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   97512篇
  免费   3056篇
  国内免费   27篇
  2019年   942篇
  2018年   4348篇
  2017年   3726篇
  2016年   3394篇
  2015年   1207篇
  2014年   1255篇
  2013年   5884篇
  2012年   2708篇
  2011年   4512篇
  2010年   3734篇
  2009年   2826篇
  2008年   3660篇
  2007年   4030篇
  2006年   1950篇
  2005年   1948篇
  2004年   1772篇
  2003年   1640篇
  2002年   1725篇
  2001年   2463篇
  2000年   2440篇
  1999年   1804篇
  1998年   897篇
  1997年   816篇
  1996年   791篇
  1992年   1574篇
  1991年   1489篇
  1990年   1462篇
  1989年   1369篇
  1988年   1307篇
  1987年   1274篇
  1986年   1367篇
  1985年   1409篇
  1984年   1191篇
  1983年   1062篇
  1982年   776篇
  1981年   813篇
  1979年   1258篇
  1978年   921篇
  1977年   759篇
  1976年   744篇
  1975年   1081篇
  1974年   1171篇
  1973年   1285篇
  1972年   1099篇
  1971年   1024篇
  1970年   946篇
  1969年   974篇
  1968年   1238篇
  1967年   1143篇
  1966年   1013篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
41.
42.
43.
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   
44.
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   
45.
46.
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   
47.
48.
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