首页 | 官方网站   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   33828篇
  免费   397篇
  国内免费   15篇
文化教育   34240篇
  2022年   155篇
  2021年   259篇
  2020年   389篇
  2019年   611篇
  2018年   2911篇
  2017年   2815篇
  2016年   2245篇
  2015年   555篇
  2014年   774篇
  2013年   4528篇
  2012年   868篇
  2011年   1369篇
  2010年   1319篇
  2009年   907篇
  2008年   1172篇
  2007年   1627篇
  2006年   491篇
  2005年   791篇
  2004年   818篇
  2003年   719篇
  2002年   486篇
  2001年   479篇
  2000年   415篇
  1999年   363篇
  1998年   204篇
  1997年   223篇
  1996年   233篇
  1995年   218篇
  1994年   164篇
  1993年   181篇
  1992年   295篇
  1991年   278篇
  1990年   286篇
  1989年   279篇
  1988年   239篇
  1987年   285篇
  1986年   253篇
  1985年   291篇
  1984年   235篇
  1983年   198篇
  1982年   173篇
  1981年   155篇
  1980年   134篇
  1979年   241篇
  1978年   174篇
  1977年   152篇
  1976年   138篇
  1975年   130篇
  1974年   133篇
  1971年   119篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
1.
Research in Higher Education - Given the significant need to increase and diversify graduate enrollments within computing fields, it is vital to understand what shapes students’ pathways to...  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.
David Kaldewey 《Minerva》2018,56(2):161-182
This article analyzes the concept of “grand challenges” as part of a shift in how scientists and policymakers frame and communicate their respective agendas. The history of the grand challenges discourse helps to understand how identity work in science and science policy has been transformed in recent decades. Furthermore, the question is raised whether this discourse is only an indicator, or also a factor in this transformation. Building on conceptual history and historical semantics, the two parts of the article reconstruct two discursive shifts. First, the observation that in scientific communication references to “problems” are increasingly substituted by references to “challenges” indicates a broader cultural trend of how attitudes towards what is problematic have shifted in the last decades. Second, as the grand challenges discourse is rooted in the sphere of sports and competition, it introduces a specific new set of societal values and practices into the spheres of science and technology. The article concludes that this process can be characterized as the sportification of science, which contributes to self-mobilization and, ultimately, to self-optimization of the participating scientists, engineers, and policymakers.  相似文献   
4.
5.
Letters     
  相似文献   
6.
Editorial     
B. Sury 《Resonance》2018,23(7):723-725
  相似文献   
7.
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-23

京公网安备 11010802026262号