Funding for this research was provided by:
National Natural Science Foundation of China (No.81672011)
Fundamental Research Funds of Shandong University (2015JC044)
Text and Data Mining valid from 2019-12-01
Received: 12 September 2019
Accepted: 13 December 2019
First Online: 27 December 2019
Ethics approval and consent to participate
: Not applicable.
: All the authors consent to publish.
: The authors declare that they have no competing interests.