BaTiO3与CaCu3Ti4O12的介电性能比较     

任清褒  蒋永清 《丽水学院学报》2006,28(5):33-38

分别采用溶胶-凝胶法和固相反应法制备BaTiO3纳米粉体和CaCu3Ti4O12多晶块材,并系统地研究两者的介电性能。实验结果表明:BaTiO3体相陶瓷的介电性能受温度的影响较大,当频率在200~150 000 Hz范围内变动时,其室温介电常数ε最高达2 967,具有很好的频率稳定性、介电损耗小,可用来制作某些电子元件;然而CaCu3Ti4O12多晶块材的介电常数ε在(1 kHz,300 K)时高达14 000,并在100~350 K的温区内基本保持恒定,具有极好的温度稳定性。因此,在现实的应用过程中,CaCu3Ti4O12多晶块材以高介电常数、受温度影响变化小、介电损耗小等优点而更具应用前景。  相似文献   

汽车12V／36V双电源系统的应用研究     

朱小春  邱浩 《深圳职业技术学院学报》2008,7(2):17-20

12V／36V双电源系统作为其中间过渡阶段,已成为现阶段汽车电源研究的热点。本文简要分析了提升汽车电源电压从12V到36V的技术原因,研究了一种汽车12V／36V双电源系统方案,通过Matlab仿真与工程样机的研制,详细分析了移相全桥DC—DC变换器在此双电源系统方案中的应用实现。  相似文献   

日本动画《十二国记》的中国元素与文化内涵解析     

焦素娥 《信阳师范学院学报(哲学社会科学版)》2011,31(6):109-113

《十二国记》是根据作家小野不由美的同名小说改编的动画作品。依托原著小说恢宏的情节设定、丰富的艺术想象、精彩的奇幻故事,加上独特的画风、精良的制作、美妙的音乐等,《十二国记》一经播出便受到了广大动漫爱好者的追捧。从《十二国记》中可以清楚地看到日本动画对中国文化的借鉴以及丰厚的文化内涵。  相似文献   

国际远程教育研究的特点与发展历程——基于国际会议文献的分析     

姜霖  苏新宁 《现代远程教育研究》2011,(3):40-47

随着科技的不断进步,远程教育的发展有了质的飞跃。ISI Proceeding数据库1987-2009年收录的国际远程教育会议文献反映：远程教育研究总体上呈不断上升的发展趋势;研究主题初期以教育理论为主,后期受新技术,如计算机技术、网络技术、通信技术等影响较大;研究机构以高等院校为主,国家和政府较少参与;研究分布十分广泛,研究力量集中在美国、欧洲和亚洲少数国家。发展我国远程教育事业需政府加大投入和扶持,引入市场机制,联合不同学科、不同研究机构,谋求教育理论和技术革新的共同发展。  相似文献   

Approaches to measuring use of research evidence in K-12 settings: A systematic review     

《Educational Research Review》2019

An increased focus on the use of research evidence (URE) in K-12 education has led to a proliferation of instruments measuring URE in K-12 education settings. However, to date, there has been no review of these measures to inform education researchers’ assessment of URE. Here, we systematically review published quantitative measurement instruments in K-12 education. Findings suggest that instruments broadly assess user characteristics, environmental characteristics, and implementation and practices. In reviewing instrument quality, we found that studies infrequently report reliability, validity, and demographics about the instruments they develop or use. Future work evaluating and developing instruments should explore environmental characteristics that affect URE, generate items that match up with URE theory, and follow standards for establishing instrument reliability and validity.  相似文献   

近两年我国击剑的实力格局与发展——以十二运为主线     

王威  ;刘莉颖 《辽宁体育科技》2014,(4):100-104

对十二运参赛地区、剑种分布、奖牌分布等情况进行统计分析,揭示我国击剑格局的变化;通过对近两年击剑个人积分排行的统计分析,探讨我国击剑发展的现状,分析预测我国各剑种的发展前景和各地区的优势项目及发展短板。  相似文献   

十二运辽宁体育场馆公共服务市场化研究     

邹月辉  李芃松 《体育成人教育学刊》2013,(5):28-31

体育场馆公共服务市场化是大型体育场馆建设和经营管理的发展趋势。十二运辽宁体育场馆公共服务市场化的对策为：加大体育场馆公共服务多样化发展的市场开发力度;充分发挥第三部门在场馆公共服务供给中的作用;辽宁体育公共服务发展战略与城市运动项目布局相结合;做好赛后体育场馆公共服务市场化的制度设计;寻求公共机制与市场机制的有机结合等。  相似文献   

The Progress and Strategy of National Training for K-12 Teachers in China in the New Era     

WANG Dinghua 《Frontiers of Education in China》2022,17(3):388

The reform of rural teacher team building has entered the deep-water zone where tough challenges must be met in the new era. In order to adapt to the new situation and cope with the new challenges, the national training of K-12 teachers in China should set up the concept of high-quality products, summarize the experience of the grass-roots level, aim at the prominent problems, give full play to the exemplary and leading role of the National Training Plan, and promote the comprehensive improvement of the quality and efficiency of teacher training. During the 13th Five-Year Plan period, the national training of K-12 teachers in China has achieved gratifying results, as well as considerable problems in the implementation of the National Training Plan. On the basis of sorting out the progress of the national training for K-12 teachers in the new era, this paper puts forward development strategies.  相似文献   

Reasons for student dropout in an online course in a rural K–12 setting     

Claire de la Varre  Matthew J. Irvin  Adam W. Jordan  Wallace H. Hannum  Thomas W. Farmer 《Distance Education》2014,35(3):324-344

Rural schools in the USA use online courses to overcome problems such as attracting and retaining teachers, geographic isolation, low student enrollment, and financial constraints. This paper reports on the reasons that 39% of rural high school students who enrolled in an online Advanced Placement course subsequently dropped the course. Students who dropped the course were asked to provide an email statement detailing their reasons for doing so. On-site facilitators—local staff members situated in the small rural schools where students were enrolled—also provided reasons whenever one of their students dropped the course. Results indicate that the reasons given by students and on-site facilitators for dropping the course often agreed, and tended to fall within the following five categories: scheduling and time constraints, academic rigor and motivation, technology problems, problems with online medium and lack of teacher immediacy, and parental influences.  相似文献   

试论12-14世纪伦敦市民阶层与王权的关系     

谭雯 《四川教育学院学报》2014,(8):97-102

中世纪中后期英国市民与王权的较量是英国历史发展的重要脉络之一,伦敦市民阶层表现尤为突出。诺曼征服后,伦敦因特殊的政治、经济地位获得城市特许状,其市民也拥有相当的自由权利。伦敦市民阶层主要包括商人、手工业者及其他获得市民权的城市居民。他们抑或通过手工业行会参与城市管理,抑或通过斗争和谈判在议会中获得一席之地。二者的关系既有冲突,也有妥协,其目的都为争取各自的利益。最终,其形成的规范和制度为英国宪政的发展和民族国家的形成作出了重要的贡献。  相似文献