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141.
Chandra Kanta Ghosh Anirban Ray Amarendra Patra 《Journal of heterocyclic chemistry》2001,38(6):1459-1463
The title aldehyde 1 in the presence of ammonia gives the pyridine derivatives 9‐11 respectively with acetylacetone, diethyl malonate and ethyl cyanoacetate, and ethyl (or methyl)‐l‐benzopyrano[4,3‐b]pyri‐dine‐3‐carboxylate 22 (or 23 ) with ethyl (or methyl) acetoacetate. Acetylacetone pretreated with ammonia condenses with 1 giving the fused pyridine 24 . Ammonia converts the ester 6 to the pyridine 13 or 14 . Chromic acid oxidation of 22 and 23 affords the coumarinopyridines 25 and 26 , respectively. 相似文献
142.
In an attempt to study the scope of a theorem due to Pati, the authors have established that φ(t) logK|t∈B
u
V in (0,π)⟹ΣA
n
(x) is |C, 0,β| forβ>1, at the pointt = x. 相似文献
143.
M. Chandra Sekhar P. Kondaiah S.V. Jagadeesh Chandra G. Mohan Rao S. Uthanna 《Applied Surface Science》2011,258(5):1789
Titanium dioxide (TiO2) films have been deposited on glass and p-silicon (1 0 0) substrates by DC magnetron sputtering technique to investigate their structural, electrical and optical properties. The surface composition of the TiO2 films has been analyzed by X-ray photoelectron spectroscopy. The TiO2 films formed on unbiased substrates were amorphous. Application of negative bias voltage to the substrate transformed the amorphous TiO2 into polycrystalline as confirmed by Raman spectroscopic studies. Thin film capacitors with configuration of Al/TiO2/p-Si have been fabricated. The leakage current density of unbiased films was 1 × 10−6 A/cm2 at a gate bias voltage of 1.5 V and it was decreased to 1.41 × 10−7 A/cm2 with the increase of substrate bias voltage to −150 V owing to the increase in thickness of interfacial layer of SiO2. Dielectric properties and AC electrical conductivity of the films were studied at various frequencies for unbiased and biased at −150 V. The capacitance at 1 MHz for unbiased films was 2.42 × 10−10 F and it increased to 5.8 × 10−10 F in the films formed at substrate bias voltage of −150 V. Dielectric constant of TiO2 films were calculated from capacitance–voltage measurements at 1 MHz frequency. The dielectric constant of unbiased films was 6.2 while those formed at −150 V it increased to 19. The optical band gap of the films decreased from 3.50 to 3.42 eV with the increase of substrate bias voltage from 0 to −150 V. 相似文献
144.
Ohne Zusammenfassung 相似文献
145.
The electronic charge distribution in tetragonal closed packed (tcp) metal is approximated by a collection of spherical charge
clouds situated midway between the ions. The anisotropy of the charge distribution is parameterized in terms of a charge shift
δ derivable from the lattice parameters and the elastic coefficients of the metal. The electric field gradient (EFG) in the
metal can be obtained through lattice summations over the charges. Numerical calculations are made to obtain the EFG in pure
indium and indium-based dilute impurity alloys. Fairly good agreement with the experiments is achieved. 相似文献
146.
Summary Polar heteroatomic concentrates were separated from deasphalted oils and asphalts of indigenous crudes by various separation techniques. Conditions have been standardized for its separation using Fuller's earth as adsorbent, and data is compared with those obtained by the techniques reported in the literature. Semiquantitative estimates of phenols, pyrrols, carboxylic acids and amides in the concentrates were also made by IR spectrometry. 相似文献
147.
Amorphous metal Fe10Ni70Si8B12 has been studied by Mössbauer spectroscopy without and with an weak applied field in the plane of ribbons. Reentrant properties have been confirmed with the existence of a canted state at low temperature. Studies with different values of the applied field have shown that a field near 50 0e is sufficient to saturate the average direction of the ferromagnetism. 相似文献
148.
Proceedings - Mathematical Sciences - 相似文献
149.
Chandra Sekhar Pedamallu Linet Özdamar Tibor Csendes Tamás Vinkó 《Journal of Global Optimization》2008,42(3):369-384
A new efficient interval partitioning approach to solve constrained global optimization problems is proposed. This involves
a new parallel subdivision direction selection method as well as an adaptive tree search. The latter explores nodes (intervals
in variable domains) using a restricted hybrid depth-first and best-first branching strategy. This hybrid approach is also
used for activating local search to identify feasible stationary points. The new tree search management technique results
in improved performance across standard solution and computational indicators when compared to previously proposed techniques.
On the other hand, the new parallel subdivision direction selection rule detects infeasible and suboptimal boxes earlier than
existing rules, and this contributes to performance by enabling earlier reliable deletion of such subintervals from the search
space. 相似文献
150.
Analysis of Ti:LiNbO3 zero-gap directional coupler for wavelength division multiplexer/demultiplexer
Pranabendu Ganguly Juran Chandra Biswas Samir Kumar Lahiri 《Optics Communications》2008,281(12):3269-3274
For the purpose of multichannel integrated-optical wavelength division MUX/DEMUX design, the wavelength tuning method of Ti:LiNbO3 zero-gap directional coupler is analysed by effective-index based matrix method (EIMM). In this method, first, the 2D refractive index profile of the Ti:LiNbO3 zero-gap directional coupler is transformed into lateral 1D effective-index profile by WKB method. Finally, matrix method is applied to this effective-index profile and the propagation constants are computed from the resonance peaks of the excitation efficiency versus propagation constant characteristics. It has been shown that the channel wavelength tuning can be achieved by varying the Y-branching angle at the input and output of the device or by a slight variation of two-mode-section length. The method of electro-optic fine tuning of the channel wavelength and channel separation of the device has also been investigated. A cascaded structure with proper parameters for four-channel application is also simulated and the results are presented. 相似文献