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   37061篇
  免费   588篇
  国内免费   630篇
教育   25834篇
科学研究   4517篇
各国文化   158篇
体育   3457篇
综合类   1233篇
文化理论   174篇
信息传播   2906篇
  2022年   288篇
  2021年   544篇
  2020年   626篇
  2019年   693篇
  2018年   794篇
  2017年   771篇
  2016年   759篇
  2015年   880篇
  2014年   1336篇
  2013年   4861篇
  2012年   1572篇
  2011年   1789篇
  2010年   1687篇
  2009年   1634篇
  2008年   1768篇
  2007年   1636篇
  2006年   1552篇
  2005年   1334篇
  2004年   1171篇
  2003年   901篇
  2002年   831篇
  2001年   807篇
  2000年   630篇
  1999年   451篇
  1998年   221篇
  1997年   255篇
  1996年   265篇
  1995年   232篇
  1994年   199篇
  1993年   188篇
  1992年   329篇
  1991年   298篇
  1990年   314篇
  1989年   350篇
  1988年   285篇
  1987年   292篇
  1986年   289篇
  1985年   313篇
  1984年   267篇
  1983年   277篇
  1982年   211篇
  1981年   199篇
  1980年   181篇
  1979年   311篇
  1978年   221篇
  1977年   220篇
  1976年   165篇
  1975年   161篇
  1974年   185篇
  1973年   166篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
武术与民族传统体育学科建设目标、困境及出路   总被引:1,自引:0,他引:1  
武术与民族传统体育学作为一门学科尚显稚嫩,其突出表现是学科知识缺乏独立性。综合运用文献资料、归纳演绎、比较分析等研究方法,沿着目标→困境→出路的逻辑线路,对武术与民族传统体育学学科建设问题展开深入探讨。主要观点:1)特色鲜明乃武术与民族传统体育学学科建设的目标,该目标达成所倚赖之原动力是实践内容的相对独立;2)边界模糊是阻碍武术与民族传统体育学学科建设保持特色鲜明、走向成熟的重要理论致因;3)反求诸己是武术与民族传统体育学学科建设打破边界模糊困境、实现特色鲜明目标的出路。如此,武术与民族传统体育学方能因获得独立性而有成长壮大之可能,才有希望摆脱学科依附阴影,乃至问鼎显学的地位。  相似文献   
3.
4.
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   
5.
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   
6.
针对多旋翼无人机目标的识别问题,提出一种基于伽柏(Gabor)变换的瞬时频率估计与快速傅里叶变换(FFT)相结合的微多普勒特征提取算法。首先建立多旋翼无人机旋翼回波模型,并通过仿真分析叶片数目、旋翼转速和初始相位等参数对微多普勒特征的影响,利用Gabor变换得到时频特征。在此基础上通过瞬时频率极大值法提取微多普勒频率,并对瞬时频率采用FFT提取旋翼数和转动频率,从而获得叶片长度估计值。实测数据验证了该算法较为准确地提取无人机的微多普勒参数。  相似文献   
7.
ABSTRACT

This forum brings together food, (in)security, and communication. The authors participating in this forum center communication as both process and tool for understanding, mitigating, and making meaning of food (in)security. The nine authors together discuss the role of communication in food (in)security, the central challenges for scholars and practitioners working on food (in)security, and the creative possibilities and impacts influencing the future of food (in)security. The forum produces a call for applied scholars to re-imagine communication frameworks in order to make meaningful differences in their communities.  相似文献   
8.
体育是“一带一路”倡议人文交流的重要依托,体育赛事对实现民心相通发挥积极作用。英联邦运动会的长期举办推动了英联邦国家的整体发展,是体育赛事交流的典型案例。通过对英联邦运动会与“一带一路”体育赛事的对比,分析其对“一带一路”体育赛事的借鉴作用,并探讨“一带一路”体育赛事交流的构想与策略。认为:开展“一带一路”体育赛事交流应建立“一带一路”体育组织,组建相应的工作机构,举办“一带一路”国家运动会;构建“多边体育合作机制”,不断扩大“一带一路”体育赛事的覆盖面,重视赛事风险并避免负面影响,鼓励、支持多国举办“一带一路”体育赛事。  相似文献   
9.
我国现阶段乡村农民体育观念的调查与研究   总被引:8,自引:0,他引:8  
采用文献研究、下乡访谈、问卷调查、数理统计、多因素分析等方法,以我国20个省、区、市部分农民(户)为研究对象,对他们参与全民健身、享受体育的现状进行调查,力求探索出一条以城市带动乡村来提高我国整体体育人口比例的道路。研究结果显示:我国9亿农民在富民政策指引下,92%基本解决“温饱”问题。“温饱”之后思什么?农民是否愿意在自己农闲时间中给体育留有一席之地?他们对健康的渴求、精神的愉悦、消费的倾向如何?需要全社会来引导与关注。  相似文献   
10.
CBA联赛中三人制与二人制裁判错漏判的比较   总被引:1,自引:0,他引:1  
为了使我国篮球运动的发展和国际接轨,促使篮球运动技术、战术水平的正常发挥,保证比赛的健康发展,2000年我国男子CBA比赛中首次实行了三人制裁判。本文通过对我国CBA比赛几个赛季几十场比赛的两种裁判制的全面比较分析,为在全国推广和提高我国裁判水平提供理论和实践依据。  相似文献   
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