Text and Data Mining valid from 2018-06-13
Received: 6 November 2017
Accepted: 31 May 2018
First Online: 13 June 2018
Ethics approval and consent to participate
: The study protocol was approved by the Institutional Review Board of Shaanxi provincial people Hospital ((the ethics approval number provided by the board was 2,009,125)), and written informed consent was obtained from all study participants.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.