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31.
A.L. Dawar O.P. Taneja S.K. Paradkar Partap Kumar B.K. Sachar P.C. Mathur 《Journal of Physics and Chemistry of Solids》1982,43(3):267-270
Hall coefficient and d.c. conductivity measurements were made on p-type PbTe epitaxial films exposed to molecular hydrogen gas at high pressures (100–500 psi) in the temperature range (100–300K). It is found that hydrogen converts p-type films to n-type at a pressure of about 300 psi. The results are explained by assuming that the action of hydrogen is to provide donor electrons. 相似文献
32.
We have used the collocation method to model the characteristics of guided-wave Bragg gratings. The collocation method being a total field method, takes into account all modes, guided as well as radiation. We have first studied the effect of the grating structural parameters such as the grating profile and the duty cycle of periodic variation and have shown that these can have significant effect on the Bragg wavelength and the reflection spectrum. We have then obtained the response characteristics of gratings for their use in strain, temperature and pressure sensing. Our results compare very well with available experimental results. Comparisons with the coupled mode theory have also been included. 相似文献
33.
In his pioneering 1954 paper on selection, Bechhofer recognized the importance of considering experiments carried out in some
design other than the completely randomized design. However, over the years, little has been done along these lines. This
paper's goal is to extend selection procedures to other designs. We first briefly review the existing state of knowledge of
selection in designed experiments, and then proceed to new results on complete factorial experiments. In particular, we formulate
and study a selection procedure which is valid in the presence of unbounded interaction, yet adapts to the presence/absence
of interaction. 相似文献
34.
C. I. Wynter D. H. Ryan S. P. Taneja L. May F. W. Oliver D. E. Brown M. Iwunzie 《Hyperfine Interactions》2005,166(1-4):499-503
Although a number of europium water insoluble chelates have been prepared for several decades, the covalent nature of these compounds has never been established in any quantitative fashion. Shifts in the I.R. bands and conductivity measurements of these salts were hitherto used to qualitatively compare their molecular nature. In this communique we have used temperature coefficients of 151Eu Mössbauer spectra to determine the Debye temperatures (θ D) of three europium chelates: namely europium oxalate, europium bissalen ammonium (recently reported) and europium benzoate and compared their θ D with the measured θ D of the known ionic EuF3. Additionally, the mean square amplitude (<x 2) of these four compounds was computed and plotted as a function of temperature giving in each case a reasonable linear plot. It was interesting to note that the θ D of the most ionic EuF3 was greatest (283 ± 10 K) followed by the oxalate (166 ± 15 K), then the europium bissalen ammonium (133 ± 5 K) and lastly the europium benzoate with a θ D of (105 ± 5 K). 相似文献
35.
S. B. Tambi Madhu Anand Vineeta Taneja C. L. Gupta R. L. Mital 《Journal of heterocyclic chemistry》1983,20(3):803-805
The synthesis of various 3-substituted derivatives of 7-fluorophenothiazin-3-ol and their 5-oxides is described. The ir, uv and mass spectral data are also included. 相似文献
36.
(R)‐2,3‐Cyclohexylideneglyceraldehyde,a Chiral Pool Synthon for the Synthesis of 2‐Azido‐1,3‐diols
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Abdul Rouf Mushtaq A. Aga Brijesh Kumar Subhash C. Taneja 《Helvetica chimica acta》2015,98(6):823-833
A new approach was proposed for the synthesis of 2‐azido‐1,3‐diols from easily available and inexpensive chiral pool synthon (R)‐2,3‐O‐cyclohexylidene‐D ‐glyceraldehyde, through Mitsunobu azidation of 1,2‐diols. Both C(2) and C(1) azides in variable ratios were obtained in alkyl substituted diols with C(2) as the major one. 相似文献
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Allyl tetrahydropyranyl ether (ATHPE) can be used as a versatile protecting reagent. In combination with NBS/I2, O-allyl group can easily be replaced by hydroxyls (including tertiary-OH) or thiols, in the molecules comprising other reactive functional groups such as halogen, nitro, acetonide and alkene under mild reaction conditions (near neutral pH and ambient temperature). 相似文献
40.
Acetoacetanilide, benzoylacetanilide and their derivatives have been examined in ultraviolet region in a series of solvents covering a broad polarity range e. e. from chloroform (Z, 63.2) to methanol (Z .83.6). Transition energies and oscillator strengths have been calculated and transition energy (ET) has been plotted against Z-values, a new empirical measurement of solvent polarity. A linear relationship was observed between the transition energy and Z-values for π → π* and n → π* transitions. These transitions are identified as charge transfer (c-t) transitions and with the solvents having carbonyl oxygen and sulphur atom a c-t complex formation has been suggested. Strong electron-donating substituents on phenyl group of the nitrogen atom also showed a weak to moderate n → π* transitions. These substituents have no influence on the position of the λmax in the same solvent. Stabilization energy of the excited state of these ligands and hence the dipole moments of the excited states have been calculated in comparison with pyridinium iodide. Solvent sensitivities of these ligands have also been calculated. 相似文献