Gu, Yuying
Yang, Hongmei http://orcid.org/0000-0001-6237-3302
Yan, Bin
Wang, Xiaodong
Zhao, Zhongying
Funding for this research was provided by:
National Statistical Research of China (No. 2015LZ59)
Key Projects of National Natural Science Foundation of China (No. 61433012)
Qingdao Scientific Development Plan of China (No. KJZD-13-28-JCH)
Natural Science Foundation of Shandong Province of China (No. ZR2014JL044)
Article History
Received: 28 July 2018
Revised: 24 January 2019
Accepted: 15 February 2019
First Online: 12 March 2019