PMC:7102662 / 33-57
Annnotations
LitCovid-sentences
{"project":"LitCovid-sentences","denotations":[{"id":"T2","span":{"begin":4,"end":12},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"19\n\nAbstract\nBackground "}