GB/T 18115.7-2006稀土金属及其氧化物中稀土杂质化学分析方法.钆中镧、铈、镨、钕、钐、铕、铽、镝、钬、铒、铥、镱、镥和钇量的测定Chemical analysis methods of rare earth impurities in rare earth metals and their oxides Gadolinium—Determiatnion of lanthanum,cerium,praseodymium,neodymium,samarium,europium,terbium,d