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141.
Kazuyuki MiyashitaHidenobu Murafuji Hiroshi IwakiEito Yoshioka Takeshi Imanishi 《Tetrahedron》2003,59(26):4873-4879
As a second-generation pyridoxal model compound for cystathionine β-synthase, we designed a novel model compound having an ionophore function and an imidazole function, application of which to the β-replacement reaction with various thiols smoothly took place to give S-substituted cysteines. Peptides having a serine-O-carbonate residue at the N-terminal position were also converted to the corresponding peptides having an S-substituted cysteine residue under the catalytic conditions of the novel pyridoxal model compound. 相似文献
142.
The chemical polymerization of aniline was carried out in media containing different linear dicarboxylic acids with the use of oxidants such as K2Cr2O7, KMnO4, K2S2O8, KIO3 and FeCl3. The highest yield and the conductivity were observed with K2Cr2O7. The yield and the conductivity of the polyaniline (PAn) synthesized were observed to decrease in the order of oxalic acid > malonic acid > succinic acid > glutaric acid > adipic acid > phthalic acid. The solubility tests carried out in solvents such as DMF, DMSO and NMP showed that the larger the dopant molecule, the higher is the solubility of polyaniline. The PAn synthesized was characterized by measurements of conductivity, intrinsic viscosity, density and FTIR, UV-VIS and TGA techniques. 相似文献
143.
144.
为增强有机锗化合物的生物活性,合成了一系列有机锗氨基酸酯类倍半氧化物,并重点研究了它们的快原子轰击质谱(FABMS)。研究结果表明:该系列化合物的各碎片离子峰与其组成及结构均有很好的对应关系及很强的规律性 相似文献
145.
Dagobert Achatz Markus A. Lang Alfons Vlkl Wolf Peter Fehlhammer Wolfgang Beck 《无机化学与普通化学杂志》2005,631(12):2339-2346
Carbonyl Complexes of Chromium, Molybdenum and Tungsten with Isocyano Acetate. Reactions of Coordinated Isocyanoacetate. Stabilization of Isocyanoacetic Acid and Isocyanoacetyl Chloride at the Metal Atom. Isocyanopeptides The reactions of [(OC)5MCNCH2CO2Et] (M = Cr, W) with Na[N(SiMe3)2] or with KOH afford the isocyanoacetate complexes [(OC)5MCNCH2CO2]? ( 1,2 ). Similarly, the complex [(OC)3Mo(CNCH2CO2?Li+)3] ( 4 ) was obtained from [(OC)3Mo(CNCH2CO2Et)3] ( 3 ) and LiOH. Protonation of 1 and 2 affords the sublimable isocyanoacetic acid complexes [(OC)5MCNCH2CO2H] ( 5 , 6 ; M = Cr, W) in which the functional isocyanide is stabilized at the metal atom. Reactions of [(OC)5WCNCH2CO2?K+] and of [(OC)3Mo(CNCH2CO2?Li+)3] with oxalyl dichloride give the isocyanoacetyl chloride compounds [(OC)5WCNCH2COCl] ( 9 ) (sublimable) and [(OC)3Mo(CNCH2COCl)3] ( 10 ); the latter ( 10 ) was not isolated. Complexes 9 and 10 were reacted in situ with β‐alanine, glycine, phenylalanine and methionine esters as well as the peptide esters GlyGlyOEt, PhePheOMe, Phe‐β‐AlaOMe, and GlyGlyGlyOMe to form the isocyanoacetyl amino acid esters ( 11 ‐ 14 ) and the isocyanoacetyl peptide esters ( 15 ‐ 18 ) which are stabilized at the molybdenum atom. 相似文献
146.
E.G. Zhizhina M.V. Simonova V.F. Odyakov K.I. Matveev 《Reaction Kinetics and Catalysis Letters》2003,80(1):171-179
Oxidation of butene-1 to butanone in the presence of homogeneous catalysts (PdSO4 + HPA-x), where HPA-x = H3+xPVxMo12-xO40, 1 £ x £ 4, was investigated. This reaction is found to be of the 1st order with respect to C4H8, and of the 0.64th order with respect to Pd. The reaction rate does not depend on the HPA-x concentration and pH of the solution.
The activation energy of the reaction is variable. A kinetic expression of the reaction is obtained for 303-343 K.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
147.
William J.?KraemerEmail author Jeff S.?Volek Barry A.?Spiering Jakob L.?Vingren 《Monatshefte für Chemie / Chemical Monthly》2005,136(8):1383-1390
Summary. Early research investigating the effects of L-carnitine supplementation has examined its role in substrate metabolism and in acute exercise performance. These studies have yielded equivocal findings, partially due to difficulties in increasing muscle carnitine concentrations. However, recent studies have proposed that L-carnitine may play a different role in exercise physiology, and preliminary results have been encouraging. Current investigations have theorized that L-carnitine supplementation facilitates exercise recovery. Proposed mechanism is as follows: 1) increased serum carnitine concentration enhances capillary endothelial function; 2) increased blood flow and reduced hypoxia mitigate the cascade of ensuing, destructive chemical events following exercise; 3) thus allowing reduced structural damage of skeletal muscle mediated by more intact receptors in muscle needed for improved protein signaling. This paradigm explains decreased markers of purine catabolism, free radical formation, and muscle tissue disruption after resistance exercise and the increased repair of muscle proteins following long-term L-carnitine supplementation. 相似文献
148.
Thepyrimidinesasaclassareknowntopossessextraordinarybiologicalpropertiesthataregenerallydistinguishedqualitativelybytheirapplicationsinpesticide,herbicide,bactericide,andmedicineinter-mediates犤1犦.Asurveyoftheseapplicationsandanum-beroftherelatedvariationsthataredevelopedrecent-ly,suchastheextraordinaryeffectiveherbicideofsulfonylsulfourea,revealsthebroadbiologicalimpor-tancejustbecauseofthewideoccurrenceofpyrimi-dinesringsystemsinthesemolecules犤2犦.Ithasbeenshownthatthemedicineintermediates… 相似文献
149.
K. A. Esikov V. Yu. Zubarev E. V. Bezklubnaya A. A. Malin V. A. Ostrovskii 《Chemistry of Heterocyclic Compounds》2002,38(8):986-991
We have obtained 5-phenyltetrazol-2-ylalkanoic acids and their derivatives containing terminal nitrile, amide, and tetrazol-5-yl groups. Tetrazolylalkanoic acids with two (pK
a 4.93) and three (pK
a 5.45) bridging methylene groups are weaker acids than the corresponding ditetrazoles pK
a 4.68 and 5.29 respectively). However, the acidity of 5-phenyltetrazol-2-ylacetic acid (pK
a 3.12), is higher than acidity of the corresponding ditetrazole (pK
a 3.27). 相似文献
150.
手性胺醇稀土配合物的合成、荧光性质及其催化芳香酮的不对称氢化反应 总被引:2,自引:0,他引:2
合成了三种新的含C2-对称轴的手性胺醇(PhOHCHCH2)2NCH2C6H4R (R=OCH3, L1; R=CH3, L2; R=Cl, L3), 将其与无水氯化稀土LnCl3•4THF (Ln=La, Sm, Gd)反应生成了九个新的胺醇类稀土配合物LLnCl•2THF (L=L1, L2, L3; Ln=La, Sm, Gd). 用元素分析、热重分析、红外和紫外光谱等手段对它们进行了表征. 荧光光谱显示一些配合物具有荧光性能. 原位催化芳香酮的不对称氢化反应表明: L1/SmCl3•4THF体系催化苯乙酮不对称氢化反应的转化率达71%, 相应的对映体过量值达32%. 相似文献