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   22080篇
  免费   98篇
  2021年   22篇
  2020年   34篇
  2019年   35篇
  2018年   3528篇
  2017年   2855篇
  2016年   2288篇
  2015年   223篇
  2014年   117篇
  2013年   262篇
  2012年   623篇
  2011年   2435篇
  2010年   2540篇
  2009年   1512篇
  2008年   1754篇
  2007年   2235篇
  2006年   93篇
  2005年   278篇
  2004年   214篇
  2003年   160篇
  2002年   105篇
  2001年   67篇
  2000年   86篇
  1999年   50篇
  1998年   54篇
  1997年   32篇
  1996年   30篇
  1995年   26篇
  1994年   22篇
  1993年   13篇
  1992年   20篇
  1991年   18篇
  1990年   22篇
  1989年   23篇
  1988年   18篇
  1987年   15篇
  1986年   14篇
  1985年   24篇
  1984年   25篇
  1982年   21篇
  1981年   20篇
  1980年   16篇
  1979年   22篇
  1978年   15篇
  1977年   21篇
  1976年   16篇
  1974年   16篇
  1973年   21篇
  1971年   12篇
  1970年   16篇
  1969年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Studies examining the effects of day care are reviewed. Little evidence was found indicating a negative impact on child development. A number of weaknesses in the day care literature were pointed out, including problems of ecological validity and failure to examine for differential effects. Suggestions for future research are made, among them a “natural history” of day care and studies of children who have experienced trauma.  相似文献   
132.
Social networks provide a larger context than that of the nuclear family in which the child develops. In order to examine the networks of young children, mothers of 75 handicapped children, aged 3 to 6 years, and a matched sample of normal children were surveyed in terms of people in the child's network and frequency of daily contact. The effects of age of subject and handicapping condition on social network composition and contact were of interest. Handicapping condition played a much greater role in the network composition than did chronological age. Handicapped children had larger networks, although they did not have daily contact with network members compared to normal children. Handicapped children thus were not isolated, but appeared to have a large network composed of relatives and adults and, to a lesser extent, peers. Normal children showed a developmental shift, in terms of an increase in the proportion of peers to adults, from 3 to 6 years, whereas handicapped children did not show this change. It is suggested that the handicapped child's developmental delay and caregiving demands may necessitate greater and more prolonged adult contact, which, consequently, constrains the nature of the social network in terms of adult and peer composition. Insufficient peer contact may restrict the handicapped child's opportunity to learn important social skills.  相似文献   
133.
134.
135.
This longitudinal study examined adolescent girls' perception of control over sexually transmitted disease (STD) acquisition. Participants were asked questions regarding their perception of their STD locus of control (internal control; control by parents, partners, peers, and health care providers; and chance) at two waves of data collection. Of the 116 participants (mean age = 17 years), 82% were African-American and 18% were Caucasian. Responses to the measure of locus of control were significantly correlated across a 6-month interval. The responses regarding internal control, control by partner, and chance were not related to the acquisition of an STD in the next 6 months. Further, they were not influenced by an STD in the preceding 6 months. These results indicate that responses to a locus of control measure were stable over a 6-month period, and internal, partner, and chance locus of control perceptions seem to be neither determined by STD experience nor directly related to future STD acquisition. However, understanding an individual's locus of control may be helpful in providing appropriate counseling. Future research could examine how adolescent girls form their perceptions of control over STD acquisition.  相似文献   
136.
Support groups are rapidly becoming an important part of the recovery process for many people who stutter, and a growing number of speech-language pathologists (SLPs) are encouraging their clients to participate in support groups. At present, however, little is known about the individuals who join stuttering support groups and the benefits they derive from their participation. This study surveyed members of the National Stuttering Association (NSA) to learn about their experiences in support groups, as well as their experiences in speech therapy. Respondents were 71 people who attended the 1999 NSA conference in Tacoma, WA. The majority of respondents had participated in treatment several times during their lives, using a variety of techniques. Respondents who had participated in fluency-shaping treatments were more likely to report that they had experienced a relapse than those who had participated in stuttering modification or combined treatments. Also, there was a strong positive correlation between respondents' satisfaction with treatment and their judgments of clinicians' competence, suggesting that improved training for SLPs should lead to improved treatment for people who stutter. Results will be used to provide a foundation for further evaluations of the benefits of support group participation for people who stutter. EDUCATIONAL OBJECTIVES: The reader will learn (a) that many people who participate in the NSA have had numerous and varied experiences with speech treatment throughout their lives, (b) which aspects of treatment and support group participation are seen as most beneficial for people who participate in the NSA.  相似文献   
137.
Learning nonlinearly separable categories by inference and classification   总被引:13,自引:0,他引:13  
Previous research suggests that learning categories by classifying new instances highlights information that is useful for discriminating between categories. In contrast, learning categories by making predictive inferences focuses learners on an abstract summary of each category (e.g., the prototype). To test this characterization of classification and inference learning further, the authors evaluated the two learning procedures with nonlinearly separable categories. In contrast to previous research involving cohesive, linearly separable categories, the authors found that it is more difficult to learn nonlinearly separable categories by making inferences about features than it is to learn them by classifying instances. This finding reflects that the prototype of a nonlinearly separable category does not provide a good summary of the category members. The results from this study suggest that having a cohesive category structure is more important for inference than it is for classification.  相似文献   
138.
In the first part of this paper we review evidence suggesting that there exists a mechanism that selects input on the basis of its similarity to the required action. This response-based input selection differs from the more established space- and object-based input selection in that it is not constrained by the structure of the input. Our evidence suggests that the two-choice Stroop effect is caused by this response-based selection mechanism. By contrast, it is known that the flanker effect is determined by the space- and object- based selection mechanisms. We explore whether the conflict resolution of the Stroop and flanker tasks is different as well by embedding these two tasks in a PRP (Psychological Refractory Period) paradigm. We show that the Stroop and the PRP effects are additive whereas the flanker and the PRP effects are underadditive, suggesting that the processes in charge of the conflict resolution in the Stroop and the flanker tasks are indeed different. We discuss possible reasons for this difference, and discuss possible ways in which the response-based mechanism can be implemented in information processing models.  相似文献   
139.
140.
Numerous previous investigators have explained species differences in spatial memory performance in terms of differences in foraging ecology. In three experiments we attempted to extend these findings by examining the extent to which the spatial memory performance of echidnas (or "spiny anteaters") can be understood in terms of the spatio-temporal distribution of their prey (ants and termites). This is a species and a foraging situation that have not been examined in this way before. Echidnas were better able to learn to avoid a previously rewarding location (to "win-shift") than to learn to return to a previously rewarding location (to "win-stay"), at short retention intervals, but were unable to learn either of these strategies at retention intervals of 90 min. The short retention interval results support the ecological hypothesis, but the long retention interval results do not. Electronic Publication  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