山西省高等学校教学改革创新项目J2016035;山西省煤矿公共卫生研究生创新中心资助项目KY2015005;山西医科大学博士启动基金项目03201415 The Teaching Reform Innovation Project of Colleges and Universities in ShanxiJ2016035;the Innovation Center of Coal Mine Public Health Graduate Student of Shanxi ProvinceKY2015005;Shanxi Medical University Doctoral Foundation Project03201415