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991.
L. G. Lin Y. Wang J. W. Yan Y. Z. Yuan J. Xiang B. W. Mao 《Electrochemistry communications》2003,5(12):995-999
We report an in situ STM study of a potential-dependent long-range surface restructuring of Au(1 1 1) electrode in neat 1-butyl-3-methylimidazolium tetrafluoroborates (BMIBF4) ionic liquid. Au(1 1 1) undergoes a significant long-range surface restructuring upon cathodic excursion to −1.0 V vs. Pt quasi-reference. The restructuring involves the formation of tiny pits, which then develops into a stable worm-like network with an average width of the network grids 2 nm. Electrochemical annealing occurs at the cathodic limit with the presence of a reduction product of cation BMI+. A smooth surface is recovered with the appearance of the typical (√3 × 22) reconstruction of Au(1 1 1). The surface restructuring is reestablished upon anodic excursion to −1.3 V after the adsorbed reduction product is oxidized. The long-range surface restructuring phenomenon is tentatively explained as a result of partial charge transfer to the weakly adsorbed BMI+, which reduces the metal–metal cohesive energy. In addition, the synergetic effect of the counter anion BF4− may also be involved. The results provide a knowledge of Au(1 1 1) electrode behavior in the neat ionic liquid and are beneficial to understanding in situ STM results involving surface morphological changes in such a media. 相似文献
992.
M. M. Kabachnik Z. S. Novikova I. A. Chadnaya A. A. Borisenko I. P. Beletskaya 《Russian Chemical Bulletin》1998,47(2):332-339
A series of phosphorus(iii)-substituted azomethines and enamines were synthesized by the reaction of lithium salts of aldimines and ketimines with derivatives
of phosphorus(iii) acids. Some properties of the compounds synthesized were studied.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 339–346, February, 1998. 相似文献
993.
J. Epsztajn J. Z. Brzeziński K. Czech 《Monatshefte für Chemie / Chemical Monthly》1993,124(5):549-558
Summary The preparation of the pyridazinones10a,10b,11a,11b, and12a,12b from the ketoamides7,8, and9 and hydrazine hydrate is described. It was found that from ketoamides8b and9b in addition to the expected pyridopyridazinones11b and12b also aminopyridopyridazines14 and15 were formed and that ketoamide7b gave exclusively aminopyridopyridazine13. The pyridopyridazinones10b,11b, and12b were alkylated with alkyl iodides.
Anwendungen von Organolithium und verwandten Reagenzien in organischen Synthesen, Teil XII. Synthese von Phenyl- und Pyridylpyridopyridazinonen und ihren Derivaten
Zusammenfassung Die Darstellung der Pyridazinone10a,10b,11a,11b und12a,12b aus Ketoamiden7,8 und9 und Hydrazinhydrat wird beschrieben. Es wurde festgestellt, daß aus Ketoamiden8b und9b außer den erwarteten Pyridopyridazinonen11b und12b auch Aminopyridopyridazine14 und15 enstanden und daß das Ketoamid7b ausschließlich ins Aminopyridopyridazin13 überführt wurde. Die Pyridopyridazinone10b,11b und12b wurden mit Alkyljodiden alkyliert.相似文献
994.
A solution of metallic ytterbium in liquid ammonia reacts readily with various carbonyl complexes of metals to form the corresponding
lanthanide carbonylmetallates. The reaction of an excess of Yb in liquid NH3 with [CpFe(CO)2]2 gave (THF)4Yb[Fe(CO)2Cp]2 in 42% yield. It was suggested that the resulting complex contains two equivalent Yb−Fe bonds.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1883–1885, October, 1997. 相似文献
995.
S. Fakirov Z. Sarac T. Anbar B. Boz I. Bahar M. Evstatiev A. A. Apostolov J. E. Mark A. Kloczkowski 《Colloid and polymer science》1997,275(4):307-314
This second part of a systematic study of the properties of crosslinked-oriented gelatin involves the effects of orientation
and water content on the glass transition temperature T
g and on the melting behavior. The samples were the same as those in the preceding study, and their transition temperatures
were determined by both differential scanning calorimetry and dynamic mechanical thermal analysis. The crosslinked gelatin
which had been room-conditioned showed two transition temperatures: the lower one was attributed to T
g of the water-plasticized gelatin, and the higher one was interpreted as T
g of dried gelatin superimposed by melting. A rather unusual situation arose because of the fact that the T
g and melting temperatures T
m (217 and 230 °C, respectively) are so similar. Using water as plasticizer not only decreases T
g but produces imperfect crystallites which melt below the T
g of the system. The presence of the amorphous phase in the glassy state would presumably make it essentially impossible to
define a melting point or crystallization temperature in the normal manner, as an equilibrium between crystalline and amorphous
phases.
Received: 8 October 1996 Accepted: 2 November 1995 相似文献
996.
997.
Application of capillary isotachophoresis in peptide analysis 总被引:1,自引:0,他引:1
This paper gives a broad and detailed review of the applications of one of the modern high-performance electromigration separation techniques--capillary isotachophoresis (ITP)--in peptide analysis. Examples are presented of the utilization of capillary ITP for peptide analysis in the fields of chemistry, general and clinical biochemistry, biology, biotechnology, pharmacy and the food industry. The complete composition of all the electrolyte systems used for peptide ITP analyses in both cationic and anionic techniques is given in tabular form. According to the purpose of analysis the applications are divided into several sections: model studies, determination of physico-chemical characteristics, purity control of both intermediate and final peptide preparations, including the determination of low-molecular-mass ionogenic admixtures, and the analysis of peptides in biological fluids and tissue extracts. In addition to the main applications the theoretical and methodological aspects of peptide ITP analysis are discussed. The basic electromigration properties of peptides (their polyampholyte character, effective and absolute mobilities, acid-base equilibria) are explained and the selection of parameters for peptide ITP analysis is described in detail. The advantages and disadvantages of ITP compared with other electrophoretic and chromatographic methods used for peptide analysis are discussed. 相似文献
998.
The influence of ammonia on propane oxidation over a Ga–Sb oxide catalyst has been studied. Acrylonitrile is formed upon the interaction of acrolein with partially dehydrogenated ammonia. Ammonia increases the rates of overall and selective oxidation of propane. This is assumed to be due to the formation of electron-donor sites promoting proton separation from the propane molecule.
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999.
1000.
Chemistry of Natural Compounds - The roots ofPrangos ferulaceae (L.) Lindl. have yielded (?)-7-methoxy-8-(β, γ-dihydroxyisopentyl)-coumarin, composition C15H18O5, with mp 128°.... 相似文献