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   9839篇
  免费   302篇
  国内免费   3篇
  2021年   87篇
  2020年   135篇
  2019年   112篇
  2018年   179篇
  2017年   168篇
  2016年   217篇
  2015年   281篇
  2014年   301篇
  2013年   1040篇
  2012年   476篇
  2011年   444篇
  2010年   384篇
  2009年   360篇
  2008年   430篇
  2007年   397篇
  2006年   340篇
  2005年   332篇
  2004年   310篇
  2003年   269篇
  2002年   250篇
  2001年   132篇
  2000年   92篇
  1999年   121篇
  1998年   104篇
  1997年   112篇
  1996年   107篇
  1995年   120篇
  1994年   100篇
  1993年   109篇
  1992年   114篇
  1991年   123篇
  1990年   104篇
  1989年   95篇
  1988年   90篇
  1987年   86篇
  1986年   87篇
  1985年   97篇
  1984年   96篇
  1983年   95篇
  1982年   103篇
  1981年   106篇
  1980年   119篇
  1979年   105篇
  1978年   110篇
  1977年   122篇
  1976年   121篇
  1975年   107篇
  1974年   108篇
  1973年   57篇
  1968年   46篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
901.
In four experiments with 4‐, 6‐, and 9‐year‐old children and adults, the hypothesis was tested that, all other conditions being equal, a novel and unusual event elicits stronger curiosity and exploratory behaviour if its suggested explanation involves an element of the supernatural than if it does not (the impossible over possible effect – the I/P effect). Participants were shown an unusual phenomenon (a spontaneous disintegration of a physical object in an apparently empty box) framed in the context of either a magical (the impossible event) or scientific (the possible event) explanation. In the verbal trial, participants showed a clear understanding of the difference between the effect of genuine magic and the effect of a trick. In the behavioural trial, both children and adults showed the I/P effect. They were more likely to run the risk of losing their valuable objects in order to explore the impossible event than the possible event. Follow‐up experiments showed that the I/P effect couldn't be explained as an artifact of the different degrees of cost of exploratory behaviour in the possible and impossible conditions or as a result of misinterpreting magic as tricks. The I/P effect emerged when the cost of exploratory behaviour was moderate and disappeared when the cost was perceived as too high or too low.  相似文献   
902.

Introduction

Depression is common in older people and its identification and treatment has been highlighted as one of the major challenges in an ageing world. Poor physical and cognitive health, bereavement, and prior depression are important risk factors for depression in elderly people. Attributional or cognitive style has been identified as a risk factor for depression in children, adolescents and younger adults but its relevance for depression and mood in elderly people has not been investigated in the context of other risk factors.

Method

Sixty-four older adults from an ‘extra care’ living scheme (aged 59-97) were recruited for a 6-week prospective study to examine the relationships between cognitive style and depressive symptoms.

Results

Regression analyses revealed that, when other risk factors were controlled for, cognitive style and its interaction with stress predicted changes in depressive symptoms, therefore partially replicating prior research.

Conclusion

Cognitive-stress-vulnerability models also apply to elderly populations, but may be rather predictive of changes in depression when facing lower levels of stress.  相似文献   
903.
The ability to discover groupings in continuous stimuli on the basis of distributional information is present across species and across perceptual modalities. We investigate the nature of the computations underlying this ability using statistical word segmentation experiments in which we vary the length of sentences, the amount of exposure, and the number of words in the languages being learned. Although the results are intuitive from the perspective of a language learner (longer sentences, less training, and a larger language all make learning more difficult), standard computational proposals fail to capture several of these results. We describe how probabilistic models of segmentation can be modified to take into account some notion of memory or resource limitations in order to provide a closer match to human performance.  相似文献   
904.
The purpose of the present study was twofold. In an analysis of data from an existing randomized control trial of brief cognitive behavioral treatment on specific phobias (One-Session Treatment, OST; Ollendick et al., 2009), we examined 1) the effect of comorbid specific phobias and other anxiety disorders on treatment outcomes, and 2) the effect of treatment of the specific phobia on these co-occurring disorders. These relations were explored in 100 youth presenting with animal, natural environment, situational, and “other” types of phobia. Youth were reliably diagnosed with the Anxiety Disorders Interview Schedule for DSM-IV: Child and Parent versions (Silverman & Albano, 1996). Clinician severity ratings at post-treatment and 6-month follow-up were examined as were parent and child treatment outcome satisfaction measures. Results indicated that the presence of comorbid phobias or anxiety disorders did not affect treatment outcomes; moreover, treatment of the targeted specific phobias led to significant reductions in the clinical severity of other co-occurring specific phobias and related anxiety disorders. These findings speak to the generalization of the effects of this time-limited treatment approach. Implications for treatment of principal and comorbid disorders are discussed, and possible mechanisms for these effects are commented upon.  相似文献   
905.
Internet-delivered psychological treatment of major depression has been investigated in several trials, but the role of personalized treatment is less investigated. Studies suggest that guidance is important and that automated computerized programmes without therapist support are less effective. Individualized e-mail therapy for depression has not been studied in a controlled trial. Eighty-eight individuals with major depression were randomized to two different forms of Internet-delivered cognitive behaviour therapy (CBT), or to a waiting-list control group. One form of Internet treatment consisted of guided self-help, with weekly modules and homework assignments. Standard CBT components were presented and brief support was provided during the treatment. The other group received e-mail therapy, which was tailored and did not use the self-help texts i.e., all e-mails were written for the unique patient. Both treatments lasted for 8 weeks. In the guided self-help 93% completed (27/29) and in the e-mail therapy 96% (29/30) completed the posttreatment assessment. Results showed significant symptom reductions in both treatment groups with moderate to large effect sizes. At posttreatment 34.5% of the guided self-help group and 30% of the e-mail therapy group reached the criteria of high-end-state functioning (Beck Depression Inventory score below 9). At six-month follow-up the corresponding figures were 47.4% and 43.3%. Overall, the difference between guided self-help and e-mail therapy was small, but in favour of the latter. These findings indicate that both guided self-help and individualized e-mail therapy can be effective.  相似文献   
906.
We identified 129 pictures relating to AIDS/HIV in 94 abnormal psychology textbooks published between 1984 and 2005. Pictures included 189 persons with AIDS/HIV status or risk and 134 AIDS‐related objects; they appeared in chapters on stress, sexual issues, substance abuse, and organic brain disorders. Individuals depicted were overwhelmingly male, White, adult, of unspecified sexual orientation, and undiagnosed with mental disorder. The most frequent AIDS‐related objects were signs and posters, hospital furnishings, and drug paraphernalia. Thematic motifs across pictures included patient, information source, junkie, support group, celebrity, child victim, protesters, memorials, condom dispensary, and viral attack. Images of AIDS continue to invoke concepts of “the Other,” death, victimization, and culpability. It is difficult to discuss AIDS without accessing its stereotypes.  相似文献   
907.
Few studies have explored the effects of fixed‐time (FT) reinforcement on escape‐maintained behavior of students in a classroom setting. We measured the effects of an FT schedule on the disruptive and appropriate academic behaviors of 2 junior high students in a public school setting. Results demonstrated that FT escape from tasks resulted in a substantial decrease in disruptive behavior and an increase in time engaged in tasks for both participants.  相似文献   
908.
The trade-off between exploration and exploitation is common to a wide variety of problems involving search in space and mind. The prevalence of this trade-off and its neurological underpinnings led us to propose domain-general cognitive search processes (Hills, Todd, & Goldstone, 2008). We propose further that these are consistent with the idea of a central executive search process that combines goal-handling across subgoal hierarchies. In the present study, we investigate 3 aspects of this proposal. First, the existence of a unitary central executive search process should allow priming from 1 search task to another and at multiple hierarchical levels. We confirm this by showing cross-domain priming from a spatial search task to 2 different cognitive levels within a lexical search task. Second, given the neural basis of the proposed generalized cognitive search process and the evidence that the central executive is primarily engaged during complex tasks, we hypothesize that priming should require search in the sense of a self-regulated making and testing of sequential predictions about the world. This was confirmed by showing that when participants were allowed to collect spatial resources without searching for them, no priming occurred. Finally, we provide a mechanism for the underlying search process and investigate 3 alternative hypotheses for subgoal hierarchies using the central executive as a search process model (CESP). CESP envisions the central executive as having both emergent and unitary processes, with one of its roles being a generalized cognitive search process that navigates goal hierarchies by mediating persistence on and switching between subgoals.  相似文献   
909.
This study examines the mediating role of student-teacher relationship quality (conflict and closeness) in grades 4, 5, and 6 on the relation between background characteristics, difficult temperament at age 4½ and risky behavior in 6th grade. The longitudinal sample of participants (N = 1156) was from the NICHD Study of Early Child Care and Youth Development. Structural equation modeling was used to estimate paths from (a) background characteristics to student-teacher relationship quality and risky behavior, (b) temperament to student-teacher relationship quality and risky behavior, and (c) student-teacher relationship quality to risky behavior. Findings indicate that students' family income, gender, receipt of special services, and more difficult temperament were associated with risky behavior. In addition, student-teacher conflict was a mediator. Students with more difficult temperaments were more likely to report risky behavior and to have conflict in their relationships with teachers. More conflict predicted more risky behavior. Closer student-teacher relationships were associated with less risky behavior. Results suggest negative relationships, specifically student-teacher relationships, may increase the risk that certain adolescents will engage in risky behavior.  相似文献   
910.
The gateway drug model is a popular conceptualization of a progression most substance-users are hypothesized to follow as they try different legal and illegal drugs. Most forms of the gateway hypothesis are that "softer" drugs lead to "harder," illicit drugs. However, the gateway hypothesis has been notably difficult to directly test - i.e., to test as competing hypotheses in a single model that licit drug use might lead to illicit drug use or the reverse. This article presents a novel statistical technique, dual-process discrete-time survival analysis, which enables this comparison. This method uses mixture-modeling software to estimate two concurrent time-to-event processes and their effects on each other. Using this method, support for the gateway hypothesis in the National Longitudinal Survey of Youth 1997 was weak. However, this paper was not designed as a strong test of causal direction but more as a technical demonstration, and suffered from certain technological limitations. Both these limitations and future directions are discussed.  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