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   3450篇
  免费   55篇
教育   2640篇
科学研究   167篇
各国文化   36篇
体育   303篇
综合类   2篇
文化理论   39篇
信息传播   318篇
  2023年   22篇
  2022年   52篇
  2021年   63篇
  2020年   108篇
  2019年   180篇
  2018年   217篇
  2017年   215篇
  2016年   194篇
  2015年   149篇
  2014年   130篇
  2013年   775篇
  2012年   116篇
  2011年   111篇
  2010年   67篇
  2009年   73篇
  2008年   88篇
  2007年   71篇
  2006年   62篇
  2005年   62篇
  2004年   52篇
  2003年   52篇
  2002年   50篇
  2001年   38篇
  2000年   22篇
  1999年   25篇
  1998年   23篇
  1997年   19篇
  1996年   50篇
  1995年   29篇
  1994年   35篇
  1993年   37篇
  1992年   26篇
  1991年   27篇
  1990年   28篇
  1989年   22篇
  1988年   16篇
  1987年   11篇
  1986年   13篇
  1985年   14篇
  1984年   18篇
  1983年   14篇
  1982年   12篇
  1981年   11篇
  1980年   14篇
  1979年   14篇
  1978年   9篇
  1977年   16篇
  1976年   9篇
  1970年   5篇
  1967年   5篇
排序方式: 共有3505条查询结果,搜索用时 15 毫秒
181.
Knowledge Management Research & Practice - Nowadays knowledge has become a key asset for firms in order to build a sustainable competitive advantage. The environment changes quickly and...  相似文献   
182.
Consumer distrust is only recently beginning to be perceived as an important e-commerce issue and, unlike online trust, the nature and role of distrust is much less established. This study examines the influence of two important consumer characteristics (ethical ideology and risk aversion) on consumer’s ethically-based distrust of online retailers. Also, the moderating role of consumer’s need for personal contact with sales staff is tested. Results from 409 online consumers confirm that both relativist-based ethical ideology and risk aversion are strongly and positively related to consumers’ distrust. Interestingly, our findings show that positive effects of relativism and risk aversion on consumer’s distrust are moderated by consumers’ need for personal interaction, which is more pronounced for those consumers with a high need for personal interaction with retail salespeople.  相似文献   
183.
Microfluidic devices allow for the production of physiologically relevant cellular microenvironments by including biomimetic hydrogels and generating controlled chemical gradients. During transport, the biomolecules interact in distinct ways with the fibrillar networks: as purely diffusive factors in the soluble fluid or bound to the matrix proteins. These two main mechanisms may regulate distinct cell responses in order to guide their directional migration: caused by the substrate-bound chemoattractant gradient (haptotaxis) or by the gradient established within the soluble fluid (chemotaxis). In this work 3D diffusion experiments, in combination with ELISA assays, are performed using microfluidic platforms in order to quantify the distribution of PDGF-BB and TGF-β1 across collagen and fibrin gels. Furthermore, to gain a deeper understanding of the fundamental processes, the experiments are reproduced by computer simulations based on a reaction-diffusion transport model. This model yields an accurate prediction of the experimental results, confirming that diffusion and binding phenomena are established within the microdevice.  相似文献   
184.
This study aimed to analyse the effect of growth during a summer break on biomechanical profile of talented swimmers. Twenty-five young swimmers (12 boys and 13 girls) undertook several anthropometric and biomechanical tests at the end of the 2011–2012 season (pre-test) and 10 weeks later at the beginning of the 2012–2013 season (post-test). Height, arm span, hand surface area, and foot surface area were collected as anthropometric parameters, while stroke frequency, stroke length, stroke index, propelling efficiency, active drag, and active drag coefficient were considered as biomechanical variables. The mean swimming velocity during an all-out 25 m front crawl effort was used as the performance outcome. After the 10-week break, the swimmers were taller with an increased arm span, hand, and foot areas. Increases in stroke length, stroke index, propelling efficiency, and performance were also observed. Conversely, the stroke frequency, active drag, and drag coefficient remained unchanged. When controlling the effect of growth, no significant variation was determined on the biomechanical variables. The performance presented high associations with biomechanical and anthropometric parameters at pre-test and post-test, respectively. The results show that young talented swimmers still present biomechanical improvements after a 10-week break, which are mainly explained by their normal growth.  相似文献   
185.
Abstract

The aim was to examine the injuries sustained by Spanish football players in the First Division and to compare injury-related variables in the context of both competition and training. The injury data were prospectively collected from 16 teams (427 players) using a specific web-based survey during the 2008/2009 season. A total of 1293 injuries were identified (145 were recurring injuries). The overall injury incidence was 5.65 injuries per 1000 h of exposure. Injuries were much more common during competition than during training (43.53 vs. 3.55 injuries per 1000 h of exposure, P < 0.05). Most of the injuries (89.6%) involved the lower extremities, and overuse (65.7%) was the main cause. Muscle and tendon injuries were the most common types of injury (53.8%) among the players. The incidence of training injuries was greater during the pre-season and tended to decrease throughout the season, while the incidence of competition injuries increased throughout the season (all P < 0.05). In conclusion, the results of this study suggest the need for injury prevention protocols in the First Division of the Spanish Football League to reduce the number of overuse injuries in the muscles and tendons in the lower extremities. In addition, special attention should be paid during the pre-season and the competitive phase II (the last four months of the season) in order to prevent training and competition injuries, respectively.  相似文献   
186.
This paper advances the ongoing discussion of methods for predicting movie box office revenues with two contributions to the methodology and an out-of-sample test of the model. The first innovation is the development of a two-stage model using publicly available pre-release indicators to predict (1) initial week and (2) subsequent run box office revenues. To incorporate the experience-good nature of movies, the second stage is estimated by incorporating a proxy variable for box office success during the first week relative to predicted first week success. The second contribution is an empirical test of De Vany and Walls’ (J Econ Dyn Control 28:1035–1057, 2004) finding that the distribution of movie revenues has “heavy tails” and follows a non-Gaussian stable distribution with infinite variance. We estimate the two-stage model of a movie’s box office success on all general release movies in 1 year with both the Gaussian and stable distribution with heavy tails and infinite variance and find no evidence for the stable distribution in either stage of the estimation. This two-stage model is validated by comparing all general release movies in 3 future years (out-of-sample data) to the model’s predictions.  相似文献   
187.
This study compared staff and elderly knowledge, attitudes, and practices related to sexual expression by elderly persons in a long‐term care setting. Volunteers (N = 194) responded agree or disagree to 159 items. Significant differences were observed between the staff and elderly responses on 36 items. Areas of greatest differences involved knowledge and attitudes about consensual sex and sexual abuse, issues related to family attitudes toward remarriage and sexual expression, and age‐related changes and health problems related to sexuality. Items related to masturbation received the greatest percentage of no response. The staff had significantly higher total scores as compared to the elderly reflecting more knowledge, positive attitudes, and support for more proactive responses toward elderly sexuality. Findings have major implications for staff training in long‐term care settings.  相似文献   
188.
189.
190.
In this study the origin and evolution of the meanings of the concepts 'amount of substance' and 'mole' are described. Serious disagreements about these concepts amongst chemistry teachers and the recommendations of the international scientific community are identified. Attention is also drawn to the didactic implications that these epistemological difficulties may have for the teaching of chemistry.  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