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   47813篇
  免费   1990篇
  国内免费   14篇
  2020年   546篇
  2019年   595篇
  2018年   840篇
  2017年   850篇
  2016年   959篇
  2015年   729篇
  2014年   824篇
  2013年   3603篇
  2012年   1538篇
  2011年   1521篇
  2010年   968篇
  2009年   938篇
  2008年   1345篇
  2007年   1320篇
  2006年   1172篇
  2005年   1128篇
  2004年   1052篇
  2003年   982篇
  2002年   976篇
  2001年   1410篇
  2000年   1324篇
  1999年   1030篇
  1998年   525篇
  1997年   456篇
  1996年   438篇
  1992年   956篇
  1991年   884篇
  1990年   889篇
  1989年   761篇
  1988年   769篇
  1987年   739篇
  1986年   779篇
  1985年   857篇
  1984年   661篇
  1983年   617篇
  1982年   434篇
  1979年   739篇
  1978年   488篇
  1977年   482篇
  1976年   471篇
  1975年   632篇
  1974年   723篇
  1973年   755篇
  1972年   641篇
  1971年   603篇
  1970年   598篇
  1969年   584篇
  1968年   782篇
  1967年   683篇
  1966年   626篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
OBJECTIVE: To test a theoretical model of how ethnic pride and self-control are related to risk and protective factors. DESIGN: A community sample of 670 African American youth (mean age = 11.2 years) were interviewed in households. MAIN OUTCOME MEASURES: Measures of cigarette smoking, alcohol use, and sexual behavior (lifetime to past month). RESULTS: Structural modeling analyses indicated parenting was related to self-control and self-esteem, and racial socialization was related to ethnic pride. Self-control and self-esteem variables were related to levels of deviance-prone attitudes and to perceptions of engagers in, or abstainers from, substance use and sexual behavior. The proximal factors (behavioral willingness, resistance efficacy, and peer behavior) had substantial relations to the criterion variables. Participant gender and parental education also had several paths in the model. Results were generally similar for the 2 outcome behaviors. CONCLUSIONS: In this population, self-esteem and self-control are related to parenting approaches and have pathways to attitudes and social perceptions that are significant factors for predisposing to, or protecting against, early involvement in substance use and sexual behavior.  相似文献   
22.
23.
24.
It is widely assumed that reinforcers are biologically relevant stimuli, or stimuli that have been associated with biologically relevant stimuli. However, brief, arbitrary stimuli have also been reported to have reinforcement-like effects, despite being unrelated to biologically relevant stimuli like food. The present study explored the potential reinforcement-like effects of brief stimuli across 5 experiments. In Experiments 1 through 4, pigeon subjects responded for food reinforcement and brief stimulus presentations in a 2-component multiple schedule. Neither baseline response rates nor resistance to change during disruption tests were systematically greater in a component with versus without brief stimulus presentations. Increasing the rate and duration of brief stimulus presentations in Experiment 4 did not reveal reinforcement-like effects when compared directly with food. In Experiment 5, pigeons chose between independent terminal links in a concurrent-chains procedure. Across conditions, varying the location, duration, and rate of brief stimulus presentations in the terminal links had no systematic effects on preference. In contrast, varying rates of food reinforcers resulted in large and reliable shifts in preference. Therefore, the present study found no systematic evidence that brief stimuli unrelated to food reliably increase response rates, resistance to change, or preference. These data demonstrate the value of systematic replication, and a behavioral momentum approach to assessing potential reinforcement-like effects.  相似文献   
25.
Subjects in five experiments read nine-digit memory lists from a cathode ray tube for immediate recall. Reading aloud always produced a localized and reliable advantage for the last item, compared to reading silently. Two experiments on whispered and mouthed lists, with or without simultaneous broadband noise, falsified expectations derived from the theory of precategorical acoustic storage. Three additional experiments showed no enhancement of recency in the silent conditions when the digits were drawn or spelled gradually on the screen, a result that is inconsistent with the changing-state hypothesis. The classic auditory-visual modality effect is large and reliable, but still poorly understood.  相似文献   
26.
27.
28.
29.
In two experiments, hungry rats were given instrumental lever-press training for an appetitive reinforcer and, in addition, were exposed to another type of food which was not contingent on lever pressing. In the first experiment, exposure to each type of food was on separate days, whereas in the second experiment rats were exposed to each type of food in strict alternation within each session. Subsequently, a food aversion was conditioned to the reinforcer for the experimental group and to the non-contingent food for the control group. In both experiments, animals with an aversion to the reinforcer responded less in an extinction test than animals with an aversion to the non-contingent food. Subsequent reacquisition tests confirmed that the aversion to the non-contingent food in the control group was of comparable strength with that to the reinforcer in the experimental group. The results were discussed in terms of whether the reinforcer is encoded in the associative structure set up by exposure to an instrumental contingency.  相似文献   
30.
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