数据库 数据库新技术 释文 document type definition, DTD 文档类型定义
- null value database
- null value relational model
- null variety
- null vector
- null width
- NUMA
- Numancia
- Numano Mitsuyoshi
- number
- number average molar mass
- number-average molar mass
- number average molecular weight
- number-average molecular weight
- number axis
- number code
- number counting
- number counts of galaxy
- number cycle
- number density
- number density profile
- number distribution function
- number domain
- numbered asteroid
- numbered set
- numbered supernova