Funding for this research was provided by:
National Natural Science Foundation of China (51561145014, 21536006)
China Postdoctoral Science Foundation (19Z102060011)
Text and Data Mining valid from 2019-05-10
Received: 25 January 2019
Accepted: 2 May 2019
First Online: 10 May 2019
Ethics approval and consent to participate
: Not applicable.
: All authors read and approved the final manuscript.
: The authors declare that they have no competing interests.