全文获取类型
收费全文 | 832篇 |
免费 | 32篇 |
国内免费 | 1篇 |
专业分类
教育 | 607篇 |
科学研究 | 39篇 |
各国文化 | 52篇 |
体育 | 59篇 |
文化理论 | 4篇 |
信息传播 | 104篇 |
出版年
2023年 | 9篇 |
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 21篇 |
2019年 | 22篇 |
2018年 | 23篇 |
2017年 | 46篇 |
2016年 | 31篇 |
2015年 | 31篇 |
2014年 | 30篇 |
2013年 | 169篇 |
2012年 | 26篇 |
2011年 | 21篇 |
2010年 | 17篇 |
2009年 | 28篇 |
2008年 | 24篇 |
2007年 | 24篇 |
2006年 | 14篇 |
2005年 | 27篇 |
2004年 | 28篇 |
2003年 | 17篇 |
2002年 | 17篇 |
2001年 | 14篇 |
2000年 | 21篇 |
1999年 | 18篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1983年 | 4篇 |
1980年 | 3篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1975年 | 6篇 |
1973年 | 4篇 |
1971年 | 3篇 |
1946年 | 3篇 |
1943年 | 4篇 |
1933年 | 3篇 |
1929年 | 3篇 |
1928年 | 3篇 |
排序方式: 共有865条查询结果,搜索用时 15 毫秒
51.
52.
G. Welch R. Purves D. Hargreaves N. Marshall 《British Educational Research Journal》2011,37(2):285-315
The article reports an Economic and Social Research Council‐funded study of the early career experiences of secondary school music teachers in England, set within a wider national picture of decreasing age‐related pupil engagement with school music, career perceptions of music teaching, variable patterns of teacher recruitment and possible mismatches between the musical biographies of young people and intending music teachers. Qualitative and quantitative data were collected from a short‐term longitudinal survey (first questionnaire: n = 74, second questionnaire: n = 29), supplemented by case studies (n = 6) and open‐ended, written questions (n = 20). Analyses suggest that only a half of the newly qualified participants chose to teach full‐time in a mainstream, state‐funded school music classroom. Of these, the majority were faced with a range of early career challenges stemming from curricular, extra‐curricular and non‐curricular school expectations. These included the need to balance their existing musical performer identity with that of being a new teacher. 相似文献
53.
This study uses longitudinal data from the UK Millennium Cohort Study to show the extent to which episodic and more persistent poverty in early childhood and the lack of other family resources disadvantage children at the start of their school careers in terms of whether they have achieved the target indicator of ‘good level of achievement’ on the Foundation Stage Profile. Positive parenting is shown to be an important contributor to school achievement that matters for children, regardless of poverty experience or family disadvantage. It is also shown to be an important mediator in redressing the effects of poverty and disadvantage. 相似文献
54.
Robert B. Anderson Julius A. Marshall Andrea L’Afflitto 《Journal of The Franklin Institute》2021,358(12):6281-6308
In classical model reference adaptive control (MRAC), the adaptive rates must be tuned to meet multiple competing objectives. Large adaptive rates guarantee rapid convergence of the trajectory tracking error to zero. However, large adaptive rates may also induce saturation of the actuators and excessive overshoots of the closed-loop system’s trajectory tracking error. Conversely, low adaptive rates may produce unsatisfactory trajectory tracking performances. To overcome these limitations, in the classical MRAC framework, the adaptive rates must be tuned through an iterative process. Alternative approaches require to modify the plant’s reference model or the reference command input. This paper presents the first MRAC laws for nonlinear dynamical systems affected by matched and parametric uncertainties that constrain both the closed-loop system’s trajectory tracking error and the control input at all times within user-defined bounds, and enforce a user-defined rate of convergence on the trajectory tracking error. By applying the proposed MRAC laws, the adaptive rates can be set arbitrarily large and both the plant’s reference model and the reference command input can be chosen arbitrarily. The user-defined rate of convergence of the closed-loop plant’s trajectory is enforced by introducing a user-defined auxiliary reference model, which converges to the trajectory tracking error obtained by applying the classical MRAC laws before its transient dynamics has decayed, and steering the trajectory tracking error to the auxiliary reference model at a rate of convergence that is higher than the rate of convergence of the plant’s reference model. The ability of the proposed MRAC laws to prescribe the performance of the closed-loop system’s trajectory tracking error and control input is guaranteed by barrier Lyapunov functions. Numerical simulations illustrate both the applicability of our theoretical results and their effectiveness compared to other techniques such as prescribed performance control, which allows to constrain both the rate of convergence and the maximum overshoot on the trajectory tracking error of uncertain systems. 相似文献
55.
56.
Fiona MURPHY 《Learned Publishing》2014,27(5):S3-S7
This article sets the scene for the special issue on research data and publishing. Research data – that material commonly accepted by the scholarly community as required evidence for hypotheses and insights, for verification and/or reproducibility of experiments – has become an increasingly critical issue for publishers given recent developments in funders' mandates, technological advances, policymakers' interests, and so forth. I outline some of the recent initiatives that are responding to policy directives, particularly Project ODE, and consider how publishers are working with data and integrating their practices with other collaborative efforts. A summary of the new policies, products, and partnerships demonstrates that the onus is now with scholarly publishers to gain an understanding of these developments and how they are affecting fellow key stakeholders within the research communications ecosystem. 相似文献
57.
58.
59.
60.