The prodrome of this paper includes main topics, research purpose, researching range and current situation about the relevant research in China and abroad, and the main methods the paper adopted.

在论文的序论中，介绍了论文的主题和研究目的，论文的研究范围，国内外相关领域的研究现状，以及论文研究采用的主要研究方式。

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The properties, applications and research situation at home and abroad of nanometer magnesia have been presented in this thesis.

本论文简要介绍了纳米氧化镁的性质、用途及国内外研究现状。

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Basic concepts and category classification of environmental hazards are reviewed according to the analysis on their present research situation home and abroad.

通过对国内外环境灾害研究现状的分析，综述了环境灾害的基本概念和类型划分。

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