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从学习者、实践者与研究者的视角,跟踪调查当前中学化学教师对教学目标的认识及其发展。调查表明:化学教师在新课程实践过程中不断深化对三维教学目标的认识,不断探索三维教学目标的实施。提出并分析了当前化学教学中存在着三维教学目标认识不清,意识淡薄,理解困惑,目标偏失等问题。 相似文献
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We start from the intensity distribution of a standing wave (SW) laser field and deduce the classical equation of atomic motion.The image distortion is analyzed using transfer function approach. Atomic flux density distribution as a function of propagation distance is calculated based on Monte-Carlo scheme and trajectory tracing method.Simulation results have shown that source imperfection,especially beam spread, plays an important role in broadening the feature width,and the focus depth of atom lens for real atomic source is longer than that for perfect source.The ideal focal plane can be easily determined by the variation of atomic density at the minimal potential of the laser field as a function of traveling distance. 相似文献
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Interference lithography is used to fabricate a nanoimprint stamp, which is a key step for nanoimprint lithography. A layer of chromium in thickness of about 20 nm is deposited on the newly cleaned fused silica substrate by thermal evaporation, and a layer of positive resist in thickness of 150nm is spun on the chromium layer. Some patterns, including lines, holes and pillars, are observed on the photoresist film by exposing the resist to interference patterns and they are then transferred to the chromium layer by wet etching. Fused silica stamps are fabricated by reactive ion etching with CHF3/O2 as etchants using the chromium layer as etch mask. An atomic force microscope is used to analyse the pattern transfer in each step. The results show that regular hole patterns of fused silica, with average full width 143nm at half maximum (FWHM), average hole depth of 76nm and spacing of 450nm, have been fabricated. The exposure method is fast, inexpensive and applicable for fabrication of nanoimprint stamps with large areas. 相似文献
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We start from the intensity distribution of a standing wave (SW) laser field and deduce the classical equation of atomic motion. The image distortion is analyzed using transfer function approach. Atomic flux density distribution as a function of propagation distance is calculated based on Monte-Carlo scheme and trajectory tracing method. Simulation results have shown that source imperfection, especially beam spread, plays an important role in broadening the feature width, and the focus depth of atom lens for real atomic source is longer than that for perfect source. The ideal focal plane can be easily determined by the variation of atomic density at the minimal potential of the laser field as a function of traveling distance. 相似文献