Ma Changyan

Winter Olympic communication "three divisions a standard", how Hebei is doing
Beijing Winter Olympics Zhangjiakou Hebei Provincial Communications Administration Ma Changyan Zhou Jingyao Hebei Unicom
02-16
How will the Winter Olympics prevent the epidemic? A new detection system that is 10 times more sensitive than conventional methods has emerged
Coronavirus aerosol School of Medicine, Tsinghua University Nucleic acid testing Ma Changyan
01-19