柯林斯词典ppm 1. ABBREVIATION for parts per million 百万分率[chem] 返回 ppm剑桥词典abbreviation for parts per million (= a unit for measuring the amount of a substance that is mixed with a liquid or another substance ) 百万分之…(衡量物质与液体或其他物质混合时的度量单位，parts per million的缩写） 返回 ppm