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: LY274614 , 3SR , 4aRS , 6SR , 8aRS - 6 - [ phosphonomethyl ] decahydr oisoquinoline - 3 - carboxylic acid , has been described as a potent antagonist of the N - methyl - D - aspartate ( NMDA ) subtype of glutamate receptor .
### Output Text:
<span class="chemical">LY274614</span> , <span class="chemical">3SR , 4aRS , 6SR , 8aRS - 6 - [ phosphonomethyl ] decahydr oisoquinoline - 3 - carboxylic acid</span> , has been described as a potent antagonist of the <span class="chemical">N - methyl - D - aspartate</span> ( <span class="chemical">NMDA</span> ) subtype of <span class="chemical">glutamate</span> receptor . 