天津市自然科学基金资助项目13JCYBJC21700;天津市卫生局科技公关项目12KG113;天津市卫生局科技基金资助项目2012K2003;This study was supported by Natural Science Foundation of Tianjin13JCYBJC21700;Scientific and Technological Project of Tianjin Bureau of Public Health12KG113;Program for Science and Technology of Tianjin Bureau of Public Health2012K2003