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排序方式: 共有271条查询结果,搜索用时 15 毫秒
1.
Anil Khurana 《Zeitschrift für Physik B Condensed Matter》1994,95(3):287-289
The Hubbard solution to the Hubbard model showed a non-trivial metal-insulator transition. The value of the one-particle density of states at the Fermi energy in that solution decreased continuously with increasing value of the Hubbard interaction and vanished at a critical value of the interaction. Such a solution is derived from a planar model, as an approximation to the exact construction of the model's one-particle Green function. 相似文献
2.
The thermal stability of some boracites, CuB7O13Cl, NiB7O13Br and FeB7O13I, was investigated using thermogravimetry in air up to 1000°, DTA in air to 1200° and evolved gas analysis in vacuum to 1200°C. Only the FeI compound showed weight loss below 1000°C. The endothermic peaks associated with melting were CuCl (1025°C), NiBr (1150°C) and FeI) (965°C). Evolved gas analysis indicated major differences in the decomposition products of the three materials. 相似文献
3.
Upendra Nath Dash Banka Behari Das Uttam Kumar Biswal Tapodhan Panda 《Thermochimica Acta》1984,80(2):331-342
The standard potentials of silver—silver bromide and silver—silver iodide electrodes in glycerol+water mixtures containing 5, 10, 20 and 30 wt% glycerol were determined from electromotive force measurements of the cell Ag(s), AgX(s), KX(c)//KCl(c), AgCl(s), Ag(s), where X is Br or I, at seven different temperatures in the range 5–35°C. The standard potentials in each solvent are represented as a function of temperature. The standard thermodynamic functions for the electrode reactions, the primary medium effects of various solvents upon X−, and the standard thermodynamic quantities for the transfer of 1 g-ion of X− from water to the respective glycerol + water media are evaluated and discussed in the light of ion—solvent interactions as well as the structural changes of the solvents. From the values of the Ag/Ag+ and Ag/AgX, X− electrodes, the thermodynamic solubility product constants of silver chloride, silver bromide and silver iodide have been determined in glycerol + water solvent mixtures at different temperatures. 相似文献
4.
-2-Chlorostilbene undergoes uncatalyzed LiAlH4 reduction giving phenanthrene and -stilbene. An electron transfer radical mechanism is proposed. LiAlH4 induced isomerization of -stilbene produces -stilbene. 相似文献
5.
Pinacol Formation and Reduction of Aromatic Carbonyls with Magnesium–Methanol at Ambient Temperature
Jitender M. Khurana Geeti Bansal Gagan Kukreja Ravi R. Pandey 《Monatshefte für Chemie / Chemical Monthly》2003,421(5):1365-1371
A simple and inexpensive procedure for the pinacol formation of aromatic aldehydes and reduction of aromatic ketones to the corresponding alcohols with magnesium in dry methanol at ambient temperature is reported. The pinacol formation and reduction are proposed to be proceeding by SET from magnesium. 相似文献
6.
Poly(vinyl chloride) (PVC)-based membrane of pentathia-15-crown-5 exhibits good potentiometric response for Hg2+ over a wide concentration range (2.51 × 10−5 to 1.00 × 10−1 mol dm−3) with a slope of 32.1 mV per decade of Hg2+ concentration. The response time of the sensor is as fast as 20 s. The electrode has been used for a period of six weeks and exhibits fairly good discriminating ability towards Hg2+ in comparison to alkali, alkaline and some heavy metal ions. The electrode can be used in the pH range from 2.7 to 5.0. 相似文献
7.
Meena Kumari Upendra Kumar Singh Abbul Bashar Khan Maqsood Ahmad Malik 《Journal of Dispersion Science and Technology》2018,39(10):1462-1468
The effect of bovine serum albumin on the surface properties of IL-type gemini surfactant ([C10-4-C10im]Br2), have been investigated by surface tension method. The critical micelle concentration (CMC) as a function of BSA concentrations at various temperatures was investigated. The CMC of [C10-4-C10im]Br2 increases with increasing the concentration of BSA as well as the temperature of the system. The interfacial parameters viz; maximum surface excess concentration (Γmax), the minimum area per molecule (Amin), and surface pressure at CMC (Πcmc) were calculated. In addition, thermodynamic parameters of adsorption and micellization were evaluated by using surface tension data. The results indicated that the binding of [C10-4-C10im]Br2 to BSA is spontaneous and exothermic in nature. The process is entropy driven and hydrophobic interactions are the major driving forces. 相似文献
8.
Arylthiols, aralkylthiols and alkane thiols can be readily alkylated by alkyl/aralkyl halides in presence of K2CO3DMF to yield unsymmetrical sulphides in nearly quantitative yields. 2-Mercaptoethanol gave the thioether chemoselectively. 相似文献
9.
Facile and convenient one-pot cascade/tandem approaches for the syntheses of privileged medicinal scaffolds, 12-aryl-2,3,4,12-tetrahydrobenzo[b]xanthene-1,6,11-trione derivatives, have been reported under extremely mild reaction conditions using a catalytic amount of H2SO4 in water or in the presence of the acidic ionic liquid bmim[HSO4], which could be recycled. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
10.
A new and efficient method has been developed for the synthesis of biologically significant 2-arylbenzimidazoles, 2-arylbenzothiazoles, and azomethines using recyclable and inexpensive polyvinyl pyrrolidone (PVP)–stabilized Ni nanoparticles in ethylene glycol at room temperature in excellent yields. 相似文献