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891.
Investigations on the thermal decomposition of FeSO4·H2O-BaO2 mixtures were carried out under isothermal conditions by using simultaneously solid electrolyte cell (EMF-method). Evoked interactions producing oxygen in the temperature range 553-673 K were established by means of a solid electrolyte oxygen analyzer. Based on Mössbauer spectroscopy data and X-ray analysis it was proved that these reactions were associated with the release of oxygen from barium peroxide, oxidation of ferrosulphate-monohydrate to FeOHSO4, and formation of barium ferrites such as BaFe2O4 and BaFe12O19. 相似文献
892.
Different tubing geometries were evaluated for use in high-speed counter-current chromatography. Standard round tubing was compared to rectangular and twisted rectangular tubing. The number of theoretical plates for a standard anthocyanin mixture from black currant was determined for each experiment. The results of twisted rectangular tubing were superior to a standard setup. 相似文献
893.
A fluorimetric determination method for N-arachidonoylethanolamine (anandamide) was developed using a precolumn fluorescence derivatization followed by coupled-column high-performance liquid chromatography (HPLC). Anandamide extracted from the rat brain tissue was derivatized with 4-N-chloroformylmethyl-N-methylamino-7-N, N-dimethylaminosulfonyl-2,1,3-benzoxadiazole (DBD-COCl), purified by a solid-phase extraction (Emporetrade mark), and assayed by the coupled-column HPLC. The HPLC consisted of phenyl (100 x 4.6 mm i.d. ) and octadecylsilica columns (250 x 4.6 mm i.d.), both connected by a six-port valve. The concentration of anandamide in rat brain was 3. 37 +/- 0.73 pmol/g with 6.47 and 3.57% of intra- and inter-day precisions, respectively. Using this method, we investigated the alteration of anandamide concentration in rat brain 30 min after administration of anandamide (2 mg/kg, i.p.) to rats pretreated with or without phenylmethylsulfonyl fluoride (PMSF; 30 mg/kg, i.p.), an inhibitor of amidohydrolase. In rats pretreated with PMSF, the brain concentration of anandamide was approx. 16-fold higher than that of rats without PMSF (p < 0.01). 相似文献
894.
X. -H. Deng S. -F. Jiao Y. Yan C. Wang G. -F. Wang B. Fang 《Russian Journal of Electrochemistry》2006,42(8):873-877
Aminylferrocene is successfully immobilized on nanosized gold colloid particles associated with a 1,4-benzenedimethanethiol
monolayer on a gold electrode surface and characterized by cyclic voltammograms and electrochemical impedance spectroscopy.
In a pH 7.0 phosphate buffer solution, the formal potential (E
0’) of Fc is 0.432 V (SCE), and the apparent surface electron-transfer rate constant is 0.89 s−. The immobilized Fc gives an excellent electrocatalytic response to the terbutaline oxidation. The catalytic-current response
of differential pulse voltammograms increases linearly with the terbutaline concentration from 1.75 × 10−7 to 5.62 × 10−4 mol/l. The detection limit is 2.30 × 10−8 mol/l. The determination of terbutaline in a tablet dosage is satisfactory. The method is simple, quick, and sensitive.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 8, pp. 969–974.
The text was submitted by the authors in English. 相似文献
895.
X. Liu F. Xu Y. Zhang L. Liu H. Huang X. Cai Y. Lin W. Chan 《Russian Chemical Bulletin》2006,55(6):1091-1092
(3R*,3aR*,9aR*)-3,9a-Dimethyl-2,3,3a,9a-tetrahydro-4H-furo[2,3-b]chromene-5,7-diol (xyloketal H), a representative of a new family of xyloketals, was isolated from the marine-derived mangrove
fungus Xylaria sp. 2508. Its structure was elucidated by spectroscopic data and single-crystal X-ray diffraction analysis.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1051–1052, June, 2006. 相似文献
896.
Merkx M Kopp DA Sazinsky MH Blazyk JL Müller J Lippard SJ 《Angewandte Chemie (International ed. in English)》2001,40(15):2725
The cover picture shows in the background the whole cell of a methanotrophic bacterium on which are superimposed components of methane monooxygenase (the structure of the hydroxylase component (top), one of the two four-helix bundles that house the catalytic diiron centers (left)) and a schematic diagram of the catalytic cycle by which the enzyme converts dioxygen and methane into methanol and water. More about this unusual enzyme system is reported by Lippard et al. on p. 2782 ff. 相似文献
897.
898.
M. Lindinger St. Becker G. Bollen K. Dasgupta R. Jertz H. -J. Kluge L. Schweikhard M. Vogel K. Lützenkischen 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,20(1):441-443
Doublet mass measurements of the isobars28Si3 and12C7 are performed by use of a Penning trap mass spectrometer and the Fourier transform ion cyclotron resonance (FT-ICR). The carbon and silicon cluster ions are produced by laser ablation. Results of these preliminary measurements are presented. 相似文献
899.
H. -L. Li Y. Ujihira S. Tanaka T. Yamashita K. Horie 《Journal of Radioanalytical and Nuclear Chemistry》1996,210(2):543-553
Positron annihilation lifetime measurements of PMMA, PEMA, PiPMA, PnPMA and PnBMA were performed in the temperature range between 15 and 300 K, where , and relaxational transitions occur for these polyalkylmethacrylates. The variations of free volume size and content calculated from the longest lifetime component against temperature are correlated to the results obtained by dielectric, viscoelastic and dynamic mechanical relaxation data of the polymers. The variations of free volume sizes and contents, apparent free volume fraction and size distribution of the polyalkylmethacrylates are well correlated with the rotational transitions of side chains. The location of free volumes, in which positronium annihilates can be estimated near the vicinity of alkyl groups bound to oxygen atom of side ester chains. 相似文献
900.
Topochemical investigations of peptide systems 总被引:4,自引:0,他引:4
M M Shemyakin Y A Ovchinnikov V T Ivanov 《Angewandte Chemie (International ed. in English)》1969,8(7):492-499
The basic principles of the topochemical approach to the investigation of the structure-function relation in peptide systems are formulated. This approach makes use of the new possibility of transforming natural peptides, consisting in the modification of the molecule as a whole and utilization of the resultant analogs to elucidate the boundaries of the stereoelectronic complementarity of the biologically active peptide to the corresponding receptor. In particular, on the example of depsipeptide antibiotics and their topochemical analogs the fruitfulness of using such compounds as tools in elucidating the physicochemical basis of functioning of biological membranes is shown. The topochemical principle has also been applied in preparing specific competitive inhibitors of proteolytic enzymes, whose study may shed light on the nature of the forces binding the substrate to the contact site of the corresponding enzyme. 相似文献