(n.) Transposition, as of the letters or syllables of a word; as, pistris for pristis; meagre for meager.
(n.) A mere change in place of a morbid substance, without removal from the body.
(n.) The act, process, or result of exchange, substitution, or replacement of atoms and radicals; thus, by metathesis an acid gives up all or part of its hydrogen, takes on an equivalent amount of a metal or base, and forms a salt.
Example Sentences:
(1) Mechanistic and synthetic studies in organometallic chemistry have provided considerable insight into olefin metathesis and Ziegler-Natta polymerization.
(2) It's called metathesis , and it's a very common, perfectly natural process.
(3) New homogeneous olefin metathesis catalysts based on high oxidation state transition metals have opened new opportunities in polymer synthesis by providing unprecedented control in ring-opening polymerization of cyclic alkenes.
(4) The sequential nature of substitution errors was further analyzed by tallying and classifying errors as anticipatory (prepositioning), reiterative (postpositioning), or metathesis.
Substituent
Definition:
(n.) Any atom, group, or radical substituted for another, or entering a molecule in place of some other part which is removed.
Example Sentences:
(1) Replacement of vinyl groups with bulkier substituents (hydroxyethyl or acetyl groups) decreases holoenzyme stability and catalytic activity.
(2) The molar refractivity has been shown to be a superior parameter for the description of the activity of sulphonamides than the sum of electronegativities of atoms making up a heterocyclic substituent in the sulphonamide molecule and molecular weight of the substituent.
(3) Energy conformational calculations on these compounds were also carried out using the empirical energy program called MOLMEC, in order to better understand how the 4-R substituents modulate receptor binding affinities and efficacies.
(4) The N-substituents included methyl, benzyl, and beta-hydroxy- and beta-chloroethyl groups.
(5) Substitution at the 5'-position resulted in decreased efficacy as inhibitors of uridine kinase, particularly if the substituent was large.
(6) Enzyme-inhibiting ability for individual alkylphenols can be estimated based on the quantitative structure-activity relationship developed by Dewhirst (1980) and is a function of the free hydroxyl group, electron-donating ring substituents, and hydrophobic aromatic ring substituents.
(7) All other broad-spectrum benzimidazole anthelmintics, regardless of substituent at the 2 position (methyl carbamate or thiazolyl group), are flat.
(8) Difference spectra for the tetracyclines were dependent on the characteristics of the ring substituents.
(9) Activity was insensitive to oxygen and CO if the substrates had no additional substituents on either ring or contained only electron-donating substituents.
(10) The hypothesis that opiate agonism requires an N substituent in the axial position does not appear to be consistent with the increased potency of beta isomers in which axial N substituents are thermodynamically more unstable.
(11) The ability of the monocarboxylate analogues to inhibit depends strongly on the nature of substituents, particularly at the second carbon.
(12) The receptor subregion that interacts with the propyl C-1 of 1 is more tolerant of bulk and of polar substituents than the subregion that interacts with propyl C-3.
(13) The relative reactivities of three o-substituted phenols can be explained in terms of steric hindrance which is minimal for a single o-substituent.
(14) Sucrose esters were prominent surface constituents and 3-methylvaleric acid, 2- and 3-methylbutyric acid, and methylpropionic acid accounted for 60%, 25% and 9%, respectively, of total C3--C7 acyl substituents.
(15) In compounds with other substituents that promote activity, C-6 alpha substitution with -CH3, -Cl, or -Br strongly enhances activity; -F, -OCH3, carbonyl, or the unsubstituted compound promotes weak binding; and -OC2H5, -OAc, -OCOOCH3, or -OH eliminates binding activity.
(16) The hypoprothrombinemia in vitamin K-deficient female rats was caused by beta-lactam antibiotics with N-methyltetrazolethiol, thiadiazolethiol and methyl-thiadiazolethiol as the 3'-position substituent of the cephem nucleus.
(17) After prolonged adaptation of strain BN6 to growth on 6A2NS, this organism readily converted all naphthalene-2-sulfonates with OH- or NH2-substituents in the 5-, 6-, 7-, or 8-position.
(18) Six new 5(1H)oxo-2,3-dihydroimidazo[1,2-a]pyrimidine-6-carboxylic ethyl esters bearing an aromatic substituent in position 1 or 2 were obtained.
(19) This radioligand was selected as a synthetic target because of its potency as a 5HT3-receptor antagonist, its selectivity for this receptor viz a viz other 5HT-receptor subtypes, and the ability to readily incorporate three tritia via the indazole N-CH3 substituent.
(20) Instead, the latter experiment yielded 1,5-anhydro-2,3-di-O-methyl-D-mannitol, establishing the presence in the polysaccharide of terminal (nonreducing) D-mannopyranosyl groups bearing 4,6-O-(1-carboxyethylidene) substituents.