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71.
A series of bis-quaternary ammonium compounds(bis-QACs) N,N’-hevamethylenebis(1-alkyl-4-carbamoyl pyridinium bromide)(4BCAP-6,n)(alkyl chain length,n=8,10,12,14,16 and 18) were synthesized and characterized.Their surface tensions,critical micelle concentrations(CMC),and antimicrobial activities were evaluated.4BCAP-6,10 exhibited the strongest antimicrobial activities except for that against Proteus vulgari.The activities of 4BCAP-6.n against Escherichia coli zk126 were not significantly influenced by temperature.pH and initial bacteria concentration.These results indicate that bis-QACs exhibit high antimicrobial activity regardless of the environmental conditions. 相似文献
72.
ZHANG HongPing LV HaiXia LI Min & SHI Chuang State Key Laboratory of Information Engineering in Surveying Mapping Remote Sensing Wuhan University Wuhan China GNSS Research Center Wuhan School of Geodesy Geomatics 《中国科学:物理学 力学 天文学(英文版)》2011,(6)
Ionospheric delay is one of the major error sources in GNSS navigation and positioning.Nowadays,the dual-frequency technique is the most widely used in ionospheric refraction correction.However,dual-frequency measurements can only eliminate the first-order term of ionospheric delay,while the effect of the second-order term on GNSS observations may be several centimeters.In this paper,two models,the International Reference Ionosphere (IRI) 2007 and International Geomagnetic Reference Field (IGRF) 11 are used... 相似文献
73.
74.
We design and analyze a novel multiband left-handed metamaterial based on a fishnet-like structure at terahertz (THz) frequencies.The metamaterial exhibits simultaneous negative refractions around the frequencies of 0.48,1.05,and 1.19 THz for the electromagnetic (EM) wave normal incidence,and around the frequencies of 0.20,0.79,and 1.13 THz for parallel incidence.The simulated results verify the left-handed properties.A particularly important observation is the capability of the proposed metamaterial with a single geometrical structure to display multifrequency operations in a unit cell.The compact metamaterial is a major step toward the miniaturization of THz materials and devices suitable for multifrequencies. 相似文献
75.
CHEN Wei & LIU PeiDe School of Mathematical Sciences Yangzhou University Yangzhou China School of Mathematics Statistics Wuhan University Wuhan 《中国科学 数学(英文版)》2011,(6)
Under appropriate conditions on Young's functions Φ1 and Φ2,we give necessary and sufficient conditions in order that weighted integral inequalities hold for Doob's maximal operator M on martingale Orlicz setting.When Φ1 = tp and Φ2 = tq,the inequalities revert to the ones of strong or weak(p,q)-type on martingale space. 相似文献
76.
In this paper, boundedness and compactness of the composition operator on the generalized Lipschitz spaces Λα (α > 1) of holomorphic functions in the unit disk are characterized. 相似文献
77.
孙梅娜 《数学物理学报(B辑英文版)》2011,31(4):1503-1512
In this note, we consider the interactions of elementary waves for the traffic flow model proposed by Aw and Rascle when the vacuum is not involved. The solutions are obtained constructively and globally when the initial data consist of three pieces of constant states. Furthermore, it can be found that the Riemann solutions are stable with respect to such small perturbations of the initial data in this particular situation by investigating the limits of the solutions as the perturbed parameter ε goes to zero. 相似文献
78.
79.
CHEN Qun & CUI Qing School of Mathematics Statistics Wuhan University Wuhan China International Center for Theoretical Physics Trieste Italy School of Mathematics Southwest Jiaotong University Chengdu 《中国科学 数学(英文版)》2011,(9)
We obtain an inequality in Sm×R and Hm×R which is similar to DDVV conjecture.As an application,we show that a minimal submanifold in H m×R with nonnegative scalar curvature must be a surface of the type γ×R,where γ is a geodesic in H m.In addition,we get a pinching theorem in Sm×R. 相似文献
80.
LIU Yan & TANG QiHe School of Mathematics Statistics Wuhan University Wuhan China 《中国科学 数学(英文版)》2011,(9)
Let {Xt,t0} be a Lévy process with Lévy measure ν on(∞,∞),and let τ be a nonnegative random variable independent of {Xt,t0}.We are interested in the tail probabilities of X τ and X(τ) = sup0≤t≤τXt.For various cases,under the assumption that either the Lévy measure ν or the random variable τ has a heavy right tail we prove that both Pr(X τ > x) and Pr(X(τ) > x) are asymptotic to Eτν((x,∞)) + Pr(τ > x/(0 ∨ EX 1)) as x →∞,where Pr(τ > x/0) = 0 by convention. 相似文献