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: Of 300 clinically evaluable patients , 175 ( 58 % ) were cured and 90 ( 30 % ) were improved at the post - therapy evaluation , resulting in a clinical success rate of 88 % .
### Output Text:
Of 300 clinically evaluable patients , 175 ( 58 % ) were cured and 90 ( 30 % ) were improved at the post - therapy evaluation , resulting in a clinical success rate of 88 % . 