In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Thermal enhancement of Adriamycin - mediated antitumor activity and normal tissue toxicities by whole body hyperthermia were compared using a F344 rat model .
### Output Text:
Thermal enhancement of <span class="chemical">Adriamycin</span> - mediated antitumor activity and normal tissue toxicities by whole body hyperthermia were compared using a F344 rat model . 