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   37052篇
  免费   734篇
  国内免费   5篇
  37791篇
  2018年   552篇
  2017年   496篇
  2016年   588篇
  2015年   421篇
  2014年   507篇
  2013年   3418篇
  2012年   882篇
  2011年   902篇
  2010年   586篇
  2009年   551篇
  2008年   858篇
  2007年   763篇
  2006年   716篇
  2005年   602篇
  2004年   580篇
  2003年   617篇
  2002年   582篇
  2001年   1171篇
  2000年   1128篇
  1999年   862篇
  1996年   493篇
  1995年   472篇
  1994年   462篇
  1993年   437篇
  1992年   901篇
  1991年   805篇
  1990年   802篇
  1989年   707篇
  1988年   710篇
  1987年   693篇
  1986年   692篇
  1985年   679篇
  1984年   605篇
  1983年   501篇
  1982年   393篇
  1981年   410篇
  1980年   381篇
  1979年   569篇
  1978年   430篇
  1976年   386篇
  1975年   528篇
  1974年   519篇
  1973年   584篇
  1972年   558篇
  1971年   501篇
  1970年   445篇
  1969年   427篇
  1968年   536篇
  1967年   458篇
  1966年   443篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
841.
An experiment is reported designed to test the hypothesis that female rats might discriminate between males that differed in the quantity of odor deposited by scent marking. Male odor donors were selected by prior screening for high or low rates of scent marking in an open arena. Females were then tested to determine whether they showed any preference for males that marked at a high rate. It was found that female rats did discriminate, but that they preferred to remain near males selected for low rates of scent marking.  相似文献   
842.
Impaired retention of an inhibitory avoidance response was observed in rats subjected to adrenalectomy (ADX) up to 120 hr before the single learning trial. Corticosterone substitution failed to normalize this behavioral deficit. Rats ADX 240 hr prior to the learning trial showed a normalized behavior. Adrenomedullectomy (ADXM) 48 or 240 hr before learning caused a similar impairment as in short-term ADX rats. The 240-hr ADX rats subjected to corticosterone substitution showed the same behavioral deficit as short-term ADX rats or ADXM ones. Immediate postlearning subcutaneous injection of adrenaline in a dose range of 0.005-5.0 micrograms/kg or of noradrenaline (0.005-0.5 microgram/kg) to 48-hr ADX rats resulted in a dose-related improvement of later retention behavior. Higher doses of catecholamines were less or ineffective. Postlearning treatment of 48-hr ADXM rats with adrenaline (0.5-500 micrograms/kg) caused a similar pattern of behavioral changes. It is concluded that adrenal catecholamines play an important role in the modulation of consolidation of memory. In addition, the high circulating ACTH levels that follow long-term ADX may correct for the behaviorial deficit induced by the absence of adrenomedullary catecholamines.  相似文献   
843.
844.
Cognitive motivation and drug use: a 9-year longitudinal study.   总被引:2,自引:0,他引:2  
The predictive precedence of expectancy constructs, operationally defined as cognitive motivations, and drug use was investigated over a 9-year period from adolescence to adulthood. Alternative predictions from three different classes of theories of expectancy-behavior relations, including expectancy theory, a Skinnerian approach, and a reciprocal determinism perspective, were evaluated. The results are most consistent with the notion based in expectancy theory that cognitive motivations are nonspurious and possibly functionally autonomous influences on the use and abuse of drugs. More limited support is found for the view that drug use leads to cognitive motivations, as postulated in other theoretical perspectives. Other findings reveal the presence of expectancy generalization processes consistent with Rotter's (1954) expectancy theory, as well as the unique status of cognitive motivations for alcohol as an independent predictor of problem drug use.  相似文献   
845.
Disintegrated experience: the dissociative disorders revisited   总被引:2,自引:0,他引:2  
We present proposed changes to the dissociative disorders section of the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders and review the concept of pathological and nonpathological dissociation, including empirical findings on the relations between trauma and dissociative phenomenology and between dissociation and hypnosis. The most important proposals include the creation of two new diagnostic entities, brief reactive dissociative disorder and transient dissociative disturbance, and the readoption of the criterion of amnesia for a multiple personality disorder diagnosis. We conclude that further work on dissociative processes will provide an important link between clinical and experimental approaches to human cognition, emotion, and personality.  相似文献   
846.
A BASIC program to generate values for variable-interval (VI) schedules of reinforcement is presented. A VI schedule should provide access to reinforcement with a constant probability over a time horizon. If the values in a VI schedule are calculated from an arithmetic progression, the probability of reinforcement is positively correlated with the time since the last reinforcer was delivered. Fleshler and Hoffman (1962) developed an iterative equation to calculate VI schedule values so that the probability of reinforcement remains constant. This easy-to-use program generates VI schedule values according to the Fleshler and Hoffman equation, randomizes the values, and saves the values in ASCII to a disk file.  相似文献   
847.
848.
849.
850.
This study, conducted within the framework of concepts of structural family therapy, examined the relationship of four family-based, clinical dimensions to the adjustment of 45 adolescents during the first 18 months of parental separation. There were two samples of mother-custody families: an Aided group that applied for treatment, and an Unaided group of paid volunteers. The inclusion of this variable addressed a major methodological deficit of previous studies. There was a significant association between perceived postseparation family structure and adolescent adjustment, demonstrating that individual adolescent adjustment is contingent on structural features of the contemporary postseparation family. Further, Aided families were perceived as more chaotic, disengaged, and enmeshed than Unaided families, while Aided adolescents were characterized by more behavior problems than Unaided adolescents. This suggests that divorce, as an unscheduled transition, might be within the realm of adaptation for many families and adolescents and is not necessarily "disastrous."  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