Funding for this research was provided by:
National Natural Science Foundation of China (21207045)
Fundamental Research Funds for the Central Universities (2662018JC009, 2662015PY047)
Text and Data Mining valid from 2019-01-05
Received: 1 November 2018
Revised: 12 December 2018
Accepted: 14 December 2018
First Online: 5 January 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This article does not contain any studies with human participants performed by any of the authors.