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   16250篇
  免费   205篇
  国内免费   119篇
教育   11174篇
科学研究   2072篇
各国文化   122篇
体育   1428篇
综合类   11篇
文化理论   129篇
信息传播   1638篇
  2021年   121篇
  2020年   229篇
  2019年   339篇
  2018年   459篇
  2017年   411篇
  2016年   416篇
  2015年   263篇
  2014年   341篇
  2013年   2818篇
  2012年   321篇
  2011年   365篇
  2010年   258篇
  2009年   269篇
  2008年   266篇
  2007年   304篇
  2006年   291篇
  2005年   280篇
  2004年   273篇
  2003年   264篇
  2002年   253篇
  2001年   264篇
  2000年   277篇
  1999年   280篇
  1998年   150篇
  1997年   161篇
  1996年   192篇
  1995年   175篇
  1994年   139篇
  1993年   152篇
  1992年   220篇
  1991年   231篇
  1990年   237篇
  1989年   270篇
  1988年   214篇
  1987年   231篇
  1986年   222篇
  1985年   252篇
  1984年   229篇
  1983年   215篇
  1982年   177篇
  1981年   176篇
  1980年   165篇
  1979年   250篇
  1978年   196篇
  1977年   182篇
  1976年   149篇
  1975年   135篇
  1974年   154篇
  1973年   133篇
  1971年   120篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
The chief purpose of this study was to identify characteristics that distinguish approach as an attachment behavior from approach serving other behavioral systems. Locomotor approaches of 16 male and 10 female white middle-class infants to an attachment figure (the mother) and to a nonattachment figure (the visitor-observer) were examined under naturalistic conditions at home. Observations were made during 4-hour home visits at 3-week intervals; those from 26 to 54 weeks were used. When approach was examined in a free-choice situation and without regard to behavioral context, infants approached the mother proportionally (though slightly) more often than the visitor (p less than .05). In 2 behavioral contexts, however, spontaneous infant approaches were sharply differential to the mother; approaches accompanied by crying and approaches terminating in a pickup appeal were directed almost exclusively to the mother (p less than .0001 for both). Touching upon completion of the approach was not differential, except in the context of a pickup appeal. Object-oriented approaches were more often directed to the visitor than to the mother (p less than .002) and may be either exploratory or affiliative. It is suggested that neither approach nor touching can be assumed to serve the attachment system without consideration of context- both environmental and behavioral.  相似文献   
52.
53.
54.
55.
In an attempt to clarify the chronological relationship between identity and equivalence conservation, normal preschool-aged children (experiment 1) were exposed to brief videotape demonstrations of a model conserving identity and equivalence, identity only, equivalence only, or neither. Subsequent performances indicate that identity was easier to accelerate than equivalence, and training in both identity and equivalence appeared to be most effective in accelerating conservation. Trainable mentally retarded (TMR) children were then exposed to either the identity-equivalence-conserving or control model (experiment 2). This population, which some have argued remains at a preoperational level of functioning, was more likely to conserve identity than equivalence. In addition, conservation in the training group increased following training, though these gains were not maintained over a 3-week retention interval.  相似文献   
56.
The behavior of narcotics-addicted and nonaddicted newborns on the first 2 days of life was assessed with the Brazelton Neonatal Behavioral Assessment Scale. In addition to classic signs of narcotics abstinence, addicted infants were less able to be maintained in an alert state and less able to orient to auditory and visual stimuli. These deficits were especially pronounced at 48 hours of age. Addicted infants were as capable of self-quieting and responding to soothing intervention as normal neonates, although they were substantially more irritable. These characteristics and addicted infants' greater resistance to cuddling are discussed in terms of their potential impact on early infant-care-giver interaction.  相似文献   
57.
58.
Formulae are derived for the deflection surface of a symmetrically loaded circular plate having several points supports which are situated at equal distances apart on a single concentric circle. There is no restriction on the diameter of the support circle, which may be as large as the diameter of the plate itself. The results of this paper compare favorably with published experimental results. Numerical deflection coefficients for a uniformly loaded plate are provided, and these could be utilized for optimizing the positions and the number of concentrated supports.  相似文献   
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