Original:  We have developed a novel and comprehensive knowledge discovery framework, textbf COVID-KG to extract fine-grained multimedia knowledge elements (entities  , relations and events) from scientific literature.
Revised:  We have developed a novel and comprehensive knowledge discovery framework, textbf COVID-KG to extract fine-grained multimedia knowledge elements (entities and their visual chemical structures, relations , relations and events) from scientific literature.
Edit intent: meaning-changed