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81.
82.
Priyanka Sarkar 《Journal of luminescence》2009,129(7):704-202
Solution-phase synthesis of nanometer-sized silver particles is reported by sodium borohydride reduction of AgNO3. Two isomeric dicarboxylates (sodium maleate and sodium fumarate) have been used as stabilizing agents. The dicarboxylate-stabilized silver nanoparticles are characterized by UV-vis spectroscopy, high-resolution transmission electron microscopy (HR-TEM) and fourier transform infrared (FT-IR) spectroscopy. A qualitative comparison is made between the UV-vis spectral characteristic of the SPR band and the simulated curve obtained from modified Mie's theory. Silver nanoparticles prepared using these two isomeric dicarboxylates show intense fluorescence in the visible region. DFT with hybrid functional (B3LYP)-based frequency (IR) calculation of both the dicarboxylates and the respective nanoparticles are in good agreement with the experimental IR frequency. On the basis of this calculation a model has been proposed for the stabilization of silver nanoparticles by these two isomeric dicarboxylate anions. 相似文献
83.
New phenylethanoid glycosides from Bacopa monniera 总被引:1,自引:0,他引:1
Chakravarty AK Sarkar T Nakane T Kawahara N Masuda K 《Chemical & pharmaceutical bulletin》2002,50(12):1616-1618
Three new phenylethanoid glycosides, viz. monnierasides I-III (1-3) along with the known analogue plantainoside B were isolated from the glycosidic fraction of Bacopa monniera. Their structures were elucidated mainly on the basis of two dimensional (2D) NMR spectral analyses. 相似文献
84.
Anindya Datta Amitava Raychaudhuri Sreerup Raychaudhuri Surajit Chakrabarti 《Zeitschrift fur Physik C Particles and Fields》1996,72(3):449-460
Many extensions of the Standard Model includeSU(2) L ×U(1) Y singlet higgs bosons,h 0, and also vector-like fermions which couple to it. The production and detection possibilities of such singlet neutral scalars at hadron colliders are considered for different scenarios of vectorlike fermions. We find that for some values of masses and couplings, detection at the CERN large hadron collider (LHC) appears to be a distinct possibility, while at the Fermilab Tevatron upgrade theh 0 might be observed only in very favourable circumstances. 相似文献
85.
In the present study we consider a mathematical model of a non-interactive type autotroph-herbivore system in which the amount of autotroph biomass consumed by the herbivore is assumed to follow a Holling type II functional response. We have also incorporated discrete time delays in the numerical response term to represent a delay due to gestation, and in the recycling term which represents the time required for bacterial decomposition. We have derived conditions for global asymptotic stability of the model in the absence of delays. Conditions for delay-induced asymptotic stability of the steady state are also derived. The length of the delay preserving stability has been estimated and interpreted ecologically. 相似文献
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Upon adsorption of various vapours, the electrical conductivity of lycopene semiconductor changes appreciably This phenomenon had been used as a probe to study the adsorption and desorption processes in these polyene crystals The adsorption and desorption kinetics have been found to follow a modified Roginsky-Zeldovich relation A three-stage adsorption process has been identified The first stage gives a Lennard-Jones potential energy curve, followed by a transition over a potential barrier to the second stage of adsorption in a potential well In the third stage a deep potential energy surface is reached by activation over a second potential barrier and strongly bound complexes between the vapour molecules and the surface molecules of the crystals are finally formed. 相似文献
90.
The composition of the precipitate formed when the Nessler's reagent is treated with ammonia, is assumed as NHn-1Hg2In, aq. and has been studied potentiometrically from iodine-hypoiodite-system. It has been observed that the value of n depends on the concentrations of [HgI4]-2 and OH- ions as well as on the amount of ammonia added and it may vary from 1 to 3. The colour of the precipitate deepens from brown to chocolate as the value of n increases. 相似文献