a

a

名词 a:

a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation

同义词：angstrom, angstrom unit

any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes

同义词：vitamin A, antiophthalmic factor, axerophthol

one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose)

同义词：deoxyadenosine monophosphate

(biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA

同义词：adenine

the basic unit of electric current adopted under the Systeme International d'Unites

同义词：ampere, amp

the 1st letter of the Roman alphabet

同义词：letter a

the blood group whose red cells carry the A antigen

同义词：type A, group A