Funding for this research was provided by:
Natural science foundation of hunan province (2017JJ4072)
Text and Data Mining valid from 2020-01-13
Received: 23 September 2019
Accepted: 18 December 2019
First Online: 13 January 2020
Ethics approval and consent to participate
: Not Applicable.
: Not applicable.
: The authors declare that they have no competing interests.