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101.
Goto K Yano Y Okada E Liu CW Yamamoto K Ueoka R 《The Journal of organic chemistry》2003,68(3):865-870
Specific acid catalysis of p-sulfonatocalix[n]arenes (n = 4, Calix-S4; n = 6, Calix-S6; n = 8, Calix-S8) was observed in the alcoholysis of N-acetyl-l-amino acids in methanol. The methanolysis rates of basic amino acid substrates (His, Lys, and Arg) were markedly enhanced in the presence of Calix-Sn, as compared with rates observed with p-hydroxybenzenesulfonic acid (pHBS), which is a noncyclic analogue of Calix-Sn. This catalytic effect of Calix-Sn was not observed for the methanolysis of Phe, Tyr, and Trp substrates. On the other hand, (1)H NMR experiments following the effect of Calix-Sn on N-acetyl-l-amino acid substrates in CD(3)OD showed that the spectrum of a mixture of the His substrate with Calix-Sn was significantly different from the combined spectra of the respective compounds. These changes in spectra support the formation of an inclusion complex of Calix-Sn with basic amino acids. Furthermore, it was obvious that methanolysis of the His substrate catalyzed by Calix-S4 and Calix-S6 obeyed Michaelis-Menten kinetics. These results indicate that the catalytic activity of Calix-Sn originates from its forming a complex with specific substrates (basic amino acids), similar to enzymatic reactions. 相似文献
102.
Nobutaka Takahashi Noboru Murofushi Saburo Tamura Nobuhide Wasada Hiroko Hoshino Toshikazu Tsuchiya Shin-Ichi Sasaki Tetsumi Aoyama Eiji Watanabe 《Journal of mass spectrometry : JMS》1969,2(7):711-722
Based on the element maps of twenty-two gibberellin methyl esters fragmentations are discussed, which are characteristic of the common structural features as well as structural modification in gibberellin homologues. 相似文献
103.
104.
D. Karakaş I. Ölmez S. Tosun G. Tuncel 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(1):187-192
Instrumental neutron activation analysis (INAA), flame atomic absorption spectrometry (FAAS), flame atomic emission spectrometry (FAES), graphite furnace atomic absorption spectrometry (GF-AAS), ion chromatography (IC) and visible spectrometry (VIS) were used to determine the composition of atmospheric aerosols, collected at a rural site in the Western Black Sea Coast of Turkey. A total of 354 daily aerosol samples were analyzed for 46 trace and major elements and ions. Sample preparation, quality control procedures, instrumental operating conditions for INAA and source apportionment work is presented. 相似文献
105.
Leyla Bitiş Sevda Süzgeç Ulaş Sözer Hasan Özçelik Josef Zapp Alexandra K. Kiemer Filiz Meriçli Ali H. Meriçli 《Helvetica chimica acta》2007,90(11):2217-2221
From the aerial parts of Delphinium buschianum Grossh ., collected in Turkey, a new diterpenoid alkaloid 1 , named budelphine, was isolated along with the known diterpenoid alkaloids karakoline ( 2 ), 18‐hydroxy‐14‐O‐methylgadesine ( 3 ), delsoline ( 4 ), lapaconidine ( 5 ), columbianine ( 6 ), 14‐benzoylneoline ( 7 ), and hetisine ( 9 ). The structure of 1 was established on the basis of 1H‐, 13C‐, DEPT, 1H,1H‐COSY, NOESY, HSQC, and HMBC NMR studies. 相似文献
106.
Supawan Joonwichien Eiji Yamasue Hideyuki Okumura Keiichi N. Ishihara 《Applied magnetic resonance》2012,42(1):17-28
Magnetic field effects (MFEs) on photocatalytic degradation of methylene blue (MB) solution over ZnO and TiO2 powders are investigated under static magnetic field up to 0.7 T with light irradiation by ultraviolet (UV) light emitting
diode. The UV–visible-near-infrared spectrometer is used to monitor the MB concentrations. The positive MFE is observed for
ZnO, while the negative MFE for TiO2, and both MFEs are increased with the increase in the magnetic field applied. By increasing the settling time (the time interval
between the preparation of MB solution and the powder dispersion into the MB solution), the photodegradation abilities under
MFEs are decreased for both the catalysts. The cause of MFE is discussed in terms of dissolved oxygen in the MB solution and
magnetic adsorption of the constituent molecules. 相似文献
107.
Congjun Yu Bünyamin Özkaya Prof. Dr. Frederic W. Patureau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(11):3682-3687
A mild and green electro-oxidative protocol to construct aromatic esters from methylarenes and alcohols is herein reported. Importantly, the reaction is free of metals, chemical oxidants, bases, acids, and operates at room temperature. Moreover, the design of the electrolyte was found critical for the oxidation state and structure of the coupling products, a rarely documented effect. This electro-oxidative coupling process also displays exceptional tolerance of many fragile easily oxidized functional groups such as hydroxy, aldehyde, olefin, alkyne, as well as neighboring benzylic positions. The enantiomeric enrichment of some chiral alcohols is moreover preserved during this electro-oxidative coupling reaction, making it overall a promising synthetic tool. 相似文献
108.
M. Emin Çorman Nilay Bereli Serpil Özkara Lokman Uzun Adil Denizli 《Biomedical chromatography : BMC》2013,27(11):1524-1531
As alternative hydrophobic adsorbent for DNA adsorption, supermacroporous cryogel disks were synthesized via free radical polymerization. In this study, we have prepared two kinds of cryogel disks: (i) poly(2‐hydroxyethyl methacrylate‐N‐methacryloyl‐l ‐tryptophan) [p(HEMA‐MATrp)] cryogel containing specific hydrophobic ligand MATrp; and (ii) monosize p(HEMA‐MATrp) particles synthesized via suspension polymerization embedded into p(HEMA) cryogel structure to obtain p(HEMA‐MATrp)/p(HEMA) composite cryogel disks. These cryogel disks containing hydrophobic functional group were characterized via swelling studies, Fourier transform infrared spectroscopy, elemental analysis, surface area measurements and scanning electron microscopy. DNA adsorption onto both p(HEMA‐MATrp) cryogel and p(HEMA‐MATrp)/p(HEMA) composite cryogels was investigated. Maximum adsorption of DNA on p(HEMA‐MATrp) cryogel was found to be 15 mg/g polymer. Otherwise, p(HEMA‐MATrp)/p(HEMA) composite cryogels significantly increased the DNA adsorption capacity to 38 mg/g polymer. Composite cryogels could be used repeatedly without significant loss on adsorption capacity after 10 repetitive adsorption–desorption cycles. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
109.
The perfect matchings in the n-cube have earlier been enumerated for n?≤?6. A dynamic programming approach is here used to obtain the total number of perfect matchings in the 7-cube, which is 391 689 748 492 473 664 721 077 609 089. The number of equivalence classes of perfect matchings is further shown to be 336 in the 5-cube, 356 788 059 in the 6-cube and 607 158 046 495 120 886 820 621 in the 7-cube. The techniques used can be generalized to arbitrary bipartite and general graphs. 相似文献
110.
S. Ö. Akdemir S. D. Eryilmaz E. Öztekin 《International journal of quantum chemistry》2012,112(6):1585-1591
In this article, extremely simple analytical formulas are obtained for rotational overlap integrals which occur in integrals over two reduced rotation matrix elements. The analytical derivations are based on the properties of the Jacobi polynomials and beta functions. Numerical results and special values for rotational overlap integrals are obtained by using symmetry properties and recurrence relationships for reduced rotation matrix elements. The final results are of surprisingly simple structures and very useful for practical applications. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 相似文献