全文获取类型
收费全文 | 1166篇 |
免费 | 30篇 |
国内免费 | 1篇 |
专业分类
教育 | 760篇 |
科学研究 | 111篇 |
各国文化 | 22篇 |
体育 | 169篇 |
综合类 | 1篇 |
文化理论 | 15篇 |
信息传播 | 119篇 |
出版年
2023年 | 12篇 |
2022年 | 15篇 |
2021年 | 27篇 |
2020年 | 38篇 |
2019年 | 61篇 |
2018年 | 87篇 |
2017年 | 85篇 |
2016年 | 82篇 |
2015年 | 42篇 |
2014年 | 42篇 |
2013年 | 242篇 |
2012年 | 45篇 |
2011年 | 36篇 |
2010年 | 36篇 |
2009年 | 27篇 |
2008年 | 45篇 |
2007年 | 25篇 |
2006年 | 18篇 |
2005年 | 22篇 |
2004年 | 19篇 |
2003年 | 12篇 |
2002年 | 11篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1973年 | 4篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1910年 | 2篇 |
1895年 | 2篇 |
1866年 | 2篇 |
排序方式: 共有1197条查询结果,搜索用时 187 毫秒
61.
We analyze the impact of exercising sports during childhood and adolescence on educational attainment. The theoretical framework is based on models of allocation of time and educational productivity. Using the rich information from the German Socio-Economic Panel (GSOEP), we apply generalized ordered probit models to estimate the effect of participation in sport activities on secondary school degrees and professional degrees. Even after controlling for important variables and selection into sport, we find strong evidence that the effect of sport on educational attainment is statistically significant and positive. 相似文献
62.
63.
Elke Achtert Christian B?hm Peer Kr?ger Peter Kunath Alexey Pryakhin Matthias Renz 《Informatik - Forschung und Entwicklung》2007,15(3):179-195
The reverse k-nearest neighbor (RkNN) problem, i.e. finding all objects in a data set the k-nearest
neighbors of which include a specified query object, has received increasing attention recently. Many
industrial and scientific applications call for solutions of the RkNN problem in arbitrary metric spaces
where the data objects are not Euclidean and only a metric distance function is given for specifying
object similarity. Usually, these applications need a solution for the generalized problem where the
value of k is not known in advance and may change from query to query. In addition, many applications
require a fast approximate answer of RkNN-queries. For these scenarios, it is important to generate
a fast answer with high recall. In this paper, we propose the first approach for efficient approximative
RkNN search in arbitrary metric spaces where the value of k is specified at query time. Our approach
uses the advantages of existing metric index structures but proposes to use an approximation of the
nearest-neighbor-distances in order to prune the search space. We show that our method scales significantly
better than existing non-approximative approaches while producing an approximation of the true query
result with a high recall. 相似文献
64.
65.
66.
67.
Takei Y Dunn JH Blucker E 《Sports biomechanics / International Society of Biomechanics in Sports》2003,2(2):141-162
The 16 highest-scored Roche vaults (G1) performed during the 2000 Olympic Games were compared with those receiving the 16 lowest-scores (G2). A 16-mm motion picture camera operating at 100 Hz recorded the vaults during the competition. The results of t tests (p < .05) indicated G1, compared to G2, had (a) shorter time of board support, greater normalised average upward vertical force and backward horizontal force exerted by the board, greater change in the vertical velocity while on the board, and greater vertical velocity at board take-off, (b) comparable linear and angular motions in pre-flight, (c) smaller backward horizontal impulse exerted by the horse, smaller loss of the horizontal velocity while on the horse, and greater horizontal and vertical velocities at horse take-off, (d) greater height and larger horizontal distance of post-flight, (e) higher body mass centre at knee release, and (f) higher mass centre, greater normalised moment of inertia, and smaller vertical velocity at mat touchdown. Therefore, gymnasts and coaches should focus on sprinting the approach; blocking and pushing-off the take-off board rapidly and vigorously; departing the board with a large vertical velocity; exerting large downward vertical force and small forward horizontal force from the hand-stand position while on the horse; departing the horse with large horizontal and vertical velocities; and completing the majority of the double salto forward near the peak of trajectory and releasing the knees above the top of the horse to prepare for a controlled landing. 相似文献
68.
69.
70.
R J Markert A J Parisi H V Barnes S Cohen K Goldenberg L E Mieczkowski M Dunn R M Siervogel 《Bulletin of the Medical Library Association》1989,77(2):133-138
The experiences of medical students, residents, and faculty with a computerized literature searching system were evaluated. Third-year medical students, internal medicine and family practice residents, and full-time and voluntary faculty at one medical school had the opportunity to use a full-text and bibliographic medical literature retrieval system free of charge for an eleven-month period. Subjects conducted nearly nine thousand literature searches over a period of 942 system hours. Questionnaire data showed that participants could learn to use and would use an electronic information system, felt capable of using the system, utilized the system for a variety of purposes and in a number of different ways, and viewed the system as a valuable tool in searching the medical literature. The results are discussed in the context of the educational needs of the four user-groups and medical education planning by institutions. 相似文献