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61.
Tianhui Hu Helou Xie Jianbo Xiao Hailiang Zhang Erqiang Chen 《Cellulose (London, England)》2010,17(3):547-558
A novel combined main-chain/side-chain liquid-crystalline polymer based on an ethyl cellulose main chain containing azobenzene
mesogens (AzoEC) was successfully synthesized. Molecular characterization of the resulting polymers with different degrees
of substitution (DS) was performed with proton nuclear magnetic resonance (1H NMR), Fourier-transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). Thermal stability was investigated
by thermogravimetric analysis (TGA). The phase transitions and liquid-crystalline behavior of these polymers were investigated
by differential-scanning calorimetry (DSC), polarized optical microscopy (POM), and wide-angle X-ray diffraction (WAXD). The
results indicate that DS has substantial effect on the liquid-crystalline behavior of these polymers. AzoEC with low DS only
shows the cholesteric phase similar to ethyl cellulose (EC). However, when DS increases to a specific value, AzoEC begins
to show fascinating supramolecular structures. The supramolecular structure of AzoEC with maximum DS consisted of a large-scale
ordered lamellar structure formed by EC main chains and a small-scale ordered structure formed by azobenzene mesogens. 相似文献
62.
Jianbo Lu Yuting Wang Yabo Wu Tianqiang Wang 《The European Physical Journal C - Particles and Fields》2011,71(11):1800
We use the Markov Chain Monte Carlo method to investigate global constraints on the generalized holographic (GH) dark energy
with flat and non-flat universe from the current observed data: the Union2 dataset of type supernovae Ia (SNIa), high-redshift
Gamma-Ray Bursts (GRBs), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation
(BAO), and the cosmic microwave background (CMB) data. The most stringent constraints on the GH model parameter are obtained.
In addition, it is found that the equation of state for this generalized holographic dark energy can cross over the phantom
boundary w
de
=−1. 相似文献
63.
A method of clarifying bioaerosol particles is proposed based on T-matrix. Size and shape characterizations are simultaneously acquired for individual bioaerosol particles by analyzing the spatial distribution of scattered light. The particle size can be determined according to the scattering intensity,while shape information can be obtained through asymmetry factor(AF) . The azimuthal distribution of the scattered light for spherical particles is symmetrical,whereas it is asymmetrical for non-spherical ones,and the asymmetry becomes intense with increasing asphericity. The calculated results denote that the 5 –10 scattering angle is an effective range to classify the bioaerosol particles that we are concerned of. The method is very useful in real-time environmental monitoring of particle sizes and shapes. 相似文献
64.
Jianguo Lv Kai Huang Xuemei Chen Jianbo Zhu Lijun Wang Xueping Song Zhaoqi Sun 《Superlattices and Microstructures》2011
The chemical composition, crystalline structure, surface morphology and photoluminescence spectra of Na-doped ZnO thin films with different heat treatment process were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy and a fluorescence spectrometer. The results show that preferred orientation, residual stress, average crystal size and surface morphology of the thin films are strongly determined by the preheating temperature. The effects of preheating temperature on microstructure and surface morphology have been discussed in detail. The photoluminescence spectra show that there are strong violet & UV emission, blue emission and green emission bands. The violet & UV emission is ascribed to the electron transition from the localized level below the conduction band to the valence band. The blue emission is attributed to the electron transition from the shallow donor level of oxygen vacancies to the valence band, and the electron transition from the shallow donor level of interstitial zinc to the valence band. The green emission is assigned to the electron transition from the level of ionized oxygen vacancies to the valence band. 相似文献
65.
基于传输线等效理论,设计了含有源频率选择表面(active frequency selective surface,AFSS)的三层可调复合吸波体,第一层是表面层,为AFSS衬底;中间层是AFSS层,由频率选择表面(frequency selective surface,FSS)和PIN二极管阵列构成;第三层是介质层.反射率测量结果表明,通过调节PIN二极管阵列偏置电压可以动态调节吸波体反射特性,在偏置电压为5 V时,可获得最佳吸波性能,在5—15 GHz和5.3—13 GHz频段分别可获得-8 dB和-
关键词:
频率选择表面
复合吸波材料
反射率
PIN二极管 相似文献
66.
When ultrafast laser pulse strikes the crystal with a van Hove singularity in the phonon density of states, it can create a pair of anti-correlated in wave-vector phonons. As a result, the atomic fluctuations in either position or momentum become squeezed in such a way that their size might fall below the vacuum level. The ultrafast pulses can also generate a biphonon state in which the constituent phonons are correlated and/or entangled. Here we show that via the interplay between one- and two-phonon interference the bound and squeezed two-phonon state in (110) oriented ZnTe single crystal can be manipulated. 相似文献
67.
This paper concerns the finite-horizon optimal reorganization problem under debt–equity swap. The model of equity is formulated as a parabolic variational inequality, or equivalently, a free boundary problem, where the free boundary corresponds to the optimal reorganization boundary. The existence and uniqueness of the solution are proven and the behavior of the free boundary, such as smoothness, monotonicity and boundedness, is studied. To the best of our knowledge, this is the first complete set of results on debt–equity swap for finite maturity obtained using PDE techniques. 相似文献
68.
The Cu(I)-catalyzed cascade coupling/cyclization reaction of N-tosylhydrazones with 3-butyn-1-ol has been explored. This new strategy represents a simple platform for the synthesis of tetrahydrofurans in moderate to good yields. 相似文献
69.
Adam Bieńkowski Zbigniew Kaczkowski Roman Szewczyk 《Czechoslovak Journal of Physics》2002,52(1):A85-A88
Initial curve, major and minor magnetostriction hysteresis loops of the NiFe2O4 ferrite as the functions of static magnetic field were investgated. Magnetostriction hysteresis loops as the functions of static induction are also presented. The experimental phenomenon of “liftoff” value of the magnetostriction loop is detected. 相似文献
70.