本文课题受北京市卫生系统高层次卫生技术人才培养计划项目编号2009-2-17;国家973计划项目编号2011CB504300;教育部高等学校博士学科点专项科研基金项目编号20130001110108;创新团队发展计划项目编号IRT13003资助@@@@This work was supported by the High-level Technical Training Project Funding of the Beijing Health System2009-2-17;the National 973 Project of Major Basic Research2011CB504300;The Research Fund for the Doctoral Program of Higher Education20130001110108;Innovative Research Team in UniversityIRT13003