1. Department III of Oncology, Binzhou City Central Hospital, Binzhou, Shandong 251700, P.R. China
2. Department of Hospital Infection-Control, Binzhou City Central Hospital, Binzhou, Shandong 251700, P.R. China
3. Department of Obstetrics, Binzhou City Central Hospital, Binzhou, Shandong 251700, P.R. China
4. Department of Senior Cadres, Binzhou City Central Hospital, Binzhou, Shandong 251700, P.R. China