Funding for this research was provided by:
Young Scientists Fund (31702261, 31702262)
Natural Science Foundation of Shandong Province (ZR2017BC057, ZR2017BC048)
Text and Data Mining valid from 2020-01-25
Received: 29 October 2019
Accepted: 6 January 2020
First Online: 25 January 2020
Compliance with ethical standards
: The authors declare no competing interests.
Free to read: This content has been made available to all.