谈撰写医学论文之五于鹤春（续）４．正文：正文是论文的主体部分，其结构包括序言、材料与方法、结果、讨论等几部分。（１）序言：或称前言、引言或导言。这是论文具体内容的开头。首先应简要介绍研究什么课题及过去有关本研究的一般情况。然后说明进行本研究的动机、理... Talking about writing medical essay in Crane Spring (Continued) 4. The main body of the text is the main part of the dissertation, whose structure includes preface, materials and methods, results, discussions and other parts. (1) Preface: or foreword, introduction or introduction. This is the beginning of the paper specific content. First of all, we should briefly introduce the research topics and the general situation of the study in the past. Then explain the motivation for the study, reason ...