针对每个小组的研究主题,初步撰写研究背景。 撰写内容要求: provide background (demographic characteristics of the population~~) 流行病学特征 Define the problem adressed and why it is important 问题的严重性 Include a brief review of the key literature 文献综述 Note any relevant controversies or disagreements in the field 研究必要性 Conclude a brief statement of the overall aim of the study 研究目的