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   861篇
  免费   13篇
  国内免费   17篇
教育   664篇
科学研究   82篇
各国文化   1篇
体育   56篇
综合类   53篇
信息传播   35篇
  2023年   4篇
  2022年   7篇
  2021年   18篇
  2020年   17篇
  2019年   25篇
  2018年   41篇
  2017年   30篇
  2016年   28篇
  2015年   20篇
  2014年   34篇
  2013年   100篇
  2012年   44篇
  2011年   55篇
  2010年   39篇
  2009年   32篇
  2008年   39篇
  2007年   61篇
  2006年   66篇
  2005年   49篇
  2004年   39篇
  2003年   39篇
  2002年   34篇
  2001年   21篇
  2000年   20篇
  1999年   6篇
  1998年   1篇
  1997年   2篇
  1996年   6篇
  1995年   6篇
  1994年   2篇
  1993年   2篇
  1992年   1篇
  1989年   2篇
  1978年   1篇
排序方式: 共有891条查询结果,搜索用时 15 毫秒
1.
ABSTRACT

The aims of this study were to identify profiles of sedentary behaviour (SB) patterns, based on leisure-time self-reported SB modalities (screen, educative, social, and relaxing) and to evaluate changes in these profiles over 2 years among Spanish youth aged 8–18 years. Latent profile analysis (LPA), a data-driven analytic approach, was used to identify groups of boys and girls (n = 1553; 48% girls; mean±SD age: 12.56 ± 2.49 y) with distinct SB profiles using the SB modalities (time/d) as input variables. Latent transition analysis, an extension of LPA that uses longitudinal data, was used to analyse 2-year changes in these profiles. At baseline, four and three SB profiles were found among boys (labelled: screen, educative, social, and relaxing) and girls (labelled: screen/social, educative, and relaxing), respectively. Overall, more girls (range: 48%-67%) had the same profile over time, than boys (40%-52%). Participants with a screen or relaxing SB profile at baseline were more likely to have an educative profile after 2 years. Youth with a social and an educative SB profile at baseline were more likely to transition to profiles characterized by higher screen and social SB, respectively. Using a novel and person-centered approach, this study identified gender-specific SB profiles that were moderately stable over time.  相似文献   
2.
运用问卷、文献资料和调查访问等研究方法,对浙江省近两年来公安类考生的考前心理状态进行了分析研究,结果表明,有针对性地从意识和行为上加强应考前心理状态的调整对发挥考生潜能,取得优异成绩有重要意义,针对考生的不利心理状态,提出了消除的方法。  相似文献   
3.
外来词属于词汇学的范畴。外来词通过潜词显化、显意符号化、显词重叠化三种途径产生,其中的显词重叠化造成了外来词与汉语词的同义关系,而外来词独特的修辞效果也使人们在同义手段选择活动中更青睐于外来词。  相似文献   
4.
便携式数据采集器在图书馆的应用   总被引:3,自引:1,他引:3  
本文对便携式数据采集器性能做介绍,论述便携式数据采集器在图书馆工作中的应用,并对比传统的图书现场采购查重和图书清点的方法,提出了新的解决思路。  相似文献   
5.
用矩阵方法对点的合成运动进行分析、研究,推导出求解点的合成运动的矩阵计算公式,这些公式有助于理论力学在计算机上的应用,并对提高理论力学的教学质量可起到积极的作用。  相似文献   
6.
在管理审计中,可以应用盈亏分析法对被审计单位的生产经营计划或工程项目进行考核、评价,据以改善管理,提高经济效益。本文除对盈亏分析法作了一般阐述外,着重通过例示介绍了在生产一种产品情况下盈亏平衡点的图示法、公式计算法,以及在生产多种产品情况下盈亏平衡点的公式计算法的应用。  相似文献   
7.
Partial discharge test on a transformer is carried out according to the items in IEC 60.During the test,unproved measuring system is calibrated by proved system at a voltage no less than 50% the rated testing voltage.The result is then extrapolated linearly,leading to an error related to the distribution of stray capacitance,which varies with the testing frequency,especially to large transformers.In this paper a factor,named the capacitive rise fact,is introduced to assess the rise.The factor can be adjusted to some extent by changing the reactance that is connected to the LV side of the testing circuit to lower the capacity of the power source.However,the factor changes when the voltage divider on the high voltage side is removed after the voltage ratio has been calculated,and a great error is resulted under unfavorable conditions.  相似文献   
8.
在日益重视现场科学观测和考察研究的海洋科学发展的现阶段,建立海上观测可移动共享平台,设置基于长期观测的开放航次,在海洋环境观测、生物资源调查和工程勘测方面具有独到之处。  相似文献   
9.
校园文化中的隐性课程会让学生淡化或摆脱课业的压抑,使学生的兴趣、爱好得到某种程度的张扬,心理压力得到一定的舒缓,文明、进步、健康、蓬勃、富有特色、奋斗不息的校园精神是校园文化的核心,具有启迪、感化学生的作用,对学生身心健康的影响是深刻而持久的.  相似文献   
10.
The objective of this study was to determine the latent profiles of reading and language skills that characterized 7,752 students in kindergarten through tenth grade and to relate the profiles to norm-referenced reading outcomes. Reading and language skills were assessed with a computer-adaptive assessment administered in the middle of the year and reading outcome measures were administered at the end of the year. Three measures of reading comprehension were administered in third through tenth grades to create a latent variable. Latent profile analysis (LPA) was conducted on the reading and language measures and related to reading outcomes in multiple regression analyses. Within-grade multiple regressions were subjected to a linear step-up correction to guard against false-discovery rate. LPA results revealed five to six profiles in the elementary grades and three in the secondary grades that were strongly related to standardized reading outcomes, with average absolute between-profile effect sizes ranging from 1.10 to 2.53. The profiles in the secondary grades followed a high, medium, and low pattern. Profiles in the elementary grades revealed more heterogeneity, suggestive of strategies for differentiating instruction.  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