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101.
A.K. Srivastava Avni Pandey Arpita Nath Shraddha Chaurasia 《Journal of Saudi Chemical Society》2009,13(3):263-267
A series of alkenyldiarylmethanes (ADAMs) were subjected to QSAR analysis by using linear free energy relationship model of Hansch. QSAR has been developed using steric, electronic and topological parameters along with appropriate dummy variable. Statistical techniques were applied to identify the structural and physicochemical requirements for ADAMs. The results are critically discussed on the basis of regression data and cross-validation techniques. 相似文献
102.
This paper brings into focus some of the interesting effects arising from the motion of the liquid free surface due to sloshing in partially filled containers of several geometrical shapes in two dimensions. The slosh characteristics that include frequencies, free surface profiles and the hydrodynamic pressure over the container walls have been reported in this study. The equations of motion of the fluid, considered inviscid, are expressed in terms of the pressure variable alone. It is assumed that the frequency of the exciting oscillation is not in the immediate neighborhood of the natural slosh frequency, so that the slope of the free surface is small. Simple harmonic oscillation and earthquake excitations are used as the prescribed boundary conditions. A finite difference‐based iterative time‐stepping technique is employed to advance the solution in the time domain. The paper presents numerical solutions for rectangular, vertically mounted annular cylindrical, trapezoidal and horizontal circular cylindrical containers. Numerical results obtained are compared with the available existing solutions to validate the code developed. The parametric study of the slosh dynamic systems shows the importance of the nature of excitation, fluid height and the geometry of the container. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
103.
Samples of the magnesium-cadmium ferrite series CdxMg1?xFe2O4 (X = 0 to 0.8) have been studied by the Mössbauer-effect technique at 4.2 K. Mössbauer spectra for X = 0.0 to 0.8 suggest the existence of two hyperfine fields, one due to the Fe3+ tetrahedral ions (A-sites) and the other due to Fe3+ octahedral ions (B-sites). The systematic dependence of the isomer shifts, quadropole interactions and nuclear magnetic fields of 57Fe3+ ions in both A- and B-sites has been determined as a function of cadmium content. The variations in the isomer shifts with Cd content are consistent with the variations in the Fe3+ -O-2 internuclear separations. It has been found here that supertransferred hyperfine interactions do not contribute to the systematics of the A- and B-site hyperfine fields. 相似文献
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107.
In the present paper, application of Talbot interferometry for real-time vibration measurement is investigated. Experiments were conducted to measure/monitor out-of-plane motion of a vibrating loudspeaker membrane. Experimental results demonstrate that by using Talbot interferometry out-of-plane vibrations as well as phase lag between driving force and membrane oscillation can be measured. 相似文献
108.
Abhishek Upadhyay Vinay K. Singh Rahul Dubey Narendra Kumar L.K. Sharma Rana Krishna Pal Singh 《Tetrahedron letters》2017,58(46):4323-4327
A highly efficient one pot, multicomponent synthesis of 4H-benzo[g]chromene and pyrano[2,3-g]chromene derivatives are reported by electrochemically stimulated condensation of an aromatic aldehyde, malononitrile and some enolizable acidic compounds in ethanol at room temperature under constant current density. By utilizing common electrode materials and a simple constant current protocol, this method is a new alternative to conventional methods. 相似文献
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Summary The viscoelastic behavior of polymeric systems based upon the Leonov model has been examined for (i) stress growth and relaxation with intermittent shear flow, (ii) stress relaxation after a step in the shear strain and (iii) elastic recovery after shear flow. A large number of modes have been conveniently incorporated through the determination of the model parameters from conventional rheological data by using an effective least-square procedure. With a sufficient number of modes, the predictions are in very good agreement with corresponding experiments in literature, including the recent data for cases (i) and (ii) obtained by optical methods.The present theory agrees also with the Lodge-Meissner relation (
11 –
22)/
12 =
0 in a step-shear experiment. In general, the Leonov model leads to results which, in these test cases, are comparable to those from Wagner's theory. It is, however, considerably less difficult to apply, thus offering the possibility of analysing flow problems of practical interest.With 16 figures and 1 table 相似文献