尽管另一些人，质疑层叠岩石化石是否是细菌活动的结果，但他们也想知道那些化石是否只是化学沉淀物。
Others, though, question whether fossil stromatolites really are the result of bacterial action, and wonder whether they might be chemical precipitates instead.
不过，从石油生产化学制品的主要目的在于，生产出大量具有明确界定的化合物，以奠定石化工业的基础。
Nevertheless, the main objective in producing chemicals from petroleum is the formation of a variety of well-defined chemical compounds that are the basis of the petrochemical industry.
目的：探讨尿路结石化学成分定性分析的方法与应用。
Objective: To discuss the methods and application of qualitative analysis of urinary calculi.
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