Liu, Shiwei
Duan, Xuening
Xu, Ling
Xin, Ling
Cheng, Yuanjia
Liu, Qian
Ye, Jingming
Zhang, Shuang
Zhang, Hong
Zhu, Sainan
Li, Ting
Liu, Yinhua
Funding for this research was provided by:
Beijing Municipal Science & Technology Commission (D090507043409010, Z131107002213007)
Beijing Municipal Commission of Health and Family Planning (2009-1011)