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以人教版新、旧教材数列习题为研究对象,从“探究”、“背景”、“运算”、“推理”、“知识含量”五个方面对两版教材习题进行比较分析,发现:数列对于“运算”的要求高于其他因素,“背景”因素难度最低,其他三个因素难度差异不大.在“运算”因素上,新、旧教材差异不大,新教材的难度稍高于旧教材,在“探究”和“推理”因素上,新教材的复习题难度高于旧教材,但是在练习题上差异不大,甚至新教材难度有所降低;在“知识含量”因素上,无论练习题与复习题,新教材难度都高于旧教材;在“背景”因素上,旧教材的难度虽高于新教材,但是以“数学文化”为背景的题有所增加. 相似文献
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Rotational manipulation of massive particles in a 2D acoustofluidic chamber constituted by multiple nonlinear vibration sources 下载免费PDF全文
Qiang Tang 《中国物理 B》2022,31(4):44301-044301
Rotational manipulation of massive particles and biological samples is essential for the development of miniaturized lab-on-a-chip platforms in the fields of chemical, medical, and biological applications. In this paper, a device concept of a two-dimensional acoustofluidic chamber actuated by multiple nonlinear vibration sources is proposed. The functional chamber enables the generation of acoustic streaming vortices for potential applications that include strong mixing of multi-phase flows and rotational manipulation of micro-/nano-scale objects without any rotating component. Using numerical simulations, we find that diversified acoustofluidic fields can be generated in the chamber under various actuations, and massive polystyrene beads inside can experience different acoustophoretic motions under the combined effect of an acoustic radiation force and acoustic streaming. Moreover, we investigate and clarify the effects of structural design on modulation of the acoustofluidic fields in the chamber. We believe the presented study could not only provide a promising potential tool for rotational acoustofluidic manipulation, but could also bring this community some useful design insights into the achievement of desired acoustofluidic fields for assorted microfluidic applications. 相似文献
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采取文本分析法和比较研究法,通过研究人教A版、北师大版和苏教版共三版教材同一数学史的不同呈现方式,分析其价值与作用、知识之间产生的联系,进而得出一些思考与启示. 相似文献
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