Xi, Hong-Qing
Zhang, Ke-Cheng
Li, Ji-Yang
Gao, Yun-He
Liang, Wen-Quan
Cui, Jian-Xin
Wei, Bo
Chen, Lin
Article History
Received: 29 August 2018
Accepted: 2 April 2019
First Online: 16 May 2019
Compliance with Ethical Standards
: Research activities involving the study of existing data are exempt from the requirement for institutional review board approval.
: The authors declare they have no competing interests.