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   476篇
  免费   8篇
教育   305篇
科学研究   42篇
各国文化   2篇
体育   96篇
文化理论   9篇
信息传播   30篇
  2023年   4篇
  2022年   11篇
  2021年   12篇
  2020年   30篇
  2019年   32篇
  2018年   41篇
  2017年   36篇
  2016年   28篇
  2015年   17篇
  2014年   14篇
  2013年   100篇
  2012年   22篇
  2011年   11篇
  2010年   10篇
  2009年   11篇
  2008年   2篇
  2007年   7篇
  2006年   3篇
  2005年   8篇
  2004年   8篇
  2003年   7篇
  2002年   6篇
  2001年   2篇
  2000年   2篇
  1999年   5篇
  1998年   3篇
  1997年   4篇
  1996年   2篇
  1995年   3篇
  1993年   4篇
  1992年   2篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1988年   5篇
  1986年   3篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1981年   4篇
  1978年   4篇
  1977年   1篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1967年   1篇
  1934年   1篇
  1926年   1篇
排序方式: 共有484条查询结果,搜索用时 15 毫秒
141.
Cooperative organization has been proposed as a means to improve the usefulness of virtual libraries. Information interchange among library and other academic applications is often hindered by the lack of application interoperability. This hindrance may be overcome through the development of standards that allow for digital libraries to exchange and share information with other applications. The Graduate Program in Production Engineering (PPGEP) of the Federal University of Santa Catarina (UFSC) launched its Theses and Dissertations Bank (BTD) in 1995. BTD is possibly the first online academic digital library of theses. From a digital document repository, BTD evolved into a system that combines bibliometry and informetry features. BTD is used by students and faculty in their research activities, but also by decision makers from industry and academia. They use it, respectively, to search for specialists and to measure interest and knowledge interchange among PPGEP research areas. This article presents the history, features, and development prospects for the BTD project. The integration of BTD with other academic applications, especially those of the Brazilian national science and technology platform, is emphasized.  相似文献   
142.
143.
William A. Lucas and Robert K. Yin's Serving Local Needs with Telecommunications (Santa Monica, Calif: Rand Corporation Report R-1345-MF, November 1973—$3.00, paper).

Fred B. Wood's The Potential for Congressional Use of Emergent Telecommunications: An Exploratory Assessment (Washington, D.C.: George Washington University, Program of Policy Studies in Science and Technology, May 1974—apparently free on request)

Walter S. Baer, Michael Botein, Leland L. Johnson, Carl Pilnick, Monroe E. Price, and Robert K. Yin's Cable Television: Franchising Considerations (New York: Crane, Russak, & Co., 1974-=T13.50)

Charles G. Woodard's Cable Television: Acquisition and Operation of CATV Systems (New York: McGraw-Hill, 1974—$27.50)

Planning Interconnection Systems: Options for the Twin Cities Metropolitan Area (Washington, D.C.: Cable Television Information Center, 2100 M St. N.W., 1974-47.50, paper)

Cablelines (Cable Communications Resource Center, 1900 L St., N.W., Washington, D.C. 20036—monthly/free on request)  相似文献   
144.
This study examined underground iron ore miners' occupational narratives to uncover how their stories socialize miners into blue-collar careers and reinforce their work identities. Through the root theme of sisu (Finnish for inner determination), underground miners create a status hierarchy that is used to construct a sense of pride around their work and to establish milestones of success for themselves and others in their workgroup. Furthermore, they communicatively construct exemplars that guide their performance and decisions during the unfolding of their work experiences. Their discourses provide alternatives to white-collar conceptualizations and practices of careers and success.  相似文献   
145.
Abstract

The aims of the this prospective study were to analyse physical activity (PA) engagement during the first and second trimesters, considering the different guidelines published on PA, to document the individual characteristics associated with the accomplishment of these guidelines and to examine pregnant women’s perceived barriers to leisure PA, using a socioecological framework. A sample of 133 pregnant women in two stages – at 10–12 weeks’ gestation (T1) and 20–22 weeks’ gestation (T2) – were evaluated. PA was assessed by accelerometry during the T1 and T2 evaluation stages. Socio-demographic characteristics, lifestyle factors and barriers to leisure PA were assessed via questionnaire. A large proportion of women (ranging from 32% to 96%) did not reach the levels of PA recommended by the guidelines. There were no significant differences between T1 and T2 with regard to compliance with PA recommendations. A decrease in PA levels from T1 to T2 was noted for all recommendations. No associations were found between participants’ characteristics and adherence to the recommendations in T1 and T2. No significant differences were found in barriers to leisure PA between T1 and T2. The most commonly reported barriers to leisure PA were intrapersonal, not health related. Our results indicate that there were no differences between trimesters regarding compliance of PA recommendations, and perceived barriers were similar in both trimesters.  相似文献   
146.
Cardiorespiratory fitness (CRF) is associated with health benefits in children, improving cardiac morphology, cardiovascular disease risk factors, and biological outcomes. This study aimed to examine the substitution effects of displaying a fixed duration of sedentary time with a fixed duration of physical activity (PA) at different intensities on children’s CRF. A total of 315 children (136 boys) were assessed (age: 10.6 ± 0.6 years old). Outcomes at baseline and follow-up (16-months) were CRF determined using a maximal cycle test and sedentary time and PA measured with accelerometers. Data were analysed by isotemporal substitution analyses estimating the effect of reallocating 30 min/day of sedentary time by light (LPA), moderate (MPA) and vigorous physical activity (VPA) on CRF. VPA was positively and significantly associated with CRF cross-sectional (β = 0.026, < 0.001) and prospectively (β = 0.010, < 0.001). Reallocating 30 min/day of sedentary time into VPA was positively cross-sectionally (β = 0.780, < 0.001) and prospectively (β = 0.303, < 0.05) associated with CRF. Conversely, relocating 30-minutes of sedentary time into 30 minutes of LPA and MPA was not associated with CRF. These results suggest that reallocating an equal amount of time from sedentary into VPA is cross-sectional and prospectively associated with a favourable CRF.  相似文献   
147.
148.
Drawing upon the concepts of civic epistemologies and sociotechnical imaginaries, this article delves into the history of nuclear energy in Portugal, analyzing the ways in which the nuclear endeavor was differently enacted by various sociopolitical collectives – the Fascist State, post-revolutionary governments and the public. Following the 1974 revolution - known as the Carnation Revolution - this paper analyzes how the nuclear project was fiercely contested by a vibrant anti-nuclear movement assembled against the construction of the Ferrel Nuclear Plant, the first sociotechnical controversy in Portugal, paving the way for the emergence of a combative civic epistemology. Supported by semi-structured interviews with scientists, activists and local residents of Ferrel and the analysis of historical material, this article presents the failed Portuguese nuclear endeavor as an emblematic case study to explore the co-production of science and society, in particular the role of revolutionary processes in the unfolding of sociotechnical controversies.  相似文献   
149.
The aim of this study was to determine the magnitude and pattern of intensity, and physiological strain, of competitive exercise performed across several days, as in adventure racing. Data were obtained from three teams of four athletes (7 males, 5 females; mean age 36 years, s = 11; cycling .VO(2 peak) 53.9 ml . kg(-1) . min(-1), s = 6.3) in an international race (2003 Southern Traverse; 96 - 116 h). Heart rates (HR) averaged 64% (95% confidence interval: +/- 4%) of heart rate range [%HRR = (HR - HR(min))/(HR(max) - HR(min)) x 100] during the first 12 h of racing, fell to 41% (+/-4%) by 24 h, and remained so thereafter. The level and pattern of heart rate were similar across teams, despite one leading and one trailing all other teams. Core temperature remained between 36.0 and 39.2 degrees C despite widely varying thermal stress. Venous samples, obtained before, during, and after the race, revealed increased neutrophil, monocyte and lymphocyte concentrations (P < 0.01), and increased plasma volume (25 +/- 10%; P < 0.01) with a stable sodium concentration. Standardized exercise tests, performed pre and post race, showed little change in the heart rate-work rate relationship (P = 0.53), but a higher perception of effort post race (P < 0.01). These results provide the first comprehensive report of physiological strain associated with adventure racing.  相似文献   
150.
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