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排序方式: 共有179条查询结果,搜索用时 78 毫秒
41.
Laura J. Parry Victoria Vinader Ian J. Scowen Vipul K. Patel Kamyar Afarinkia 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):195-199
Abstract The Horner-Wittig reaction between diphenyl(2-phenylpropyl)phosphine oxide and 1-naphtaldehyde affords an equal mixture of the cis and trans isomers even though the formation of the initial adduct is selective. 相似文献
42.
Aditya M. Vora 《Frontiers of Physics in China》2007,2(4):430-435
The theoretical investigation of the superconducting state parameters (SSP) viz. electron-phonon coupling strength λ, Coulomb pseudopotential μ*, transition temperature T
c, isotope effect exponent α and effective interaction strength N
0
V of ten Cu
C
Zr100−C
metallic glasses have been reported using Ashcroft’s empty core (EMC) model potential. Three local field correction functions
proposed by Hartree (H), Taylor (T) and Ichimaru-Utsumi (IU) are used in the current investigation to study the screening
influence on the aforesaid properties. It is observed that the electron-phonon coupling strength λ and the transition temperature T
C
are quite sensitive to the selection of the local field correction functions, whereas the Coulomb pseudopotential μ*, isotope effect exponent α and effective interaction strength N
0
V show weak dependences on local field correction functions. The T
c obtained from IU-local field correction function are found an excellent agreement with available theoretical or experimental
data. Also, the present results are found in qualitative agreement with other such earlier reported data, which confirms the
superconducting phase in metallic glasses.
相似文献
43.
Y. K. Agrawal G. Shah S. B. Vora 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(2):453-459
Summary A method for solvent extraction, separation and recovery of uranium was developed using a new reagent, N-phenylbenzo-18-crown-6-hydroxamic
(PBCHA) in the presence of cerium, thorium and lanthanides. Uranium was extracted with a dichloromethane solution of PBCHA
producing an orange coloured complex at lmax = 400 nm with a molar absorptivity of 5.0 . 104 l . mol-1 . cm-1 and which obeyed Beer's Law in the range of 0.48-5.76 ppm. For ICP-AES the extract was directly introduced into the plasma
to enhance the sensitivity several folds with a detection limit of 0.5 ppb. The extraction constants of uranium crown hydroxamic
acid complexes were also determined. The selectivity factors Kuranyl(b2K/K or b2K'e/K) for uranium crown hydroxamate were evaluated by comparing the Kuranyl with the stability constants of competing metal cations (K) and anions (K) and were found remarkably large. Uranium was recovered in 99.95% purity from monazite sand and phosphate rocks. It could
be also preconcentrated and determined in environmental samples. 相似文献
44.
Das Ritu Dhiman Abhijeet Kapil Arti Bansal Vipul Sharma Tarun Kumar 《Analytical and bioanalytical chemistry》2019,411(6):1229-1238
Analytical and Bioanalytical Chemistry - Despite of various advancements in biosensing, a rapid, accurate, and on-site detection of a bacterial pathogen is a real challenge due to the lack of... 相似文献
45.
46.
Wojciechowski J Chase-Baldwin K Wasieloski LP Padilla S Vora GJ Taitt CR 《Analytica chimica acta》2010,679(1-2):85-90
Microarray performance depends upon the ability to screen samples against a vast array of probes with the appropriate sensitivity and selectivity. While these factors are significantly influenced by probe design, they are also subject to the particular detection methodology and reagents employed. Herein we describe the incorporation of super avidin-biotin system (SABS) and secondary enzymatic enhancement (SEE) as post-hybridization signal amplification techniques to improve the sensitivity of oligonucleotide microarrays. To these ends, we tested these methods on electrochemically interrogated arrays using both purified influenza A PCR products and randomly amplified genomic Francisella tularensis DNA as targets. While SABS treatment did not improve sensitivity for CombiMatrix ElectraSense(?) arrays using purified influenza A cDNA, chip sensitivity was improved 10-fold for randomly amplified targets. SEE improved performance to a greater degree and was able to lower the detection limits 10-fold for influenza A and 100-fold for F. tularensis DNA. These results indicate the promising capability of post-hybridization amplification techniques for enhancing microarray performance. 相似文献
47.
Compounds of a new smectogenic homologous series of α-methyl-cinnamates were prepared by condensing different 4-n-alkoxybenzoyl chloride with methoxyethyltrans-4-hydroxy-α-methylcinnamate. In this series, the first six members are non-mesogenic.n-Heptyloxy derivative exhibits monotropic smectic A phase whereas rest of the members exhibit enantiotropic smectic A mesophase.
The compounds are characterized by combination of elemental analysis and spectroscopic techniques. Enthalpies of few homologues
are measured by DSC techniques. Fluorescent properties are also observed. The thermal stabilities of the present series are
compared with those of other structurally related mesogenic homologous series. 相似文献
48.
A simple, selective, rapid, precise and accurate reverse phase high pressure liquid chromatographic method has been developed for the simultaneous estimation of diclofenac sodium and rabeprazole sodium from pharmaceutical formulations. The method was developed using a HiQ SiL C18 (250 mm × 4.6 mm i.d.) column with a mobile phase consisting of methanol:water, (80:20 v/v), at a flow rate of 1.25 mL min−1. Detection was carried out at 284 nm. Indapamide was used as an internal standard. The developed method was validated for linearity, accuracy, precision, limit of detection and limit of quantitation. The proposed method can be used for the estimation of these drugs in combined dosage forms.
相似文献49.
Superconducting State Parameters of CucZr100-c Binary Amorphous Alloys by Pseudopotential Approach 下载免费PDF全文
Aditya M. Vora 《中国物理快报》2007,24(9):2624-2627
We present the screening dependence theoretical investigations of the superconducting state parameters, i.e. electron-phonon coupling strength A, Coulomb pseudopotential μ*, transition temperature To, isotope effect exponent α, and effective interaction strength NoV of some CucZr100-c (C = 25, 30, 33, 35, 40, 45, 50, 55, 57, 60 at.%) binary amorphous alloys by employing the well-known empty core model potential of Ashcroft. Five screening functions proposed by Hartree, Taylor, Ichimaru-Utsumi, Farid et al. and Sarkar et al. are used to study the screening influence on the aforesaid superconducting properties. The transition temperature Tc obtained from the Ichimaru-Utsumi screening function is found to be in excellent agreement with available theoretical or experimental data. Also, the present results are found in qualitative agreement with the other earlier reported data, which confirms the superconducting phase in the amorphous alloys. 相似文献
50.
Aditya M. Vora 《Central European Journal of Physics》2008,6(2):263-276
The theoretical computation of the superconducting state parameters (SSP) viz; electron-phonon coupling strength λ, Coulomb pseudopotential μ
*, transition temperature T
c
, isotope effect exponent α and effective interaction strength N
O
V of some monovalent (Cu and Au), divalent (Ca, Sr, Ba, αHg, βHg and Ra) and polyvalent (Lu, Rh, Sc, Y, La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Ac, Th, Hf, Ru, Os, Ir, V, Ta, Pa, Cr, Mo,
U, Re, Np and Pu) amorphous metals based on the different groups of the periodic table have been carried out for the first
time using the well known Ashcroft’s empty core (EMC) model pseudopotential. Herein, we have employed five different types
of local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) to study the exchange and correlation effects on the present investigations. A very strong influence of all the exchange
and correlation functions have been observed in the present study. Our results are in fair agreement with documented theoretical
as well as experimental data. A strong dependency of the SSP of amorphous metals on the valency Z was found.
相似文献