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991.
Y. E. Kutsovsky A. G. Mariasov Y. I. Aristov V. N. Parmon 《Reaction Kinetics and Catalysis Letters》1990,42(1):19-24
The ESE method was successfully used for investigating the texture of the adsorbents and catalysts. Equations were obtained for the kinetics of ESE signal decay due to dipole-dipole interaction between motionless paramagnetic centers distributed uniformly on the fractal surface of solid.
, . , , .相似文献
992.
Performance of the apparatus was evaluated in terms of stationary phase retention, partition efficiency and sample loading capacity. Preliminary studies with short coils revealed high retention of the stationary phase under a proper combination of the head-tail elution and planetary motion. Preparative capability of the apparatus was successfully demonstrated on efficient multigram separations of 2,4-dinitrophenyl amino acids, indole auxins, and bacitracin in a pair of large multilayer coils with a total capacity of 1.5 l. 相似文献
993.
Some water-soluble organic iodine compounds (aqueous solution) can be analyzed for iodine by isotopically exchanging with labelled elementary iodine (organic solution). The method is applicable to exchange systems in which the rate of the exchange is rather small but measurable, before the exchange equilibrium is attained. The iodine content of iodoaromatic amino acids such as 5-iodouracil and 3,5-diiodotyrosine can be determined within an error of ±4%. 相似文献
994.
L. Margulies N. Friedman M. Sheves Y. Mazur M.E. Lippitsch M. Riegler F.R. Aussenegg 《Tetrahedron》1985,41(1):191-195
Linear dichroism spectra of several retinoids and related polyenes incorporated in stretched polyethylene films were determined. It is suggested that the retinoids are oriented with the plane of the ring parallel to the stretching direction of the film, the long polyene chain being displaced from that direction. 相似文献
995.
Y Ito 《Journal of chromatography. A》1984,301(2):387-403
Extensive studies have been performed on hydrodynamic distribution of two immiscible solvent phases in helical and spiral columns by means of coil planet centrifugation. Under the Scheme IV [see Fig. 1 in Y. Ito, J. Chromatogr., 301 (1984) 377] planetary motion, the two phases display unilateral distribution in the coil, i.e., one phase travels toward the head and the other phase toward the tail. This hydrodynamic trend is sensitively affected by various factors such as physical properties of the solvent system, helical diameter of the column, revolutional radius, etc. Phase distribution diagrams obtained from a set of conventional two-phase solvent systems under various experimental conditions provide extremely useful information for both basic hydrodynamic studies and practical application in high-speed counter-current chromatography. 相似文献
996.
A novel thin-layer amperometric detector (TLAD) based on chemically modified ring-disc electrode and its application for simultaneous measurements of nitric oxide (NO) and nitrite (NO2−) in rat brain were demonstrated in this work. The ring-disc electrode was simultaneously sensitive to nitric oxide (NO) and nitrite (NO2−) by modifying its inner disc with electropolymerized film of cobalt(II) tetraaminophthalocyanine (polyCoTAPc)/Nafion and its outer ring with poly(vinylpyridine) (PVP), respectively. The ring-disc electrode was used to constitute a novel TLAD in radial flow cell for simultaneous measurements of NO and NO2− in rat brain combined with techniques of high performance liquid chromatography (HPLC) and in vivo microdialysis. It was found that the basal concentration of NO in the caudate nucleus of rat brain is lower than 1.0×10−7 mol l−1, NO2− concentration is 5.0×10−7 mol l−1 and NO exists in brain maybe mainly in the form of its decomposed product. 相似文献
997.
Kolev TM Yancheva DY Stamboliyska BA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(8):1805-1813
The FTIR spectra of pyridinium-betaine of squaric acid in 4000-100 cm(-1) frequency region in solid state were measured. In addition, the structure and harmonic vibrational frequencies of this molecule were theoretically evaluated using restricted Hartree-Fock and B3LYP density functional methods. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the experimental bands observed. Comparison with the experimental spectra provides important information about the ability of these computational methods to describe the vibrational modes in these highly polar strained ring compounds. 相似文献
998.
The performance of conventional and low-flow nebulizer systems with liquid chromatography in differentiating four arsenic species in urine was evaluated. Two low-flow (DIN and MCN) chamber assemblies and a conventional (CFN) nebulizer-spray chamber assembly were compared in the hyphenation of anion-exchange microbore liquid chromatography with inductively coupled plasma mass spectrometry. Under optimal analytical conditions, the detection limits of the four arsenic species were 0.2-0.6 ng ml(-1) for all the nebulizer systems tested. The chromatographic resolution was best in the case of DIN due to its minimal off-column dead volume and superior transport efficiency. Four arsenic species were determined in the certified reference materials NIST SRM 2670E and 2670N. 相似文献
999.
A modification of the procedure reported byJohnson andWalseth
1 for the preparation of (-32P)ATP:(-32P)GTP with a specific activity of more than 5000 Ci/mmol was made firstly, then it was used as the phosphate donor in the reaction catalyzed by the polynucleotide kinase, to transfer its radioactive phosphate to the 5-position of the 3-AMP, resulting (5-32P)3-ADP. After that, (5-32P)3-ADP was hydrolysed to (5-32P)AMP under the catalysis of Nuclease P1, the late was then phosphorylated to produce (-32P)ATP by the action of myokinase and pyruvate kinase. By this method, we firstly prepared (-32P)ATP with a specific activity of more than 4000 Ci/mmol which was measured by HPLC analysis. 相似文献
1000.