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71.
聚合物支载的不对称有机合成 总被引:3,自引:0,他引:3
聚合物支载的不对称有机合成比相应的小分子合成体系有独特的优越性。本文综述了近10年来取得了较大进展的聚合物支载的不对称有机合成体系。 相似文献
72.
采用一种设备简单、原料低廉的新型方法,在镀有ZnO先驱薄膜的(0001)蓝宝石上利用水热 法制备出了柱状ZnO阵列薄膜.用扫描电镜(SEM),X射线衍射(XRD)对样品的形貌和结构进行 了表征,结果显示ZnO薄膜为柱状阵列,基于蓝宝石衬底沿c轴择优生长,且(0004)摇摆曲线 半高宽度(FWHM)约为1.8°.此ZnO阵列薄膜具有很强的紫外发射光谱(PL).
关键词:
柱状ZnO阵列薄膜
水热法
(0001)蓝宝石
PL谱 相似文献
73.
An investigation was conducted on enhanced scratch resistance of polycarbonate (PC) substrates by low temperature plasma-polymerized organo-silicon oxynitride (SiOxCyNz) with various N2 flow rates. It was found that the low temperature plasma-polymerized SiOxCyNz with tetramethylsilane (TMS)-O2-N2 plasmas in room temperature (23 °C) can be used for improving the scratch resistance of PC substrates. Scratch test demonstrates this improvement. The scratch resistance of PC substrates was greatly enhanced from the overwhelming presence of scratching (90%) on un-treated PC substrates to a complete lack of scratching (0%) on TMS-O2-N2 plasma-polymerized PC substrates with steel wool for 200 cycles at 300 g loading. The results of this study indicate the performance of scratch resistance on PC substrates was highly dependent on the surface characteristics of PC substrates. The hardness of PC substrates was determined by the pencil test. The surface morphology of PC substrate was monitored by atomic force microscopy (AFM) and field emitted scanning electron microscopy (FESEM). The atomic compositions and chemical bondings of TMS-O2-N2 plasma-polymerized SiOxCyNz were analyzed by X-ray photoelectron spectroscopy (XPS). 相似文献
74.
《International Journal of Infrared and Millimeter Waves》2007,28(10):821-829
This work presents a fullwave analysis for annular ring microstrip antennas on uniaxial anisotropic substrates. The effect
of the anisotropic substrates on the antenna performance at the millimeter wave band is investigated. The analysis is performed
in the Hankel transform domain using Hertz vector potentials and Galerkin Method. Numerical results are presented for the
antenna main characteristics such as resonant frequency and radiation pattern. 相似文献
75.
The development of the colloidal alkali silicate gelation process (the Shoup Method) has established that intricately shaped large size monolithic glass samples are achievable without the need for long drying procedures or the use of a critical drying process. The ability to fabricate gels with large pores (diameter range of 100–300 nm) and the ability to dry them simply and quickly (with the help of a microwave oven) has made Sol-Gel technology accessible to the artist. The ability to cast from flexible molding compounds, to cast without major finishing, to dope and color directly with metal oxides, establishes new possibilities for the artistic forming of glass. 相似文献
76.
77.
In this work, the electric charging effect on the spreading of droplet impacting on dielectric substrates has been investigated. The charged water droplets were directed on the paraffin wax and the Teflon-coated plates. The impinging behavior was visualized and recorded using a CCD camera to identify the maximum extent of the flattened droplets. Droplet diameter and velocity approaching the wall were measured as well. The diameter of the electrically charged droplet at the maximum spread turned out to be larger compared to that of neutral droplet (at the maximum spread), and the difference becomes larger with increasing of the electric charge ratio (defined as the ratio of the actual electric charge to the Rayleigh limit). This phenomenon is considered to be due to reduction of effective interfacial tensions between the liquid and the gas and between the liquid and the solid by electric charging. Finally, an improved model was proposed to predict the maximum spreading ratio for electrically charged droplets by introducing correlations on the liquid–gas and the liquid–solid interfacial tensions. 相似文献
78.
Dr. Yogesh Somasundar Iris C. Lu Dr. Matthew R. Mills Lisa Y. Qian Ximena Olivares Prof. Dr. Alexander D. Ryabov Prof. Dr. Terrence J. Collins 《Chemphyschem》2020,21(11):1083-1086
Understanding the catalysis of oxidative reactions by TAML activators of peroxides, i. e. iron(III) complexes of tetraamide macrocyclic ligands, advocated a spectrophotometric procedure for quantifying the catalytic activity of TAMLs for colorless targets (kII′, M−1 s−1), which is incomparably more advantageous in terms of time, cost, energy, and ecology than NMR, HPLC, UPLC, GC-MS and other similar techniques. Dyes Orange II or Safranin O (S) are catalytically bleached by non-excessive amount of H2O2 in the presence of colorless substrates (S1) according to the rate law: −d[S]/dt=kIkII[H2O2][S][TAML]/(kI[H2O2]+kII[S]+kII′[S1]). The bleaching rate is thus a descending hyperbolic function of S1 : v=ab/(b+[S1]). Values of kII′ found from a and b for phenol and propranolol with commonly used TAML [FeIII{o,o′-C6H4(NCONMe2CO)2CMe2}2(OH2)]+ are consistent with those for S1 (phenol, propranolol) obtained directly by UPLC. The study sends vital messages to enzymologists and environmentalists. 相似文献
79.
Characteristics of the self-organized quantum dots (QDs) such as electron and hole energy levels and wave functions are dependent to the state of strain and electric field produced during the growing process of QDs in a semiconductor substrate. The calculation of the strain and electric field is one of the most challenging components in the QDs simulation process. It involves material anisotropy induced coupling between the elastic and electric fields and it must include the full three-dimensional and usually intricate shapes of the QDs. Numerical simulations are often performed by finite difference, finite element, or atomistic techniques, all require substantial computational time and memory. In this paper, we present a new Green’s function approach which takes into account QDs of arbitrary shape and semiconductor substrates with the most general class of anisotropy and piezoelectricity. Following the literature of micromechanics, the problem is formulated as an Eshelby inclusion problem of which the solution can be expressed by a volume-integral equation that involves the Green’s functions and the equivalent body-force of eiegenstrain. The volume integral is subsequently reduced to a line integral based on exploiting a unique structure of the Green’s functions. The final equations are cast in a form that most of the computational results can be repeatedly used for QDs at different locations—a very attractive feature for simulating large systems of QD arrays. The proposed algorithm has been implemented and validated by comparison with analytical solutions. Numerical simulations are presented for pyramidal QDs in the substrates of gallium arsenide (GaAs) (0 0 1). 相似文献
80.
本文采用EBSD(电子背散射衍射)等分析手段对{110}〈110〉取向的银基带的织构形成机理进行了深入研究,发现了冷轧织构与不同退火温度下再结晶织构间的取向转变关系,研究发现,{110}面附近且非{110}〈211〉取向的冷轧织构组分,900℃退火可以转变为强的{110}〈110〉织构.织构转变中有孪晶形成,{110}〈110〉和{110}〈114〉取向互为孪晶关系. 相似文献