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   674篇
  免费   4篇
  国内免费   2篇
教育   464篇
科学研究   74篇
各国文化   4篇
体育   54篇
文化理论   13篇
信息传播   71篇
  2020年   5篇
  2019年   7篇
  2018年   14篇
  2017年   12篇
  2016年   17篇
  2014年   7篇
  2013年   216篇
  2012年   10篇
  2011年   11篇
  2010年   13篇
  2009年   15篇
  2008年   15篇
  2007年   13篇
  2005年   10篇
  2003年   11篇
  2002年   6篇
  2001年   8篇
  2000年   12篇
  1999年   10篇
  1998年   9篇
  1997年   10篇
  1996年   5篇
  1995年   4篇
  1993年   6篇
  1992年   9篇
  1991年   5篇
  1990年   5篇
  1989年   4篇
  1988年   10篇
  1987年   12篇
  1986年   12篇
  1985年   7篇
  1984年   6篇
  1983年   8篇
  1982年   11篇
  1981年   4篇
  1980年   7篇
  1979年   5篇
  1977年   6篇
  1975年   8篇
  1974年   6篇
  1973年   6篇
  1971年   4篇
  1970年   6篇
  1969年   7篇
  1968年   4篇
  1927年   3篇
  1925年   5篇
  1924年   5篇
  1912年   3篇
排序方式: 共有680条查询结果,搜索用时 15 毫秒
61.
62.
Some sort of reportorial process is necessary for evaluation of undergraduate laboratory work. A variety of methods currently employed are not entirely satisfactory. Ideally, such a process should accomplish its purpose with a minimum expenditure of time and effort and, wherever possible, enhance the educational efficiency of the laboratory. Under certain conditions, verbal communication may be employed to these ends. In addition to more efficient use of time, other results include: more accurate evaluation, increased effectiveness of laboratory problems as teaching devices, and useful training in the use of verbal communication. In other terms, the communication channel between instructor and student may be given greater capacity, less noise, and changed more nearly into a closed loop.  相似文献   
63.
64.
65.
This paper examines how the role of patents and utility models in innovation and economic growth varies by level of economic development. Using a panel dataset of over 70 countries, we find that patent protection is an important determinant of innovation and that patentable innovations contribute to economic growth in developed countries, but not in developing. Instead, in developing economies, a minor form of intellectual property rights (IPRs) - namely utility models - is conducive to innovation and growth, controlling for other factors. Using Korean firm level data as a case study, we find that utility model innovations contribute to firm performance when firms are technologically lagging and that those minor innovations can be a learning device and thus a stepping stone for developing more patentable inventions later on. Upon reaching higher levels of technological capabilities, firms become more reliant upon patents and less on utility models. Thus the lesson here is that patent protection enhances innovation and economic growth in countries where the capacity to conduct innovative research exists. Where this capacity is weaker, a system that provides incentives to conduct minor, incremental inventions is more conducive to growth. The significance of this paper is to emphasize the importance not just of the strength of IPRs but of the appropriate type of IPRs for economic development.  相似文献   
66.
67.
Because random assignment is not possible in observational studies, estimates of treatment effects might be biased due to selection on observable and unobservable variables. To strengthen causal inference in longitudinal observational studies of multiple treatments, we present 4 latent growth models for propensity score matched groups, and evaluate their performance with a Monte Carlo simulation study. We found that the 4 models performed similarly with respect to model fit, bias of parameter estimates, Type I error, and power to test the treatment effect. To demonstrate a multigroup latent growth model with dummy treatment indicators, we estimated the effect of students changing schools during elementary school years on their reading and mathematics achievement, using data from the Early Childhood Longitudinal Study Kindergarten Cohort.  相似文献   
68.
Assistant teachers are a ubiquitous yet virtually overlooked part of the early education workforce. Assistant teacher education level and its relationship to various classroom characteristics and the roles lead teachers feel assistants play in classroom management and teaching were examined in a nationally representative sample of 3,191 state-funded prekindergarten classes. Research Findings: Most classrooms had at least 1 paid assistant teacher, and classrooms with multiple assistants were more likely to be in Head Start. Lead teachers in public schools were more likely to have a bachelor's degree or higher, to be paired with an assistant with a high school degree, and to report fewer release hours for planning (alone or shared with assistants) than teachers in Head Start. Hierarchical multiple regression indicated that assistant teachers were rated as most useful to teaching duties when the classroom was in a Head Start setting, when the discrepancy between the lead and assistant teachers’ education was smaller, and when there were more shared release hours for planning. Practice and Policy: Implications focus on future prekindergarten teacher workforce needs, the need for more shared planning time and guidance in its use, and the need for more attention to and support for the training and roles of assistant teachers.  相似文献   
69.
70.
Eccentric exercise has been associated with an increase in serial sarcomere number in some studies,1 but not in others.2 Similarly,increasing excursion of muscles resulted in sarcomerogenesis in some studies using growing animals,3 but not in others using skeletally mature animals.4 However,chronic elongation and chronic shortening appears to be a strong regulator of sarcomere number increase5,6 and decrease,5,7 respectively,in animal models.Despite an abundance of research on the regulation of sarcomerogenesis under a variety of conditions,the mechanisms underlying in series sarcomere number adaptations in skeletal muscles remain a puzzle,especially in non-invasive human studies where measurements of sarcomerogenesis following interventions have not been possible to date.  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