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: Apomorphine , a nonselective dopamine agonist , was selected due to its biphasic behavioral effects , its ability to induce hypothermia , and to produce distinct changes to dopamine turnover in the rodent brain .
### Output Text:
<span class="chemical">Apomorphine</span> , a nonselective <span class="chemical">dopamine agonist</span> , was selected due to its biphasic behavioral effects , its ability to induce hypothermia , and to produce distinct changes to <span class="chemical">dopamine</span> turnover in the rodent brain . 