1. Life Sciences School of Lanzhou University, Lanzhou 730000, P.R. China
2. Department of General Surgery, Second Hospital of Lanzhou University, Lanzhou 730030, P.R. China
3. Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou 730030, P.R. China
4. Nursing School of Lanzhou University, Lanzhou 730000, P.R. China
5. Department of Intensive Care Unit, First Hospital of Lanzhou University, Lanzhou 730030, P.R. China