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   20044篇
  免费   267篇
  国内免费   57篇
教育   14546篇
科学研究   1728篇
各国文化   187篇
体育   1391篇
综合类   51篇
文化理论   162篇
信息传播   2303篇
  2022年   100篇
  2021年   206篇
  2020年   246篇
  2019年   383篇
  2018年   598篇
  2017年   673篇
  2016年   699篇
  2015年   457篇
  2014年   535篇
  2013年   3562篇
  2012年   614篇
  2011年   646篇
  2010年   519篇
  2009年   451篇
  2008年   505篇
  2007年   487篇
  2006年   481篇
  2005年   1050篇
  2004年   786篇
  2003年   577篇
  2002年   377篇
  2001年   444篇
  2000年   323篇
  1999年   279篇
  1998年   172篇
  1997年   162篇
  1996年   179篇
  1995年   148篇
  1994年   158篇
  1993年   138篇
  1992年   213篇
  1991年   214篇
  1990年   231篇
  1989年   207篇
  1988年   163篇
  1987年   182篇
  1986年   175篇
  1985年   168篇
  1984年   164篇
  1983年   152篇
  1982年   117篇
  1981年   125篇
  1980年   118篇
  1979年   173篇
  1978年   145篇
  1977年   100篇
  1976年   114篇
  1975年   106篇
  1973年   103篇
  1971年   102篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
Early childhood is a sensitive period for learning and social skill development. The maturation of cerebral regions underlying social processing lays the foundation for later social-emotional competence. This study explored myelin changes in social brain regions and their association with changes in parent-rated social-emotional development in a cohort of 129 children (64 females, 0–36 months, 77 White). Results reveal a steep increase in myelination throughout the social brain in the first 3 years of life that is significantly associated with social-emotional development scores. These findings add knowledge to the emerging picture of social brain development by describing neural underpinnings of human social behavior. They can contribute to identifying age-/stage-appropriate early life factors in this developmental domain.  相似文献   
2.
ABSTRACT

The aims of this study were to identify profiles of sedentary behaviour (SB) patterns, based on leisure-time self-reported SB modalities (screen, educative, social, and relaxing) and to evaluate changes in these profiles over 2 years among Spanish youth aged 8–18 years. Latent profile analysis (LPA), a data-driven analytic approach, was used to identify groups of boys and girls (n = 1553; 48% girls; mean±SD age: 12.56 ± 2.49 y) with distinct SB profiles using the SB modalities (time/d) as input variables. Latent transition analysis, an extension of LPA that uses longitudinal data, was used to analyse 2-year changes in these profiles. At baseline, four and three SB profiles were found among boys (labelled: screen, educative, social, and relaxing) and girls (labelled: screen/social, educative, and relaxing), respectively. Overall, more girls (range: 48%-67%) had the same profile over time, than boys (40%-52%). Participants with a screen or relaxing SB profile at baseline were more likely to have an educative profile after 2 years. Youth with a social and an educative SB profile at baseline were more likely to transition to profiles characterized by higher screen and social SB, respectively. Using a novel and person-centered approach, this study identified gender-specific SB profiles that were moderately stable over time.  相似文献   
3.
4.
In this digital ITEMS module, Dr. Jeffrey Harring and Ms. Tessa Johnson introduce the linear mixed effects (LME) model as a flexible general framework for simultaneously modeling continuous repeated measures data with a scientifically defensible function that adequately summarizes both individual change as well as the average response. The module begins with a nontechnical overview of longitudinal data analyses drawing distinctions with cross-sectional analyses in terms of research questions to be addressed. Nuances of longitudinal designs, timing of measurements, and the real possibility of missing data are then discussed. The three interconnected components of the LME model—(1) a model for individual and mean response profiles, (2) a model to characterize the covariation among the time-specific residuals, and (3) a set of models that summarize the extent that individual coefficients vary—are discussed in the context of the set of activities comprising an analysis. Finally, they demonstrate how to estimate the linear mixed effects model within an open-source environment (R). The digital module contains sample R code, diagnostic quiz questions, hands-on activities in R, curated resources, and a glossary.  相似文献   
5.
6.
7.
从上个世纪80年代的海归到今时今日的“海待”.究竟是什么在其中引起了化学反应?海归怎么了.招谁惹谁了?现今人才市场.到底是国家政策不够有力,还是国内经济环境不够景气?是混日子的”海龟”太多太滥,还是企业过度地贬低了海归?且看看海归自己的看法——  相似文献   
8.
9.
10.
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