nucleus

n. 核,核心,原子核

These 1000 books will form the nucleus of the new school library.

这一千本书将构成学校新图书馆藏书的基础。

The nutritive tissue that is derived from the nucleus and surrounds the embryo of the seed.

外胚乳包在种子胚芽外，产生于细胞核的营养性组织