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: In the periphery of the ischemic territory , SG in the cortex was greater ( less edema accumulation ) in the hypertensive group ( 1 . 041 + / - 0 . 001 vs 1 . 039 + / - 0 . 001 , P less than 0 . 05 ) .
### Output Text:
In the periphery of the ischemic territory , SG in the cortex was greater ( less edema accumulation ) in the hypertensive group ( 1 . 041 + / - 0 . 001 vs 1 . 039 + / - 0 . 001 , P less than 0 . 05 ) . 