Funding for this research was provided by:
National Natural Science Foundation of China (61574117, 61574119)
Natural Science Foundation of Guangdong Province (2018B030311002)
Text and Data Mining valid from 2019-11-25
Received: 18 July 2019
Accepted: 2 October 2019
First Online: 25 November 2019
: The authors declare that they have no competing interests.