcomes are: whether the plaintiff had witnesses, the severity and frequency of the SH, and Federal Circuit Court jurisdiction. Finally, the study also shows that past criticisms of this method may be addressed with modifications to data collection and coding techniques.  相似文献   
995.
Measures of impairment in psychological and behavioral functioning have a long history in the field of children's mental health, and appear particularly useful in eligibility determination, treatment planning, and outcome evaluation of services for children and adolescents with serious emotional disturbance (SED). One recently developed multidimensional measure of functional impairment—the Child and Adolescent Functional Assessment Scale (CAFAS; K. Hodges, 1989, 1997)—has enjoyed widespread use nationwide. It has been adopted as a tool for making treatment eligibility decisions and documenting outcomes on a statewide level in more than 20 states and on a local level in dozens of research and demonstration projects. In this paper, the technical merits of the CAFAS are closely examined, with the conclusion that empirical evidence is lacking to support its valid use in making the types of treatment decisions for which it is currently being employed across the nation. Furthermore, there appears to be little concern among mental health researchers, practitioners, administrators, and state legislators about these apparent limitations of the CAFAS. The potential benefits of establishing objective and valid level-of-need criteria, using the CAFAS are numerous and the interest in doing so is clear; however, the psychometric limitations of the scale identified in this review need to be addressed before its full potential can be realized.  相似文献   
996.
We predicted that when (1) people are faced with diagnostic but personally challenging social comparison information in a domain, and (2) their self-regard is salient, they will be less likely to use the comparison information when judging their standing in the domain (making the judgment less inductive). Participants in Study 1 estimated their standing on risk factors for two health problems, and some did so after their self-regard was made salient. Moreover, some received information (about their peers' standing on these risk factors) that challenged participants' self-serving comparative beliefs. As expected, estimates of personal risk factor standing among high self-regard salience/comparison information participants were less correlated with similar estimates collected 2 months earlier, suggesting the estimates had become less inductive. There was also tentative evidence that, in this condition, self-esteem played a greater role in constructing these estimates. In Study 2, participants were led to believe that their comparative standing on risk factors was better than it actually was, and in this case, they were more likely to use this information when making self-judgments about their personal risk. Evidently, the extent to which people use diagnostic comparison information inductively when making self-inferences depends on the favorability of that information.  相似文献   
997.
Genic selectionism holds that all selection can be understood as operating on particular genes. Critics (and conventional biological wisdom) insist that this misrepresents the actual causal structure of selective phenomena at higher levels of biological organization, but cannot convincingly defend this intuition. I argue that the real failing of genic selectionism is pragmatic – it prevents us from adopting the most efficient corpus of causal laws for predicting and intervening in the course of affairs – and I offer a Pragmatic account of causation itself which ultimately bears out the claim that genic selectionism misrepresents the causal structure of selective contexts.  相似文献   
998.
The present study investigated nighttime fears in normal school children aged 4 to 12 yr (N=176). Children and their parents were interviewed about the frequency, content, origins, coping behaviors and severity of children's nighttime fears. Results showed that 73.3% of the children reported nighttime fears, indicating that these fears are quite prevalent. Inspection of the developmental course of nighttime fears revealed that these fears are common among 4- to 6-year-olds, become even more frequent in 7- to 9-year-olds and then remain relatively stable in 10- to 12-year-olds. Inspection of the origins of nighttime fears revealed that most of the children (i.e., almost 80%) attributed their fear to negative information; conditioning and modeling were endorsed less frequently (25.6% and 13.2%, respectively). A substantial percentage of the children (24.0%) indicated that learning experiences had not played a role in the acquisition of their nighttime fears. Children reported a variety of coping strategies in order to deal with their nighttime fears and generally rated these strategies as helpful in reducing anxiety. Furthermore, children's nighttime fears were associated with moderate levels of anxiety. Moreover, in about 10% of the children, nighttime fears were related to one or more DSM-III-R anxiety disorders. Finally, parental reports of children's nighttime fears substantially deviated from children's reports. Most importantly, parents provided a marked underestimation of the frequency of nighttime fears, at least as reported by their children.  相似文献   
999.
Previous research has shown that the Interpersonal Concerns factor of the Depressive Experiences Questionnaire (DEQ; Blatt, D'Affliti, & Quinlan, 1976, 1979; Depressive Experiences Questionnaire for Adolescent [DEQ-A]; Blatt, Schaffer, Bers, & Quinlan, 1992) assesses 2 levels of interpersonal relatedness in young adults and older adolescents: neediness and relatedness. However, studies investigating the relation of the DEQ and DEQ-A with social functioning have not used the Neediness and Relatedness subscales of the Interpersonal Concerns factor. This study investigated (a) whether the Neediness and Relatedness subscales can be differentiated in a sample of early adolescents and (b) how the 2 subscales are differentially associated with indexes of social functioning. Results indicate that this differentiation of Neediness and Relatedness, and their associations with social functioning, emerges in early adolescence, especially for girls.  相似文献   
1000.
Binocular rivalry occurs when the two eyes are presented with incompatible stimuli and the perceived image alternates between the two stimuli. The aim of this study was to find out whether the periodic perceptual loss of a monocular stimulus during binocular rivalry is mirrored by a comparable loss of contrast sensitivity. We presented brief test stimuli to one eye while its conditioning stimulus was dominant or suppressed. The test stimuli were varied widely across four stimulus domains--namely, the relative stimulation of medium- and long-wavelength-sensitive cones, duration, spatial frequency, and grating orientation. The result in each case was the same. Suppression depended slightly or not at all on the type of test stimulus, and contrast sensitivity during suppression was around 64% of that during dominance. The effect of suppression on sensitivity is therefore very weak, relative to its effect on the perceived image. Furthermore, suppression was largely independent of the similarity between the conditioning and the test stimuli, indicating that our results are better explained by eye suppression than by stimulus suppression. A model is presented to account for the small, monocular sensitivity loss during suppression: It assumes that test detection precedes conditioning stimulus perception in the visual pathway.  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