| MRV | minute respiratory volume; mixed respiratory vaccine |
|---|---|
| RI | radiation intensity; radioactive isotope; radioimmunology; recession index; recombinant inbred [stra... |
| RR | radiation reaction; radiation response; rate ratio; rational recovery [group]; recovery room; relati... |
| URD | unspecified respiratory disease; upper respiratory disease |
| URI | uniform resource identifier; upper respiratory illness; upper respiratory infection |