isomers


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isomers

[ī′səmərz]
compounds that have the same formula but different structures, resulting in different properties.

isomers (ī´sōmurz),

n.pl 1. organic compounds having the same empirical formula–i.e., the same number of the same atoms but different structural formulas and therefore different physical and chemical properties.
n 2. one of several nuclides having the same number of neutrons and protons but capable of existing, for a measurable time, in different quantum states with different energies and radioactive properties. The isomer of higher energy commonly decays to one with lower energy by a process known as isomeric transition.
isomers, optical,
n.pl two isomers whose structures, dextro- and levo-, differ only in a spatial arrangement that makes them mirror images. This occurs only when there is an asymmetric carbon atom–i.e., one attached to four different substituents. The pharmacologic activity often resides very largely in one of the two forms.
isomers, stereo-,
n.pl molecules that differ only in the spatial arrangement of the atoms. This term includes optical isomers.
References in periodicals archive ?
Assuming that the latent heat of fusion is only due to melting of crystalline trans isomers, the "ideal" crystallinity may be written as follows:
The 3-methoxybenzoic acid methyl ester contained in the same sample does not show ion 105, but instead identifies that fragment as 107 (see Figure 2) - the two isomers are clearly differentiated.
25 [micro]m thick 70 % cyanopropyl polysilphenylene-siloxane stationary phase was used in the separation of the methyl esters of the fatty acid isomers.
These findings further support the important antioxidant functions and roles that lutein and zeaxanthin isomers play in maintaining healthy vision.
In animal studies, some but not all of those isomers were thought to be bioactive.
In a study involving 362 asthmatic patients, single-isomer albuterol, called 1evalbuterol, was therapeutically equivalent to standard albuterol formulations, which are racemic (50:50) mixtures of R and S isomers but at one-quarter the dose and with fewer side effects.
In addition to similar morphology/property relationships like those in the methylene (diphenyldiisocyanate) (MDI) based elastomers, the existence of steric isomers of both [H.
Even when it was understood that in isomers the same number of the same sorts of atoms must be arranged differently, it was not clear what the difference in arrangement might be.
com/research/7b4c32/pentanol_amyl_alc) has announced the addition of the "Pentanol (Amyl Alcohol) And Isomers Thereof: Trends and Prospects in International Trade" report to their offering.
TTE data indicate that total branched isomers crossed the placenta more efficiently than did linear isomers for both PFOS (p < 0.
The method will help dietary supplement and food manufacturers make sure that no zeaxanthin isomers other than 3R 3'R are present in the zeaxanthin they source for their finished products, and make sure they are in compliance with GMP standards and FDA and EU regulations.