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   529篇
  免费   2篇
教育   376篇
科学研究   34篇
各国文化   12篇
体育   57篇
信息传播   52篇
  2021年   5篇
  2020年   11篇
  2019年   13篇
  2018年   20篇
  2017年   18篇
  2016年   16篇
  2015年   6篇
  2014年   14篇
  2013年   146篇
  2012年   12篇
  2011年   9篇
  2010年   5篇
  2009年   6篇
  2008年   9篇
  2007年   7篇
  2006年   11篇
  2005年   10篇
  2004年   5篇
  2003年   7篇
  2002年   7篇
  2001年   5篇
  2000年   4篇
  1999年   4篇
  1998年   5篇
  1997年   5篇
  1996年   8篇
  1995年   8篇
  1994年   6篇
  1993年   5篇
  1992年   7篇
  1991年   11篇
  1990年   6篇
  1989年   7篇
  1988年   6篇
  1987年   6篇
  1986年   3篇
  1985年   8篇
  1984年   9篇
  1983年   5篇
  1979年   10篇
  1978年   5篇
  1977年   4篇
  1976年   6篇
  1974年   3篇
  1973年   4篇
  1970年   3篇
  1960年   2篇
  1935年   2篇
  1897年   2篇
  1868年   5篇
排序方式: 共有531条查询结果,搜索用时 312 毫秒
21.
22.
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   
23.
24.
25.
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   
26.
In the Australian context, children living in disadvantaged circumstances, whose second language is English, are one of the groups at risk of failing in mathematics. This paper explores the impact purposely developed learning activities (Representations, Oral Language and Engagement in Mathematics Learning activities) have on pupils' mathematics outcomes in the first three years of formal schooling (Foundation, Year 1 and Year 2). The participating group (n = 461) comprised 328 English language learners and 133 mainstream pupils. To ascertain the impact of the learning experience, pre- and post-tests were conducted at the commencement and completion of each school year. The results indicate that all of the children significantly improved, with English as a second language pupils showing the greatest gains, and achieving norm-referenced expectations for their age.  相似文献   
27.
28.
29.
If T maps a convex domain DT into itself, and if {ωn} is a real sequence with range in (0, 1] then the recursive averaging process,
Xn+1=(1?omega;n) XnnnTxn, x0=ξ?DT
generates a sequence {x?n}; with range in DT. Under suitable conditions on DT, T and {ωn} the sequence {x?n} will converge in some sense to a fixed point of T. We prove that if DT is a closed convex subset of a complex Hilbert space H, if Tω = (1 ? ω) I + ωT is a strict contraction for some ω ? (0, 1], and if {ωn} satisfies the conditions,
ωn → 0
and
n=0ωn=∞
then, for arbitrary ξ ? DT, {x?n} converges strongly to (the unique) fixed point of T. We also prove that if DT and {ωn} satisfy the foregoing conditions, if T has at least one fixed point, and if Tω is non-expansive for some ω ? (0, 1], then for all ξ ? DT, {x?n} converges at least weakly to some fixed point of T. Finally, we apply these results to linear equations involving bounded normal operators and obtain an extension of the classical Neumann operator series.  相似文献   
30.
A team of performance consultants looks closely at the operations of a cable services provider to identify existing performance gaps, barriers to performance, declining customer satisfaction ratings, and increased call volumes. The team used performance‐centered design (PCD) solutions in order to overcome technical support challenges through increased first‐call resolution. This article summarizes the root cause analysis, process, and the application of PCD solutions to close performance gaps, along with lessons learned from this case study.  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