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211.
Kazuko Komeda Sakae Iwamoto Seiji Kominami Takeo Ohnishi 《Photochemistry and photobiology》1997,65(1):115-118
Abstract— When Escherichia coli cells were irradiated by UVA in the presence of 6-mercaptopurine (6-MP) or 2-thiouracil (S2 Ura), two kinds of repair-deficient strains of recA − and uvrA − were killed more efficiently than the parental wild-type strain having normal repair capacities. In addition, these agents with UVA exposure greatly induced the incidence of mutations in the uvrA − strain as compared with the wild-type strain but not the uvrA − strain. Furthermore, the induction of expression of umuDC genes was investigated in two Salmonella typhimurium strains, TA1S35 and TA1538, carrying a pSK1002 plasmid. In these systems, it is easy to measure β-galactosidase activities for the induced activities of SOS responses. These agents with UVA exposure also induced expression of the umuDC genes. These results suggest that 6-MP and S2 Ura with UVA induce DNA damage which is repairable by the excision repair mechanism. 相似文献
212.
Tai Hasegawa Shin-Ichi Nishikiroi Toschitake Iwamoto 《Journal of inclusion phenomena and macrocyclic chemistry》1984,1(4):365-368
Inclusion compounds with the general formula Cd(NH2(CH2)
n
NH2)Ni(CN)4·xG were prepared forn=4 to 8, and for G of such an aromatic guest molecule as pyrrole, benzene, aniline, toluene, toluidine, xylene, xylidine, dichlorobenzene, trimethylbenzene, tetramethylbenzene, ethylbenzene, styrene, or isopropylbenzene, with varyingx. Generally, longer chain lengths of ,-diamine in the host permit the inclusion of bulkier guest molecules. However, the presence of an amino group on the phenyl ring of the guest appears to impart a special affinity with the hosts. 相似文献
213.
Seiichi Iwamoto Chung-lie Wang 《Journal of Mathematical Analysis and Applications》1983,96(1):119-129
We present in this paper some results concerning the following nonlinear system of P.D.E. where .The above system is a mathematical model which describes coupled flexural and torsional oscillations of an open cross-section beam. In Part I we consider the abstract initial value problem associated with the above system, prove the existence and uniqueness of solutions in a weak sense and mention two applications. In Part II we obtain regular solutions when adequate conditions on the data are assumed. 相似文献
214.
T Toukairin K Uchino M Iwamoto S Murakami T Tatebayashi H Ogawara Y Tonosaki 《Chemical & pharmaceutical bulletin》1991,39(6):1480-1483
New 5'-nucleotidase inhibitors designated as NPF-88BU-IA, NPF-88BU-IB, NPF-88BU-IIA and NPF-88BU-IIB, respectively, were isolated from the seeds and skin of the wine grape "Koshu". They were purified by solvent extraction, dialysis, and reversed-phase high performance liquid chromatography (HPLC). Their physico-chemical properties revealed these compounds to be polyphenolic substances. The average relative molecular masses of the four were estimated by gel permeation chromatography (GPC) analysis to be 7850, 5950, 11900, and 11300, respectively. They strongly inhibited 5'-nucleotidase activities from snake venom and rat liver membrane, and displayed significant therapeutic activity against Ehrlich ascites carcinoma. They also showed inhibitory effects on the growth of Streptococcus mutans MT8148(c), a primary cariogenic bacterium. Furthermore, these 5'-nucleotidase inhibitors inhibited the glucan formation from sucrose. These results suggest that the 5'-nucleotidase inhibitors can prevent the cause of caries of tooth. 相似文献
215.
Salting effects of metal chelate electrolytes Fe(phen)3Br2, Fe(bpy)3Br2, Co(phen)3Br2, Co(phen)3Br3, Co(en)3Br3, and Co(pn)3Br3 (where phen=1,10-phenanthroline, bpy=2,2-bipyridyl, en=ethylenediamine, and pn=1,2-propylenediamine) on the solubilities of nitrobenzene,o-,m-,and p-dinitrobenzenes (DNB), and toluene were studied in water at 25°C and compared to the results for sodium bromide and tetrabutylammonium bromide (Bu4NBr). The Co(phen)
3
3+
, Fe(phen)
3
2+
, and Fe(bpy)
3
2+
ions showed much stronger salting-in effects than did the Bu4N+ ion, while the effects of the Co(en)
3
3+
and Co(pn)
3
3+
ions are comparable with those of Bu4N+. A great dependence of salting-in on the polarity of dinitrobenzene isomers was found for Co(phen)
3
3+
and Fe(phen)
3
2+
. The results were related to the partial molal volume of the respective cations. The very strong salting-in was considered to be mainly due to hydrophobic hydrations of the metal chelate cations and partly due to van der Waals interactions between the aromatic ligands and the nonelectrolytes. The small salting-in effects by Co(en)
3
3+
and Co(en)
3
3+
were interpreted in terms of hydrogen bonding between oxygen atoms of the nitro compounds or the solvent water molecules and hydrogen atoms attached to nitrogens in the complexes. 相似文献
216.
A Two‐Coordinate Cyclic (Alkyl)(amino)silylene: Balancing Thermal Stability and Reactivity 下载免费PDF全文
Tomoyuki Kosai Prof. Dr. Shintaro Ishida Prof. Dr. Takeaki Iwamoto 《Angewandte Chemie (International ed. in English)》2016,55(50):15554-15558
A crystalline two‐coordinate cyclic (alkyl)(amino)silylene ( 1 ) was successfully synthesized and isolated. Its 29Si NMR and UV/Vis spectra indicate that the electronic properties of 1 fall between those of cyclic dialkylsilylenes and diaminosilylenes. At very low temperature, the color of a solution of 1 turned from colorless to yellow, which was monitored by UV/Vis spectroscopy. DFT calculations supported the hypothesis that head‐to‐head dimers (disilenes) with a very long Si–Si distance are formed at such low temperatures. Although 1 is thermally stable, it readily undergoes cycloadditions, Si?H insertions, and photochemical reactions with benzene similar to dialkylsilylenes. At higher temperatures, 1 is also susceptible to intermolecular benzylic C?H insertion reactions, as well as unprecedented dehydrogenation reactions with cyclohexa‐1,4‐diene and 9,10‐dihydroanthracene to afford benzene and anthracene, respectively. 相似文献
217.
Meccanica - This study is concerned with an eigenvalue problem of a vibro-acoustic coupled system. In the conventional modal coupling method, the particle velocity normal to the surface of a panel... 相似文献
218.
219.
220.
Prof. Dr. Shintaro Ishida Takuroh Hatakeyama Takuya Nomura Maiko Matsumoto Dr. Kimio Yoshimura Prof. Dr. Soichiro Kyushin Prof. Dr. Takeaki Iwamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(68):15811-15815
The catalyst-free hydrosilylation of CO2 under mild conditions remains limited. Herein, we report the synthesis, characterization, and reactivity of 5,10,15,20-tetraphenylporphyrinato(dihydrido)silicon(IV) ( 1 ) as a six-coordinate silicon dihydride. The Si-H moiety of 1 reacts with polar double bonds and CO2 in the absence of a catalyst to afford hydrosilylated products. Combining the hydrosilylation with subsequent transformation furnishes formic acid from CO2. Computational studies indicate that the hydride-donor properties of 1 are exceptionally high for a neutral silicon hydride, and that the direct hydride transfer from silicon to carbon is a pivotal step in the hydrosilylation of CO2 with 1 . 相似文献