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1.
本文从商品化的间溴苯甲醚和对甲氧基苯甲醛出发,通过傅-克酰基化反应、串联的羟醛缩合及1,4-迈克尔加成反应,得到三芳基取代的1,5-二酮,然后用查尔酮(Chalcone)作氧化剂,二酮与BF3.Et2O 反应形成吡喃鎓盐,再与苯基乙酸钠盐缩合得到芳香二溴代衍生物,产物的DMA溶液在DBU和钯催化剂的作用下,160°C 加热12 h进行脱卤化氢环化反应, 生成四甲氧基取代的二苯并并四苯(DBN)类衍生物。并报道了产物的晶体结构和在溶液中的聚集效应。 相似文献
2.
CHENG Xiao-hong HOEGER Sigurd 《高等学校化学研究》2007,23(1):35-43
IntroductionDiscotic liquid crystals can exhibit both columnarand nematic mesophases. The columnar mesophaseshave wider potential applications to conducting andphotoconducting systems, optical data storage, light-emitting diodes, photovoltaic solar cells,… 相似文献
3.
A.C. Galca V. StancuM.A. Husanu C. DragoiN.G. Gheorghe L. TrupinaM. Enculescu E. Vasile 《Applied Surface Science》2011,257(14):5938-5943
The paper presents the influence of pulsed laser deposition (PLD) parameters on the structural and optical properties of PZT thin films grown on platinum substrate. X-ray diffraction (XRD), spectroscopic ellipsometry (SE) and X-ray photoelectron spectroscopy (XPS) are used to determine the thin film properties. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) are employed to get additional information. By changing the distance between target and substrate, different crystalline orientations of PZT are obtained. The thin film thickness and its roughness, as well as the refractive index are also influenced by the chosen distance. 相似文献
4.
J.-P. Nguenang T. Njassap Njassap T. C. Kofané 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(4):539-545
A quintic complex Ginzburg-Landau equation is derived from a Landau-Lifshitz-Gilbert equation and is used to describe the
magnetization dynamics in a one-dimensional uni-axial ferromagnet. Trough the use of suitable approximations, we derive the
magnetic solitary wave excitations solutions which have pulse-like shapes. Subsequent numerical simulations reveal domain
wall propagation. 相似文献
5.
Michal?Landa Petr?Sedlák Hanu??Seiner Luděk?Heller Lucie?Bicanová Petr??ittner Václav?Novák 《Applied Physics A: Materials Science & Processing》2009,96(3):557-567
Recent experimental and theoretical improvements of resonant ultrasound spectroscopy (RUS) are summarized to investigate elastic
constants of phases in shape memory alloys. The proposed inversion procedure, described in this work, is particularly suitable
to reliable evaluation of the temperature dependence of elastic constants of low-symmetry ferroelastic materials which may
be strongly elastically anisotropic and tend to exist in twinned forms. The method is applicable even for the evaluation of
single-crystal elastic constants from RUS measurements on microtwinned crystals, since it involves a homogenization algorithm
based on the macroscopic deformation response of the layered structure. This potentially allows performing meaningful acoustic
studies on samples with a general submicron-size layered structure. 相似文献
6.
A new sample component is presented for the Monte Carlo, ray-tracing program, McStas, which is widely used to simulate neutron scattering instruments. The new component allows the sample to be described by its material dynamic structure factor, which is separated into coherent and incoherent contributions. The effects of absorption and multiple scattering are treated and results from simulations and previous experiments are compared. 相似文献
7.
Y. W. Li Z. G. Hu F. Y. Yue W. Z. Zhou P. X. Yang J. H. Chu 《Applied Physics A: Materials Science & Processing》2009,95(3):721-725
(La0.5Sr0.5)CoO3 (LSCO) thin films have been fabricated on silicon substrate by the pulsed laser deposition method. The effects of substrate
temperature and post-annealing condition on the structural and electrical properties are investigated. The samples grown above
650°C are fully crystalline with perovskite structure. The film deposited at 700°C has columnar growth with electrical resistivity
of about 1.99×10−3 Ω cm. The amorphous films grown at 500°C were post-annealed at different conditions. The sample post-annealed at 700°C and
10−4 Pa has similar microstructure with the sample in situ grown at 700°C and 25 Pa. However, the electrical resistivity of the
post-annealed sample is one magnitude higher than that of the in situ grown sample because of the effect of oxygen vacancy.
The temperature dependence of resistivity exhibits semiconductor-like character. It was found that post-annealing by rapid
thermal process will result in film cracks due to the thermal stress. The results are referential for the applications of
LSCO in microelectronic devices. 相似文献
8.
S. To Y. H. Zhu W. B. Lee X. M. Liu Y. B. Jiang G. Y. Tang 《Applied Physics A: Materials Science & Processing》2009,96(4):939-944
Phase transformations of an electropulsing-treated ZA22 alloy were studied after tensile deformation by using scanning electron
microscopy and transmission electron microscopy. It was found that electropulsing tremendously accelerated phase transformations
consequentially in the two stages: (a) quenching from supersaturated state approaching the final stable state, i.e., α+ε→T′+η, and (b) up-quenching from the final stable state to a higher temperature state, i.e., T′+η→α+ε. The mechanism of electropulsing-induced phase transformation is discussed from the point of view of Gibbs free energy, and
electropulsing kinetics. 相似文献
9.
Using a contrast matching technique of small angle neutron scattering (SANS), we have investigated a phase separation to liquid-disordered
and liquid-ordered phases on ternary small unilamellar vesicles (SUVs) composed of deuterated-saturated, hydrogenated-unsaturated
phosphatidylcholine lipids and cholesterol, where the equilibrium size of these domains is constrained to less than 10nm by
the system size. Below a miscibility temperature, we observed characteristic scattering profiles with a maximum, indicating
the formation of nano-meter-sized domains on the SUVs. The observed profiles can be described by a multi-domain model rather
than a mono-domain model. The nano-meter-sized domain is agitated by thermal fluctuations and eventually ruptured, which may
result in the multi-domain state. The kinetically trapped nano-meter-sized domains grow to a mono-domain state by decreasing
temperature. Furthermore, between the miscibility and disorder-order transition temperature of saturated lipid, the integrated
SANS intensity increased slightly, indicating the formation of nano-meter-sized heterogeneity prior to the domain nucleation. 相似文献
10.
D.?YamaguchiEmail author H.?Mayama S.?Koizumi K.?Tsujii T.?Hashimoto 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(2):153-163
The unique structure of a set of self-assembled porous silica materials was
characterized through a combined small-angle scattering (CSAS) method using
small- and ultra-small angle neutron scattering as well as small-angle X-ray
scattering. The porous silica specimens investigated were prepared by a
sol-gel method under the presence of alkylketene dimer (AKD) template
particles and through calcination, which leads to the development of porous
silica having a mass-fractal structure over length scales from ~ 100 nm
to ~ 10 μm. Furthermore, the specimens posses a hierarchical
structure, which consist of a fractal porous structure, and also contain
primary silica particles less than 10 nm in size, which form a continuous
silica matrix. To characterize these complex structures, observation over a
broad range of length scales is indispensable. We propose a CSAS technique
that serves this purpose well. 相似文献