超音波法液位元元元元元元测定
ultra-sonic method of liquid meaduremert
单位元的附加
adjunction of an identity element
射影坐标系的单位元素
unit elements of projective coordinate system
超单元组合—超单元—单元划分
divition of “super unit combine—super unit—unit
乘法单位群
multiplicative group of units
紧群的群环
group ring of compact group
局部单位元半群
locally identiries semigroup
具有足够幂等元的群分次环
group graded ring with enough idempotents