Lu, Mengjiao
Yan, Haiying
Yu, Cuixiang
Yuan, Lei
Sun, Shujuan
Funding for this research was provided by:
Department of Health of Shandong Province (2016GSF201187, 2016GSF201187, 2016GSF201187, 2016GSF201187, 2016GSF201187)
Article History
Received: 16 April 2019
Accepted: 4 December 2019
First Online: 16 January 2020
Competing interests
: The authors declare no competing interests.