A comprehensive summary of researches on pressure drop calculation methods and models for structured packing was presented. Theoretical aspects and applicability of the models were analyzed.

综述了文献中关于规整填料压降的计算方法和模型，并对这些模型的理论基础和适用条件做了简要分析和比较。

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The characteristic and mechanism of impact drilling machine are introduced followed by the summary of the present status of impact drilling machine tower researches at home and abroad.

本文首先介绍了冲击钻机的特点及工作原理，综述了国内外冲击钻机塔架的研究现状。

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Through reviewing related literature and materials in China in recent years, a systematic summary is made in present thesis on current researches of integration of rural and urban education.

通过整理近年来国内的相关文献，笔者对当前城乡教育一体化研究成果进行了系统的总结和归纳。

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