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杂交稻不育系提纯复壮、繁殖技术的好坏是确保杂交水稻大面积高产、稳产、优质的关键。而对优良新组合同田早晚两季繁殖的合理安排及技术研究,又是迅速普及推广化良组合的重要环节。 相似文献
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聚焦数学核心素养发展的课堂会让学生走得更远.数学表达是一种聚焦学生数学核心素养发展,让学生走得更远的教学实践范式.以“认识不等式”一课的教学片断为例,展示了从数学表达视角下对初中数学概念教学进行设计,通过数学表达及转换助力学生思维显性化,从而使学生不仅掌握了扎实的数学基础知识,更通过数学表达发促使深度学习发生从而切实地形成数学素养. 相似文献
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An approach was presented to intensify the mixing process. Firstly, a novel concept, the dissipation of mass transfer ability(DMA) associated with convective mass transfer, was defined via an analogy to the heat-work conversion. Accordingly, the focus on mass transfer enhancement can be shifted to seek the extremum of the DMA of the system. To this end, an optimization principle was proposed. A mathematical model was then developed to formulate the optimization into a variational problem. Subsequently, the intensification of the mixing process for a gas mixture in a micro-tube was provided to demonstrate the proposed principle. In the demonstration example, an optimized velocity field was obtained in which the mixing ability was improved, i.e., the mixing process should be intensified by adjusting the velocity field in related equipment. Therefore, a specific procedure was provided to produce a mixer with geometric irregularities associated with an ideal velocity. 相似文献
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基于长线传输理论 ,研究变频调速系统中电机端过电压的产生机理 ,分析电缆长度和特性阻抗变化对过电压的影响 .并根据阻抗匹配原则 ,设计一套安装在电机端的阻抗匹配网络 ,经实验证明能有效地抑制电机端过电压 相似文献
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为适应新时代育人目标对教育发展的新要求,在OBE理念的指导下,对浙教版七年级下册数学书第6章“数据的收集与整理”单元积极探索设计并实施项目化学习,引导学生综合运用数学学科和跨学科的知识与方法解决问题. 相似文献