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   553篇
  免费   17篇
  570篇
  2019年   10篇
  2018年   7篇
  2017年   11篇
  2016年   17篇
  2015年   11篇
  2014年   10篇
  2013年   49篇
  2012年   23篇
  2011年   19篇
  2010年   12篇
  2009年   12篇
  2008年   18篇
  2007年   21篇
  2006年   15篇
  2005年   12篇
  2004年   15篇
  2003年   15篇
  2002年   18篇
  2001年   7篇
  2000年   6篇
  1999年   8篇
  1998年   7篇
  1997年   6篇
  1995年   6篇
  1994年   6篇
  1993年   5篇
  1992年   10篇
  1991年   6篇
  1990年   11篇
  1989年   7篇
  1988年   15篇
  1987年   8篇
  1986年   7篇
  1985年   7篇
  1984年   10篇
  1983年   8篇
  1982年   8篇
  1980年   5篇
  1979年   8篇
  1978年   8篇
  1977年   8篇
  1976年   9篇
  1975年   8篇
  1974年   7篇
  1973年   10篇
  1972年   5篇
  1970年   8篇
  1968年   6篇
  1967年   8篇
  1966年   7篇
排序方式: 共有570条查询结果,搜索用时 15 毫秒
221.
The case records of the Psychological Clinic of the University of Pennsylvania the first established in this country, have been transferred to microfilm to save them from desctruction. A survey of the records indicate that they may be valuable in both historical and follow-up research. The microfilms can be made available to qualified investigators with worthy projects.  相似文献   
222.
223.
Heterosexual and gay physicians indicated their own attitudes on several issues related to the AIDS epidemic and attributed a position on each issue to the target group "most people." The heterosexual physicians' attitudes were more negative than the gay physicians' attitudes. Both groups judged that "most people" hold attitudes more negative than their own. The distance between own and attributed position as much greater for the gay individuals. This distance effect was due primarily to differences in self-ratings between the two groups. Own and attributed position correlated positively for each group of physiaans. Additionally, the tendency to assume similarity was marginally stronger for heterosexuals with high than low homophobia. Theoretical interpretation is presented.  相似文献   
224.
Job analysis is an important aspect of human resource management. This study was conceived to further our understanding of how job analysis may best be used to enhance the variety of human resource management activities that rely on it. Nine geographically dispersed organizations, carefully selected on the basis of their exemplary job analysis functions, were each visited and their job analysis functions studied for a period ranging from one to three days. These organizations represented a wide range of industries. We found that job analysis functions are typically highly centralized and part or all of these functions are often housed in a unit dealing with compensation. The idea of a fully integrated personnel system based on a comprehensive job analysis data base is not quite ready for widespread adoption. However, a multipurpose approach, designed to serve several applications, is feasible to develop. Little progress has been made in estimating the costs of job analysis functions. Rudimentary cost estimates prepared by us on anad hoc basis revealed that the annual costs for job analysis functions ranged from $150,000 to $4,000,000 with a median of$280,000.  相似文献   
225.
Behavioral stress impairs long-term potentiation in rodent hippocampus   总被引:12,自引:0,他引:12  
A number of hormones secreted from the pituitary-adrenal system during stress affect learning and memory processes. The phenomenon of hippocampal long-term potentiation (LTP) is viewed by many as a putative mechanism of memory storage and has proved a most valuable model for study of neuronal plasticity at the cellular level. The present study was conducted to investigate the possibility that stressful events which occur prior (in vivo) to the preparation of brain slices may influence the electrophysiology of the in vitro hippocampal explant when tested for LTP. Adult male rats (Long-Evans male X Sprague-Dawley female) were pair-housed 1 week prior to testing. One animal in each pair was either placed in a restraining tube for 30 min and received no tail shocks (Restraint) or placed in a restraining tube and received tail shocks (1 microA, 1 s) every minute for 30 min (Restraint + Shock). The other animal in each pair was taken directly from the home cage and received no restraint or tail shock (Control). In vitro hippocampal slices were then prepared immediately from these animals according to standard methods. Our results demonstrate a marked impairment of LTP in hippocampal explants taken from rats exposed to stress. The significance of this result with respect to cellular mechanisms underlying the relationship between stress, cognition, and learning is discussed.  相似文献   
226.
227.
Social and naturally occurring choice phenomena are often of the pick-any type in which the number of choices made by a subject as well as the set of alternatives from which they are chosen is unconstrained. These data present a special analytical problem because the meaning of non-choice among pick-any choice data is always ambiguous: A non-chosen alternative may be either unacceptable, or acceptable but not considered, or acceptable and considered but not chosen. A model and scaling method for these data are introduced, allowing for this ambiguity of non-choice. Subjects are represented as points whose coordinates are proportional to the centroids of the points representing their choices. Alternatives are represented at points whose coordinates are proportional to the centroids of the points representing subjects who have chosen them. This centroid scaling technique estimates multidimensional joint spaces from the pick-any data.I am indebted to John Baird, Clyde Coombs, David Eames, John Hunter, Michael J. Levine, Elliot Noma, Robert Z. Norman, William S. Roy, Joseph Schwartz, Daniel Velleman, the editor, and anonymous reviewers for ideas and suggestions that have been incorporated into this work. Conferences organized by Hans J. Hummel for the Deutsche Forschungsgemeinschaft (1977) and by Samuel Leinhardt for the National Science Foundation (1975) were instrumental in the development of this work.  相似文献   
228.
A series of experiments assessed the effects of ACTH and the ACTH analogue ACTH4-10 on drinking in conditioned taste aversion and neophobic situations. Both substances delayed the extinction of a conditioned taste aversion established by a single pairing of lithium chloride with milk (Experiment 1). However, in this situation, the ACTH parent peptide was more potent behaviorally. Administration of ACTH suppressed milk consumption in animals with no toxicosis experience (Experiment 2). This effect was apparently not due to the conditioning of a taste aversion (Experiment 3) with ACTH serving as a weak aversive unconditioned stimulus. Administration of exogenous ACTH (Experiment 4) or ACTH4-10 (Experiment 5) did not enhance neophobia; however, repeated injections of ACTH suppressed drinking. This ACTH suppression was related to the familiarity/novelty of the subtance being consumed. The neophobic response to milk eas no accompanied by pituitary-adrenal activation (Experiment 6). Both neophobic and conditioned taste aversion situation appear to be useful for assessing peptide effects on consummatory behavior.  相似文献   
229.
This study examined the relation between the amount of mathematical input in the speech of preschool or day-care teachers and the growth of children's conventional mathematical knowledge over the school year. Three main findings emerged. First, there were marked individual differences in children's conventional mathematical knowledge by 4 years of age that were associated with socioeconomic status. Second, there were dramatic differences in the amount of math-related talk teachers provided. Third, and most important, the amount of teachers' math-related talk was significantly related to the growth of preschoolers' conventional mathematical knowledge over the school year but was unrelated to their math knowledge at the start of the school year.  相似文献   
230.
Recent evidence demonstrated that neuropsychological assessment may be considered a valid marker of neurodegeneration in idiopathic REM sleep behaviour disorder (iRBD). However, little is known about the possible neuropsychological heterogeneity within the iRBD population. This retrospective study aimed to identify and describe different neuropsychological phenotypes in iRBD patients by means of a data-driven approach using latent class analysis. A total of 289 iRBD patients underwent a neuropsychological assessment evaluating cognitive domains: global cognition, language, short- and long-term memory, executive functions and visuospatial abilities. The presence of mild cognitive impairment (MCI) was also assessed. Latent class analysis was carried out to identify iRBD subtypes according to neuropsychological scores. The most parsimonious model identified three latent classes. Groups were labelled as follows: Class 2 “severely impaired” (n = 83/289): mean pathological scores in different tests, a high percentage of MCI multiple-domain and impairment in all neuropsychological domains. Class 1 “moderately impaired” (n = 44/289): mean neuropsychological score within the normal value, a high percentage of MCI (high risk to phenoconversion) and great impairment in the visuospatial domain. Class 3 “slightly impaired” (n = 162/289): no deficit worthy of attention except for short- and long-term memory. Our results suggest three different clinical phenotypes within the iRBD population. These findings may be relevant in the future for predicting the clinical trajectories of phenoconversion in iRBD.  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