chemical samplingmedical dictionary

A sample that is obtained by whatever means is convenient and then purified of irrelevant elements before analysis; the assumption of thorough mixing is not necessary.

(05 Mar 2000)

chemical sequencingmedical dictionary

A lab technique used to determine the sequence of nucleotides in a DNA molecule. The DNA molecule is labelled with radioactive phosphorous (chemical element P), cut into fragments, and analysed through electrophoresis.

(09 Oct 1997)

chemical shiftmedical dictionary

Dependence of the resonance frequency of a nucleus on the chemical binding of the atom or molecule in which it is contained.

See: chemical shift artifact.

(05 Mar 2000)

chemical shift artifactmedical dictionary

In magnetic resonance imaging, a dark band caused by a biochemical difference in resonant frequency of adjacent regions rather than a true anatomic separation.

(05 Mar 2000)

chemical solutionmedical dictionary

Preferred term: solution

chemical sympathectomymedical dictionary

<procedure>

<surgery> Destruction of the periareterial sympathetic nerves, as in Doppler's operation, by a corrosive such as phenol.

(05 Mar 2000)

chemical synapsemedical dictionary

<physiology> A nerve to nerve or nerve to muscle junction where the signal is transmitted by the release of a chemical neurotransmitter from one nerve ending that binds to a corresponding receptor in the receptor nerve. This allows the conduction of signals from one to another and only in one direction.

(11 Mar 2008)

chemical synergismmedical dictionary

Interaction of chemicals in a mixture to produce a greater toxic effect than would be expected from the sum of the toxicities of the individual chemicals.

(09 Oct 1997)