Funding for this research was provided by:
National Natural Science Foundation of China (21621004, 21776209, 21576200)
Text and Data Mining valid from 2018-09-29
Received: 29 July 2018
Accepted: 20 September 2018
First Online: 29 September 2018
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: For this type of study formal consent is not required.
: Informed consent was obtained from all individual participants included in the study.