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   14257篇
  免费   228篇
  国内免费   13篇
教育   9872篇
科学研究   1711篇
各国文化   131篇
体育   1089篇
综合类   17篇
文化理论   170篇
信息传播   1508篇
  2022年   100篇
  2021年   148篇
  2020年   222篇
  2019年   295篇
  2018年   425篇
  2017年   453篇
  2016年   415篇
  2015年   276篇
  2014年   388篇
  2013年   2381篇
  2012年   349篇
  2011年   334篇
  2010年   327篇
  2009年   279篇
  2008年   298篇
  2007年   305篇
  2006年   289篇
  2005年   256篇
  2004年   268篇
  2003年   243篇
  2002年   255篇
  2001年   328篇
  2000年   343篇
  1999年   268篇
  1998年   153篇
  1997年   190篇
  1996年   183篇
  1995年   133篇
  1994年   140篇
  1993年   125篇
  1992年   200篇
  1991年   195篇
  1990年   226篇
  1989年   213篇
  1988年   188篇
  1987年   199篇
  1986年   178篇
  1985年   215篇
  1984年   155篇
  1983年   142篇
  1982年   132篇
  1981年   114篇
  1980年   125篇
  1979年   179篇
  1978年   139篇
  1977年   118篇
  1976年   98篇
  1975年   94篇
  1974年   101篇
  1973年   94篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
In the article we solve path planning task for an agent being multirotor unmanned aerial vehicle (multicopter). We propose an approach of estimating path geometry constraints based on UAV flight dynamics model and control constraints. Than we introduce a new path finding method which takes into consideration those geometry constraints and study this method both theoretically and empirically.  相似文献   
93.
94.
ABSTRACT

The aims of the present study were to provide an in-depth comparison of inter-limb asymmetry and determine how consistently asymmetry favours the same limb during different vertical jump tests. Eighteen elite female under-17 soccer players conducted unilateral squat jumps (SJ), countermovement jumps (CMJ) and drop jumps (DJ) on a portable force platform, with jump height, peak force, concentric impulse and peak power as common metrics across tests. For the magnitude of asymmetry, concentric impulse was significantly greater during the SJ test compared to CMJ (p = 0.019) and DJ (p = 0.003). No other significant differences in magnitude were present. For the direction of asymmetry, Kappa coefficients revealed fair to substantial levels of agreement between the SJ and CMJ (Kappa = 0.35 to 0.61) tests, but only slight to fair levels of agreement between the SJ and DJ (Kappa = ?0.26 to 0.18) and CMJ and DJ (Kappa = ?0.13 to 0.26) tests. These results highlight that the mean asymmetry value may be a poor indicator of true variability of between-limb differences in healthy athletes. The direction of asymmetry may provide a useful monitoring tool for practitioners in healthy athletes, when no obvious between-limb deficit exists.  相似文献   
95.
ABSTRACT

The objective of this study was to analyse the effect of the use of social networks in smartphones or playing video games on the passing decision-making performance in professional soccer athletes. Participants were 25 male professional soccer athletes (mean ± SD: age 23.4 ± 2.8 years). The participants performed three randomised conditions divided into three groups: control (CON), smartphone (SMA), and video game (VID). Before and after each experimental condition, the Stroop Task assessed the level of induced mental fatigue. Then, the athletes performed a simulated soccer match. A CANON® camera recorded the matches for further analysis on passing decision-making performance. A group effect was identified (< .01) with impairment on passing decision-making performance for the SMA (p = .01, ES = 0.5) and VID (p = .01, ES = 0.5) conditions. We concluded that the use of social networks on smartphones and/or playing video games right before official soccer matches might impair the passing decision-making performance in professional soccer athletes.  相似文献   
96.
97.
98.
ABSTRACT

Recently, there has been much controversy over the International Association of Athletics Federation (IAAF) regulations regarding eligibility to compete and natural testosterone levels in female athletes. Much interest lies in the analysis of Caster Semenya's extraordinary performance. The objective of this work were, a) Complete an analysis of Caster Semenya's results during the 800m finals and b) search for existing similar performances by other female athletes. We analysed the results of the finals of all IAAF World Championships and Olympic Games from 1984–2016, including the 800m results of the Diamond Leagues 2016–2018. Exponential curves were fit to the data to characterise and predict performance for each event. Caster Semenya's finishing times before her ineligibility to compete and after the suspension of the IAAF hyperandrogenism regulation were found to be 1.24% and 1.49%, respectively, faster than the characteristic performance of the elite-standard in the women’s 800m final. Other female athletes, with finishing times faster than the ones predicted by the characteristic curves were also discovered. The percentage difference in performance between Caster Semenya and the other participants did not reach 3% in the 800m event. No conclusions can be drawn regarding extraordinary results ever performed during the 100m, 200m or 400m finals.  相似文献   
99.
The present article explores the utility and feasibility of treatment validation consultation (TVC). Although evidence exists for behavioral consultation, few findings have been reported for TVC. TVC is based on core components of behavioral consultation, but has several unique characteristics. In this article, TVC is situated within the behavioral consultation literature; one case study is used to demonstrate TVC’s utility and feasibility; and considerations for future TVC research are explored.  相似文献   
100.
With the recent adoption of the Common Core standards in many states, there is a need for quality information about textbook alignment to standards. While there are many existing content analysis procedures, these generally have little, if any, validity or reliability evidence. One exception is the Surveys of Enacted Curriculum (SEC), which has been widely used to analyze the alignment among standards, assessments, and teachers’ instruction. However, the SEC can be time‐consuming and expensive when used for this purpose. This study extends the SEC to the analysis of entire mathematics textbooks and investigates whether the results of SEC alignment analyses are affected if the content analysis procedure is simplified. The results indicate that analyzing only every fifth item produces nearly identical alignment results with no effect on the reliability of content analyses.  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