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排序方式: 共有1119条查询结果,搜索用时 31 毫秒
131.
Hiroshi Kimura Koichiro Aikawa Yuichi Masubuchi Jun-ichi Takimoto K. Koyama Keiji Minagawa 《Rheologica Acta》1998,37(1):54-60
The mechanism of the electrorheological (ER) effect in two types of liquid crystalline polymer (LCP)/dimethylsiloxane (DMS)
blends was investigated by rheological measurements and by structure observation under electric field and shear flow. The
results show that the phase structures of these immiscible blends can be categorized into slipping (low viscosity) and non-slipping
(high viscosity) states. In the non-slipping state, higher viscosity LCP domains connect the electrodes. In the slipping state,
on the other hand, LCP domains do not connect the electrodes and the shear is mainly confined in the lower viscosity DMS domains.
The ER effect (electrically induced viscosity increase) originates from the electrically induced slipping to non-slipping
transition. In one of the blends, the ER effect occurs only at high shear rate, since this blend is in non-slipping state
even under no field if the shear rate is low.
Received: 29 April 1997 Accepted: 3 November 1997 相似文献
132.
An integral treatment was proposed for analysis of non-Darcy free convection over a vertical flat plate and cone within a fluid-saturated porous medium. A flexible one-parameter family of third order polynomials was employed to cope with vast changes in the velocity and temperature profiles encountered in the Darcy flow limit through to the Forchheimer flow limit. Zero curvature requirement for the temperature profile at the wall was exploited as an auxiliary relation to determine the shape parameter. Comparison of the approximate results with the exact solution reveals a high performance of the present integral procedure for heat transfer rat prediction. 相似文献
133.
Koichiro DotaTadashi Shimizu Shoji HasegawaMasaaki Miyashita Keiji Tanino 《Tetrahedron letters》2011,52(8):910-912
An efficient method for constructing a 10-membered carbocycle with an oxygen bridge has been developed on the basis of a formal [6+4] cycloaddition reaction. Under the influence of EtAlCl2, a dicobalt hexacarbonyl acetylene complex possessing a benzoyloxy group and an allylsilane moiety reacted with furan to give a 11-oxabicyclo[6.2.1]undec-9-ene derivative. On treatment with iodine, the cycloadduct underwent decomplexation followed by rearrangement of the oxygen bridge to afford a 11-oxabicyclo[5.3.1]undeca-1,5-diene derivative. 相似文献
134.
Palladium-catalyzed arylative cyclization of propargyl-substituted malonate esters with aryl halides offers a stereoselective approach to alkylidenecyclopropanes. The reaction proceeds by an anti-carbopalladation pathway, which guarantees the exclusive stereocontrol of the resulting double bond. The highly strained as well as densely substituted skeletons of the products facilitate further versatile transformations, which underscores the importance of the products as synthetic intermediates. 相似文献
135.
Ogawa A Miyamae Y Honma A Koyama T Yazawa K Shigemori H 《Chemical & pharmaceutical bulletin》2011,59(5):672-675
A new compound, pycnalin (1), together with four known compounds, ginnalins A (2), B (3), C (4), and 3,6-di-O-galloyl-1,5-anhydro-D-glucitol (3,6-di-GAG) (5), were isolated from Acer pycnanthum. The structure of 1 was determined on the basis of 2D-NMR spectral data and synthesis of 1. Pycnalin (1) is the first 1,5-anhydro-D-mannitol linked to a gallic acid, while compounds 2-5 were 1,5-anhydro-D-glucitol linked to gallic acids. All compounds were tested in vitro for α-glucosidase inhibitory and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities. Pycnalin (1) exhibited moderate α-glucosidase inhibitory activity as well as free radical scavenging activity. Ginnalin A (2) and 3,6-di-GAG (5), which have two galloyl groups, exhibited potent α-glucosidase inhibition, compared to those of other compounds 1, 3, and 4 containing a galloyl group. These results suggest that α-glucosidase inhibition is influenced by the number of galloyl groups. 相似文献
136.
Horie H Koyama I Kurahashi T Matsubara S 《Chemical communications (Cambridge, England)》2011,47(9):2658-2660
The linear codimerization of acrylates and alkynes to produce 1,3-dienes is successfully demonstrated using a nickel catalyst in association with 2-aminopyridine as an additive. 相似文献
137.
Shun Koyama Yoshitaka Aoki Shinji Nagata Hiroki Habazaki 《Journal of Solid State Electrochemistry》2011,15(10):2221-2229
Zr–Al alloys containing up to 26 at.% aluminum, prepared by magnetron sputtering, have been anodized in 0.1 mol dm−3 ammonium pentaborate electrolyte, and the structure and dielectric properties of the resultant anodic oxide films have been
examined by grazing incidence X-ray diffraction, transmission electron microscopy, Rutherford backscattering spectroscopy,
and AC impedance spectroscopy. The anodic oxide film formed on zirconium consists of monoclinic and tetragonal ZrO2 with the former being a major phase. Two-layered anodic oxide films, comprising an outer thin amorphous layer and an inner
main layer of crystalline tetragonal ZrO2 phase, are formed on the Zr–Al alloys containing 5 to 16 at.% aluminum. Further increase in the aluminum content to 26 at.%
results in the formation of amorphous oxide layer throughout the thickness. The anodic oxide films become thin with increasing
aluminum content, while the relative permittivity of anodic oxide shows a maximum at the aluminum content of 11 at.%. Due
to major contribution of permittivity enhancement, the maximum capacitance of the anodic oxide films is obtained on the Zr–11 at.%
Al alloy, being 1.7 times than on zirconium at the formation voltage of 100 V. 相似文献
138.
139.
Guksik Lee Fumito Araoka Ken Ishikawa Yuichi Momoi Osamu Haba Koichiro Yonetake Hideo Takezoe 《Particle & Particle Systems Characterization》2013,30(10):847-852
Ordering transitions are observed in azo‐dendrimer‐dissolved nematic liquid crystal (NLC) droplets dispersed in a glycerol matrix. The dendrimer molecules are spontaneously attached at the interface between NLC and glycerol, so that the nematic directors orient perpendicular to the interface, in the radial configuration. Photoisomerization makes the directors be tangential to the interface, in a photoinduced ordering transition from radial to bipolar structure. Similar experiments are conducted both in cholesteric (Ch) and smectic‐A (SmA) LC droplets. Complicated photoinduced ordering transitions are also observed in Ch and SmA droplets, and the associated molecular orientation changes are discussed. Photoisomerizable azo‐dendrimer molecules provide a possible way to control orientation, even in microdroplet systems in which the interface cannot be treated by conventional surface agents. 相似文献
140.