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排序方式: 共有841条查询结果,搜索用时 46 毫秒
71.
72.
4-(3,17Beta-dihydroxyestra-1,3,5(10)-trien-6alpha- and 6beta-yl)amino-7-nitro-2,1,3-benzoxadiazoles have been synthesized and characterized as fluorescent probes for use in a receptor assay and/or a homogeneous immunoassay for estradiol. The fluorescence intensities are strongly dependent upon the solvent polarity used. The intensities in water were reduced to less than 1% of those in ethyl acetate, and a blue shift was also observed in polar solvents. The quenched fluorescence in aqueous solution was recovered by adding bovine serum albumin or an anti-estradiol antibody. Adding intact estradiol inhibited the fluorescence recovered by the antibody. 相似文献
73.
Takashi Takebe 《Communications in Mathematical Physics》1997,183(1):161-181
An elliptic analogue of theq deformed Knizhnik-Zamolodchikov equations is introduced. A solution is given in the form of a Jackson-type integral of Bethe
vectors of the XYZ-type spin chains. 相似文献
74.
Yukio Kanda Masafumi Taira Kazuhiko Chimura Tomoyuki Takano Motoaki Sawabe 《Analytical sciences》2005,21(6):629-634
A reliable and convenient system to generate accurate and stable standard gas mixtures of various atmospheric compounds at parts-per-billion levels has been developed. The system is of simple design; the generator is a coil consisting of an inner tube of microporous polytetrafuluoroethylene (PTFE) membrane tubing and an outer tube of silicone tubing. An aqueous solution of the given compound continuously flows through the inner microporous tube and the purge gas flows through the annulus between the inner and outer tubes. In addition to the generation of gas mixtures based on Henry's law, the proposed flow-type system offers generation based on chemical reactions, leading to a distinct advantage of the availability of continuous sources of various compounds. The generation system was tested for preparing standard gas mixtures of HCHO and H2O2 on the basis of Henry's law, and those of HNO2, NO, and SO2 on the basis of chemical reactions. A stable generation of the desired low concentrations of various kinds of gas mixtures can be readily achieved by adjusting the concentration of the solution without the use of high-dilution flow. 相似文献
75.
A series of experiments were carried out to study the degradation of methylene blue by the irradiation of ultrasound onto TiO(2) in aqueous solution. A statistically significant decrease in the concentration of methylene blue was observed after 60 min irradiation. While the reduction was 22% of the initial concentration without H(2)O(2), addition of H(2)O(2) significantly enhanced the degradation of methylene blue for the TiO(2) containing system (85% reduction of the initial concentration). The addition of H(2)O(2) had no effect on the methylene blue degradation when the system contained Al(2)O(3). The degradation ratio of methylene blue was dependent on the amount of TiO(2) and also the specific surface area of TiO(2) in the solution. The effects of radical scavenging agents on the degradation of methylene blue were also investigated for the system with TiO(2). It was found that the radical scavenging agents dimethyl sulfoxide (DMSO), methanol, and mannitol suppressed the degradation, with DMSO being the most effective. The effect of pH on the degradation of methylene blue was further investigated. An U-shaped change in the concentration of methylene blue in the presence of TiO(2) was observed along with the change in pH values (pH 3-12), and the highest degradation ratio was observed at around pH 7. In conclusion, ultrasound irradiation of TiO(2) in aqueous solution resulted in significant generation of hydroxyl radicals, and this process may have potential for the treatment of organic dyes in wastewater. 相似文献
76.
Reconstitution of Biosynthetic Machinery for the Synthesis of the Highly Elaborated Indole Diterpene Penitrem
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Dr. Chengwei Liu Koichi Tagami Dr. Atsushi Minami Tomoyuki Matsumoto Jens Christian Frisvad Hideyuki Suzuki Jun Ishikawa Katsuya Gomi Prof. Dr. Hideaki Oikawa 《Angewandte Chemie (International ed. in English)》2015,54(19):5748-5752
Penitrem A is one of the most elaborated members of the fungal indole diterpenes. Two separate penitrem gene clusters were identified using genomic and RNA sequencing data, and 13 out of 17 transformations in the penitrem biosynthesis were elucidated by heterologous reconstitution of the relevant genes. These reactions involve 1) a prenylation‐initiated cationic cyclization to install the bicyclo[3.2.0]heptane skeleton (PtmE), 2) a two‐step P450‐catalyzed oxidative processes forming the unique tricyclic penitrem skeleton (PtmK and PtmU), and 3) five sequential oxidative transformations (PtmKULNJ). Importantly, without conventional gene disruption, reconstitution of the biosynthetic machinery provided sufficient data to determine the pathway. It was thus demonstrated that the Aspergillus oryzae reconstitution system is a powerful method for studying the biosynthesis of complex natural products. 相似文献
77.
Cover Picture: Reconstitution of Biosynthetic Machinery for the Synthesis of the Highly Elaborated Indole Diterpene Penitrem (Angew. Chem. Int. Ed. 19/2015)
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78.
Dr. Shintaro Ishida Dr. Takashi Abe Dr. Fumiya Hirakawa Tomoyuki Kosai Katsuhiro Sato Prof. Dr. Mitsuo Kira Prof. Dr. Takeaki Iwamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15100-15103
A persistent dialkylsilanone was synthesized by the dehydrobromination of a dialkylbromosilanol with tris(trimethylsilyl)silyl potassium in solution at ?80 °C: It was characterized by NMR and IR spectroscopy, and was tested in several reactions. In 29Si NMR spectrum in [D8]toluene, the signal due to the unsaturated silicon nuclei was observed at 128.7 ppm. Reactions of the dialkylsilanone with water and mesitonitrile oxide gave a silanediol and a [2+3] cycloadduct, respectively. The silanone remains intact in [D8]toluene below ?80 °C for at least two days, while it undergoes unprecedented isomerization to give a siloxysilene by means of 1,3‐silyl migration at higher temperatures. 相似文献
79.
We propose a conformational search method to find a global minimum energy structure for protein systems. The simulated annealing is a powerful method for local conformational search. On the other hand, the genetic crossover can search the global conformational space. Our method incorporates these attractive features of the simulated annealing and genetic crossover. In the previous works, we have been using the Monte Carlo algorithm for simulated annealing. In the present work, we use the molecular dynamics algorithm instead. To examine the effectiveness of our method, we compared our results with those of the normal simulated annealing molecular dynamics simulations by using an α-helical miniprotein. We used genetic two-point crossover here. The conformations, which have lower energy than those obtained from the conventional simulated annealing, were obtained. 相似文献
80.
Ueda A Kato D Kurita R Kamata T Inokuchi H Umemura S Hirono S Niwa O 《Journal of the American Chemical Society》2011,133(13):4840-4846
We have developed a new carbon film electrode material with thornlike surface nanostructures to realize efficient direct electron transfer (DET) with enzymes, which is very important for various enzyme biosensors and for anodes or cathodes used in biofuel cells. The nanostructures were fabricated using UV/ozone treatment without a mask, and the obtained nanostructures were typically 2-3.5 nm high as confirmed by atomic force microscopy measurements. X-ray photoelectron spectroscopy and transmission electron microscopy revealed that these nanostructures could be formed by employing significantly different etching rates depending on nanometer-order differences in the local sp(3) content of the nanocarbon film, which we fabricated with the electron cyclotron resonance sputtering method. These structures could not be realized using other carbon films such as boron-doped diamond, glassy carbon, pyrolyzed polymers based on spin-coated polyimide or vacuum-deposited phthalocyanine films, or diamond-like carbon films because those carbon films have relatively homogeneous structures or micrometer-order crystalline structures. With physically adsorbed bilirubin oxidase on the nanostructured carbon surface, the DET catalytic current amplification was 30 times greater than that obtained with the original carbon film with a flat surface. This efficient DET of an enzyme could not be achieved by changing the hydrophilicity of the flat carbon surface, suggesting that DET was accelerated by the formation of nanostructures with a hydrophilic surface. Efficient DET was also observed using cytochrome c. 相似文献