Funding for this research was provided by:
National Natural Science Foundation of China (31670954)
Text and Data Mining valid from 2019-05-20
Received: 6 April 2019
Accepted: 14 May 2019
First Online: 20 May 2019
Ethics approval and consent to participate
: The investigation was performed with the approval of the Xi’an Jiaotong University Ethics Committee.
: All subjects signed an approved informed consent after the study procedures had been explained and consented for publication.
: The authors declare that they have no competing interests.