abundance
ratio of something within a given environment or sample
natural abundance
relative proportion of an isotope as found in nature; abundance of isotopes of a chemical element as naturally found on a planet
partial pressure
hypothetical pressure of gas if it alone occupied the volume of the mixture at the same temperature
abundance of the chemical elements
any of several measures of the occurrence of different chemical elements
volume fraction
dimensionless quantity
mass fraction
ratio of one substance's mass to the mass of the total mixture
relative species abundance
Concept in ecology
amount-of-substance fraction
proportion of a constituent to the total amount of all constituents in a mixture, expressed in mol/mol
allele frequency
relative frequency of a variant of a gene at a particular locus in a population