【医】 兆比率(百万分之几)

million PER per per- a million to one make a million million electron volts per diem per contra per head per digit per se parts per million concentration parts per million (ppm) parts per hundred million(pphm) parts per hundred million concentration equivalent per million(EPM) million instruction per second part per hundred million part per million million gallons per day equivalent per million million instructions per second