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141.
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Strong fluence dependence of photodesorption cross sections is observed in femtosecond laser photodesorption of NO from (NO)2 on silver nanoparticles, in contrast to femtosecond photodesorption on bulk metals. The time scale of excitation buildup is found to be equal or less than the pulse duration of ~100 fs; NO translational energies are independent of fluence and pulse duration. We propose a nanoparticle-specific nonlinear mechanism in which, due to confinement, strongly nonthermal hot-electron distributions are maintained during the femtosecond pulses, enhancing the normal desorption pathway. 相似文献
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We show that locally conformally flat gradient Ricci solitons, possibly incomplete, are locally isometric to a warped product of an interval and a space form. Consequently, we get that complete gradient shrinking and steady Ricci solitons with vanishing Weyl tensor are rotationally symmetric, from which their classification follows. 相似文献
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Toshihiko Ueki Matsumi Doe Yoshiki Morimoto Takamasa Kinoshita Rika Tanaka Kazuo Yoshihara 《Journal of heterocyclic chemistry》2001,38(1):165-172
Hyperolactones A ( 1 ) and C ( 3 ) have been synthesized starting from (S)‐malic acid by a straightforward route. The unique spirolactone skeleton was efficiently constructed by one‐pot reaction as a key step. The absolute stereochemistry of hyperolactones was unambiguously established by this synthesis. 相似文献
148.
A useful pulse sequence for measuring long‐range C? H coupling constants (JC? H) named high resolution‐HMBC (HR‐HMBC) has been developed. In this pulse sequence, the J‐scaling pulse [(nt1)/2? 180° (H/C) ? (nt1)/2] is incorporated after the spin evolution period, and then followed by an 1H 180° pulse to reverse the magnetization of JC? H couplings. As a result, splittings of the cross peaks due to the long‐range JC? H are realigned with separations of nJC? H along the F1 dimension, and thus even the small long‐range JC? H values can easily be determined. The efficiency of measuring the long‐range JC? H using the proposed pulse sequences has been demonstrated in application to the complicated natural product, portmicin. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
149.
Kazuo Yoshino Kotaro Hachiman Akihiro Yokoyama Tsutomu Yokozawa 《Journal of polymer science. Part A, Polymer chemistry》2010,48(6):1357-1363
Chain‐growth condensation polymerization of p‐aminobenzoic acid esters 1 bearing a tri(ethylene glycol) monomethyl ether side chain on the nitrogen atom was investigated by using lithium 1,1,1,3,3,3‐hexamethyldisilazide (LiHMDS) as a base. The methyl ester monomer 1a afforded polymer with low molecular weight and a broad molecular weight distribution, whereas the polymerization of the phenyl ester monomer 1b at ?20 °C yielded polymer with controlled molecular weight (Mn = 2800–13,400) and low polydispersity (Mw/Mn = 1.10–1.15). Block copolymerization of 1b and 4‐(octylamino)benzoic acid methyl ester ( 2 ) was further investigated. We found that block copolymer of poly 1b and poly 2 with defined molecular weight and low polydispersity was obtained when the polymerization of 1b was initiated with equimolar LiHMDS at ?20 °C and continued at ?50 °C, followed by addition of 2 and equimolar LiHMDS at ?10 °C. Spherical aggregates were formed when a solution of poly 1b in THF was dropped on a glass plate and dried at room temperature, although the block copolymer of poly 1b and poly 2 did not afford similar aggregates under the same conditions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1357–1363, 2010 相似文献
150.
Summary A new analytical procedure for the determination of magnesium and calcium ions in sea water was developed with a capillary type isotachophoresis after adsorption on sodium form cation-exchange resin and elution with EDTA solution. Linear working curves were obtained for 3% sodium chloride solutions containing up to 2,000 mg/l of these ions, adjusted to pH 8 with 0.1 N sodium carbonate solution. A supporting electrolyte containing 0.01 M hydrochloric acid and 0.5% methyl cellulose buffered to pH 8.5 with tris(hydroxymethyl)aminomethane and a 40 cm long FEP tube as the main column were used. The proposed method was applied to the determination of magnesium and calcium ions in coastal sea water samples collected in Osaka Bay in April, 1984 and in artificial samples prepared with artificial or natural sea water.
Bestimmung von Magnesium und Calcium in Meerwasser mit Hilfe der Capillar-Isotachophorese
Zusammenfassung Das Verfahren beruht auf der Isotachophorese nach vorhergehender Adsorption an Kationen-Austauscher in Na-Form und Elution mit EDTA-Lösung. Für 3%ige NaCl-Lösungen mit <2000 mg/l Mg und Ca (auf pH 8 mit 0,1 N Natriumcarbonatlösung eingestellt) wurden lineare Eichkurven erhalten. Als Trägerelektrolyt diente 0,01 M Salzsäure mit 0,5% Methylcellulose, gepuffert auf pH 8,5 mit Tris(hydroxymethyl)aminomethan. Hauptsäule war eine 40 cm lange FEP-Röhre. Das vorgeschlagene Verfahren wurde zur Mg- und Ca-Bestimmung in Küstenwasser der Osaka-Bucht sowie in synthetischen Proben eingesetzt.相似文献