全文获取类型
收费全文 | 1067篇 |
免费 | 16篇 |
专业分类
教育 | 736篇 |
科学研究 | 68篇 |
各国文化 | 25篇 |
体育 | 112篇 |
文化理论 | 8篇 |
信息传播 | 134篇 |
出版年
2023年 | 4篇 |
2022年 | 15篇 |
2021年 | 17篇 |
2020年 | 28篇 |
2019年 | 54篇 |
2018年 | 71篇 |
2017年 | 69篇 |
2016年 | 57篇 |
2015年 | 21篇 |
2014年 | 34篇 |
2013年 | 261篇 |
2012年 | 27篇 |
2011年 | 42篇 |
2010年 | 30篇 |
2009年 | 26篇 |
2008年 | 41篇 |
2007年 | 26篇 |
2006年 | 27篇 |
2005年 | 19篇 |
2004年 | 15篇 |
2003年 | 19篇 |
2002年 | 10篇 |
2001年 | 14篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 8篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 10篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 9篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1973年 | 3篇 |
1967年 | 2篇 |
1964年 | 1篇 |
1939年 | 1篇 |
1931年 | 1篇 |
1860年 | 2篇 |
排序方式: 共有1083条查询结果,搜索用时 31 毫秒
51.
Braided composite materials for the production of lightweight, high rigidity golf shafts 总被引:1,自引:1,他引:0
Braiding is not currently used in the production of golf shafts. The objective of this work was to develop, through a modelling
process consisting of altering lamina sequence, a golf shaft, using braided laminas, which would have mass, stiffness and
torque comparable to commercially available composite and steel shafts. A 2D conical braided composite model was previously
developed and validated to predict elastic constants of braided closed meshed structures. Energy methods were used to calculate
the stiffness and torque of shafts using prescribed industry approaches. Shaft mass was calculated based on geometry and density
of constitutent materials. Modelled shafts had both braided and unidirectional layers and compared favourably with or were
better than commercially available composite and steel shafts in terms of deflection force and twist angle; they had the same
weight as composite shafts but were much lighter than steel shafts. If these findings are verified, braided composites would
be a viable and effective approach to the design of future golf shafts. 相似文献
52.
Jason R. Sattizahn Daniel J. Lyons Carly Kontra Susan M. Fischer Sian L. Beilock 《Mind, Brain, and Education》2015,9(3):164-169
Student difficulties in science learning are frequently attributed to misconceptions about scientific concepts. We argue that domain‐general perceptual processes may also influence students' ability to learn and demonstrate mastery of difficult science concepts. Using the concept of center of gravity (CoG), we show how student difficulty in applying CoG to an object such as a baseball bat can be accounted for, at least in part, by general principles of perception (i.e., not exclusively physics‐based) that make perceiving the CoG of some objects more difficult than others. In particular, it is perceptually difficult to locate the CoG of objects with asymmetric‐extended properties. The basic perceptual features of objects must be taken into account when assessing students' classroom performance and developing effective science, technology, engineering, and mathematics (STEM) teaching methods. 相似文献
53.
This study employs issue ownership theory to examine the partisan dynamics surrounding the idea of American exceptionalism in presidential discourse. We conducted a content analysis of invocations of American exceptionalism in all major U.S. presidential addresses—domestic and foreign—from the end of World War II through Trump’s 1st year in office. We find that even though Republicans have traditionally claimed ownership of American exceptionalism, patterns in presidential discourse tell a very different story. Specifically, our results show (a) in domestic contexts, Republican and Democratic presidents were very similar in their invocations of American exceptionalism during the Cold War but that Democrats have held a substantial advantage over Republicans throughout the post–Cold War era, including on issue areas that Republicans are perceived to “own” (e.g. national security); (b) in foreign contexts, Democrats have been much more outspoken in their embrace of American exceptionalism throughout both the Cold War and post–Cold War; and (c) President Trump has diverged significantly, both in substance and frequency, from his Democratic and Republican predecessors in his invocation of American exceptionalism. We reflect on the implications of these findings on our broader understanding of issue—and trait—ownership, presidential discourse, and American exceptionalism in American politics. 相似文献
54.
Homemade PowerPoint games are a low-tech alternative for using game design in classrooms. To date, much of the research examining the games has not shown an improvement in performance. This has led some to question whether the games are properly aligned with the instructional strategies researchers have used as justifications to support using them. This study examined how increasing the structure of the game design project affected student performance when compared to control groups, as well as those who created games in previous iterations of the study. In addition, we examined the effects of student performance when two of the instructional strategies (microtheme writing and question writing) were tested in isolation. Most of the comparisons showed no statistical difference in performance; however, results from the final iteration yielded significant gains when compared to the control group. 相似文献
55.
The effect of technology-enhanced learning (TEL) strategies in higher education has arguably been transformative despite the not-insignificant barriers existing in this context. Throughout the discourse very little attention has been paid to those primarily responsible for this implementation—academic teaching staff. This paper aims to highlight the impact of academic workload allocations, an often silent barrier to the uptake of TEL strategies in higher education. We will discuss the effects of academic identity and culture, preferential time allocation to associative activities, academic technological capacity, university policies and workload and funding models on the uptake, and implementation on TEL in higher education. Our aim is to highlight the risks to staff, students and institutions should these concerns not be addressed and to propose a model for utilisation by all staff responsible for implementing flexible workload models supportive of further implementation of TEL strategies across the sector. 相似文献
56.
57.
Fu-Ming Chen Jason Sheng-Hong Tsai Ying-Ting Liao Shu-Mei Guo Ming-Chung Ho Fu-Zen Shaw Leang-San Shieh 《Journal of The Franklin Institute》2014
An improvement on the transient response of tracking for the sampled-data system based on an improved PD-type iterative learning control (ILC) is proposed in this paper. The developed analog ILC method and the high-gain property tracker design methodology are first combined to significantly reduce learning epochs and overcome the initial condition shift problem and discontinuous reference input in the traditional ILC. Besides, the proposed ILC improves the transient response and decreases the rate of weighting matrices Q to R under the traditional linear quadratic tracker design. First, the off-line observer/Kalman filter identification (OKID) is used to determine the appropriate (low-) order system parameters and state estimator for the physical system with unknown system equation, so that the model-based PD-type ILC can be implemented for practical applications. Then, to improve the transient response and decrease the control effort, the proportional difference type (PD-type) ILC algorithm is combined with the high-gain property linear quadratic tracker (LQT) design to construct the high performance tracker for the model-based sampled-data systems. Furthermore, the discrete-time version high performance tracker design for the unknown stochastic sampled-data system via the iterative learning control method is proposed in this paper based on the Euler method and the digital redesign approach. Finally, some examples are given for illustrating the effectiveness of the proposed method. 相似文献
58.
Tony Bennett 《Cultural Trends》2006,15(2-3):193-212
The literature on cultural capital has had relatively little to say about television viewing, except insofar as television has served as a negative point of reference in relation to which other cultural practices register their distinctiveness. This article, by contrast, examines the respects in which practices of distinction are operative within the space of broadcast television. Looking first at the ‘internal economy’ of television as expressed in the relations between genre, programme and channel preferences, it then examines how these preferences are related to occupational class, gender, level of education and ethnicity. While showing that divisions within the space of broadcasting are most powerfully articulated in terms of age and gender, the article also shows that occupational class and level of education play important roles in stratifying television audiences along traditional ‘high’/‘low’ lines. A closer analysis of the relations between these variables reveals more complex patterns of distinction, particularly in the place occupied by ‘new drama’ and ‘new comedy’ in the preferences of younger, well-educated viewers. 相似文献
59.
The purpose of this article is to enumerate a series of security steps that might be taken by those researchers or organizations that are contemplating web-based tests and performance assessments. From a security viewpoint, much of what goes on with web-based transactions is similar to other general computer activity, but the recommendations here focus on what can be done to avoid the loss, compromising, or modification of data collected by or stored through the Internet. 相似文献
60.
Kenneth R. Pugh W. Einar Mencl Annette R. Jenner Jun Ren Lee Leonard Katz Stephen J. Frost Sally E. Shaywitz Bennett A. Shaywitz 《Learning disabilities research & practice》2001,16(4):240-249
Converging evidence from a number of neuroimaging studies, including our own, suggest that fluent word identification in reading is related to the functional integrity of two left hemisphere posterior systems: a temporo-parietal system and a ventral occipito-temporal system. These posterior systems are functionally disrupted in developmental dyslexia. Reading disabled, relative to nonimpaired, readers demonstrate heightened reliance on both inferior frontal and right hemisphere posterior regions, presumably in compensation for the LH posterior difficulties. We propose a neurobiological account suggesting that for normally developing readers the temporo-parietal system predominates at first, and is associated with aspects of processing critical in learning to integrate orthography with phonological and lexical-semantic features of printed words. The occipito-temporal system, by contrast, constitutes a fast, late-developing, word-identification system that underlies fluent word recognition in skilled readers. 相似文献