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: Effects of tetrandrine and fangchinoline on experimental thrombosis in mice and human platelet aggregation .
### Output Text:
Effects of <span class="chemical">tetrandrine</span> and <span class="chemical">fangchinoline</span> on experimental thrombosis in mice and human platelet aggregation . 