| Label | Id | |
|---|---|---|
| acenaphthylene | 33081 | |
| acephenanthrylene | 33085 | |
| acetoprole | 133321 | |
| acetylenes | 33644 | |
| actinium | 33337 | |
| actinoids | 33320 | |
| adenosine | 16335 | |
| alachlor | 2533 | |
| aldimine | 33271 | |
| aldimines | 33271 | |
| aldoheptose | 33918 | |
| aldohexose | 33917 | |
| aldooctose | 33919 | |
| aldopentose | 33916 | |
| aldotetrose | 33915 |