全文获取类型
收费全文 | 433篇 |
免费 | 6篇 |
专业分类
教育 | 261篇 |
科学研究 | 52篇 |
各国文化 | 7篇 |
体育 | 77篇 |
综合类 | 1篇 |
文化理论 | 4篇 |
信息传播 | 37篇 |
出版年
2023年 | 1篇 |
2022年 | 11篇 |
2021年 | 16篇 |
2020年 | 17篇 |
2019年 | 29篇 |
2018年 | 41篇 |
2017年 | 36篇 |
2016年 | 33篇 |
2015年 | 23篇 |
2014年 | 25篇 |
2013年 | 55篇 |
2012年 | 23篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 4篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1996年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有439条查询结果,搜索用时 15 毫秒
431.
The consensus problem for networks of multiple agents consists in reaching an agreement between certain coordinates of interest using a distributed controller. It may be desirable that all the agents find a consensus at a given desired leader coordinate (Leader Follower Consensus Problem LFCP), or it may be only necessary that they agree at a certain coordinates value (Leaderless Consensus Problem LCP). Consensus has many practical applications in robot networks systems, where the interconnection of the agents may present variable time delays, hence rendering the stability analysis and control design more complex. Another problem that may arise is the possible lack of velocity measurements. In this work, a Proportional plus damping injection (P + d) controller together with a linear velocity observer is introduced. Our approach is able to solve both the LFCP and the LCP in networks of robots modeled as undirected weighted graphs with unknown asymmetric (bounded) variable time delays. Local (semi global) asymptotic stability is proven and simulation results are provided to test the performance of the proposed scheme. 相似文献
432.
433.
Fernando K. Borszcz Artur F. Tramontin Kristopher M. de Souza Lorival J. Carminatti 《Research quarterly for exercise and sport》2018,89(1):120-125
Purpose: Several studies have demonstrated that physiological variables predict cycling endurance performance. However, it is still unclear whether the predictors will change over different performance durations. The aim of this study was to assess the correlations between physiological variables and cycling time trials with different durations. Methods: Twenty trained male cyclists (maximal oxygen uptake [VO2max] = 60.5 ± 5.6 mL/kg/min) performed 4 separate experimental trials during a 2-week period. Cyclists initially completed an incremental exercise test until volitional exhaustion followed by 3 maximal cycling time trials on separate days. Each time trial consisted of 3 different durations: 5 min, 20 min, and 60 min performed in a randomized order. Results: The main results showed that the physiological measures strongly correlated with long cycling performances rather than short and medium time trials. The time-trial mean power output was moderately high to highly correlated with peak power output and VO2max (r = .61–.87, r = .72–.89, respectively), and was moderately to highly correlated with the lactate threshold Dmax method and second ventilatory threshold (r = .52–.75, r = .55–.82, respectively). Conclusions: Therefore, trained cyclists should develop maximal aerobic power irrespective of the duration of time trial, as well as enhancements in metabolic thresholds for long-duration time trials. 相似文献
434.
João Martins Adilson Marques António Rodrigues Hugo Sarmento Marcos Onofre Francisco Carreiro da Costa 《Sport, Education and Society》2018,23(5):505-519
Based on a socio-ecological framework for physical education (PE), this study explored and analysed the perspectives of physically active and inactive adolescent boys and girls with different socioeconomic status (SES), regarding the meanings that PE had on their physical activity (PA) lifestyles throughout childhood and adolescence. An interpretative and qualitative design was adopted and operationalised through an individual two-hours in-depth interview. Thematic analysis identified five main themes that distinguish active from inactive adolescents: ‘Early experiences of PE at primary school’; ‘PE experiences in middle and secondary school’; ‘Friendly, professional and pedagogue. That’s what I want from my PE teacher’; ‘Friends in PE and PA’; ‘Active lifestyles? Are schools and PE ready for making a difference?…’. Regardless of the lifestyle, girls revealed more PE negative experiences, related to uninteresting and competitive activities, groups’ constitution and logistic factors. SES played a major role on their PA and PE experiences, with low SES adolescents having limited opportunities inclusively within the primary school PE context. This study provides evidence for the importance of promoting positive PE and PA experiences in early years. Based on adolescents’ voices, several recommendations are discussed that can be considered for improving PE professionals’ effectiveness in promoting active lifestyles. 相似文献
435.
da Silva Renan Amorim de Vasconcelos Flávia Cristina Gomes Catunda 《Education and Information Technologies》2022,27(5):6967-6987
Education and Information Technologies - This paper presents an analysis of cognitive skill levels expressed in high school students’ performance using laboratory simulations. We address... 相似文献
436.
437.
Boutefara Tarek Mahdaoui Latifa Ghomari Abdessamed Réda 《Education and Information Technologies》2022,27(5):6173-6195
Education and Information Technologies - A personal annotation is a rich object with an important cognitive facet. In the e-Learning context, learners’ annotation can contain important... 相似文献
438.
439.