全文获取类型
收费全文 | 14668篇 |
免费 | 201篇 |
国内免费 | 12篇 |
专业分类
教育 | 10183篇 |
科学研究 | 1722篇 |
各国文化 | 120篇 |
体育 | 1137篇 |
综合类 | 17篇 |
文化理论 | 177篇 |
信息传播 | 1525篇 |
出版年
2022年 | 106篇 |
2021年 | 157篇 |
2020年 | 244篇 |
2019年 | 336篇 |
2018年 | 509篇 |
2017年 | 500篇 |
2016年 | 461篇 |
2015年 | 292篇 |
2014年 | 436篇 |
2013年 | 2448篇 |
2012年 | 359篇 |
2011年 | 340篇 |
2010年 | 343篇 |
2009年 | 299篇 |
2008年 | 318篇 |
2007年 | 319篇 |
2006年 | 300篇 |
2005年 | 244篇 |
2004年 | 278篇 |
2003年 | 236篇 |
2002年 | 240篇 |
2001年 | 330篇 |
2000年 | 356篇 |
1999年 | 266篇 |
1998年 | 149篇 |
1997年 | 184篇 |
1996年 | 182篇 |
1995年 | 124篇 |
1994年 | 134篇 |
1993年 | 123篇 |
1992年 | 203篇 |
1991年 | 192篇 |
1990年 | 220篇 |
1989年 | 214篇 |
1988年 | 184篇 |
1987年 | 194篇 |
1986年 | 174篇 |
1985年 | 213篇 |
1984年 | 151篇 |
1983年 | 134篇 |
1982年 | 131篇 |
1981年 | 110篇 |
1980年 | 116篇 |
1979年 | 177篇 |
1978年 | 131篇 |
1977年 | 117篇 |
1976年 | 90篇 |
1975年 | 94篇 |
1974年 | 98篇 |
1973年 | 94篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Analytical expressions are derived from a single symmetrical relay feedback test for the identification of open loop stable and unstable non-minimum phase processes. The second derivative of the limit cycle output helps in finding the time delay of the process. The derived expressions can be used to identify the process models with up to five unknowns. The effectiveness of the proposed identification method is verified through different simulation results. 相似文献
992.
Michael S. Moss 《Archival Science》2011,11(3-4):409-425
Trust is an overused concept in our contemporary world. This paper explores the complex relationship of trust, efficiency, accountability, transparency and responsibility and their relationship to recordkeeping in our globalizing culture. It focuses on the profound changes that have taken place in the meaning and practice of audit within neo-liberal societies and how the ??rituals of verification?? and the ??managerialism?? may pervert the resulting record. It challenges the unthinking use of much of the rhetoric surrounding these concepts by archivists to justify their existence. It reflects on why the archival voice often remains silent or at best goes unheard in much of the discussion about these questions that have profound consequences for democratic societies. It is easy to lay the blame at the door of a perceived breakdown of trust rather than to consider whether the root of the problem lies with archivists and records managers themselves. This paper draws on my experience in directing the Information Management and Preservation MSC programme at the University of Glasgow and wide and serendipitous reading, which has sometimes been brought to my notice by students. 相似文献
993.
994.
Greene NP Greene ES Carbuhn AF Green JS Crouse SF 《Research quarterly for exercise and sport》2011,82(2):264-273
We compared cardiorespiratory responses to exercise on an underwater treadmill (UTM) and land treadmill (LTM) and derived an equation to estimate oxygen consumption (VO2) during UTM exercise. Fifty-five men and women completed one LTM and five UTM exercise sessions on separate days. The UTM sessions consisted of chest-deep immersion, with 0, 25, 50, 75, and 100% water-jet resistance. All session treadmill velocities increased every 3 min from 53.6 to 187.8 m x min(-1). Cardiorespiratory responses were similar between LTM and UTM when jet resistance for UTM was 50%. Using multiple regression analysis, weight-relative VO2 could be estimated as: VO2 (mLO2 c kg(-1) x min(-1)) = 0.19248 x height (cm) + 0.17422 x jet resistance (% max) + 0.14092 x velocity (m x min(-1)) -0.12794 x weight (kg)-27.82849, R2 = .82. Our data indicate that similar LTM and UTM cardiorespiratory responses are achievable, and we provide a reasonable estimate of UTM VO2. 相似文献
995.
996.
Bone turnover is affected by exercise throughout the lifespan, especially during childhood and adolescence. The objective of this study was to investigate the impact of different sports on total and regional bone mineral density in male Brazilian adolescent athletes. Forty-six adolescents aged 10-18 years participated in the study: 12 swimmers, 10 tennis players, 10 soccer players, and 14 sedentary individuals. The athletes had engaged in physical activities for more than 10 h per week in the previous 6 months. Bone mineral density of the lumbar spine (L1-L4), left proximal femur region, and whole body was evaluated by dual-energy X-ray absorptiometry. Results showed higher mean values in the proximal femur region of tennis and soccer players (1.02 ± 0.18; 0.96 ± 0.16, respectively) than swimmers and controls (0.91 ± 0.14 and 0.87 ± 0.06, respectively) (P < 0.05). In relation to the impact of sporting activities based on bone age determination, we observed significant differences in bone mineral density at all evaluated sites at the end of puberty (16-18 years) compared with 10-12 years, with increases of 78% in the lumbar spine, 47% in the proximal femur, and 38% in the whole body. 相似文献
997.
This article presents a systematic review of the literature examining the relationship between self-talk and performance. "Second-generation questions" regarding potential mediators and moderators of the self-talk-performance relationship were also examined. A total of 47 studies were analyzed. Results indicated beneficial effects of positive, instructional, and motivational self-talk for performance. Somewhat surprisingly, two evidence-based challenges to popular current viewpoints on self-talk emerged. First, negative self-talk did not impede performance. Second, there was inconsistent evidence for the differential effects of instructional and motivational self-talk based on task characteristics. Results from the mediation-based analysis indicate that cognitive and behavioral factors had the most consistent relationships with self-talk. The findings are discussed in the context of recent theoretical advances, and the article includes recommendations for future research (e.g., the use of designs allowing the testing of meditational hypotheses) and for current applied practice (e.g., avoiding the use of thought-stopping techniques). 相似文献
998.
Innovation increasingly relies on collaboration in teams instead of individual efforts. Although the advantages of teams for innovating are virtually undisputed, we have only a very rudimentary understanding of their success drivers. To shed more light on innovation teams, we conceptualize multiplicity in expertise as nonredundant expertise and distinguish it from factors that facilitate or hinder the integration of this expertise. These factors are overlap in expertise, disparity in team members’ status, and whether or not teams use automation technology. We use the empirical context of molecular biology, especially the part of this field in which teams produce and exchange genetic material in the form of so-called plasmids. Combining data about plasmids from a central plasmid repository (AddGene) with bibliometric data endows us with a rich dataset capturing information about team diversity in addition to two innovation performance measures (the number of plasmid orders and the number of citations attracted by publications). Our analysis shows that multiplicity in expertise increases innovation performance; this relationship is strengthened by the overlap in expertise and weakened by disparity in status and the use of the automation technology. Our paper provides a more detailed theory of expertise diversity and contributes to the diversity literature. Our findings also lead to implications for practitioners. 相似文献
999.
Alghamdi Amani Khalaf H. Al Ghamdi Kholoud S. Kim Sun Young 《Journal of Science Education and Technology》2022,31(5):583-593
Journal of Science Education and Technology - It is of great importance that science educators teach COVID-19 and related pandemics to boost students’ scientific literacy. A mixed methods... 相似文献
1000.
Journal of Science Education and Technology - In this paper, the effectiveness of training faculty in laboratory teaching (the teaching of science in a laboratory setting using experiments and... 相似文献