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排序方式: 共有133条查询结果,搜索用时 343 毫秒
1.
R. Venkat narayan Vinod Kanniah Aruna Dhathathreyan 《Journal of Chemical Sciences》2006,118(2):179-184
Cobalt oxides were prepared by three different methods: (1) by reacting cobalt nitrate with oxalic acid, (2) co-precipitating
cobalt nitrate with sodium carbonate, and (3) using sodium dodecyl sulphate as organic surfactant. All three samples were
characterized before and after calcination by solvent extraction and the resulting products examined by IR spectroscopy. In
the case of method 3, the removal of surfactant was followed by TGA studies. Products from all three methods were identified
by XRD. Peaks in low angle XRD indicate the porous nature of the oxides. The morphology of the pores was studied by transmission
electron microscopy. Some irregular pore structures were obtained for samples from methods 1 and 2, with an average size of
4–6 nm. Only the product from method 3 using SDS as template showed ordered structure and optimum size, and Brunauer-Emmet-Teller
surface areas of the as-prepared, as well as the treated samples, exhibited H3 type hysteresis. The samples from the three
methods were used as catalysts in the oxidation reaction of cyclohexane under mild conditions and the catalytic efficiency
of the cobalt oxide was comparable with mesoporous cobalt oxides. 相似文献
2.
Starting with the unification hypothesis of mixings of quarks and leptons and small quark-like mixings at the see-saw scale,
we find that two large mixings for νe —νx03BC; andv
μ—v
τ at the weak scale are obtained as a result of renormalization group evolution and radiative magnification if the three neutrinos
are quasi degenerate in masses and possess the same CP parity. We also find thatU
e3
remains small and well within the CHOOZ-Palo Verde bound since the correspondingV
ub
for CKM mixing is very small. Several testable pedictions are pointed out. 相似文献
3.
Vutukuri DR Bharathi P Yu Z Rajasekaran K Tran MH Thayumanavan S 《The Journal of organic chemistry》2003,68(3):1146-1149
A mild deprotection strategy for allyl ethers under basic conditions in the presence of a palladium catalyst is described. Under these conditions, aryl allyl ethers can be cleaved selectively in the presence of alkyl allyl ethers. These conditions are also effective in the deprotection of allyloxycarbonyl groups. The utility of the current methodology in sequence specific dendrimer synthesis is demonstrated. 相似文献
4.
Rate constants for the reaction of ethyl bromoacetate with three series of substituted naphthoate ions have been measured
in an acetone-water mixture (90% v/v). Using σ
p
values rate constants at 30o correlate well with the Hammett equation yielding ρ=−0.54, −0.19 and −0.25 for (4,1−), (6,1−) and (6,2−) series, respectively.
Comparison of these ρ values with those of the reaction of phenacyl bromide reveals the failure of the reactivity-selectivity
principle RSP in these reactions. Failure of RSP has been explained in terms of isoselective temperature. 相似文献
5.
V. N. Vijayakumar T. R. Rajasekaran K. Baskar 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(13):2578-2584
A novel supramolecular liquid crystal (LC) is synthesized from the binary complex of 4-decyloxy benzoic acid and cholesteryl acetate. Fourier transform infrared (FTIR) spectroscopic study confirms the formation of intermolecular hydrogen bond between the mesogens. Various mesophases and corresponding textural changes in the complex are observed by comparing with its constituents through polarizing optical microscopic (POM) studies. The thermal stability factor of smectic phase for present complex is calculated. An interesting observation of present work is that investigation of extended thermal span of mesomorphic phases, decreased enthalpy, a nematic phase with a high clearing point and a low melting point. This is due to an arrangement of molecular reorientations and the development of new associations by hydrogen bonding. Optical tilt angle for smectic C phase is determined and the same is fitted to a power law. 相似文献
6.
B.V. Subba Reddy Govindaraju Karthik Tamilselvan Rajasekaran Aneesh Antony B. Sridhar 《Tetrahedron letters》2012,53(19):2396-2401
A rhodium(II) catalyzed [4+2]/[2+2] cycloaddition reaction of N-protected isatin-3-arylimine with acylketene derived from α-diazocarbonyl compounds has been achieved for the first time for the preparation of a novel class of spiro(oxindolyl)oxazinone and spiro(oxindolyl)-β-lactam derivatives. 相似文献
7.
Investigations are made to get the experimental conditions for obtaining periodic crystallisation of magnesium hydroxide in agar-agar gel. A detailed study is made on the dependence of the velocity constant (K), the spacing coefficient \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {p = \frac{{x_{n + 1} }}{{x_n }}} \right)'$\end{document} the length of the continuous precipitate and the width of the rings on the concentrations of the inner and outer electrolytes. Using SHINOHARA 's revised coagulation theory, the flocculation value F is calculated. F = Γ + C30, where Γ is the characteristic concentration of the outer electrolyte for which the flocculation starts and C30 is the reduced concentration of the reaction product. The value of the concentration of the outer electrolyte for which the flocculation stops (γ) is calculated. The dependence of F on the concentrations of the reactants is also discussed. Observation of a coneshaped precipitation is also reported. 相似文献
8.
J. D. Londono A. Habenschuss J. G. Curro J. J. Rajasekaran 《Journal of Polymer Science.Polymer Physics》1996,34(17):3055-3061
Wide-angle X-ray diffraction measurements were performed on polymer melts of isotactic and syndiotactic polypropylene (IPP and SPP), poly(ethylenepropylene) (PEP), polystyrene (PS), polyisobutylene (PIB), and polyethylene (PE), to study the dependence of the short-range structure of polymer liquids on chain architecture. Total structure functions, which comprise intra- and intermolecular contributions, were derived from the scattering data. The trivial Fourier components of the intramolecular structure (C(SINGLE BOND)>C ≃ 1.54 Å and C(SINGLE BOND)C(SINGLE BOND)C ≃ 2.55 Å) were subtracted from the total structure functions. The remaining functions contain only those intramolecular contributions dependent on the chain's conformational degrees of freedom, plus the intramolecular contributions. The structural differences between the polymers in momentum space are discerned only when the trivial components are subtracted. This subtraction also reduces the effects of truncation errors on Fourier transformation to real space. The short-range structure of PIB appears very different compared to all the others, which correlates with anomalies in a number of physical properties for this polymer. © 1996 John Wiley & Sons, Inc. 相似文献
9.
K. Balakrishnan B. Vengatesan N. Kanniah P. Ramasamy 《Crystal Research and Technology》1990,25(6):633-636
Single crystals of ternary chalcopyrite semiconductors such as CuInS2, CuInSe2, CuInTe2, and CuInSSe, a pseudo-ternary semiconductor, have been grown by Chemical Vapour Transport (CVT) technique using iodine as the transporting agent. Microstructural analysis was carried out with the help of Scanning Electron Microscope (SEM) and optical microscope for the grown single crystals. 相似文献
10.
Organoclay-modified hydroxylterminated polysulfone (PSF)/epoxy interpenetrating network nanocomposites (oM-PSF/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polysulfone and epoxy resin (PSF/EP) using diaminodiphenylmethane (DDM) as curing agent.The mechanical properties like tensile strength,tensile modulus,flexural strength,flexural modulus and impact properties of the nanocomposites were studied as per ASTM standards.Differ... 相似文献