nucleus

The nucleus of an atom is composed of protons and neutrons, which carry almost all of its mass.

(Chinese) 原子的核心由质子和中子组成，它们承载了原子的几乎全部质量。

In biology, the nucleus is often described as the 'control center' of the cell because it houses the DNA.

(Chinese) 在生物学中，细胞核常被描述为细胞的“控制中心”，因为它含有DNA。