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31.
Sako M Kihara T Tanisaki M Maki Y Miyamae A Azuma T Kohda S Masugi T 《The Journal of organic chemistry》2002,67(3):668-673
The UV irradiation of pyrrolnitrin (1a), which is an antibiotic clinically useful against dermatophytosis and possesses a unique 2-(pyrrol-3-yl)nitrobenzene moiety in the molecule, in an anhydrous aprotic solvent resulted in the exclusive formation of transient 7,4'-dichlorospiro[1,3-dihydrobenzo(c)isoxazole-3,3'-pyrrolin-2'-one] (2a) via the intramolecular oxidation of the juxtaposed pyrrole ring by the triplet-excited nitro group. The irradiation in an aqueous aprotic solvent, however, allowed the concurrent occurrence of intramolecular cyclization by the singlet-excited nitro group in 1a and the hydroxylation at the 2-position of the pyrrole ring by water to afford 3,7-dichloro-8-hydroxy-8,8a-dihydropyrrolo[2,3-b]indol-2-one (3a), accompanied by the formation of 2a. Elongation of the irradiation time in these photoreactions caused a rapid consumption of the products, 2a and 3a, to give undetermined polar polymeric products. The present results indicate that the photodegradation of 1a is significantly influenced by the presence of water in the reaction media and by the nature of its excited state. Thus, the loss of the antifungal activities by the photosensitive antibiotic 1a was chemically proved. 相似文献
32.
Tanaka Y Hoshino W Shimizu S Youfu K Aratani N Maruyama N Fujita S Osuka A 《Journal of the American Chemical Society》2004,126(10):3046-3047
When heated, bis-Cu(II) octaphyrin(1.1.1.1.1.1.1.1) is quantitatively split into two Cu(II) porphyrins both in solution and film states, which is accompanied by large absorption spectral changes. 相似文献
33.
Single puffs of cigarette smoke with a wide continuous range of volatility are directly analyzed using a new system. The system consists of a smoking machine, an online thermal desorption system (TDS), and a multidimensional gas chromatograph-mass spectrometer (MDGC-MS) system. The online TDS with the smoking machine collects the single-puff cigarette smoke with glass beads as the cryogenic adsorbent. The MDGC is composed of three capillary columns, Poraplot Q, and DB-WAX for separation and a deactivated capillary column for pressure balance, which enables simultaneous separation of the two different phases. The smoke desorbed from the TDS is divided into vapor and semivolatile phases and analyzed individually with each column by the MDGC. Thus, the system enables the overall analysis of the two phases simultaneously, including acetaldehyde and 1,4-benzenediol. This system also provides more appropriate analysis for compounds crossing the two phases such as toluene and pyridine. For the approach of introducing internal standards, a gas mixture of toluene-d(8) and o-xylene-d(10) is applied and the compounds are detected in the vapor and semivolatile phases, respectively. 相似文献
34.
The aim of this paper is to study the exponential symmetric product formula for the semigroup of the one-dimensional harmonic
oscillator to discuss its convergence pointwise of the integral kernels as well as in norm with sharp optimal error bound.
相似文献
35.
Kitajima K Yoshikawa T Seo Y Ohno Y Yano Y Miki A Kanda T Kanata N Azuma T Sugimura K 《Magnetic resonance imaging》2011,29(4):579-583
Budd-Chiari syndrome (BCS) is a rare disorder caused by the obstruction of hepatic venous outflow, leading to sinusoidal congestion, ischemic injury to liver cells and portal hypertension. Long-term survival largely depends on whether hepatocellular carcinoma occurs. A recently available liver-specific contrast medium, gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA), reportedly has high diagnostic capability for detection of malignant liver tumors. However, there has been no report of the sue of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) for BCS. We present a case of chronic BCS who underwent both gadopentetate dimeglumine (Gd-DTPA) and Gd-EOB-DTPA-enhanced MRI. Hepatic congestion and edema were seen as slightly hypointense areas on Gd-EOB-DTPA-enhanced hepatobiliary-phase images, although these areas were observed as slightly hyperintense on previously obtained Gd-DTPA-enhanced delayed-phase image. Reduced uptake of Gd-EOB-DTPA by hepatocytes in the region of congestion or edema may account for this difference, which should be recognized in image interpretations. 相似文献
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38.
M. Koizumi T. T. Inamura K. Morita M. Takami M. Wakasugi A. Yoshida M. Azuma H. Katsuragawa T. Horiguchi T. Ishizuka I. Nakamura M. Nakaoka A. Iivonen K. Valli S. Matsuki T. Murayama K. Shimomura T. Shinozuka I. Sugai Y. Tagishi 《Hyperfine Interactions》1992,74(1-4):181-191
We have constructed a fast atomic-beam collinear laser spectroscopy system connected to the on-line isotope separator facility
GARIS/IGISOL at RIKEN. This system is potentially powerful in studying refractory elements. To test the system, an off-line
collinear experiment was made on stable Hf isotopes produced by means of laser ablation technique. For production of radioactive
Hf isotopes, the use of the inverse kinematics of a fusion reaction,9Be(166Er,xn)175-x
Hf, was investigated. The radioactive isotope169Hf was successfully extracted from GARIS/IGISOL and accelerated up to 30 keV. 相似文献
39.
Sang-Woo Kim Teruhisa Kotani Masaya Ueda Shizuo Fujita Shigeo Fujita 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):601
Selective formation of ZnO nanodots grown by metalorganic chemical vapor deposition (MOCVD) was achieved on focused-ion beam (FIB)-nanopatterned SiO2 and Si substrates. The selective formation characteristics, dimension, and density of ZnO nanodots on FIB-nanopatterned substrates strongly depended on the FIB-patterning and MOCVD-growth conditions. The mechanism of the selective formation of ZnO nanodots on FIB-nanopatterned SiO2 substrates is attributed to a surfactant effect of the implanted Ga which leads to the formation of the preferred nucleation sites for the growth of ZnO nanodots, while that of ZnO nanodots on nanopatterned Si substrates is mainly considered in terms of the generation of surface atomic steps and kinks, which are created by Ga+ ion sputtering, on the patterned Si areas. 相似文献
40.
We studied, experimentally, the pattern dynamics and free surface deformation in Bénard–Marangoni convection, in a circular
container (aspect ratio = 6). The free surface deformation fields were visualized by interferometry and temperature fields
by infrared thermography. We considered the influence of the Marangoni (up to 2,623), Biot and Prandtl numbers. More dynamics
are induced by increasing the Biot number and transition to a time-dependent flow has been observed. Conversely, increasing
the Prandtl number reduces the dynamics. The deformation increases as a function of the Marangoni number until it reaches
asymptotic values, which are functions of the Biot and Prandtl numbers. 相似文献