309968 NR non-responders 921 309973 NR Newton-Raphson 22 309969 NR nirmatrelvir/ritonavir 19 309966 NR nonrestricted 5 309967 NR non-relapsing 3 309974 N-R Nelson-Riley 2 309965 N-R N back to R 1 309971 N-R Nissen-Rossetti 1 309972 N-R Nitrenes 1 309970 N-R no-risk group 1 309963 N-R normal Krebs solution 1 309964 N-R novel minus repeated conditions 1