Flavin: Any of a class of organic compounds, pale yellow biological pigments that fluoresce green.黄素: 一组浅黄 、 绿萤光生物色素,在植物和动物组织中分布很广,含量少.The cheaper FNDs fluoresce roughly as well as those produced with an electron beam.此种...
a flag high atop a pole高挂在旗杆顶端的旗子There is a seagull perched atop the mast.有一只海鸥停歇在桅杆上.A tuft of grass atop the wall sways right and left in the wind.墙上一棵草,风吹两边倒....