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: The chronological study showed an effect of a cumulative dose on body weight ( R = - 0 . 99 , p = 0 . 011 ) , necrosis ( R = 1 . 00 , p = 0 . 004 ) , TAP ( R = 0 . 95 , p = 0 . 049 ) , and DNA SBs ( R = - 0 . 95 , p = 0 . 049 ) .
### Output Text:
The chronological study showed an effect of a cumulative dose on body weight ( R = - 0 . 99 , p = 0 . 011 ) , necrosis ( R = 1 . 00 , p = 0 . 004 ) , TAP ( R = 0 . 95 , p = 0 . 049 ) , and DNA SBs ( R = - 0 . 95 , p = 0 . 049 ) . 