| Abbreviation | Definition |
|---|---|
| Ra | Radium |
| RACHEL | Random Access Chemical Hazards Electronic Library |
| RACHEL | Real-time Automated Combinatorial Heuristic Enhancement of Lead compounds |
| RACHEL | Remote Access Chemical Hazards Electronic Library |
| RACI | Royal Australian Chemical Institute |
| RACI | Royal Australian Chemistry Institute |
| RACM | Regional Atmospheric Chemistry Mechanism |
| RAI | radioactive iodine |
| RAMP | Rapid Analyte Measurement Platform |
| RAMP | Regional Aquatics Monitoring Program (Alberta Oil Sands) |
| RAP | Rubidium Acid Phthalate |
| RAPC | Recent Appointees in Physical Chemistry |
| RAPDF | Residue-specific all-Atom conditional Probability Discriminatory Function |
| RAR | Retinoic Acid Receptor |
| RARA | Retinoic Acid Receptor Alpha |
| RARB | Retinoic Acid Receptor Beta |
| RARE | Retinoic Acid Response Element |
| RARG | Retinoic Acid Receptor Gamma |
| RAS | Replicate And Simulate |
| Rb | Rubidium |