| 435 / | HD | CHEMISTRY: MOLECULAR BIOLOGY AND MICROBIOLOGY | 
| 41 | DF | MICRO-ORGANISM, TISSUE CELL CULTURE OR ENZYME USING PROCESS TO SYNTHESIZE A DESIRED CHEMICAL COMPOUND OR COMPOSITION {26} | 
| 117 | DF | .~ Preparing heterocyclic carbon compound having only O, N, S, Se, or Te as ring hetero atoms {4} | 
| 123 | DF | .~.~ Oxygen as only ring hetero atom {3} | 
| 125 |  | .~.~.~ Containing six-membered hetero ring (e.g., fluorescein, etc.) |