A New Kind of Surfactant: Long-chain Alkyltriphenylphosphonium& ⅵ. Determination of the Average Aggregate Number of Dodecyltriphenylphosphonium Bromide Micelle Based on Steady-state Fluorescence Quenching 一类新的表面活性剂长链烷基三苯基鏻Ⅵ.稳态荧光猝灭法测定十二烷基三苯基溴化鏻胶束的平均簇集数