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: These improvements or normalizations of impaired cognitive functions were seen at oral aniracetam doses of 10 - 100 mg / kg .
### Output Text:
These improvements or normalizations of impaired cognitive functions were seen at oral <span class="chemical">aniracetam</span> doses of 10 - 100 mg / kg . 