查词历史：
- rad racquetball
- Noun
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1. a unit of absorbed ionizing radiation equal to 100 ergs per gram of irradiated material
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2. the unit of plane angle adopted under the Systeme International d'Unites; equal to the angle at the center of a circle subtended by an arc equal in length to the radius (approximately 57.295 degrees)
- synonym： radian
医学
- 1.拉德：词组radiation absorbed dose的首字母缩略词，系测量电离辐射吸收剂量的单位，相当于每克吸收物质(包括组织)转移100尔格能量。1拉德的生物学效应随接触辐射的组织而异。参见gray
