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排序方式: 共有203条查询结果,搜索用时 15 毫秒
1.
Peng Li Assem Abolmaaty Christine D’Amore Stefanie Demming Constantine Anagnostopoulos et al. 《Applied biochemistry and biotechnology》1992,36(2):88-96
Materials and Methods
Synthesis of thionyl chloride-activated succinamidopropyl-glass beads 相似文献
2.
Susan Lefkopoulou Julia Stephanidou-Stephanatou Constantine Tsoleridis Nicholas E. Alexandrou 《Helvetica chimica acta》1985,68(6):1748-1753
The thermal base-catalysed and photochemical transformation (Boulton-Katritzky rearrangement) of the title tetrahydrobenzo[c][1,2,5]oxadiazoles to tetrahydro-2H-benzo[d][1,2,3]triazoles is studied. Attempts to induce analogous rearrangement in tetrahydro-2H-benzo[d][1,2,3]triazol-4-one arylhydrazones or oximes failed. Some CNDO/2 calculation are also carried out. 相似文献
3.
Olga Igglessi-Markopoulou Constantine Sandris 《Journal of heterocyclic chemistry》1985,22(6):1599-1606
The reaction of aceturic acid p-nitrophenyl ester with active methylene compounds Y-CH2-CO2R has been found to give either the normally expected C-acylation compounds 2 (Y = -CN, -CO2R, -COCH3) or N-acetyl-α-Y-substituted tetramic acids 3 (Y = -CO2R,-COCH3), depending on the reaction conditions. Moreover, the intramolecular condensation of the C-acylation compounds 2 derived from malonic and acetoacetic esters (Y = -CO2R, -COCH3) to α-Y-substituted tetramic acids is shown to proceed through initial cyclization to the corresponding N-acetyl-α-Y-substituted tetramic acids 3 (Y = -CO2R, -COCH3). 相似文献
4.
Constantine J. Callias 《Communications in Mathematical Physics》1983,88(3):357-385
The small time asymptotics of the kernel ofe ?tH is defined and derived for \(H = \frac{{d^2 }}{{dx^2 }} + \frac{\kappa }{{x^2 }}\) on ?1. Lemmas on singular asymptotics in the sense of distributions are formulated and used. The results are applied to derive an index formula on ?1. 相似文献
5.
Electrostatic fields produced by flat electrodes are often used to manipulate particles in solution. To study the field produced by such an electrode, we consider the problem of an infinite strip of width 2a with imposed constant potential immersed in an electrolyte solution. Sufficiently close to the edge of the strip, the solution is determined by classical electrostatics and results in a field singularity. We examine two limiting cases, (a) when strip width a<1k, the Debye screening length, and (b) when strip width is much greater than the Debye screening length, a>1k. We present exact results for the two cases in the limit of small potentials where the Poisson-Boltzmann equation can be linearized. By drawing on an analogy with antiplane shear deformations of solids, and by employing the path-independent J integral of solid mechanics, we present a new method for determining the strength of the edge singularity. The strength of the singularity defines an exact near-field solution. In the far field the solution goes to that of a line of charge. The accuracy of the solution is demonstrated by comparison with the numerical solutions of the Poisson-Boltzmann equation using the finite element method. 相似文献
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7.
Current microfluidic paper-based devices lack crucial components for fluid manipulation. We created a fluidic diode fabricated entirely on a single layer of paper to control the wicking of fluids. The fluidic diode is a two-terminal component that promotes or stops wicking along a paper channel. We further constructed a trigger and a delay valve based on the fluidic diode. Furthermore, we demonstrated a high-level functional circuit, consisting of a diode and a delay valve, to manipulate two fluids in a sequential manner. Our study provides new, transformative tools to manipulate fluid in microfluidic paper-based devices. 相似文献
8.
9.
Asbestos fibers, of the chrysotile variety, were coated with a thin polyamide film by an in situ polycondensation technique. Ionomer-based composites were prepared containing the so-modified asbestos fibers in a random in-plane orientation; results of testing the tensile properties of these asbestos/polyamide/ionomer composites are presented. Parameters investigated comprise the asbestos content in the composite and the polyamide content deposited on asbestos. A significant improvement in the tensile performance was established, especially at the intermediate polyamide content of 3.4 phr. The behavior is discussed in terms of possible interactions between the phases present in the composite material. 相似文献
10.
Electronically modified PHOX ligands 3a-e were synthesized to probe the mechanism of the enantioselective palladium-catalyzed allylic alkylation and amination reactions. Alkylation with dimethyl sodiomalonate produced only a small variation in the ee (89.3% to 93.4%), but amination with benzylamine gave a much wider variation in the ee (16.4% to 66.6%). Hammett analysis suggests that the substituents interact more significantly with phosphorus and supports a combined electronic and steric basis for enantioselection. [reaction: see text] 相似文献