Funding for this research was provided by:
National Natural Science Foundation of China (11301235)
Candidate Talents Training Fund of Yunnan Province (2016PY027)
Text and Data Mining valid from 2019-03-08
Received: 12 June 2018
Accepted: 21 February 2019
First Online: 8 March 2019
: The authors declare that they have no competing interests.