Background and purposes: Tinnitus is an auditory phantom sensation experienced when no external sound is present.

背景与目的耳鸣是在无外界相应声源刺激时耳内有响声的一种主观感觉，发病率极高。

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This paper introduced some general information and background for cost accounting in public health institutions as well as the contents and purposes of cost accounting.

介绍公共卫生机构成本核算的现况及背景，并对成本核算的层次、内容和目的进行了探讨。

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Chapter one introduces the present situation of the current research field and the theoretical background. Purposes of the research and significance of the study are discussed in chapter one as well.

第一章介绍了此项调查研究的理论背景以及目前的研究情况，同时陈述了此项研究的研究目的以及研究意义。

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