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121.
Ryoichi Suzuki Yoshinori Kobayashi Tomohisa Mikado Hideaki Ohgaki Mitsukuni Chiwaki Tetsuo Yamazaki 《Hyperfine Interactions》1994,84(1):345-353
A positron pulsing system for an intense positron beam generated by an electron linac is reported. The pulsing system generates an intense pulsed positron beam of variable energy and variable pulse period. The pulsed positron beam is used as a non-destructive probe for various material research. In this paper, we also discuss applications of the pulsed positron beam: positron lifetime spectroscopy, age-momentum correlation spectroscopy, positronium time-of-flight measurement, and positron annihilation-induced Auger electron spectroscopy with a time-of-flight technique. 相似文献
122.
An efficient synthetic method for the formation of 2,3-dihydro-1H-inden-1-one derivatives through a Ni-catalyzed intramolecular hydroacylation of 2-(prop-2-ynyl)benzaldehydes has been developed. Examination of various nickel and other transition metal catalysts and phosphine ligands showed that the use of Ni(COD)2 catalyst combined with P(i-Pr)3 ligand was the best choice to the success of the present intramolecular hydroacylation. A wide range of functional groups were tolerated, affording the corresponding substituted α-lidene-2,3-dihydro-1H-inden-1-ones in good to high yields with a sole E-selectivity under present reaction conditions. 相似文献
123.
Tanaka S Kubo Y Yokoyama Y Toda A Taguchi K Kajioka H 《The Journal of chemical physics》2011,135(23):234503
We investigated the phase separation phenomena in dilute surfactant pentaethylene glycol monodedecyl ether (C(12)E(5)) solutions focusing on the growth law of separated domains. The solutions confined between two glass plates were found to exhibit the phase inversion, characteristic of the viscoelastic phase separation; the majority phase (water-rich phase) nucleated as droplets and the minority phase (micelle-rich phase) formed a network temporarily, then they collapsed into an usual sea-island pattern where minority phase formed islands. We found from the real-space microscopic imaging that the dynamic scaling hypothesis did not hold throughout the coarsening process. The power law growth of the domains with the exponent close to 1/3 was observed even though the coarsening was induced mainly by hydrodynamic flow, which was explained by Darcy's law of laminar flow. 相似文献
124.
Yoshinori Takahashi 《Zeitschrift für Physik B Condensed Matter》1990,78(2):199-206
We propose a model Hamiltonian for the high temperature superconductivity from the analogy of the BCS model hamiltonian. We seek a possibility of real space electron pairing. It follows then the magnetic exchange interaction is not a source of pairing and we propose a form of pairing interaction from the argument of the broken symmetry of electron number conservation. Based on a variational wave function, the ground state energy of our model is studied. 相似文献
125.
Regio- and diastereoselective reaction of oxygen and sulfur substituted allylic carbanions with aldehydes is described. Either threo or erythro isomer can be obtained predominantly or exclusively by merely choosing an additive. 相似文献
126.
Nakamura I Mizushima Y Gridnev ID Yamamoto Y 《Journal of the American Chemical Society》2005,127(27):9844-9847
A new catalytic cyclization of o-alkynylbenzaldehyde acetals 1 to the functionalized indenes 2 was found to be strictly controlled by the number of triphenylphosphine ligands on the Pd catalyst. Only complexes with three available coordination sites on Pd catalyze this reaction. Mechanistic study suggests that pi-coordination of Pd to the benzene ring is a key step controlled by the number of vacant coordination sites. 相似文献
127.
Miyagawa T Nagai K Yamada A Sugihara Y Fukuda T Fukuda T Uchida R Tomoda H Omura S Nagamitsu T 《Organic letters》2011,13(5):1158-1161
The first total synthesis of citridone A has been achieved through regioselective intramolecular iodocyclization and regio- and stereoselective Pd(0)-catalyzed coupling as key reactions. 相似文献
128.
Highly enantioselective gem-chlorofluorination of active methylene compounds was carried out by using a copper(II) complex of a chiral spiro pyridyl monooxazoline ligand. This reaction yielded α-chloro-α-fluoro-β-keto esters and α-chloro-α-fluoro-β-keto phosphonates with up to 92% ee. The resulting dihalo β-keto ester was converted into various α-fluoro-α-heteroatom-substituted carbonyl compounds via nucleophilic substitution without loss of optical purity. A fully protected β-amino acid with a gem-chlorofluoromethylene function was also synthesized. 相似文献
129.
Sano S Okubo Y Handa A Nakao M Kitaike S Nagao Y Kakegawa H 《Chemical & pharmaceutical bulletin》2011,59(7):885-888
Isoliquiritigenin [ILG, (E)-1] was readily prepared via the Horner-Wadsworth-Emmons reactions using β-ketophosphonates 5a, b. An improved protocol for the synthesis of (E)-1 via the Claisen-Schmidt condensation was also presented. 相似文献
130.
Terthiophene-appended gold nanoparticles were prepared by the reduction of AuCl4−(C8H17)4N+ with NaBH4 in the presence of bis[2,5-di(3-hexylthiophen-2-yl)thiophene-3-carboxyloxyhexanyl]disulfide. A hexagonal self-assembly of particles with gold core diameters (1.9±0.1 nm) was detected by high-angle annular dark-field scanning transmission electron microscopy. The electric conductivity of the iodine-doped film was 9.1×10−6 S cm−1, which was ascribable to the terthiophene-based inter-ligand π-π interactions. The Au/terthiophene hybrid spin-coated film consisted of a highly three-dimensional assembled structure of terthiophenes, as inferred from grazing-incidence small-angle X-ray scattering, indicating that such monodispersed and small-sized gold nanoparticles can serve as a template for this organization. In this study, a gold nanoparticle-templated assembly of oligothiophenes has been fabricated for proposing a method to develop tailor-made organizations of π-conjugated oligomers. 相似文献