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: RESULTS : Clomipramine exposure in immature rats produced significant behavioral and biochemical changes that include enhanced anxiety ( elevated plus maze and marble burying ) , behavioral inflexibility ( perseveration in the spontaneous alternation task and impaired reversal learning ) , working memory impairment ( e . g . , win - shift paradigm ) , hoarding , and corticostriatal dysfunction .
### Output Text:
RESULTS : <span class="chemical">Clomipramine</span> exposure in immature rats produced significant behavioral and biochemical changes that include enhanced anxiety ( elevated plus maze and marble burying ) , behavioral inflexibility ( perseveration in the spontaneous alternation task and impaired reversal learning ) , working memory impairment ( e . g . , win - shift paradigm ) , hoarding , and corticostriatal dysfunction . 