Funding for this research was provided by:
National Natural Science Foundation of China (31571652)
Natural Science Foundation of Beijing Municipality (6122002, 6162002)
National Key R&D Program of China (2016ZX08009003-004)
Youth Innovative Research Team of Capital Normal University
Text and Data Mining valid from 2019-07-11
Received: 22 January 2019
Revised: 4 June 2019
Accepted: 30 June 2019
First Online: 11 July 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 or animals performed by any of the authors.