PMC:7143846 / 4430-4525 JSONTXT

{"project":"LitCovid-PD-CLO","denotations":[{"id":"T18","span":{"begin":44,"end":45},"obj":"http://purl.obolibrary.org/obo/CLO_0001020"}],"text":" in China, it was very difficult to conduct a traditional paper survey in the affected areas; o"}