RT Journal Article SR Electronic T1 N-Acetylcysteine and disease progression in COPD JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 622 OP 622 VO 60 IS 8 A1 K Satkunam YR 2005 UL http://thorax.bmj.com/content/60/8/622.abstract AB