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341.
Reactions of 4a,5-epoxy-5-deazaflavins with aqueous potassium carbonate, Vilsmeier reagent (dimethylformamide-phosphorus oxychloride), acetic anhydride-acetic acid, pyridine and triethanolamine gave the corresponding oxazolonoquinolines, 5-chloro-5-deazaflavins, 4a,5-diacetoxy-5-deazaflavins, 1,5-dihydro-5-deazaflavin-5-ones, and deoxygenated 5-deazaflavins, respectively. 相似文献
342.
Hiroshi Tanida Tadashi Irie Yoshiharu Wakisaka 《Journal of heterocyclic chemistry》1986,23(1):177-181
Treatment of 5,6,7,8-tetrahydro-5,8-methanoisoquinoline N-oxide ( 2 ) with fuming nitric acid afforded 3-nitro-5,6,7,8-tetrahydro-5,8-methanoisoquinoline N-oxide ( 3 ), an example of formation of an α-nitropyridine N-oxide derivative by nitration of N-oxides. Further reaction of 3 resulted in deoxygenation giving 3-nitro-5,6,7,8-tetrahydro-5,8-methanoisoquinoline ( 4 ). No aromatic nitration was observed by similar treatment of 5,6,7,8-tetrahydro-5,8-methanoisoquinoline ( 1 ) or 5,6,7,8-tetrahydroisoquinoline N-oxide ( 11 ). Some other aromatic substitutions with 1 and 2 were caried out to obtain mainly the 3-substituted derivatives. Significant mutagenicity of 3 is briefly reported. 相似文献
343.
Maeda Isamu Chowdhury Wasimul Q. Idehara Kenji Yagi Kiyohito Mizoguchi Tadashi Akano Toru Mlyasaka Hltoshi Furutani Toshio Ikuta Yoshiaki Shioji Norio Miura Yoshiharu 《Applied biochemistry and biotechnology》1998,(1):301-310
In photosynthetic bacteria, after transition to light-anaerobic and nitrogen-deficient conditions, hydrogen evolution starts
with expression of nitrogenase activity. Until the expression of enough activity,Rhodovulum sulfidophilum consumed substrates and converted them to poly(3-hydrox-ybutyrate) (PHB), resulting in a decrease in the proportion of substrate
converted into hydrogen gas. To prevent conversion to PHB during the period when nitrogenase activity is derepressed, the
authors employed a cultivation method consisting of three stages: cell growth, nitrogenase derepression, and hydrogen production.
Cells cultivated by this method exhibited no lag time before the commencement of hydrogen evolution and gave an improved yield
of hydrogen from the algal fermentative products. 相似文献
344.
Kiyoshi Tanaka Kiyoshi Kohayakawa Takayuki Irie Satoru Iwata Kazuto Taguchi 《Journal of fluorine chemistry》2007,128(10):1094-1097
Photoirradiation of the pentafluorophenyl-substituted Z-hemithioindigo 1 causes a novel type of photoinduced cyclization, to produce the intramolecularly cyclized alcohol 2 and its dehydrated ether 3. For this photoinduced cyclization, the o-fluorine atoms of the phenyl group of 1 are found to be crucial. 相似文献
345.
Alon N.; Kohayakawa Y.; Mauduit C.; Moreira C. G.; Rodl V. 《Proceedings London Mathematical Society》2007,95(3):778-812
Mauduit and Sárközy introduced and studied certainnumerical parameters associated to finite binary sequences EN {–1, 1}N in order to measure their level of randomness.Those parameters, the normality measure (EN), the well-distributionmeasure W(EN), and the correlation measure Ck(EN) of order k,focus on different combinatorial aspects of EN. In their work,amongst others, Mauduit and Sárközy (i) investigatedthe relationship among those parameters and their minimal possiblevalue, (ii) estimated (EN), W(EN) and Ck(EN) for certain explicitlyconstructed sequences EN suggested to have a pseudorandomnature, and (iii) investigated the value of those parametersfor genuinely random sequences EN. In this paper, we continue the work in the direction of (iii)above and determine the order of magnitude of (EN), W(EN) andCk(EN) for typical EN. We prove that, for most EN {–1,1}N, both W(EN) and (EN) are of order N, while Ck(EN) is oforder for any given 2 k N/4. 相似文献
346.
347.
Tsuge T Watanabe S Sato S Hiraishi T Abe H Doi Y Taguchi S 《Macromolecular bioscience》2007,7(6):846-854
Amino acid substitutions at two residues downstream from the active-site histidine of polyhydroxyalkanoate (PHA) synthases are effective for changing the composition and the molecular weight of PHA. In this study, saturation mutagenesis at the position Ala505 was applied to PHA synthase (PhaCAc) from Aeromonas caviae to investigate the effects on the composition and the molecular weight of PHA synthesized in Ralstonia eutropha. The copolymer composition and molecular weight of PHA were varied by association with amino acid substitutions. There was a strong relationship between copolymer composition and PHA synthase activity of the cells. This finding will serve as a rationale for producing tailor-made PHAs. 相似文献
348.
Nakamura T Kiyono K Yoshiuchi K Nakahara R Struzik ZR Yamamoto Y 《Physical review letters》2007,99(13):138103
We describe the nature of human behavioral organization, specifically how resting and active periods are interwoven throughout daily life. Active period durations with physical activity count successively above a predefined threshold, when rescaled with individual means, follow a universal stretched exponential (gamma-type) cumulative distribution with characteristic time, both in healthy individuals and in patients with major depressive disorder. On the other hand, resting period durations below the threshold for both groups obey a scale-free power-law cumulative distribution over two decades, with significantly lower scaling exponents in the patients. We thus find universal distribution laws governing human behavioral organization, with a parameter altered in depression. 相似文献
349.
When the photochromism of 2-(3'-pyridylmethylene)-7-ethylbenzo[b]thiophen-3(2H)-ones (4) was investigated, high thermal stability of the E isomer of 4, 4(E) and good repeatability of the photoinduced E,Z-isomerization were found. Association constants of the 1:1 complexations of 4(Z) and 4(E) with the ureidoporphyrin 1 and with the pentafluorobenzamidoporphyrin 2 were evaluated. We found that 1 captures 4(E) preferentially to 4(Z) and, reversely, 2 prefers 4(Z) to 4(E). On the basis of these differences in the binding ability, we concluded that the repeatable movement of the hemithioindigo, so-called the hemithioindigo shuttle, between two kinds of porphyrins was controlled by the photoirradiation. These movements were applied to create a molecular switch for changes in the quinone distribution between two kinds of porphyrins. 相似文献
350.
Trimethylstannyllithium promotes cyclization of (o-alkynylphenyl)silane into a 3-stannylbenzosilole, via addition to the triple bond followed by intramolecular cyclization in a cascade fashion. This intermediate can be functionalized with either electrophiles or nucleophiles to allow modular synthesis of 2,3-disubstituted benzosiloles. One of these compounds, a phenylene-bis(benzosilole) compound, shows electron drift mobility as high as 6 x 10-4 cm2/Vs in an amorphous film, making this class of compounds promising electronic materials for organic light emitting devices and organic photovoltaic cells. 相似文献