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   15236篇
  免费   244篇
  国内免费   14篇
教育   10490篇
科学研究   1775篇
各国文化   135篇
体育   1229篇
综合类   18篇
文化理论   175篇
信息传播   1672篇
  2022年   104篇
  2021年   150篇
  2020年   246篇
  2019年   340篇
  2018年   473篇
  2017年   522篇
  2016年   456篇
  2015年   311篇
  2014年   441篇
  2013年   2642篇
  2012年   377篇
  2011年   365篇
  2010年   342篇
  2009年   312篇
  2008年   344篇
  2007年   334篇
  2006年   328篇
  2005年   280篇
  2004年   296篇
  2003年   269篇
  2002年   262篇
  2001年   332篇
  2000年   351篇
  1999年   275篇
  1998年   155篇
  1997年   193篇
  1996年   191篇
  1995年   130篇
  1994年   145篇
  1993年   136篇
  1992年   217篇
  1991年   193篇
  1990年   234篇
  1989年   226篇
  1988年   198篇
  1987年   198篇
  1986年   179篇
  1985年   217篇
  1984年   158篇
  1983年   138篇
  1982年   131篇
  1981年   114篇
  1980年   117篇
  1979年   177篇
  1978年   132篇
  1977年   122篇
  1976年   97篇
  1975年   94篇
  1974年   97篇
  1973年   100篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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   
92.
93.
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   
94.
Abstract

Maternal dietary habits influence maternal and foetal health, representing a pathway for intervention to maximise pregnancy outcomes. Advice on energy intake is provided on a trimester basis, with no additional calories required in the first trimester and an additional 340?kcal?d?1 and 452?kcal?d?1 needed for the second and third trimesters. Energy intake depends on pre-gravid body mass index (BMI); underweight women are recommended an increase of 150, 200 and 300?kcal?d?1 during the first, second and third trimester, normal weight women an increase of 0, 350 and 500?kcal?d?1 and obese women an increase of 0, 450 and 350?kcal?day?1. The recommendations for carbohydrate and protein intake are 175?g?d?1 and 0.88–1.1?g?kgBM?d?1, with no change to fat intake. The number of pre-gravid obese women is rising; therefore, we need to regulate weight in women of childbearing age and limit gestational weight gain to within the recommended ranges [overweight women 6.8–11.3?kg and obese women 5.0–9.1?kg]. This can be achieved using nutritional interventions, as dietary changes have been shown to help with gestational weight management. As pregnancy has been identified as a risk factor for the development of obesity, normal weight women should gain 11.5–16.0?kg during pregnancy. While some research has shown that dietary interventions help to regulate gestational weight gain and promote postpartum weight loss to some extent, future research is needed to provide safe and effective guidelines to maximise these effects, while benefitting maternal and foetal health.  相似文献   
95.
96.
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   
97.
There remains significant confusion surrounding the purpose, audience, and proposed application of the Framework for Information Literacy for Higher Education. This exploratory study addresses the question of whether undergraduate students can understand the language and concepts in this document. By presenting student responses to pretest questions recorded at the beginning of a semester-long research methods course, this article shows that students can, even on first impression, begin to make sense of the complexity and richness found in the Framework for Information Literacy for Higher Education.  相似文献   
98.
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