排序方式： 共有73条查询结果，搜索用时 15 毫秒
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设H是Hilbert空间,{Wi}i∈I是H中的子空间框架。构造了一个算子序列Tn（.）=∑i∈Inv2iUn-2PnπWi（·）,运用有限维逼近方法,证明了算子序列Tn在强拓扑意义下收敛于子空间框架算子SW,v之逆SW-,1v. 相似文献
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Nicholas C. Block 《科学教学研究杂志》2020,57(3):454-478
Science students are increasingly challenged to use technical language related to the topics that they are studying, and therefore, science teachers benefit from knowing which tools are effective to support students in learning to use new terms. This study examined the impact of using one such tool—sentences frames—to teach science vocabulary, as measured through a science-writing task. Using an experimental approach with extant middle school science classes that offered a sample of 75 mainly Latino school students from grades six through eight, the researcher together with participating teachers identified 10 essential terms per science unit. The teachers used vocabulary-focused sentence frames for teaching the terms in one science unit, and a more traditional science text-based approach for teaching vocabulary in another unit. The writing task required at the end of the units consisted of essays in response to science-based prompts that directed students to use as many target science words as possible; matching/cloze format quizzes were also used to measure pretest and posttest receptive vocabulary knowledge. Findings indicated that there were advantages for teaching new science vocabulary via sentence frames as measured by use of the words in writing, but there were no advantages for sentence frames on quizzes measuring receptive vocabulary. Advantages of sentence frames for writing approached but did not reach statistical significance. There was some evidence that current and previous English language learners benefited more than initial English speakers from sentence frames, implying that utilizing sentence frames to teach science vocabulary might offer needed support especially for these subgroups. Limitations of the study included the sample size and the possibility that the strategy utilized in the comparison group might have offered some of the same advantages in producing language with technical vocabulary that the sentence frames unit offered. 相似文献
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《Journalism Practice》2013,7(10):1311-1331
Climate change frames in the media affect the political and public debate. However, focusing on the frames in texts, most framing research overlooks the factors which influence frame-building by reporters. However, this is crucial for a fuller understanding of the potential implications and meanings of frames. Besides, the existing frame-building research is exclusively engaged with mainstream media. Also, visual frame-building is under-researched. Therefore, we have conducted interviews with 26 climate journalists, photo editors, chiefs and opinion-makers, working for three mainstream and two progressive alternative outlets in northern Belgium. The findings were combined with the outcome of a deductive framing analysis of 114 climate articles. The results show a strong overlap among journalist frames and news frames. Anthropocentric Subframes prevail in the mainstream news articles and among the reporters. A mixture of Biocentric and Anthropocentric Subframes was found in the context of the alternative outlets. We explain this by presenting the studied mainstream newsrooms as machines and the (progressive) alternative newsrooms as organisms. We conclude that the mainstream journalists are guided towards Anthropocentric Subframes by various (internalised) pressures. The practices in the alternative media liberate reporters to introduce a broader variety of frames. 相似文献
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视频关键帧提取是视频信号处理中的一个重要内容。由于一个镜头中视觉内容的变化具有连续性,本文采用了距离累加的算法;同时,为了提高检测相邻帧间的相似度,本文将颜色特征与运动变化信息相结合,提出一种关键帧提取方法。实验证明,与过去的关键帧提取方法相比,本文算法提取的关键帧能较完整地表现序列图像的运动过程,更有利于对视频内容的理解。 相似文献
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基于用户数据包的防火墙技术的探讨 总被引：2，自引：0，他引：2
张韬 《广州广播电视大学学报》2006,6(1):20-22
随着计算机网络的迅猛发展和普及,网络安全已经愈来愈受到研究人员的重视,目前运用在防火墙上的核心技术仍然是包过滤和代理网关服务,为提高防火墙的检测效率和降低开发费用,本文从协议上入手,提出了在MAC层捕获数据包,然后在应用层过滤处理的策略,大大提高了防火墙的应用能力。 相似文献
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黄吉忠 《昆明师范高等专科学校学报》2000,22(4):108-110
近几年各地的中考数学试题，除了常规的填空题、选择题、计算题、证明题外，又涌现了一大批格调清新、设计优美、个性独特的开放性试题。这类题型的出现不仅题型本身别出新裁，使人赏心尽悦目，而且还扩大了知识和能力的覆盖面。 相似文献
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王会 《连云港职业技术学院学报》2012,25(1):14-16
对一个单层单跨钢框架结构进行抗火反应分析,运用大型有限元分析软件ANSYS中的三维热力耦合单元对该结构进行温度计算和力学分析,研究了火灾下结构的薄弱环节,得到结构的耐火时间和临界温度,并得出了各个时刻结构的温度场和变形,从而更加真实地反映出平面钢框架结构的抗火性能。 相似文献
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建筑与气候的关系本来应是个不言自明的“话题”。从生态建筑学的角度看,作为人“第三层皮肤”的建筑从产生之初就是为了庇护各种气候下的人流,但是这种自然的关系却往往受到人们的思想观念和滥用技术的影响而被忽视,“顺天应人”的良性循环被破坏,人本身也遭遇不幸,各种城市病、室内病便是应证。文章主要解释了微气候建筑设计的基本概念和设计方法,简要介绍了夏热冬暖地区的微气候建筑设计的设计原则。 相似文献
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This study examined the different and combined effects of regulatory focus (i.e. prevention-focused vs. promotion-focused) and issue involvement (i.e. high vs. low) with message frames (i.e. prevention-framed vs. promotion-framed) on attitude toward ads, message preference, and voting intention. Taken together, our findings revealed statistically significant two-way interaction effects of regulatory focus and message frames on all dependent measures, including attitude toward ads, message preference and voting intention; however, neither regulatory focus nor message frames exhibited primary effects on those dependent variables. Further, issue involvement was found to have a statistically significant main effect on dependent measures, which negated our expectation of both its interaction effect with message frames and its moderating role between regulatory focus and message frames. 相似文献