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1.
Aequationes mathematicae - We discuss equivalence conditions for the non-existence of non-trivial meromorphic solutions to the Fermat Diophantine equation $$f^m(z)+g^n(z)=1$$ with integers $$m,n\ge... 相似文献
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Yu H Li J Loomis RA Gibbons PC Wang LW Buhro WE 《Journal of the American Chemical Society》2003,125(52):16168-16169
Soluble CdSe quantum wires are prepared by the solution-liquid-solid mechanism, using monodisperse bismith nanoparticles to catalyze wire growth. The quantum wires have micrometer lengths, diameters in the range of 5-20 nm, and diameter distributions of +/-10-20%. Spectroscopically determined wire band gaps compare closely to those calculated by the semiemipirical pseudopotential method, confirming 2D quantum confinement. The diameter dependence of the quantum wire band gaps is compared to that of CdSe quantum dots and rods. Quantum rod band gaps are shown to be delimited by the band gaps of dots and wires of like diameter, for short and long rods, respectively. The experimental data suggest that a length of ca. 30 nm is required for the third dimension of quantum confinement to fully vanish in CdSe rods. That length is about six times the bulk CdSe exciton Bohr radius. 相似文献
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Copper(I) catalyzed radical benzylation and cyclization reaction of tertiary enamides was investigated and 3,3-disubstituted N-Alkyl isoindolin-1-ones were obtained in moderate to good yields. In this reaction, two new C–C bonds were formed in one step with high atom economy. Possible reaction pathway for the formation of the products was also discussed in this paper. 相似文献
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Based on previous works, most of the transition metal phosphides (TMPs) were directly prepared by decomposing NaH2PO2 with the precursors at high temperatures, which resulted in different degrees of phosphidation in the final product. Therefore, it is necessary to design an innovative approach to enhance the degree of phosphidation in the material using crystal defects. Here, oxygen-vacancy iron oxide/iron foam (Ov-Fe2O3/IF) was firstly prepared by generating oxygen vacancy in situ in an iron foam through heating in vacuum conditions. Subsequently, FeP/IF was formed by phosphating Ov-Fe2O3/IF. Under the effects of oxygen vacancies, oxygen-vacancy iron oxide could be completely phosphatized to produce more active sites on the surface of the material. This, in turn, could result in a catalyst with exceptional hydrogen evolution activity. Thus, the successful fabrication of FeP/IF demonstrated in this work provides an effective and feasible way for the preparation of other high-efficiency catalysts. 相似文献
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Two-stage ignition exists in the low-temperature combustion process of n-heptane and the first-stage ignition also shows a negative temperature coefficient(NTC) phenomenon. To study key reactions and understand chemical principles affecting the first-stage ignition of n-heptane, a lumped skeletal mechanism with 62 species is obtained based on the detailed NUIGMech1.0 mechanism using the directed relation graph method assisted by sensitivity analysis and isomer lumping. The lumped mechanism shows good performance on ignition delay time under wide conditions. The study revealed that the temperature after the first-stage ignition is higher and a larger amount of fuel is consumed at lower initial temperatures. The temperature at the first-stage ignition is relatively insensitive to the initial temperature. Further sensitivity analysis and reaction path analysis carried out based on the lumped mechanism show that the decomposition of RO2 to produce alkene and HO2is the most important reaction to inhibit the first-stage ignitions. The chain branching explosion closely related to the first-stage ignition will be terminated when the rate constant for the RO2 decomposition is larger than that of the isomerization of RO2 to produce QOOH. The NTC behavior as well as other characteristics of the first-stage ignition can be rationalized from the competition between these two reactions. 相似文献
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Zhang Jingbo Sun Chuanzhen Li Yajiao Bai Shouli Luo Ruixian Chen Aifan Liu Kun Lin Yuan 《Journal of Solid State Electrochemistry》2017,21(3):883-889
Journal of Solid State Electrochemistry - We report on the interfacial passivation mechanism in CdSe quantum dot-sensitized ZnO nanocrystalline thin film, where different sulfide semiconductors... 相似文献
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Auricularia polytricha is an edible mushroom, quite popular in China. Modern pharmacology research indicate that A. polytricha polysaccharides possess antitumor and immunomodulatory activities. In this paper, an antitumor Auricularia polytricha polysaccharide (APS)-2 was purified by radial flow chromatography (RFC) in a column of 500 mL bed-volume (40 cm i.d × 15 cm) packed with DEAE52-cellulose anion ion-exchange resin. The optimal separation conditions were: sample flow-velocity 15–20 mL min?1, sample volume 160–200 mL, and elution with distilled water and 0.2 M NaCl at a velocity of 35–45 mL min?1. The yield and content of APS-2 obtained under these conditions were 182 mg g?1 total polysaccharides and 98.35 %, respectively. The study provides guidelines for the separation and purification of polysaccharides using a radial flow chromatography column. 相似文献