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   193685篇
  免费   8524篇
  国内免费   155篇
  2020年   2783篇
  2019年   3450篇
  2018年   3722篇
  2017年   4147篇
  2016年   4757篇
  2015年   3934篇
  2014年   4811篇
  2013年   23455篇
  2012年   5179篇
  2011年   4559篇
  2010年   4199篇
  2009年   4902篇
  2008年   4617篇
  2007年   4291篇
  2006年   4684篇
  2005年   4549篇
  2004年   4039篇
  2003年   3636篇
  2002年   3475篇
  2001年   4241篇
  2000年   4127篇
  1999年   3778篇
  1998年   2930篇
  1997年   2742篇
  1996年   2656篇
  1995年   2469篇
  1994年   2435篇
  1993年   2399篇
  1992年   3135篇
  1991年   2966篇
  1990年   2802篇
  1989年   2646篇
  1988年   2641篇
  1987年   2612篇
  1986年   2661篇
  1985年   2857篇
  1984年   2815篇
  1983年   2559篇
  1982年   2473篇
  1981年   2444篇
  1980年   2277篇
  1979年   2622篇
  1978年   2390篇
  1977年   2275篇
  1976年   2079篇
  1975年   2311篇
  1974年   2423篇
  1973年   2372篇
  1972年   1934篇
  1971年   1817篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Experiment 1 replicated Yaniv and Meyer's (1987) finding that lexical decision and episodic recognition performance was better for words previously yielding high-accessibility levels (a combination of feeling-of-knowing and tip-of-the-tongue ratings) in comparison with those yielding low-accessibility levels in a rare word definition task. Experiment 2 yielded the same pattern even though lexical decisions preceded accessibility estimates by a full week. Experiment 3 dismissed the possibility that the Experiment 2 results may have been due to a long-term influence from the lexical decision task to the rare word judgment task. These results support a model in which Ss (a) retrieve topic familiarity information in making accessibility estimates in the rare word definition task and (b) use this information to modulate lexical decision performance.  相似文献   
122.
123.
124.
125.
As the complexity of the challenges presented by our interactions with our planet continues to grow, we must develop new modes of knowledge production. In these modes, distinctions between multidisciplinary and inter-disciplinary activities and processes have renewed importance. There are at least two distinct types of interdisciplinary activities distinguished by the disciplinary breadth they attempt to bridge. In the narrow case, reductionist processes reveal a common underlying principle or process which can serve as a Rosetta stone. In the broad case, no such common arbiter exists. Investigators must develop integrating vocabulary in the context of the full breadth of their work. His primary activities are the fostering of university-wide interdisciplinary research and curriculum programs focused on global change with the goal of developing Columbia into a world leader in issues related to global stewardship.  相似文献   
126.
127.
Most studies of suicide in younger patients have demonstrated significant alterations in the serotonin system. Although a high percentage of completed suicides occur in late-life, to date very few studies of the biology of suicide have focused on this age group. This chapter describes age-related changes in the central nervous system pertinent to the biology of suicide, then reviews post-mortem biological studies of the brains of suicides and suicide attempters. As suicide attempts in the elderly are characterized by the use of violent means, biologic studies of impulsive violence are discussed. Finally we describe data on the effect of degenerative diseases on the serotonin system and the possible link to increased suicidal behavior in affected patients. This review underscores the need for further study of the biology of suicide in the geriatric age group.  相似文献   
128.
Three experiments, each using a single group of pigeons, are reported. In Experiment 1 subjects were initially trained with two stimuli, one of which was always followed by food, the other being reinforced according to a 50% partial reinforcement schedule. Subsequently a serial procedure was adopted in which an additional stimulus, C, was consistently followed by the partially reinforced CS. A second additional stimulus, A, was followed on half of its occurrences by the continuously reinforced CS, its remaining presentations being followed by nothing. The rate of autoshaped keypecking was substantially greater during A than during C. In the remaining experiments subjects received first-order conditioning with a single stimulus that was either partially (Experiment 2) or continuously (Experiment 3) reinforced. The stimuli A and C were then again introduced for serial autoshaping. Stimulus A was occasionally paired with the CS and occasionally followed by nothing, whereas stimulus C was always followed by the CS. As in Experiment 1, the rate of responding during A was greater than during C. It is proposed that one influence on the rate of autoshaped keypecking during a CS is the accuracy with which the immediate consequences of that CS are predicted.  相似文献   
129.
ABSTRACT In this essay the argument set forth by Michael Levin regarding the abnormality of homosexual behaviour is reviewed and criticized. Against his argument which holds that homosexual behaviour is abnormal because it constitutes an evolutionary aberration, I argue that Levin's and all similarly constructed arguments fail to show that evolutionary origins of sexual behaviour have any significant normative force. I contend that his notion of homosexuality is confused and that he fails to consider alternative methods of how homosexuality might have indeed served evolutionary adaptive purposes or been the result of surplus adaptations. I argue, too, that Levin's linking of unhappiness with homosexual behaviour is spurious and ill-supported. Consequently, I reject Levin's claims that public policy ought to do what it can to minimize the incidence of such behaviour. I argue by contrast that if happiness is the end of public policy decisions, then society ought to take what measures it can to protect persons in respect of their homosexual behaviour and identities.  相似文献   
130.
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