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排序方式: 共有173条查询结果,搜索用时 515 毫秒
1.
The temperature dependence of the electric quadrupole interaction frequency
l
o
, experienced by the181Ta probe occupying Hf site in the compounds Hf1-xTaxV2 has been measured for x=0.06, 0.10 and 0.20 in the temperature region between 8.5 K to 296 K. The measurements show lattice transformation in all the three compounds below 120 K. 相似文献
2.
Zirconyl chloride promoted highly efficient solid phase synthesis of amide derivatives 总被引:1,自引:0,他引:1
Cherkupally Sanjeeva Reddy Adki Nagaraj Pochampally Jalapathi 《中国化学快报》2007,18(10):1213-1217
An efficient solid phase route for the synthesis of amide derivatives by the reaction of carboxylic acids with urea in the presence of catalytic amount of zirconyl chloride under microwave irradiation conditions was described.In this way,a range of interesting amide derivatives was obtained in good to excellent yields.The catalyst was recycled with fresh reactants and it gave almost similar results without significant loss of activity up to the third run. 相似文献
3.
Kessel L Kalinin S Nagaraj RH Larsen M Johansson LB 《Photochemistry and photobiology》2002,76(5):549-554
The intrinsic fluorescence from the human lens on excitation in the UV region, referred to as blue lens autofluorescence, increases with age or in the presence of diabetes. The present study reveals that the relative contribution of compounds responsible for the blue autofluorescence appears to be a constant with age. Three potential candidates for the blue fluorescence were also studied with respect to fluorescence spectroscopic properties. These were argpyrimidine and pentosidine, both advanced glycation end products, and 3-hydroxykynurenine (3-OH-kynurenine), a photooxidative derivative of tryptophan. It was shown that the spectral properties of argpyrimidine and pentosidine are compatible with the observed blue fluorescence of the human lens, whereas the fluorescence from 3-OH-kynurenine is negligible. 相似文献
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Chilakapati Venkata Vishnu Vardhan Sajal Ghosh Subramaniam Nagaraj Raghavachary Sridharan Thiagarajan Gnanasekaran 《Journal of Thermal Analysis and Calorimetry》2013,112(1):127-131
A study of binary, CaBr2–CaHBr system was carried out by differential thermal analysis (DTA), covering the composition range from 100 % CaBr2 to 100 % CaHBr between room temperature and 800 °C. From DTA results, the contour of solidus and liquidus temperatures with composition is plotted and the phase diagram of CaBr2–CaHBr system is constructed. The system shows an eutectic reaction at 576 °C and the eutectic composition is 79.6 mol% CaBr2. Co-existing phases in different phase fields are characterized by X-ray diffraction analysis. 相似文献
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S. Nagaraj C. V. Vishnuvardhan Sajal Ghosh R. Sridharan 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1835-1839
The phase diagram of binary LiBr–CaBr2 system was investigated using differential thermal analysis (DTA) between room temperature and 800 °C. From the DTA results obtained over the entire range of composition from pure LiBr to pure CaBr2 in steps of ~5 mol%, the phase diagram was constructed and is reported here. The results indicated the possible existence of a compound at 50 mol% LiBr, namely, LiCaBr3. The compound undergoes peritectic decomposition at 552 °C. The system shows a eutectic reaction at 532 °C between this compound and LiBr phase, and the eutectic composition is close to 80 mol% LiBr. The compound LiCaBr3 decomposes into CaBr2 and LiBr phases below 272 °C. Co-existing phases in different phase fields are characterized by X-ray diffraction analysis. 相似文献
10.
Karuppiah Nagaraj Sankaralingam Arunachalam 《Journal of inclusion phenomena and macrocyclic chemistry》2014,79(3-4):425-435
The surfactant–cobalt(III) complex, cis-[Co(trien)(4AMP)(DA)](ClO4)3, trien = triethylenetetramine, 4AMP = 4-aminopyridine, DA = dodecylamine was synthesized and characterized by various spectroscopic and physico-chemical techniques. The critical micelle concentration (CMC) value of this surfactant–cobalt(III) complex in aqueous solution was found out from conductance measurements. The conductivity data (at 303, 308, 313, 318 and 323 K) were used for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔG m ° , ΔHm and ΔS m ° ). Also the kinetics of reduction of this surfactant–cobalt(III) complex by hexacyanoferrate(II) ion in micelles, β-cyclodextrin, ionic liquids (ILs) and in liposome vesicles (DPPC) media were studied at different temperature. The rate constant for the electron transfer reaction in micelles was found to increase with increase in the initial concentration of the surfactant–cobalt(III) complex. This peculiar behaviour of dependence of second-order rate constant on the initial concentration of one of the reactants has been attributed to the presence of various concentration of micelles under different initial concentration of the surfactant–cobalt(III) complex in the reaction medium. Inclusion of the long aliphatic chain of the surfactant complex ion into β-cyclodextrin leads to decrease in the rate constant. Below the phase transition temperature of DPPC, the rate decreased with increasing concentration of DPPC, while above the phase transition temperature the rate increased with increasing concentration of DPPC. It is concluded that below the phase transition temperature, there is an accumulation of surfactant–cobalt(III) complex at the interior of the vesicle membrane through hydrophobic effects, and above the phase transition temperature the surfactant–cobalt(III) complex is released from the interior to the exterior surface of the vesicle. In the presence of ionic liquid medium the second order rate constant for this electron transfer reaction for the same complex was found to increase with increasing concentration of ILs has also been studied. An outer-sphere mechanism is proposed for all these reactions and the results have been explained based on the hydrophobicity of the ligand and the reactants with opposite charges. 相似文献