The migration mechanism of elements in stream sediments is the theoretics part of regional geochemical surveys.

水系沉积物元素迁移机理是区域化探方法的理论基础。

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On the other hand, the population migration affects the spatial structure of intraregional economic, social and other elements and changes in industrial distribution.

另一方面，人口的迁移变动也影响着区域内部经济、社会等各种要素结构和布局的变化。

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Appropriate relative timing of formation of these elements and the processes of generation, migration and accumulation are necessary for hydrocarbons to accumulate and be preserved.

适当的这些要素形成的相关时间及生成作用、运移和聚集作用的过程是烃类聚集和保存所必需的。

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However, the fact that immigrants eventually surpass their native-born counterparts also suggests that migration is a selective process, bringing the more ambitious or venturesome elements of a population.

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