全文获取类型
收费全文 | 24258篇 |
免费 | 376篇 |
国内免费 | 60篇 |
专业分类
教育 | 17871篇 |
科学研究 | 1638篇 |
各国文化 | 323篇 |
体育 | 1807篇 |
综合类 | 47篇 |
文化理论 | 202篇 |
信息传播 | 2806篇 |
出版年
2022年 | 145篇 |
2021年 | 245篇 |
2020年 | 371篇 |
2019年 | 543篇 |
2018年 | 766篇 |
2017年 | 802篇 |
2016年 | 758篇 |
2015年 | 527篇 |
2014年 | 669篇 |
2013年 | 4986篇 |
2012年 | 651篇 |
2011年 | 668篇 |
2010年 | 593篇 |
2009年 | 558篇 |
2008年 | 657篇 |
2007年 | 579篇 |
2006年 | 597篇 |
2005年 | 536篇 |
2004年 | 384篇 |
2003年 | 418篇 |
2002年 | 372篇 |
2001年 | 488篇 |
2000年 | 392篇 |
1999年 | 350篇 |
1998年 | 252篇 |
1997年 | 253篇 |
1996年 | 272篇 |
1995年 | 252篇 |
1994年 | 255篇 |
1993年 | 219篇 |
1992年 | 309篇 |
1991年 | 300篇 |
1990年 | 326篇 |
1989年 | 295篇 |
1988年 | 249篇 |
1987年 | 247篇 |
1986年 | 249篇 |
1985年 | 244篇 |
1984年 | 236篇 |
1983年 | 236篇 |
1982年 | 202篇 |
1981年 | 206篇 |
1980年 | 212篇 |
1979年 | 256篇 |
1978年 | 212篇 |
1977年 | 152篇 |
1976年 | 167篇 |
1975年 | 151篇 |
1974年 | 134篇 |
1971年 | 141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.
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
3.
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.
Javier Horcajo David Santos Joshua J. Guyer Rafael Mateos 《Journal of sports sciences》2020,38(19):2242-2252
ABSTRACT To better understand doping-related attitude change, it is important to consider not only the amount of thinking (i.e., elaboration) done by message recipients, but also the favourability of their thoughts in response to the proposal, as well as the perceived validity in their thoughts. The main goal of the present study was to analyse the effects of a meta-cognitive process (i.e., thought validation) on attitudes related to doping. Thus, we randomly assigned participants to read a message either against or in favour of legalising several doping behaviours. Participants listed their thoughts regarding the proposal and indicated the perceived validity in their thoughts, then reported their attitudes. As hypothesised, the message against legalisation elicited more unfavourable thoughts and attitudes than the message in favour of legalisation. Most relevantly, the effects of the message direction on attitudes were greater for participants with higher (vs. lower) levels of thought validity. Furthermore, consistent with the thought validation process, results revealed that thought favourability was a better predictor of attitudes for participants with higher (vs. lower) perceived thought validity, indicating that perceiving one’s thoughts as valid plays an important role in persuasion. These findings provide novel insights for research and interventions regarding doping in sports. 相似文献
7.
David C. Berliner 《Journal of Personnel Evaluation in Education》1990,4(1):75-90
8.
Measuring Search Engine Quality 总被引:12,自引:3,他引:9
The effectiveness of twenty public search engines is evaluated using TREC-inspired methods and a set of 54 queries taken from real Web search logs. The World Wide Web is taken as the test collection and a combination of crawler and text retrieval system is evaluated. The engines are compared on a range of measures derivable from binary relevance judgments of the first seven live results returned. Statistical testing reveals a significant difference between engines and high intercorrelations between measures. Surprisingly, given the dynamic nature of the Web and the time elapsed, there is also a high correlation between results of this study and a previous study by Gordon and Pathak. For nearly all engines, there is a gradual decline in precision at increasing cutoff after some initial fluctuation. Performance of the engines as a group is found to be inferior to the group of participants in the TREC-8 Large Web task, although the best engines approach the median of those systems. Shortcomings of current Web search evaluation methodology are identified and recommendations are made for future improvements. In particular, the present study and its predecessors deal with queries which are assumed to derive from a need to find a selection of documents relevant to a topic. By contrast, real Web search reflects a range of other information need types which require different judging and different measures. 相似文献
9.
David Pearson 《Health information and libraries journal》2001,18(3):139-143
This paper addresses the need to recognize the importance, and the challenges, of preserving the hugely expanding record of medicine today for historians of the future. We are faced not only with an increase in traditional publishing formats, but also with the rapid growth in electronic communications. Two celebrated medical cases, one from the late seventeenth century and one from the late twentieth, are used to illustrate the differences and the difficulties. The need for active and effective professional collaboration is stressed; libraries should work together to address these issues. 相似文献
10.