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 results show that reserpine produces different and abnormal movements , which are related to dose and schedule employed and can be considered as parkinsonian - like and tardive dsykinesia signs .
### Output Text:
These results show that <span class="chemical">reserpine</span> produces different and abnormal movements , which are related to dose and schedule employed and can be considered as parkinsonian - like and tardive dsykinesia signs . 