Effect  of  frailty on  rehospitalization for acute  exacerbations of COPD
Wang Lua, Tian Ronga, Zhou Weia, Niu Jianruia, Gao Maolongb
Clinical Focus . 2019, (4): 321 -325 .  DOI: 10.3969/j.issn.1004-583X.2019.04.006