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   88902篇
  免费   3615篇
  国内免费   30篇
  2020年   850篇
  2019年   1078篇
  2018年   1454篇
  2017年   1498篇
  2016年   1621篇
  2015年   1181篇
  2014年   1390篇
  2013年   6464篇
  2012年   2610篇
  2011年   2748篇
  2010年   1727篇
  2009年   1668篇
  2008年   2437篇
  2007年   2429篇
  2006年   2205篇
  2005年   1989篇
  2004年   1857篇
  2003年   1749篇
  2002年   1858篇
  2001年   2799篇
  2000年   2744篇
  1999年   2068篇
  1998年   1007篇
  1997年   884篇
  1996年   880篇
  1992年   1823篇
  1991年   1703篇
  1990年   1706篇
  1989年   1541篇
  1988年   1515篇
  1987年   1449篇
  1986年   1532篇
  1985年   1610篇
  1984年   1318篇
  1983年   1200篇
  1982年   832篇
  1981年   826篇
  1979年   1415篇
  1978年   988篇
  1977年   851篇
  1975年   1196篇
  1974年   1335篇
  1973年   1423篇
  1972年   1224篇
  1971年   1146篇
  1970年   1062篇
  1969年   1082篇
  1968年   1419篇
  1967年   1268篇
  1966年   1111篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
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   
53.
Parent–adolescent conflict has been studied both as a precursor of long-term macrolevel developmental risks and as an outcome of microlevel, moment-to-moment interaction patterns. However, the family-level processes underlying the maintenance or regulation of conflict in daily life are largely overlooked. A meso-level understanding of parent–adolescent conflict offers important practical insights that have direct implications for interventions. The present study explores day-to-day reciprocal processes and carryover in parents’ and adolescents’ experiences of anger and conflict. Daily diary data provided by parent–adolescent dyads (N = 151) from two-caregiver households (adolescents: 61.59% female, mean age = 14.60 years) over 21 days were examined using a multivariate Poisson multilevel model to evaluate the circular causality principle in parents’ and adolescents’ daily conflict and anger. Findings offer empirical support for the theory, suggesting that parents’ and adolescents’ anger and conflict exist together in a feedback loop wherein conflict is both a consequence of past anger and also an antecedent of future anger, both within and across persons. Increased understanding of the daily interaction patterns and maintenance of parent–adolescent conflict can guide more informed, targeted, and well-timed interventions intended to ameliorate the consequences of problematic parent–adolescent conflict sequences.  相似文献   
54.
Parents who experienced infertility have increasingly used medically assisted reproduction (MAR) to add children to their families over the past few decades. These parents will need to decide if they will tell their children about being conceived using MAR. Although MAR information sharing operates within family contexts, little is known about the role of conversation orientation—one family contextual factor—in child outcomes associated with MAR information sharing in middle childhood. Derived from the Family Communication Patterns Theory, this study proposes that conversation orientation moderates the associations between MAR information sharing and children's psychosocial adjustment. This proposal was tested using a sample of 81 6- to 12-year-old MAR-conceived children from 55 families and a structured observational measure of conversation orientation. Multiple regression analyses showed that MAR information sharing interacted with conversation orientation to influence children's behavioral and attention problems but not emotional problems. In families with high conversation orientation, MAR information sharing was not significantly associated with children's behavioral and attention problems. In families with low conversation orientation, MAR information sharing was significantly associated with an increase in children's behavioral and attention problems. Results of this exploratory study demonstrate the potential significance of general communication orientation in understanding child outcomes of MAR information sharing and highlight the needed family context nuances in MAR research.  相似文献   
55.
56.
57.
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   
58.
59.
60.
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