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: Patients developing ESRD had a 6 - year survival after onset of ESRD of 27 % for the patients receiving hemodialysis versus 71 . 4 % for the patients developing ESRD who subsequently received kidney transplants .
### Output Text:
Patients developing ESRD had a 6 - year survival after onset of ESRD of 27 % for the patients receiving hemodialysis versus 71 . 4 % for the patients developing ESRD who subsequently received kidney transplants . 