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201.
Giovanni Gilardi Sanshui Xiao Romeo Beccherelli Antonio d’Alessandro N. Asger Mortensen 《Photonics and Nanostructures》2012,10(1):177-182
We numerically demonstrate near-zero transmission of light through two-dimensional arrays of isolated gold rings. The analysis of the device as an optofluidic sensor is presented to demonstrate the tuning of the device in relation to variations of volume and refractive index of an isotropic fluid positioned over the structure. We also evaluate the performance of the device with respect to geometrical parameters of the rings. 相似文献
202.
Cocchi M Franchini G Manfredini M Marchetti A Pigani L Seeber R Tassi L Ulrici A Vignali M Zanardi C Zannini P 《Annali di chimica》2002,92(3):177-185
A study on polythiophene coated microelectrodes is reported, the goal being that of checking the capability of these electrochemical systems to work in low conductive media. The possibility of electrochemically p-doping the polymer in the presence of very low concentrations or even in the absence of supporting electrolyte in the solution is ascertained, opening the way to the use of similar systems in pure solvent media. This result is obtained in such conditions that the presence of residual charges--and corresponding counterions--trapped inside the film coating can be reasonably hypothesised. 相似文献
203.
Cucinotta V Giuffrida A Grasso G Maccarrone G Messina M 《Journal of chromatography. A》2002,979(1-2):137-145
Six different racemates of the profen family were used as analytes in order to test the chiral selector properties of three members of a new class of cyclodextrin derivatives, hemispherodextrins (HMs), in capillary electrophoresis. In addition to experiments carried out to separate each enantiomeric pair one by one, other experiments were carried out on samples containing all six enantiomeric pairs. Electropherograms were obtained either by adding a single HM to the background electrolyte (BGE), or a binary mixture of HMs. The results obtained confirm the excellent chiral selector properties of the HMs, and furthermore show that these compounds can also be used for achiral selection. When mixing different HMs, a complementary effect in chiral selectivity is observed, which, in our opinion, deserves further study. 相似文献
204.
Lavilla R Bernabeu MC Brillas E Carranco I Díaz JL Llorente N Rayo M Spada A 《Chemical communications (Cambridge, England)》2002,(8):850-851
One-electron reduction of pyridinium salts (NAD+ analogues) generates dihydropyridyl radicals which may then be engaged in radical addition processes to regioselectively form gamma-substituted dihydropyridines. 相似文献
205.
Mordini A Sbaragli L Valacchi M Russo F Reginato G 《Chemical communications (Cambridge, England)》2002,(7):778-779
Aziridinyl ethers are selectively and easily converted to either amino vinyl ethers or alkoxy allylamines by treatment with mixed metal bases (superbases). 相似文献
206.
Vistoli G Pedretti A Villa L Testa B 《Journal of the American Chemical Society》2002,124(25):7472-7480
The objective of this study was to determine if and how a solvent influences internal motions in a solute molecule. Acetylcholine was chosen as the object of study given its interesting molecular structure and major biological significance. Molecular dynamics simulations were carried out in the vacuum (10 ns), water (5 ns), methanol (5 ns), and octanol (1.5 ns). Seven clusters of conformers were identified, namely, +g+g, -g-g, +gt, -gt, t+g, t-g, and tt, where the gauche and trans labels refer to the dihedral angles tau(2) and tau(3), respectively. As expected, the relative proportion of these conformational clusters was highly solvent-dependent and corresponded to a progressive loss of conformational freedom with increasing molecular weight of the solvent. More importantly, the conformational clusters were used to calculate instantaneous and median angular velocity (omega and omega(M), respectively) and instantaneous and median angular acceleration (alpha and alpha(M), respectively). Angular velocity and angular acceleration were both found to decrease markedly with increasing molecular weight of the solvent, i.e., vacuum (epsilon = 1) > water > methanol > octanol. The decrease from the vacuum to octanol was approximately 40% for tau(2) and approximately 60% for tau(3). Such solvent-dependent constraints on a solute's internal motions may be biologically and pharmacologically relevant. 相似文献
207.
We implement a dynamic model that describes the polarization behavior in vertical-cavity surface-emitting lasers that contain an absorbing region surrounding the active zone. We find four regions of qualitatively different behavior: stable linearly polarized operation, intensity pulsations of a linearly polarized component, pulsations of both total-intensity and polarization components, and polarization self-pulsation with constant total intensity. We characterize the four regions by computing the polarization-resolved optical and power spectra. The predicted behavior agrees with recent experimental results. 相似文献
208.
A regio- and steroselective conversion of the totally synthetic 3α, 18-di-O-benzyl-17-nor-14-aphidicolen-16-one (5), into (±)-aphidicolin 1 , by hydroxylation of the 2-methylidenebicyclo[3.2.1] oct-3-ene derivative 6 is described. Compound 5 was a key intermediate in our previously described total synthesis of 2 , which represented a formal synthesis of 1 . 相似文献
209.
210.
Summary In this paper we study, in the framework of Sobolev weight spaces, differential operators of elliptic type, with singular
coefficients, perturbed by a potential. Conditions for compactness of embedding W
s,σ
r,p
(Ω)↪W
s,0
0,p
(Ω)=L
s
p
(Ω) for density ofD(Ω) on W
s,σ
r,p
(Ω) and discretness conditions for the spectrum of Aσ in the Banach spaces L
s
p
(Ω), have been established.
Entrata in Redazione il 20 dicembre 1977.
Lavoro eseguito, nell'ambito del Gruppo Nazionale per l'Analisi Funzionale e le sue Applicazioni del C.N.R. 相似文献
Entrata in Redazione il 20 dicembre 1977.
Lavoro eseguito, nell'ambito del Gruppo Nazionale per l'Analisi Funzionale e le sue Applicazioni del C.N.R. 相似文献