Funding for this research was provided by:
National Natural Science Foundation of China (81800226, 81670354, 81270402, 81770243)
a major project from Shaan Xi Province of China (2016KTCL03-11)
Text and Data Mining valid from 2019-02-14
Received: 10 December 2018
Accepted: 28 January 2019
First Online: 14 February 2019
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee of Fourth Military Medical University.
: Not applicable.
: The authors declare that they have no competing interests.
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