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   93314篇
  免费   3535篇
  国内免费   31篇
  2020年   853篇
  2019年   1082篇
  2018年   2531篇
  2017年   2393篇
  2016年   2272篇
  2015年   1125篇
  2014年   1408篇
  2013年   6544篇
  2012年   2721篇
  2011年   3536篇
  2010年   2487篇
  2009年   2192篇
  2008年   3001篇
  2007年   3215篇
  2006年   2325篇
  2005年   2062篇
  2004年   1947篇
  2003年   1822篇
  2002年   1860篇
  2001年   2744篇
  2000年   2763篇
  1999年   2087篇
  1998年   1025篇
  1997年   916篇
  1996年   894篇
  1993年   808篇
  1992年   1740篇
  1991年   1616篇
  1990年   1624篇
  1989年   1487篇
  1988年   1437篇
  1987年   1387篇
  1986年   1459篇
  1985年   1539篇
  1984年   1273篇
  1983年   1159篇
  1982年   855篇
  1981年   830篇
  1979年   1342篇
  1978年   1019篇
  1975年   1124篇
  1974年   1250篇
  1973年   1360篇
  1972年   1123篇
  1971年   1045篇
  1970年   905篇
  1969年   962篇
  1968年   1231篇
  1967年   1116篇
  1966年   991篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Previous research demonstrates that older adults are poor at dual tasking, but there is less agreement on whether their decrement is worse than that predicted from single-task performance. This study investigated whether task domain moderates dual-task costs in old age. In two experiments, young and older adults retrieved either previously learned associates (episodic retrieval) or overlearned category members (semantic retrieval) under single or working-memory load conditions, using cued recall (Experiment 1) and recognition (Experiment 2) procedures. In both experiments the proportional costs of dual tasking were age invariant for semantic retrieval but were particularly marked for episodic retrieval, although the size of the age effect was reduced in recognition compared to cued recall. The data suggest that age effects in dual tasking may be domain specific.  相似文献   
42.
Evaluated the effect of varied physician affect on subject recall, anxiety, and perceptions in a simulated tense and ambiguous medical situation. Forty women at risk for breast cancer viewed videotapes of an oncologist presenting--with either worried or nonworried affect--mammogram results. Although the mammogram results and the oncologist were the same in both presentation, analyses indicated that, compared to the women receiving the results from a nonworried physician, the women receiving the results from a worried physician recalled significantly less information, perceived the clinical situation as significantly more severe, reported significantly higher levels of state anxiety, and had significantly higher pulse rates. These results suggest that physician affect plays a critical role in patient reaction to medical information. Implications for compliance research, patient satisfaction, and physician training are discussed.  相似文献   
43.
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   
44.
45.
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   
46.
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   
47.
48.
Convergent and divergent stereo mechanisms were compared in their ability to recover structure from motion. Contrary to a recent result reported by Richards and Lieberman, no difference in their performance was found; both mechanisms appeared equally capable of supporting the perception of good structure from motion. Possible reasons for the disparate results are discussed.  相似文献   
49.
50.
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