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为了全面了解学生近视的发展、变化趋势和影响因素 ,进行本次定群研究。1 对象和方法1.1 对象 选取我市一所省级重点中学和一所学生来源与该校相近、教材相同的普通中学 1991年 9月入学的初中一年级学生共 40 9名作为观察对象 (重点中学学生 187名 ,普通中学学生2 2 1名 ) ,
In order to fully understand the development of students’ myopia, changing trends and influencing factors, this study was conducted in this study. 1 Subjects and methods 1.1 Object selection A major provincial secondary school in our city and a source of students similar to the school, the textbooks of the same general secondary school in September 1991 admitted a total of 409 first-year students as the observation object (key middle school 187 students, 22 2 ordinary middle school students),