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981.
We propose and investigate a novel technique to realize non-return-to-zero (NRZ) to return-to-zero (RZ) format conversion of a multichannel 4-ary amplitude shift keying (4-ASK) signal. The proposed format converter composed of two modulators and a dispersion compensating fiber (DCF) is theoretically inves-tigated using numerical simulation as basis. Research shows that a 4-channel 20-Gb/s NRZ-4-ASK signal can be converted to a RZ-4-ASK signal simultaneously without wavelength shifting and signal quality degradation, with the converted signal multiplexed to 40 Gb/s. 相似文献
982.
We consider the problem of discriminating between states of a specified set with maximum confidence. For a set of linearly independent states unambiguous discrimination is possible if we allow for the possibility of an inconclusive result. For linearly dependent sets an analogous measurement is one which allows us to be as confident as possible that when a given state is identified on the basis of the measurement result, it is indeed the correct state. 相似文献
983.
Willart JF Hédoux A Guinet Y Danède F Paccou L Capet F Descamps M 《The journal of physical chemistry. B》2006,110(23):11040-11043
Kinetic investigations of the polymorphic form alpha of anhydrous trehalose have been performed below its apparent melting temperature (Tm) by differential scanning calorimetry (DSC) and X-ray diffraction. The results reveal a spontaneous isothermal vitrification process which indicates that the phase alpha is in a very unusual superheating situation. This behavior has been attributed to the fact that the effective melting temperature (Tm(eff)) of the phase alpha is likely to be located far below the glass transition temperature (Tg) of this compound. The high viscosity of the liquid trehalose between Tm(eff) and Tg is thus invoked to explain the long lifetime of the phase alpha in this temperature range. 相似文献
984.
The syntheses and biological evaluation of six epothilone D analogues are reported. These side-chain variants of the (E)-9,10-didehydroepothilone scaffold contain C-15 thiazole appendages that are derived from bromomethyl ketone intermediates. Although each of these analogues is less cytotoxic than the parent (E)-9,10-didehydroepothilone D, three maintain IC(50) values in the double-digit nanomolar range against both susceptible and resistant cell lines. 相似文献
985.
Wei Q Wu D Du B Li Y Duan C 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(3):532-535
In this paper, the binding characteristics of human serum albumin (HSA) and m-nitrophenylfluorone (m-NPF)-molybdenum (Mo(VI)) complex have been studied by fluorophotometry. The binding constants are measured at different temperature. Based on the theory of Forster energy transfer, the binding distance and the energy transfer efficiency between m-nitrophenylfluorone-Mo(VI) complex and protein are obtained. According to the thermodynamic parameters, the main sort of binding force can be judged. The results indicate that HSA and m-NPF-Mo(VI) complex have strong interactions. The mechanism of quenching belongs to static quenching and the main sort of binding force is electrostatic gravitation. 相似文献
986.
987.
为了寻找高效、毒性小的抗肿瘤药物,设计并合成了一系列新型的喹唑啉衍生物,其结构经1H NMR、 13C NMR、 IR、 MS(ESI)和元素分析表征。采用细胞增殖抑制实验法(MTT法)测定了化合物3a~10c对人盲肠腺癌细胞(HCT-8)、人肝癌细胞(HepG2)、人肺癌细胞(A549) 和人高转移性肝癌细胞(MHCC-97H)的体外抑制活性。结果表明:4-位为氨基苯甲基丙二酸二甲酯时(3a~6c),化合物的肿瘤抑制作用比其相应水解产物(7a~10c)更强;氨基在苯甲基丙二酸二甲酯间位时,抑制活性明显优于对位取代。其中,5c对HCT-8、 A549及MHCC-97H的抑制活性较显著,IC50值分别为13.613 μmol/L, 13.578 μmol/L和25.804 μmol/L。
相似文献
988.
989.
Dynamic fragility of bulk metallic glass (BMG) of Zr64Cu16Ni10Al10 alloy is studied by three-point beam bending methods. The fragility parameter mfor Zr64Cu16Ni10Al10 BMG is calculated to be 24.5 at high temperature, which means that the liquid is a "strong" liquid, while to be 13.4 at low temperature which means that the liquid is a "super-strong" liquid. The dynamical behavior of Zr64Cu16Ni10Al10 BMG in the supercooled region undergoes a strong to super-strong transition. To our knowledge, it is the first time that a strong-to-superstrong transition is found in the metallic glass. Using small angle x-ray scattering experiments, we find that this transition is assumed to be related to a phase separation process in supercooled liquid. 相似文献
990.
Dan Zhang Laixin Shi Ping Shen Qiaoli Lin Qichuan Jiang 《Applied Physics A: Materials Science & Processing》2010,98(3):601-607
The wetting behaviors of molten Mg drops on polycrystalline ZrO2 substrate surfaces were studied in a controlled Ar atmosphere at 948–1173 K using an improved sessile drop method. The ZrO2 substrate is virtually not wetted by molten Mg at temperatures below 1173 K. The wetting and evaporation stages according
to different variation behaviors of contact angle, contact diameter and drop height were identified. Six representative modes
were proposed to describe the evaporation-coupled wetting behaviors during different stages. The competitions between surface
oxidation, chemical reaction and drop evaporation were discussed to account for the mechanisms for various wetting behaviors
at different temperatures. The chemical reaction leads to the formation of more wettable MgO phase at the interface; however,
it yields only an inconspicuous improvement in the wetting due to enhanced Mg evaporation. 相似文献