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排序方式: 共有792条查询结果,搜索用时 15 毫秒
1.
2.
In this article we prove the existence of the solution to the mixed problem for Euler–Bernoulli beam equation with memory term. The existence is proved by means of the Faedo–Galerkin method and the exponential decay is obtained by making use of the multiplier technique combined with integral inequalities due to Komornik. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
3.
Yong Nam Choi Shin Ae Kim Sung Kyu Kim Sung Baek Kim Chang-Hee Lee Pavel Mikula 《Pramana》2004,63(1):175-181
In a conventional diffractometer having single monochromator, only one position, parallel position, is used for the diffraction
experiment (i.e. detection) because the resolution property of the other one, anti-parallel position, is very poor. However,
a bent perfect crystal (BPC) monochromator at monochromatic focusing condition can provide a quite flat and equal resolution
property at both parallel and anti-parallel positions and thus one can have a chance to use both sides for the diffraction
experiment. From the data of the FWHM and the Δd/d measured on three diffraction geometries (symmetric, asymmetric compression and asymmetric expansion), we can conclude that
the simultaneous diffraction measurement in both parallel and anti-parallel positions can be achieved. 相似文献
4.
Man Young Kim Seung Wook Baek 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,90(3-4):377-388
Radiative heat transfer in an axisymmetric enclosure with absorbing, emitting, and scattering medium is studied here by using the different methods such as MDOM, FVM, and MFVM with emphasis on the treatment of angular derivative term, which appears in curvilinear coordinates due to angular redistribution. After final discretization equation for MFVM is introduced by using the step scheme and directional weights, the present approach is validated by applying it to three different benchmarking problems with absorbing, emitting, and scattering medium. All of the results presented here support its accuracy as well as moderate efficiency. Finally, the present approaches are applied to a truncated cone-shaped enclosure as a body-fitted geometry case. 相似文献
5.
[reaction: see text]. A novel synthetic methodology for 2,5-disubstituted tetrahydrofurans having an allenyl group at the 3-position via Prins-type cyclization was developed. The reaction led to excellent selectivity and moderate to high yields. 相似文献
6.
7.
Woo-Jin Lee Su-Il Pyun Tae-Hyun Yang Joong-Do Kim Young-Ho Baek Han-Gyu Kim 《Journal of Solid State Electrochemistry》1997,1(2):120-125
Hydrogen transport through a Pd-Ni alloy electrodeposited on a Pd substrate (Pd-Ni/Pd bilayer symmetric electrode) has been
investigated using cyclic voltammetry and a.c. impedance spectroscopy combined with the electrochemical hydrogen permeation
method. The permeation build-up current transients and the measured impedance spectra were analyzed using the time-lag method
for the bilayer electrode and a complex non-linear least squares data-fitting method based upon the derived Faradaic admittance
for the hydrogen absorption into and diffusion through the bilayer electrode under the permeable boundary condition, respectively.
The value of the hydrogen diffusivity in the Pd-Ni layer was lower than that in the Pd layer. Furthermore, the values of the
charge transfer resistance and equilibrium absorption constant for the Pd-Ni/Pd bilayer electrode were higher than those for
the Pd single layer electrode. From the experimental results, the role of the thin Ni(OH)2 film formed on the Pd-Ni layer surface in the hydrogen transport through the Pd-Ni/Pd bilayer electrode is discussed in terms
of its passivating effect and extremely large hydrogen solubility.
Received: 22 January 1997 / Accepted: 15 April 1997 相似文献
8.
Choi SJ Yoo PJ Baek SJ Kim TW Lee HH 《Journal of the American Chemical Society》2004,126(25):7744-7745
We describe a novel UV-curable mold that is stiff enough for replicating dense sub-100-nm features even with a high aspect ratio. It also allows for flexibility when the mold is prepared on a flexible support such that large area replication can be accomplished. The composite material of the mold is inert to chemicals and solvents. The surface energy is made low with a small amount of releasing agent such that the mold can be removed easily and cleanly after patterning. In addition, the material allows self-replication of the mold. These unique features of the mold material should make the mold quite useful for various patterning purposes. 相似文献
9.
Hong SB Lee SH Shin CH Woo AJ Alvarez LJ Zicovich-Wilson CM Camblor MA 《Journal of the American Chemical Society》2004,126(42):13742-13751
Here, we report that synthetic gallosilicate molecular sieves with the NAT topology and Si/Ga ratios close to but slightly higher than 1.50 undergo an in situ transformation under their crystallization conditions. The materials have been studied ex situ by using powder X-ray diffraction, elemental and thermal analyses, and multinuclear MAS NMR. The transformation is characterized by a change in the distribution of Si and Ga of the NAT framework, from a quite (but not completely) disordered phase to a very highly (but not completely) ordered one, accompanied by a change from tetragonal to orthorhombic symmetry. During most of the solution-mediated transformation, no noticeable signs of fresh precipitation, phase segregation, or changes in the chemical composition are detected. Intermediate materials show variations in the degree of Si-Ga ordering and orthorhombic distortion and are not physical mixtures of the disordered and ordered phases. Ab initio calculations strongly suggest a preferential siting of Si in the tetrahedral sites involved in a smaller number of 4-rings in the NAT topology (i.e., the low multiplicity site). The cost of violations of Loewenstein's rule has also been calculated. For this topology and chemical composition the preferential siting and Loewenstein's rule drive together the system to the ordered configuration. A Monte Carlo sampling procedure affords a reasonable model for the initial, mainly disordered state, which fits well within the experimental disorder-order series. 相似文献
10.
Ohne Zusammenfassung 相似文献