The family size of nobles in the Northern Dynasty was smaller under the three level administration system than that under the supervision and protection of big families because a large unmber of protected people were checked by the three level administration system.
北朝豪族家庭规模 ,在三长制下比在宗主督护制下要小些 ,原因是三长制括出了大量荫附人口。
A new process of preparing tri-long-chain alkyl tertiary amine has been developed through catalytic amina-tion under atmospheric pressure.
专题开发了醇一步常压催化胺化制备三长链烷基叔胺新工艺。