RI

• radiation intensity;

• radioactive isotope;

• radioimmunology;

• recession index;

• recombinant inbred [strain];

• recurrent inhibition;

• refractive index;

• regenerative index;

• regional ileitis;

• regional information system;

• regular insulin;

• relapse incidence;

• relative intensity;

• release inhibition;

• remission induction;

• renal index;

• renal insufficiency;

• replicative intermediate;

• resistive index;

• resistance indices;

• respiratory illness;

• respiratory index;

• response interval;

• reticulocyte index;

• retroactive inhibition;

• retroactive interference;

• ribosome;

• rosette index (or inhibition)

• intracellular resistivity