[1
]
Department of Respiratory Medicine, West China Medical School and West China Hospital,
Sichuan University, No. 3, Guo Xie Xiang, Chengdu, Sichuan 610000, China.
[2
]
Department of Respiratory Medicine, West China Medical School and West China Hospital,
Sichuan University, No. 3, Guo Xie Xiang, Chengdu, Sichuan 610000, China. Electronic
address: liangzongan@hotmail.com.