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971.
Paul V. Bernhardt Dr. Geoffrey A. Lawrance Brian W. Skelton Allan H. White 《无机化学与普通化学杂志》2007,633(7):1036-1039
Cations derived by protonation of the ligand title compound (L1) have been structurally characterized in their di‐ and tetra‐ protonated forms in the salts [H2L1][ClO4]2·2H2O and [H4L1][ZnCl4]2·4H2O. In both structures, one half of the formula unit comprises the asymmetric unit of the structure, the macrocycle being centrosymmetric, with the two macrocycles adopting similar conformations. In both salts, a pair of diagonally opposed macrocyclic secondary amine groups are protonated; in the [H4L1]4+ salt, the additional pair of protons are accommodated on the exocyclic pendant amine groups. The dispositions of the pendent amines differ between the two structures, being ‘equatorial’ with respect to the macrocyclic ring in the [H2L1]2+ salt, and ‘axial’ in the [H4L1]4+ salt. In other structurally characterized compounds containing [H4L1]4+ the equatorial disposition was found in the ferricyanide adduct, while in the tetraperchlorate salt the axial disposition was identified. The differences in disposition of the exocyclic groups are ascribed to the extensive H‐bonding in the lattices. 相似文献
972.
Ag2C4, the second silver carbide to be fully characterized, has been synthesized as a light-gray powder (contaminated with metallic silver) that is explosive at high temperature (130 degrees C) and sensitive to mechanical shock, rather like the well-known prototype Ag2C2. In the pair of hydrated double salts Ag2C4.6AgNO3.nH2O (n = 2, 3), the nearly linear, centrosymmetric 1,3-butadiyne-1,4-diyl dianion C42-exhibits an unprecedented mu8-coordination mode, each terminal being capped by four sigma-bonded silver(I) atoms with pi-interaction to one of them. 相似文献
973.
Effective monitoring of residues of nortestosterone and its major metabolite in bovine urine and bile 总被引:1,自引:0,他引:1
L A van Ginkel R W Stephany H J van Rossum H van Blitterswijk P W Zoontjes R C Hooijschuur J Zuydendorp 《Journal of chromatography. A》1989,489(1):95-104
The results of a newly developed method for the detection and identification of residues of nortestosterone (NT) and one of its major metabolites, 17 alpha-nortestosterone (epiNT) are described. The method is based on sample clean-up by immunoaffinity chromatography and detection by high-performance liquid chromatography and/or gas chromatography-mass spectrometry (selected-ion monitoring). All samples of bile from calves that had been treated with NT contained significant amounts of epiNT (6-18 micrograms/l). The NT content of these samples, if detectable, was below 1 microgram/l. Urine contained, with one exception, less than 1 microgram/l epiNT. NT itself if detectable, was, present in urine or bile at levels below 0.1 microgram/l. The results corresponds well with results obtained with a radioimmunoassay procedure. 相似文献
974.
975.
High density (98% of theoretical) was achieved at 900°C for an all-alkoxide derived bulk celsian gel prior to crystallisation. TEM indicated that crystallisation was dominated by volume nucleation and growth of hexagonal disc shaped hexacelsian. Kinetic studies using SEM indicate a maximum nucleation rate at 980°C and an activation energy for crystal growth of 566 KJ/mol. The high rates of densification and of nucleation are attributed to the high OH content in the gel-derived glass. 相似文献
976.
A micellar electrokinetic capillary chromatography (MECC) method for the separation of three active components, imperatorin (IM), isoimperatorin (IO) and scopoletin (SC), in Angelica dahurica Benth and its preparation was developed. The optimum separation for these analytes was achieved using 10 mM borate, 20 mM SDS and 10%(v/v) acetonitrile, with applied voltage of 22 kV. All experiments were performed using a 50.0 cm (42.5 cm effective length)x75 mum I.D. fused-silica capillary. The linear calibration range was 12.0-800.0 mug ml(-1) for IM, 10.0-850.0 mug ml(-1) for IO and 3.5-600.0 mug ml(-1) for SC. The recoveries of three constituents were from 91.3 to 108.7%. Also, the dissociation constant (pKa) of SC was determined by the CE method established in this paper. 相似文献
977.
Clifford J. M. Smyth M. R. Smyth W. Franklin 《Analytical and bioanalytical chemistry》1974,270(3):198-200
Analytical and Bioanalytical Chemistry - A combination of differential solvent extraction based on physical chemical properties of the species involved and differential pulse polarography has been... 相似文献
978.
S. Kushinsky J. Coyotupa K. Honda M. Hiroi K. Kinoshita M. Foote C. Chan R. Y. Ho W. Paul W. J. Dignam 《Mikrochimica acta》1970,58(3):491-503
Summary A gas Chromatographic method for the determination of estrone, estradiol and estriol in plasma of normal females is described. Purification is done by means of TLC of the free compounds and the acetates and quantitation is achieved by electron capture-gas chromatography of the estrogen heptafluorobutyrates. Experiments on the validation of the method are described along with some examples of its application.
Supported by USPHS Grants AM 09908 and RCDA 5 K 3-AM-31, 321 (S. K.) and a grant from the Ford Foundation. 相似文献
Zusammenfassung Eine gaschromatographische Methode zur Bestimmung von Östron, Östradiol und Östriol im normalen weiblichen Plasma wurde beschrieben. Die Reinigung erfolgte durch Dünnschichtchromatographie der freien Verbindungen und ihrer Acetate. Die quantitative Bestimmung wurde gaschromatographisch mit Hilfe eines Elektroneneinfangdetektors an Hand der Östrogenheptafluorobutyrate bewerkstelligt. Versuche zur Bewertung dieser Methode sowie Beispiele für ihre Anwendung wurden beschrieben.
Supported by USPHS Grants AM 09908 and RCDA 5 K 3-AM-31, 321 (S. K.) and a grant from the Ford Foundation. 相似文献
979.
H. W. Dürbeck 《Analytical and bioanalytical chemistry》1970,251(2):108-111
Separation of isomeric aromatic hydrocarbons from each other has been obtained using packed columns and Bentone 34 modified with silicone oil and lanolin. For maximum resolution the proportions of the modifying agents are very important. Retention data and chromatograms of two different column types are given (column 1∶6% Bentone 34; 2,5% lanolin; 1,5% silicone oil. Column 2∶10% silicone oil; 5% bentone 34; 4% lanolin) 相似文献
980.
Controlled growth of calcium carbonate by poly(ethylenimine) at the air/water interface 总被引:1,自引:0,他引:1
Two metastable calcium carbonate polymorphs, hemispherical vaterite and needle-like aragonite, are selectively formed at the air/water interface by the mediation of poly(ethyleneimine)(with molecular weights of 25000 and 2000, respectively) dissolved in supersaturated calcium bicarbonate solution. 相似文献