数据库 数据库理论 释文 external schema 外模式
- umbrella clause
- umbrella effect
- umbrella fern
- umbrella fern family
- umbrella ferns
- umbrella graph
- umbrella hydro-generator
- umbrella pine family
- umbrella sampling
- umbrella species
- Umbrians
- umbric epipedon
- Umbriel
- Umeda Hiroaki
- Umehara Ryūzaburō
- Ume Kenjiro
- Umezaki Haruo
- UMHK
- UMi
- Umicore
- UMi system
- umkehreinwand
- umklapp process
- umklapp process, U-process
- umklapp scattering