国家自然科学基金81471520;国家留学基金2011911033;北京市自然科学基金5122015;北京市卫生系统高层次卫生技术人才培养项目2014-3-075Fund programNational Natural Science Foundation of China81471520;State Scholarship Fund2011911033;Natural Science Foundation of Beijing5122015;Project of Training High-level Medical Technical Personnel in Health System of Beijing2014-3-075