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   2425篇
  免费   30篇
  国内免费   6篇
教育   1745篇
科学研究   221篇
各国文化   30篇
体育   212篇
综合类   13篇
文化理论   40篇
信息传播   200篇
  2023年   10篇
  2022年   23篇
  2021年   58篇
  2020年   66篇
  2019年   123篇
  2018年   152篇
  2017年   159篇
  2016年   117篇
  2015年   73篇
  2014年   88篇
  2013年   404篇
  2012年   90篇
  2011年   73篇
  2010年   80篇
  2009年   60篇
  2008年   63篇
  2007年   58篇
  2006年   47篇
  2005年   77篇
  2004年   80篇
  2003年   101篇
  2002年   75篇
  2001年   69篇
  2000年   41篇
  1999年   25篇
  1998年   12篇
  1997年   6篇
  1996年   8篇
  1995年   18篇
  1994年   8篇
  1993年   6篇
  1992年   6篇
  1991年   13篇
  1990年   7篇
  1989年   13篇
  1987年   5篇
  1986年   5篇
  1985年   6篇
  1982年   8篇
  1981年   7篇
  1980年   8篇
  1978年   6篇
  1977年   7篇
  1976年   4篇
  1975年   4篇
  1974年   8篇
  1973年   4篇
  1967年   4篇
  1966年   6篇
  1963年   6篇
排序方式: 共有2461条查询结果,搜索用时 250 毫秒
101.
Abstract

The aim of this study was to develop a performance test set-up for America's Cup grinders. The test set-up had to mimic the on-boat grinding activity and be capable of collecting data for analysis and evaluation of grinding performance. This study included a literature-based analysis of grinding demands and a test protocol developed to accommodate the necessary physiological loads. This study resulted in a test protocol consisting of 10 intervals of 20 revolutions each interspersed with active resting periods of 50 s. The 20 revolutions are a combination of both forward and backward grinding and an exponentially rising resistance. A custom-made grinding ergometer was developed with computer-controlled resistance and capable of collecting data during the test. The data collected can be used to find measures of grinding performance such as peak power, time to complete and the decline in repeated grinding performance.  相似文献   
102.
103.
We propose an approach to enhancing knowledge sharing and connectedness in distributed teams. Termed ‘Narrating Your Work’ (NYW), the approach involves members of distributed team using a microblogging tool to post regular updates about their current work, accomplishments, and issues. The NYW approach was evaluated within a geographically and temporally distributed team at Shell International for a period of one month, using a mixed-method research design. Methodology comprised of a quantitative survey, followed by semi-structured interviews and analysis of microblogging updates posted during the month in which the approach was being trialled. The evaluation results suggest that NYW was viewed as a valid and practical approach to enhancing knowledge sharing and connectedness. A range of barriers and enablers that could impact the future application and embedding of the approach are identified and recommendations for implementation are outlined.  相似文献   
104.
105.
The use of contemporary technology is widely recognised as a key tool for enhancing competitive performance in swimming. Video analysis is traditionally used by coaches to acquire reliable biomechanical data about swimming performance; however, this approach requires a huge computational effort, thus introducing a delay in providing quantitative information. Inertial and magnetic sensors, including accelerometers, gyroscopes and magnetometers, have been recently introduced to assess the biomechanics of swimming performance. Research in this field has attracted a great deal of interest in the last decade due to the gradual improvement of the performance of sensors and the decreasing cost of miniaturised wearable devices. With the aim of describing the state of the art of current developments in this area, a systematic review of the existing methods was performed using the following databases: PubMed, ISI Web of Knowledge, IEEE Xplore, Google Scholar, Scopus and Science Direct. Twenty-seven articles published in indexed journals and conference proceedings, focusing on the biomechanical analysis of swimming by means of inertial sensors were reviewed. The articles were categorised according to sensor’s specification, anatomical sites where the sensors were attached, experimental design and applications for the analysis of swimming performance. Results indicate that inertial sensors are reliable tools for swimming biomechanical analyses.  相似文献   
106.
Joint moments can be used as an indicator of joint loading and have potential application for sports performance and injury prevention. The effects of changing walking and running speeds on joint moments for the different planes of motion still are debatable. Here, we compared knee and ankle moments during walking and running at different speeds. Data were collected from 11 recreational male runners to determine knee and ankle joint moments during different conditions. Conditions include walking at a comfortable speed (self-selected pacing), fast walking (fastest speed possible), slow running (speed corresponding to 30% slower than running) and running (at 4 m · s?1 ± 10%). A different joint moment pattern was observed between walking and running. We observed a general increase in joint load for sagittal and frontal planes as speed increased, while the effects of speed were not clear in the transverse plane moments. Although differences tend to be more pronounced when gait changed from walking to running, the peak moments, in general, increased when speed increased from comfortable walking to fast walking and from slow running to running mainly in the sagittal and frontal planes. Knee flexion moment was higher in walking than in running due to larger knee extension. Results suggest caution when recommending walking over running in an attempt to reduce knee joint loading. The different effects of speed increments during walking and running should be considered with regard to the prevention of injuries and for rehabilitation purposes.  相似文献   
107.
A novel microfluidic device which consists of two stages for particle focusing and separation using a viscoelastic fluid has been developed. A circular capillary tube was used for three-dimensional particle pre-alignment before the separation process, which was inserted in a polydimethylsiloxane microchannel. Particles with diameters of 5 and 10 μm were focused at the centerline in the capillary tube, and the location of particles was initialized at the first bifurcation. Then, 5 and 10 μm particles were successfully separated in the expansion region based on size-dependent lateral migration, with ∼99% separation efficiency. The proposed device was further applied to separation of MCF-7 cells from leukocytes. Based on the cell size distribution, an approximate size cutoff for separation was determined to be 16 μm. At 200 μl/min, 94% of MCF-7 cells were separated with the purity of ∼97%. According to the trypan blue exclusion assay, high viability (∼90%) could be achieved for the separated MCF-7 cells. The use of a commercially available capillary tube enables the device to be highly versatile in dealing with particles in a wide size range by using capillary tubes with different inner diameters.  相似文献   
108.
The feature is a part of the series about medical library services in various countries. It gives an overview of medical library services to support research, education and clinical practice in Switzerland. Data were collected by means of an online survey and set in the wider context of the Swiss healthcare system. Key findings are that library services, including support by academic librarians, are provided to health care staff in hospitals – both university and others, while there is no information service infrastructure to serve the large number of GPs and specialists who mostly run their own practice. The authors recommend that – if the health authorities take EBM seriously – information services should be introduced for these small practices. J.M.  相似文献   
109.
For almost a half century David F. Treagust has been an exemplary science educator who has contributed through his dedication and commitments to students, curriculum development and collaboration with teachers, and cutting edge research in science education that has impacted the field globally, nationally and locally. A hallmark of his outstanding career is his collaborative style that inspires others to produce their best work.  相似文献   
110.
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