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51.
Selective introducing of aryl and amino groups: reaction of benzanthrone and organometallic reagents
Rui Umeda Teruaki Namba Tomohiro Yoshimura Masamichi Nakatsukasa Yutaka Nishiyama 《Tetrahedron》2013,69(5):1526-1531
The reaction of benzanthrone and aryl magnesium bromides produced 6-aryl-substituted benzanthrones in moderate to good yields. Similarly, 6-alkylaminobenzanthrones were selectively prepared by the reaction of benzanthrone and lithium alkylamides. In contrast, for the lithium arylamides, the arylamino groups were selectively introduced at the 4-position of the benzanthrone. 相似文献
52.
Yamashita M Ohta N Shimizu T Matsumoto K Matsuura Y Kawasaki I Tanaka T Maezaki N Ohta S 《The Journal of organic chemistry》2003,68(4):1216-1224
The first total synthesis of (+/-)-Linderol A, a hexahydrodibenzofuran constituent of Lindera umbellata bark, with potent inhibitory activity on the melanin biosynthesis of cultured B-16 melanoma cells, was achieved through 19 steps of reaction in 6.6% overall yield, in which the critical step was a tandem reaction of a 3-ethoxycarbonylcoumarin derivative with dimethylsulfoxonium methylide to yield the 2-ethoxycarbonylcyclopenta[b]benzofuran-3-ol derivative. 相似文献
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55.
Affoune AM Yamada A Umeda M 《Langmuir : the ACS journal of surfaces and colloids》2004,20(17):6965-6968
Surface morphology modification of the Nafion 117 membrane has been investigated by atomic force microscopy. The effects of water and methanol on the topography and structure of the surface were studied using the contact and tapping atomic force microscopy modes. Nafion topography considerably changes when samples absorb water. However, samples stored in methanol are characterized by flat surfaces. Surface modification was linked to an expansion phenomenon during the swelling of Nafion by solvents. Tapping-mode phase images showed that ionic and cluster domains are distinguishable from the surface of samples impregnated either in water or methanol. 相似文献
56.
Momoko Kumemura Dominique Collard Christophe Yamahata Naoyoshi Sakaki Gen Hashiguchi Hiroyuki Fujita 《Chemphyschem》2007,8(12):1875-1880
This paper presents a systematic method to isolate and trap long single DNA segments between integrated electrodes in a microfluidic environment. Double stranded lambda-DNA molecules are introduced in a microchip and are isolated by electrophoretic force through microfluidic channels. Downstream, each individual molecule is extended and oriented by ac dielectrophoresis (900 kHz, 1 MV m(-1)) and anchored between aluminium electrodes. With a proper design, a long DNA segment (up to 10 microm) can be instantly captured in stretched conformation, opening way for further assays. 相似文献
57.
Kenji Wada Yasuhiko Satomura Hiroshi Kamie Takafumi Kiuchi Hiromichi Horinaka Yoshio Cho Tokuo Umeda Kenji Nakamura 《Optical Review》2000,7(5):432-435
Aiming at the realization of optical computed tomography (optical CT), a compact system comprised of two cw-lasers and a detector was proposed for the extraction of quasi-straightforward propagating photons from scattered light transmitting through a scattering medium. The extraction ability of the system based on the sum-frequency generation technique was investigated using a standard scattering medium of Intralipid-10% aqueous solution and was found to be 78 dB in dynamic range. The optical CT image of absorbers placed in the scattering medium was successfully obtained with high contrast using the proposed system. 相似文献
58.
Considerable research efforts are being devoted toward the development of chemical sensors and biosensors based on the so卜gel technology. We have prepared an ECL-optic sensor having a Pt electrode coated doubly with a Ru(bpy)32+-modified chitosan and silica gel membrane. In the present paper we would like to report on the substrate selectivities of ECL electrode having a silica gel layers modified with amino or alkyl groups. The new ECL electrode were prepared by the same method as reported previously, except that organotrialkoxysilanes were added to the silica-sol precursor solution. Experimental results at an applied potential of 1.10 V vs. Ag/AgCI in 0.05 M phosphate buffer (pH 6.8) for a several substrates are summarized as follows. 相似文献
59.
Kazuaki Yokota Toyoji Kakuchi Toshifumi Satoh Stoshi Umeda Masatoshi Kamada 《Macromolecular Symposia》2000,157(1):13-20
The selective cyclopolymerization of 1,2:5,6‐dianhydrohexitols corresponding to diepoxides was a new synthetic strategy for polycarbohydrates, though the polymer is a lack of the anomeric linkage which is found in the naturally occurring polysaccharides. 1,2:5,6‐Dianhydro‐3,4‐di‐O‐methyl‐D‐mannitol, L‐iditol, and D‐glucitol were polymerized using t‐BuOK and BF3·Oet2 to produce the polymers consisting of five‐membered rings. On the other hand, the polymers consisting of six‐membered rings were obtained by the cationic and anionic polymerizations of meso allitol and galactitol monomers, respectively. 相似文献
60.
This paper proposes a novel method for evaluating the dynamic characteristics of shock accelerometers under high acceleration
levels and a wide frequency bandwidth. High accelerations of 103∼105m/s2 can be generated by the reflection of an elastic wave pulse propagating in a metal bar known as the Davies bar. The elastic
wave pulse is produced by the collision of a projectile against one end of the bar, and is detected by straingages. The accelerometer
to be characterized is attached to the other end of the bar. The one-dimensional theory of elastic waves enables the derivation
of an input acceleration to the accelerometer from the measured strain. The dispersion of the elastic waves caused by the
lateral inertia of the bar is compensated for by using a two-dimensional analytical solution. This method was validated by
an experiment characterizing a piezoelectric-type accelerometer within the frequency band approximately 1 kHz∼70 kHz. 相似文献