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   95184篇
  免费   3006篇
  国内免费   25篇
  2020年   722篇
  2019年   912篇
  2018年   4362篇
  2017年   3746篇
  2016年   3376篇
  2015年   1149篇
  2014年   1236篇
  2013年   5768篇
  2012年   2710篇
  2011年   4546篇
  2010年   3745篇
  2009年   2814篇
  2008年   3611篇
  2007年   4055篇
  2006年   1965篇
  2005年   1922篇
  2004年   1783篇
  2003年   1624篇
  2002年   1724篇
  2001年   2499篇
  2000年   2497篇
  1999年   1871篇
  1998年   907篇
  1997年   806篇
  1996年   780篇
  1992年   1572篇
  1991年   1449篇
  1990年   1471篇
  1989年   1354篇
  1988年   1327篇
  1987年   1272篇
  1986年   1351篇
  1985年   1380篇
  1984年   1144篇
  1983年   1042篇
  1982年   758篇
  1981年   738篇
  1979年   1227篇
  1978年   880篇
  1977年   739篇
  1975年   1058篇
  1974年   1111篇
  1973年   1174篇
  1972年   1013篇
  1971年   938篇
  1970年   849篇
  1969年   927篇
  1968年   1120篇
  1967年   1014篇
  1966年   910篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
32.
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   
33.
34.
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   
35.
36.
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   
37.
38.
39.
40.
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