Funding for this research was provided by:
National Natural Science Foundation of China (81701331)
Xi’an science and technology project (No.SF1510(4))
Text and Data Mining valid from 2019-05-21
Received: 8 March 2017
Accepted: 29 April 2019
First Online: 21 May 2019
Ethics approval and consent to participate
: Not applicable.
: The authors provide consent for publication.
: The authors declare that they have no competing interests.