PMC:7558333 / 149-172
Annnotations
LitCovid-sentences
{"project":"LitCovid-sentences","denotations":[{"id":"T3","span":{"begin":2,"end":10},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"\n\nAbstract\n(1) Backgrou"}