Funding for this research was provided by:
National Natural Science Foundation of China (81402620, 81220108016, 81672692, 81430073)
Text and Data Mining valid from 2018-01-18
Received: 10 July 2017
Revised: 3 January 2018
Accepted: 12 January 2018
First Online: 18 January 2018
Compliance with ethical standards
: The authors have declared that no competing interest exists.
: The study protocol was approved by the Medical Research Ethics Committee at Xijing Hospital of the Fourth Military Medical University (Xi’an China). Written, informed consent was obtained from all participants prior to the study.