短语词组短语cetyl trimethyl ammonium bromide precipitation 十六烷基三乙基溴化铵沉淀法cetyl trimethyl ammonium bromide ctab 十六烷基三甲基溴化铵ammonium cetyl trimethyl bromide 溴化十六烷基三甲铵 返回 cetyl trimethyl ammonium bromide