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   15505篇
  免费   190篇
  国内免费   119篇
教育   10625篇
科学研究   2049篇
各国文化   110篇
体育   1352篇
综合类   11篇
文化理论   122篇
信息传播   1545篇
  2020年   210篇
  2019年   308篇
  2018年   426篇
  2017年   373篇
  2016年   386篇
  2015年   243篇
  2014年   316篇
  2013年   2632篇
  2012年   298篇
  2011年   339篇
  2010年   242篇
  2009年   242篇
  2008年   253篇
  2007年   287篇
  2006年   275篇
  2005年   270篇
  2004年   254篇
  2003年   248篇
  2002年   238篇
  2001年   257篇
  2000年   271篇
  1999年   276篇
  1998年   144篇
  1997年   150篇
  1996年   185篇
  1995年   170篇
  1994年   131篇
  1993年   144篇
  1992年   217篇
  1991年   222篇
  1990年   230篇
  1989年   258篇
  1988年   209篇
  1987年   227篇
  1986年   220篇
  1985年   250篇
  1984年   222篇
  1983年   212篇
  1982年   177篇
  1981年   171篇
  1980年   158篇
  1979年   246篇
  1978年   192篇
  1977年   181篇
  1976年   148篇
  1975年   132篇
  1974年   151篇
  1973年   132篇
  1972年   108篇
  1971年   119篇
排序方式: 共有10000条查询结果,搜索用时 7 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