Funding for this research was provided by:
National Natural Science Foundation of China (81400072)
Natural Science Foundation of Shandong Province (2013HQ047)
Medicine and health development plan of Shandong Province (2017WS113)
Humanities and social sciences youth team project of Shandong University (IFYT18036)
Article History
Received: 9 July 2018
Accepted: 8 March 2019
First Online: 22 March 2019