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排序方式: 共有1319条查询结果,搜索用时 15 毫秒
151.
H Horino T Mimura K Kagechika M Ohta H Kubo M Kitagawa 《Canadian Metallurgical Quarterly》1998,46(4):602-609
A series of 3,4-dihydro-3-hydroxy-4-[(5-oxo-3,4-diazabicyclo[4.1.0]hept- 2-en-2-yl)oxy]-2H-1-benzopyrans and their analogues were synthesized and evaluated on potassium channel opening and hypotensive activities. Compound (-)-13B with a (4-methyl-5-oxo-3,4-diazabicyclo[4.1.0]hept-2-en-2-yl)oxy group for the 4-position of the benzopyran ring was 3 times as potent as EMD 57283 (II), the lead compound, in hypotensive activity. The results would demonstrate that 5-oxo-3,4-diazabicyclo[4.1.0]hept-2-en-2-yloxy moieties are effective as the substituents at the 4-position of benzopyran-type potassium channel openers. 相似文献
152.
Lipopeptides carrying a farnesyl thioether or a palmitic acid thioester and a farnesyl thioether were prepared from S-farnesyl cysteine methyl ester by N-terminal extension of the peptide chain employing the base labile Fmoc blocking group of the palladium(0) sensitive Aloc urethane. By means of this technique a lipohexapeptide representing the completely functionalized, i.e. palmitoylated and farnesylated C-terminus of the human N-Ras protein, was prepared. If acid labile blocking functions like the Boc group were used, upon deprotection an undesired addition of the acid to the double bonds of the farnesyl residue occurred. Therefore, acid labile blocking groups should not be employed in the synthesis of farnesylated lipopeptides. The lipopeptide methyl esters which carry only a farnesyl group do not inhibit protein farnesyl transferase, whereas palmitoylated peptides are weak inhibitors of this enzyme. 相似文献
153.
A 49-year-old female presented with a 2-year history of occipitalgia, a 3-month history of dysesthesia, and dull sensation of the left upper extremity. T1-weighted magnetic resonance (MR) imaging revealed a low-intensity mass without gadolinium-diethylenetriaminepenta-acetic acid enhancement extending from the cisterna magna to the spinal canal. T2-weighted MR imaging revealed a high-intensity mass. Neuroradiological findings were inadequate to establish the mass as intra-axial or extra-axial. Operative findings discovered an intra-axial mass which was totally removed. Histological examination found the mass was an oligoastrocytoma. Cerebellar glioma developing exophytically is very rare. Adequate surgical removal is possible and likely to be curative if total. 相似文献
154.
Tokuda T. Sakano Y. Mori D. Ohta J. Nunoshita M. Vaccaro P.O. Vorob'ev A. Kubota K. Saito N. 《Electronics letters》2004,40(21):1333-1334
A micromirror structure with SiGe/Si heteroepitaxial layer on a silicon-on-insulator (SOI) substrate using a 'Micro-origami' technique has been successfully fabricated. The micromirror is supported by two curved hinge structures. The device is driven by application of a current, and net angular displacements larger than 10/spl deg/ (static) and 30/spl deg/ (in resonance) were obtained. These values are comparable with or even larger than the reported values for other MEMS optical switches or beam scanning devices. The experimental results suggest that the movement is evoked by a thermal effect. The Micro-origami device has advantages of low operation voltage smaller than 2 V, and structural compatibility with the Si or SiGe LSIs. 相似文献
155.
156.
Numata K. Oowaki Y. Itoh Y. Hara T. Tsuchida K. Ohta M. Watanabe S. Ohuchi K. 《Solid-State Circuits, IEEE Journal of》1989,24(4):900-904
A nibbled-page architecture which can be used to access all column addresses on the selected row address randomly in units of 8 bits at the 100 Mbit/s data rate is discussed. To realize such high-speed architecture, three key circuit techniques have been developed. An on-chip interleaved circuit has been used for the high-speed serial READ and WRITE operations. Column address prefetch and WE signal prefetch techniques have been introduced to eliminate idle time between 8 bit units. The nibbled-page architecture has been successfully implemented in an experimental 16 Mb DRAM, and 100 Mb/s operation has been achieved. The DRAM with nibbled-page mode is very effective in simplifying the design of high-speed data transfer systems 相似文献
157.
Kiyoshi Dowaki Tsuyoshi Ohta Yasukazu Kasahara Mitsuo Kameyama Koji Sakawaki Shunsuke Mori 《Renewable Energy》2007,32(1):80-94
Recently, in Japan, recycling technologies have been developed using waste biomass material. Waste biomass is traded in the waste materials market between users and a third-party, who receives a fee for processing them. This study is an environmental and economic analysis of a biomass energy system, which can produce hydrogen fuel for fuel cells (purity of 99.99%) as an example of an environmental business model. The experimental apparatus was made based on the moving-bed gasifier by the German company, DM2 Inc., and the hydrogen gas yield was measured. Finally, the economic viability of the future hydrogen business was estimated.The experimental results obtained gave the gas concentration of 57.5% in a Steam/Carbon ratio of 1.40 at 900 °C.Assuming the plant scale of 10 t/d, the production amount of hydrogen gas would be 21.3 kg/h. Based on the law concerning waste processing in Japan, a sizeable amount of waste biomass could be expected. Therefore, if the processing fee which is paid to the group (contractor) ranges between 5.0 and 10.0 $/t, and if the whole investment cost is 6 million dollars and the depreciation period is 15 years, the bio-hydrogen production cost using the experimental data would be 5.75–7.86 $/kg-H2 without receiving related subsidies. In a one-third grant proportion, the cost would become 4.60–6.72 $/kg-H2. 相似文献
158.
T Wada H Yokoyama N Tomosugi Y Hisada S Ohta T Naito K Kobayashi N Mukaida K Matsushima 《Canadian Metallurgical Quarterly》1994,46(2):455-460
To clarify the mechanism of neutrophil infiltration in glomerulonephritis, both urinary and plasma levels of a potent neutrophil chemotactic cytokine, interleukin-8 (IL-8), were measured in 40 healthy volunteers and 96 patients with various renal diseases. The plasma IL-8 levels were less than 16 pg/ml. The urinary IL-8 levels were elevated in several renal diseases including IgA nephropathy (17 of 43), acute glomerulonephritis (4 of 6), lupus nephritis (11 of 15), purpura nephritis (2 of 4), membranoproliferative glomerulonephritis (1 of 1), and cryoglobulinemia (2 of 2). IL-8 was detected immunohistochemically in diseased glomeruli, suggesting its local production. Elevated urinary IL-8 levels during the acute phase or exacerbations were found to be decreased during spontaneous or steroid pulse therapy-induced convalescence in all patients examined. The urinary IL-8 levels were higher in patients with glomerular leukocyte infiltration than in those without infiltration. Collectively, local production of IL-8 in diseased glomeruli might be involved in the pathogenesis of the glomerular diseases and measurement of IL-8 in the urine might be useful for monitoring the glomerular diseases. 相似文献
159.
The present report describes the improved transformation of the 17-oxo group in 3 beta-acetoxy-5 alpha-androstan-17-one to a 17 alpha-hydroxy group. A mixture of 17 alpha-acetoxy and 16-ene compounds, which are usually produced by the standard synthetic route, were treated with peracetic acid (epoxidation of the 16-ene compound) and then sodium borohydride-sodium hydroxide (reduction-hydrolysis) to give the desired 17 alpha-hydroxy compound in much better yield than that in previous reports. Recrystallization of the crude product with cyclohexane-methanol gave the pure compound in 54% yield (total yield from starting ketone). 相似文献
160.
Yasube Kashiwaba Katsuaki Isojima Koji Ohta 《Solar Energy Materials & Solar Cells》2003,75(1-2):253-259
Thin-film photovoltaic cells composed of p-type Cu-doped CdS (CdS(Cu)) and n-type CdS layers (CdS(Cu)/CdS system) were fabricated by an all-vacuum deposition process. The cells showed a higher response in the longer-wavelength side than at the absorption edge of CdS with an increase in the thickness of the CdS(Cu) layer. High efficiency (over 8.5%) was obtained by improvement in CdS(Cu) layer fabrication. It is thought that the photovoltic effect of the cells is caused by a p-CdS(Cu)/n-CdS homojunction. 相似文献