Methods: Using the methods of retrospective survey study, 270 senile patients who had intact clinical data during 1987-1998 for the first implantment were analysed.
方法：将1987～1998年间270例首次入院植入心脏起搏器的临床资料进行回顾性分析。
Methods Retrospective epidemiological cohort study and field survey were conducted for dermatological examination, occupational hygiene and occupational exposure history for 2 876 workers.
方法采用现况调查和回顾性队列研究方法，对2 876名队列成员进行皮肤科检查和现场职业卫生学及个人职业史的调查。
Method: Survey by a retrospective study of clinical cases and collecting the relative data.
方法：通过临床病历回顾性调查，收集相关资料。
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