在化学等领域曾长期使用的 ppm,pphm,ppb,ppt 等缩写字,已被废弃。本刊已停止使用,希望作者予以配合。如涉及此类用法,均应指明它们所表示的物理量,并代之以它们所代表的数字。例如:2.6ppm,如果指质量分数或质量比值,则应写成 w=2.6×10~(-6);如指体积分数或体积比值,则应写成(?)=2.6×10~(-6)。pphm 则应表示为10~(-8)。 Abbreviations such as ppm, pphm, ppb, ppt, which have long been used in the chemical and other fields, have been discarded. This publication has been discontinued, I hope the author to cooperate. Where such usage is involved, the physical quantities they represent should be indicated and replaced by the numbers they represent. For example: 2.6ppm, if it refers to the mass fraction or mass ratio, it should be written as w = 2.6 × 10 ~ (-6); if refers to the volume fraction or volume ratio, . pphm should be expressed as 10 ~ (-8).