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: Nefiracetam ( DM - 9384 ) reverses apomorphine - induced amnesia of a passive avoidance response : delayed emergence of the memory retention effects .
### Output Text:
<span class="chemical">Nefiracetam</span> ( <span class="chemical">DM - 9384</span> ) reverses <span class="chemical">apomorphine</span> - induced amnesia of a passive avoidance response : delayed emergence of the memory retention effects . 