全文获取类型
收费全文 | 21359篇 |
免费 | 349篇 |
国内免费 | 123篇 |
专业分类
教育 | 14797篇 |
科学研究 | 2239篇 |
各国文化 | 190篇 |
体育 | 1478篇 |
综合类 | 302篇 |
文化理论 | 103篇 |
信息传播 | 2722篇 |
出版年
2022年 | 143篇 |
2021年 | 330篇 |
2020年 | 331篇 |
2019年 | 390篇 |
2018年 | 556篇 |
2017年 | 607篇 |
2016年 | 566篇 |
2015年 | 499篇 |
2014年 | 692篇 |
2013年 | 3612篇 |
2012年 | 811篇 |
2011年 | 844篇 |
2010年 | 799篇 |
2009年 | 742篇 |
2008年 | 788篇 |
2007年 | 816篇 |
2006年 | 787篇 |
2005年 | 684篇 |
2004年 | 396篇 |
2003年 | 411篇 |
2002年 | 379篇 |
2001年 | 489篇 |
2000年 | 377篇 |
1999年 | 341篇 |
1998年 | 229篇 |
1997年 | 198篇 |
1996年 | 199篇 |
1995年 | 170篇 |
1994年 | 183篇 |
1993年 | 132篇 |
1992年 | 210篇 |
1991年 | 201篇 |
1990年 | 238篇 |
1989年 | 203篇 |
1988年 | 170篇 |
1987年 | 169篇 |
1986年 | 173篇 |
1985年 | 168篇 |
1984年 | 163篇 |
1983年 | 146篇 |
1982年 | 113篇 |
1981年 | 123篇 |
1980年 | 116篇 |
1979年 | 170篇 |
1978年 | 142篇 |
1977年 | 97篇 |
1976年 | 108篇 |
1975年 | 101篇 |
1973年 | 97篇 |
1971年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 15 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.
[目的/意义]研究时间因素对专利被引频次的影响,可以减少时间因素对技术评价活动的制约,提高评价的准确性和可信度。[方法/过程]采集1975-2017年的美国专利数据,开展基于固定效应法的专利被引频次的修正研究。将专利按照不同公开年份和不同技术领域分组,选定组内均值和6个TOP分位数为被引频次基准,统计当前时间点的被引频次基准线及基准线的历史时序变化情况。建立神经网络模型,拟合基准线的时序变化规律,并预测未来统计时间点的基准线。[结果/结论]专利公开年份和统计年份的时间差异,使得专利被引频次无法直接进行比较。本文建立了基于不同技术领域、不同公开年份和不同统计年份的专利被引频次基准线,为专利评估提供参考。 相似文献
3.
David Sánchez-Oliva Rebecca M. Leech Alberto Grao-Cruces Irene Esteban-Cornejo Carmen Padilla-Moledo Oscar L. Veiga 《Journal of sports sciences》2020,38(9):1062-1069
ABSTRACTThe 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.
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.
罗华颖 《六盘水师范高等专科学校学报》2003,15(3):61-62
对钢琴音乐的审美价值与钢琴教学之间的关系进行了阐述,提出了教学实践中如何通过审美活动培养学生的方法。 相似文献
7.
古典式摔跤跪撑技术的趋向 总被引:4,自引:0,他引:4
对 2 0 0 0年全国古典式摔跤锦标赛跪撑技术进行统计 ,分析古典式摔跤跪撑技术的发展趋向 ,结果显示 :使用跪撑技术成功与否是获得古典式摔跤比赛胜利的关键 ,而在跪撑技术的使用中又侧重于滚桥和提抱这两种跪撑技术动作。 相似文献
8.
9.
10.
21世纪初我国体育健身消费市场的形成与可持续发展 总被引:18,自引:2,他引:16
采用文献资料研究方法,对21世纪初我国体育健身消费市场的形成与可持续发展等问题,进行了论述。认为,国家政策的扶植、生活消费水平的提高、体育健身消费的功能等因素,是促进现阶段我国体育健身消费市场形成的有利条件;提出了有利于我国体育健身消费市场可持续发展的对策。 相似文献