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   71536篇
  免费   939篇
  国内免费   176篇
教育   51320篇
科学研究   7490篇
各国文化   622篇
体育   4775篇
综合类   56篇
文化理论   870篇
信息传播   7518篇
  2021年   575篇
  2020年   952篇
  2019年   1435篇
  2018年   3758篇
  2017年   3718篇
  2016年   3172篇
  2015年   1179篇
  2014年   1635篇
  2013年   11825篇
  2012年   1698篇
  2011年   2210篇
  2010年   1954篇
  2009年   1563篇
  2008年   1866篇
  2007年   2259篇
  2006年   1185篇
  2005年   1426篇
  2004年   1376篇
  2003年   1270篇
  2002年   1083篇
  2001年   1070篇
  2000年   1014篇
  1999年   962篇
  1998年   555篇
  1997年   593篇
  1996年   694篇
  1995年   601篇
  1994年   537篇
  1993年   549篇
  1992年   804篇
  1991年   809篇
  1990年   833篇
  1989年   846篇
  1988年   731篇
  1987年   725篇
  1986年   726篇
  1985年   842篇
  1984年   713篇
  1983年   671篇
  1982年   604篇
  1981年   557篇
  1980年   519篇
  1979年   742篇
  1978年   611篇
  1977年   547篇
  1976年   483篇
  1975年   410篇
  1974年   448篇
  1973年   429篇
  1971年   394篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
1.
Working memory training improves children's cognitive performance on untrained tasks; however, little is known about the underlying neural mechanisms. This was investigated in 32 typically developing children aged 10–14 years (19 girls and 13 boys) using a randomized controlled design and multi-modal magnetic resonance imaging (Devon, UK; 2015–2016). Training improved working memory performance and increased intrinsic functional connectivity between the bilateral intraparietal sulci. Furthermore, improvements in working memory were associated with greater recruitment of the left middle frontal gyrus on a complex span task. Repeated engagement of fronto-parietal regions during training may increase their activity and functional connectivity over time, affording greater working memory performance. The plausibility of generalizable cognitive benefits from a neurobiological perspective and implications for neurodevelopmental theory are discussed.  相似文献   
2.
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   
3.
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   
4.
5.
Letters     
  相似文献   
6.
Editorial     
B. Sury 《Resonance》2018,23(7):723-725
  相似文献   
7.
Genetic variation in the angiotensin II type 1 receptor (AT1R) has an important effect on the outcome of acute coronary syndrome (ACS) initiated treatment with captopril. This study aims to investigate the impact of genetic polymorphism of AT1R (rs5186 and rs275651) on the ACS outcome in Iraqi patients treated with captopril. A total of 250 Iraqi individuals with ACS were included in this case—control study and they were divided into two study groups; Study group 1 included 125 participants who were prescribed captopril, 25 mg twice daily and study group 2 included 125 participants who received no captopril as part of their ACS treatment (control study). The AT1R gene (rs5186) CC genotype was found to be associated with ST-elevation myocardial infarction (STEMI) (Odd’s ratio (O.R) = 1.2, P = 0.7), while AC was associated with Non-ST-elevation myocardial infarction (NSTEMI) and unstable angina (UA) (O.R = 1.2, P = 0.8). AC genotype is more prone to have Percutaneous coronary intervention (PCI) after ACS attack (O.R = 1.2, P = 0.6). CC genotype had a risk to get less improvement (O.R = 1.6, P = 0.5), so might require higher doses of captopril during acute coronary insult. The AT1R gene (rs275651) AA genotype was associated with UA (O.R = 1.3, P = 0.9). AA and AT genotypes were more prone to have PCI after ACS attack (O.R = 3.9 P = 0.2, O.R = 3.5, P = 0.3 respectively) and thus requiring higher doses of captopril. We conclude that the AT1R rs5186, rs275651 genetic polymorphisms might partially affect the clinical outcome of ACS patients treated with captopril and might have captopril resistance which requires higher doses.  相似文献   
8.
ABSTRACT

For many forcefully displaced people worldwide, notions around one’s sense of “home” and “place” in the world are perpetually unsettled. This article explores how digital technologies interact with embodied, material experiences within the geographical location refugees are residing in. Empirical examples from ethnographic research conducted among Iraqi urban refugees, living in prolonged uncertainty in Jordan, shows how situated experiences of legal, material, and social uncertainty reinforce particular mediated socialities. Pivotal studies have shown how digital connections engender virtual home-making practices and a wide variety of connected presences. This study points to the other side of the same coin: the cultivation of “absent presence.” “Absent presence” refers to feelings—the ambivalence that experiences of prolonged displacement bring about—but also to active disengagement and affective tactics in response. These engender a further separation from the physical world where forced migrants are not deemed welcome.  相似文献   
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