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   155篇
  免费   13篇
  国内免费   1篇
教育   121篇
科学研究   25篇
各国文化   6篇
体育   4篇
文化理论   1篇
信息传播   12篇
  2023年   2篇
  2022年   6篇
  2021年   5篇
  2020年   6篇
  2019年   5篇
  2018年   18篇
  2017年   12篇
  2016年   16篇
  2015年   10篇
  2014年   12篇
  2013年   16篇
  2012年   2篇
  2011年   8篇
  2010年   7篇
  2009年   3篇
  2008年   5篇
  2007年   5篇
  2006年   1篇
  2005年   3篇
  2004年   2篇
  2003年   2篇
  2002年   2篇
  2001年   1篇
  2000年   5篇
  1999年   1篇
  1995年   1篇
  1993年   2篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1987年   1篇
  1986年   1篇
  1979年   1篇
  1978年   1篇
  1975年   1篇
  1967年   1篇
  1958年   1篇
排序方式: 共有169条查询结果,搜索用时 31 毫秒
11.
Education and Information Technologies - Owing to COVID-19 the Ministry of Education in the United Arab Emirates mandated educational institutions to shift to remote learning. In this study the...  相似文献   
12.
Education and Information Technologies - Computer security competitions have been playing a significant role in encouraging students to get into cybersecurity, as well as enhancing the...  相似文献   
13.
Abstract

This paper examines the factors that cause universities to undertake academic change, specifically, changes to achieve more effective teaching and learning. Based on an analysis of 30 reform‐oriented US colleges and universities, it suggests that universities respond to diverse environmental pressures, not solely to external mandates. There is evidence, too, that internal forces within universities can be an impetus for change.  相似文献   
14.
The paper explores the application of thermodynamic formalism to model and control transportation networks. Specifically, by considering the vehicles as the abstract energy supplied to the system, we show in certain circumstances that certain thermodynamic concepts such as temperature, thermal capacity and thermal equilibrium can have the corresponding notions in transportation context. In addition, despite the lack of a natural principle in transportation context that corresponds to the second law of thermodynamic as we will show, the most important thermodynamic notion, which is the entropy, can be also defined in order to measure the disorder of transportation systems. It is then shown that the state when all lanes have the same occupancy corresponds to the thermal equilibrium arising in isolated thermodynamic system. This equilibrium occupancy leads to a minimum entropy corresponding to a minimal disorder. Besides, by taking the transportation entropy as the storage function, a robust dissipativity based control strategy is presented to reduce the disorder and render the system better organized. Finally, an example is worked out to illustrate the results.  相似文献   
15.
Hardwoods and softwoods were used side by side throughout Egyptian history, and importing softwoods that had an attractive color and texture was common. Over the decades, artifacts based on hardwoods and softwoods underwent deterioration phenomena, sometimes reaching either a level of brittleness or turning into a wood powder that may easily crumble. These levels of decay/degradation are often difficult to handle in terms of conservation treatments. To study or identify the reasons for decay has always been a point of interest for conservation purposes, but to assess decay and choose an appropriate treatment according to the state of preservation for the sake of keeping an artifact intact has become a subject of major importance. It is difficult at times to understand the deterioration process, because hardwoods and softwoods are different in structure, properties, and chemical composition. For this preliminary study, decayed samples from three commonly used softwood types, cypress (Cupressus sp.), cedar (Cedrus sp.), and pine (Pinus sp.), were identified and chosen. Scanning electron microscopy (SEM) of the samples indicated the degree of decay. Decayed and non-aged samples of the same wood type were analyzed using Fourier transform infrared spectroscopy (FTIR), and all the major carbohydrate and lignin bands were recorded. The strong hydrogen bonded (O–H) stretching absorption associated with water linked by hydrogen bonds to the –OH groups of cellulose and hemicelluloses in all decayed samples increased with decay. The brown powdery, fragile samples that had been evidently affected by microbial decay had a higher amount of lignin. The lignin/carbohydrate ratio was calculated and results compared. The increase of either lignin percentage or extractives in some of the samples had caused a darkening of color in both cypress and cedar samples, but the pine sample did not have the same texture and appearance. In cases where the lignin percentage decreased the samples had changed to a slightly lighter color. FTIR results explained the decay phenomena observed in SEM micrographs and helped assess wood decay and also confirmed results that had been previously obtained while applying traditional chemical analysis on wood.  相似文献   
16.
A double-blind randomized controlled trial of n-3 long-chain polyunsaturated fatty acid (n-3 LCPUFA) supplementation or matching placebo during third trimester of pregnancy was conducted within the COPSAC2010 mother-child cohort consisting of 736 women and their children. The objective was to determine if maternal n-3 LCPUFA pregnancy supplementation affects offspring neurodevelopment until 6 years. Neurodevelopment was evaluated in 654 children assessing age of motor milestone achievement, language development, cognitive development, general neurodevelopment, and emotional and behavioral problems. Maternal n-3 LCPUFA supplementation during pregnancy improved early language development and reduced the impact of emotional and behavioral problems. The n-3 LCPUFA supplementation was in boys associated with the earlier achievement of gross motor milestones, improved cognitive development, and a reduced impact of emotional and behavioral problems.  相似文献   
17.
For primarily undergraduate institutions, institutional repositories can become effective tools for communicating and showcasing faculty and student research, facilitating open access initiatives, or supporting new scholarly communication practices. Choosing the right software platform is crucial to the success of a repository initiative. The literature suggests that there are only two or three software platforms heavily used in undergraduate libraries. This article aims to give a landscape of the repository platforms used in sixty-seven undergraduate libraries in the United States in late 2013; it also includes the results of a short survey about current institutional repository software platforms and users/administrators’ satisfaction.  相似文献   
18.
Predicting item difficulty is highly important in education for both teachers and item writers. Despite identifying a large number of explanatory variables, predicting item difficulty remains a challenge in educational assessment with empirical attempts rarely exceeding 25% of variance explained.

This paper analyses 216 science items of key stage 2 tests which are national sampling assessments administered to 11 year olds in England. Potential predictors (topic, subtopic, concept, question type, nature of stimulus, depth of knowledge and linguistic variables) were considered in the analysis. Coding frameworks employed in similar studies were adapted and employed by two coders to independently rate items. Linguistic demands were gauged using a computational linguistic facility. The stepwise regression models predicted 23% of the variance with extended constructed questions and photos being the main predictors of item difficulty.

While a substantial part of unexplained variance could be attributed to the unpredictable interaction of variables, we argue that progress in this area requires improvement in the theories and the methods employed. Future research needs to be centred on improving coding frameworks as well as developing systematic training protocols for coders. These technical advances would pave the way to improved task design and reduced development costs of assessments.  相似文献   

19.
INTRODUCTION Increase in wireless system capacity through 3G services and innovative low bit rate video coding techniques have made it possible to have mobile multimedia services on hand-held systems. High quality real-time multimedia services are slowly be- ing deployed on hand-held systems. However large scale deployment at low cost is still to be realized due to technological challenges such as stringent power control under severely fading environments and the susceptibility of high qu…  相似文献   
20.
This study (a) assessed the influence of three history of science (HOS) courses on college students' and preservice science teachers' conceptions of nature of science (NOS), (b) examined whether participants who entered the investigated courses with a conceptual framework consistent with contemporary NOS views achieved more elaborate NOS understandings, and (c) explored the aspects of the participant HOS courses that rendered them more “effective” in influencing students' views. Participants were 166 undergraduate and graduate students and 15 preservice secondary science teachers. An open‐ended questionnaire in conjunction with individual interviews, was used to assess participants' pre‐ and postinstruction NOS views. Almost all participants held inadequate views of several NOS aspects at the outset of the study. Very few and limited changes in participants' views were evident at the conclusion of the courses. Change was evident in the views of relatively more participants, especially preservice science teachers, who entered the HOS courses with frameworks that were somewhat consistent with current NOS views. Moreover, explicitly addressing certain NOS aspects rendered the HOS courses relatively more effective in enhancing participants' NOS views. The results of this study do not lend empirical support to the intuitively appealing assumption held by many science educators that coursework in HOS will necessarily enhance students' and preservice science teachers' NOS views. However, explicitly addressing specific NOS aspects might enhance the effectiveness of HOS courses in this regard. Moreover, the study suggests that exposing preservice science teachers to explicit NOS instruction in science methods courses prior to their enrollment in HOS courses might increase the likelihood that their NOS views will be changed or enriched as a result of their experiences with HOS. © 2000 John Wiley & Sons, Inc. J Res Sci Teach 37: 1057–1095, 2000  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