Funding for this research was provided by:
National Natural Science Foundation of China (51505061, U1608256)
Text and Data Mining valid from 2019-04-01
Received: 16 November 2018
Revised: 28 January 2019
Accepted: 22 February 2019
First Online: 1 April 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: The main codes and raw data corresponding to each figure are submitted as supplementary materials.