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Curvature-induced dielectrophoresis for continuous separation of particles by charge in spiral microchannels 总被引：1，自引：0，他引：1
The separation of particles from a heterogeneous mixture is critical in chemical and biological analyses. Many methods have been developed to separate particles in microfluidic devices. However, the majority of these separations have been limited to be size based and binary. We demonstrate herein a continuous dc electric field driven separation of carboxyl-coated and noncoated 10 μm polystyrene beads by charge in a double-spiral microchannel. This method exploits the inherent electric field gradients formed within the channel turns to manipulate particles by dielectrophoresis and is thus termed curvature-induced dielectrophoresis. The spiral microchannel is also demonstrated to continuously sort noncoated 5 μm beads, noncoated 10 μm beads, and carboxyl-coated 10 μm beads into different collecting wells by charge and size simultaneously. The observed particle separation processes in different situations are all predicted with reasonable agreements by a numerical model. This curvature-induced dielectrophoresis technique eliminates the in-channel microelectrodes and obstacles that are required in traditional electrode- and insulator-based dielectrophoresis devices. It may potentially be used to separate multiple particle targets by intrinsic properties for lab-on-a-chip applications. 相似文献
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赵宝爱 《烟台师范学院学报(哲学社会科学版)》2001,18(3):35-39
国际法作为调整国际间相互关系的准则，理应得到国际社会的尊重和遵从。本文通过对中法战争期间，法国任意曲解国际公法，并以清政府违反国际公法为由肆意制造观间桥事件并挑起全面侵华战争以及战争期间以英国为首的西方列强在国际公法面前对待中法两国不同态度的考察和分析，得出了在“强权即公理”的近代国际社会中，国际法不过是强权政治遮羞布的结论。 相似文献
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修订后的《九年义务教育全日制小学语文教学大纲》在教学目的中明确指出：要在语文教学过程中“培育学生的创造力”。如何达到这一目的 ?关键在于教师。心理学认为，只有教师本人是创新型的，他才会发现、重视并有目的、有计划地开发学生的创新能力。 课堂教学是培养学生创新情趣和创造能力的主阵地。我们应借助课文内容，逐步引导学生读书时设疑解疑的兴趣和习惯，培养探索、求异的精神和能力。例如： 在教《蛇与庄稼》这篇课文时，学生学习了第一段，弄清了蛇与庄稼的联系后，我问学生：“洪水为什么能淹死蛇而不能淹死田鼠 ?”同… 相似文献
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班级是个集体。一个集体要有凝聚力，要有创新精神，应使个性都得到充分的发展，具有较强的自我管理能力和自我管理意识。过去“严父”“慈母”式的班主任已不适应当前的管理模式。事无巨细，事必躬亲也未必好。班主任跟班在低年级是必需的，到高年级管理班级则不一定天天跟班走。但教师的创新精神不能少，时代呼唤着教师必须有创新精神。 一、营造创新氛围 营造创新氛围是建立一个和谐、民主、平等、宽松的朋友式的师生关系，形成良好的学习氛围，上好每一节课的基础，也是管理好班级的基础。学生“亲其师，信其道”的心理要充分利… 相似文献
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Properties of school Chinese: implications for learning to read 总被引：12，自引：0，他引：12
The properties of the 2,570 Chinese characters explicitly taught in Chinese elementary schools were systematically investigated, including types of characters, visual complexity, spatial structure, phonetic regularity and consistency, semantic transparency, independent and bound components, and phonetic and semantic families. Among the findings are that the visual complexity, phonetic regularity, and semantic transparency of the Chinese characters taught in elementary school increase from the early grades to the later grades: Characters introduced in the 1st or 2nd grade typically contain fewer strokes, but are less likely to be regular or transparent, than characters introduced in the 5th or 6th grade. The inverse relation holds when characters are stratified by frequency. Low-frequency characters tend to be visually complex, phonetically regular, and semantically transparent whereas high-frequency characters tend to be the opposite. Combined with other findings, the analysis suggests that written Chinese has a logic that children can understand and use. 相似文献
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This study explores the lived experiences of Chinese teachers in American Chinese Schools. Max van Manen’s methodology for hermeneutic phenomenological research provides a framework for the study, and the philosophical writings of Heidegger, Gadamer, and Derrida guide the textual interpretations. Pedagogical voices of Aoki, Pinar, and Greene, and cultural journeys of Hongyu Wang and Xin Li reveal possibilities for understanding the experiences of Chinese teachers, as the question is addressed: “What is the meaning of teaching Chinese in American Chinese Schools?” Ten Chinese teachers engaged in a series of open-ended conversations. The conversations illuminate the experience of Confucian teaching meeting American pedagogies around two main themes. First, in following the metaphor of Chinese knotwork, the teachers speak of their struggles and challenges between Chinese Confucian and American pedagogies, reflect on splitting and splicing the knots through changing and adjusting their method of Confucian teaching. Second, they tell of the experiences of building bridges in a third space through dialogically connecting the different cultures and pedagogies in order to seek the appropriate way of teaching and learning Chinese well in American Chinese Schools. 相似文献
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洪秀全与杨秀清是太平天国农民运动的两位杰出领袖,大部分的太平天国官方文书都记载着洪秀全与杨秀清在金田起义时期以兄弟关系为主线,同心协力,共秉朝政;在定都天京后以君臣关系为主线,后来矛盾萌发,最终激化,终于演出了骨肉相残的悲剧。 相似文献
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（一）实验的指导思想和总体目标十多年来,我校在小学语文教学中进行了不少改革尝试,但由于这些改革仅仅着眼于语文教学的某些方面、某些局部问题,仅仅着眼于语文课本、语文课堂教学的改革,没有树立大语文观念,以致收效甚微,有的甚至中途夭折。“更新教学观念”是这项改革的思想基础。要搞好这项实验,我们要高瞻远瞩,从时代对人才素质的需要出发,从语文这门工具课的特殊功能出发,重新认识语文教学。变语文教学的封闭式为开放式,变单一的课堂教学为以课堂教学为主体,以课外活动、语言环境为两翼的新的教学体系,全面沟通课内与课… 相似文献
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要使学生学会创造性的学习，促进创造力的形成和发展，数学教学有着特殊的功能。数学教学中可以通过引趣激发学生的求知欲；树立发现问题的意识，多问几个“为什么”；利用问题教学培养学生良好的思维习惯和创造性思维能力。 相似文献