Funding for this research was provided by:
National Natural Science Foundation of China (81573834)
Text and Data Mining valid from 2019-05-27
Received: 21 November 2018
Accepted: 26 April 2019
First Online: 27 May 2019
Ethics approval and consent to participate
: This study was conducted with approval from the Ethics Committee of Minzu University of China (ECMUC2019003CO). All participants were enrolled in the study after obtaining both written and verbal consent.
: Not applicable.
: The authors declare that they have no competing interests.
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