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91.
Yoshitsugu Arai Shū-ichi Kuwayama Yoshio Takeuchi Toru Koizumi 《Tetrahedron letters》1985,26(50):6205-6208
The Diels-Alder reaction of a novel chiral dienophile, alkyl ()-2--tolylsulfinylacrylates 1 with anthracene and cyclopentadiene showed high diastereoselectivity under the chelation controlled condition. 相似文献
92.
Summary A miniaturized flow cell for an electrical conductivity detector has been made and applied to the ion chromatography of inorganic anions. It consisted of stainless steel tubes (0.13 mm ID×0.31 mm OD) and PTFE tubes (0.25 mm ID×2 mm OD). The detection limit for chloride at S/N=3 was 36 pg or 0.33 ppm for a 0.11 l injection. 相似文献
93.
[Reaction: see text] Cycloisomerization of 1,6-enynes proceeded smoothly in water under heterogeneous conditions in the presence of a palladium complex supported on polystyrene-poly(ethylene glycol) copolymer resin to give the corresponding cyclopentanes with a high level of chemical greenness. Multistep asymmetric synthesis of a hydrindane framework was achieved via palladium-catalyzed asymmetric pi-allylic alkylation, propargylation, and cycloisomerization of 1,6-enynes, where all three steps were performed in water with recyclable polymeric catalysts. 相似文献
94.
Horiyama S Suwa K Yamaki M Kataoka H Katagi T Takayama M Takeuchi T 《Chemical & pharmaceutical bulletin》2002,50(7):996-1000
Hydroxylamines gradually undergo oxidation to their oximes on being dissolved in organic solvent (e.g. methanol). This phenomenon was followed by (1)H-NMR and liquid chromatography-mass spectrometry (LC-MS). The oxidation rate was estimated from the peak area observed on the mass chromatogram at the protonated molecule or fragment ion on LC-atmospheric pressure chemical ionization (APCI)-MS. The results showed that the oxidation rate of hydroxylamines depended on the solvent type. 相似文献
95.
Takimiya K Kunugi Y Konda Y Niihara N Otsubo T 《Journal of the American Chemical Society》2004,126(16):5084-5085
2,6-Diphenylbenzo[1,2-b:4,5-b']dichalcogenophenes including thiophene, selenophene, and tellurophene analogues as organic semiconductors for field-effect transistors were effectively synthesized in three steps from commercially available 1,4-dibromobenzene. All three benzodichalcogenophenes acted as good p-type semiconductors, and particularly the selenophene analogue, 2,6-diphenylbenzo[1,2-b:4,5-b']diselenophene, showed high FET mobility of 0.17 cm2 V-1 s-1. 相似文献
96.
Summary Atomic absorption spectrometry combined with extraction is described for the determination of tri- and hexavalent chromium. The chromium diethyldithiocarbamate chelate was used for chromium (VI), whereas hydroxyquinolate or thenoyltrifluoroacetonate chelate for chromium(III). The method is rapid and precise.
Zusammenfassung Extraktion und darauffolgende Messung der Atomarabsorption wurden zur Bestimmung von drei- und sechswertigem Chrom verwendet. Die Chelatverbindung mit Diäthyldithiocarbamat wurde für Chrom(VI), der Chelatkomplex mit Hydroxychinolin oder Thenoyltrifluoraceton für Chrom(III) verwendet. Das Verfahren ist rasch und genau.相似文献
97.
Nano-sized phosphine and pyridine ligands having tetraphenylphenyl-, m-terphenyl-, poly(benzylether) moieties were synthesized. These ligands showed a remarkable effect on homogeneous transition
metal catalyzed reactions. Pd(II) complexes with tetraphenylphenyl substituted pyridine ligands show high catalytic activities
for oxidation of ketones suppressing Pd black formation and maintains the catalytic activity for a long time. Rh(I) complex
catalysts with m-terphenyl substituted phosphine ligands showed remarkable rate acceleration in the hydrosilylation of ketones. In addition,
several phosphinocalixarene ligands were synthesized and their coordination studies with Pd(II), Pt(II), Ru(II), Ir(I), and
Rh(I) metals were documented. Ir(I) and Rh(I) cationic complexes with a 1,3,5-triphosphinocalix[6]arene ligand showed dynamic
behavior with size-selective molecular recognition. 相似文献
98.
Kazuhisa Maeda Yasushi Tomita Masako Naganuma Hachiro Tagaml 《Photochemistry and photobiology》1996,64(1):220-223
Guinea pig skin becomes more pigmented following exposure to UV rays. This melanization was accompanied by enhanced intensity of tyrosinase-staining and increased number of tyrosinase-positive melanocytes (MELty+), with resultant enhancement of melanin synthesis. To clarify the regulatory mechanism for melanization following UV irradiation, organ-cultured guinea pig skins have been used to examine their melanogenic responses to exogenous stimulation. This organ culture system responded well to UV irradiation, by increasing melanogenic activity. Also, in this system, phospholipases (PL), arachidonic acid, interleukin-1α and melanocytestimulating hormone, but not endothelin-1 or phosphatidylinositol-specific PLC (PI-PLC), stimulated melanogenesis to various extents as indicated by the number of MELty+ and morphological changes. Among them, the PLA2 and PLD were found to have a potent stimulatory property for melanocytes. They might affect melanocytes directly or indirectly through an effect on keratinocytes. These results suggest that PLA2 and PLD play a key role in epidermal hyperpigmentation after UV irradiation or inflammation. 相似文献
99.
Hiroshi Takeuchi Makoto Nakagawa Takayuki Saito Toru Egawa Kiyoshi Tanaka Shigehiro Konaka Toshiyuki Mitsuhashi 《International journal of quantum chemistry》1994,52(6):1339-1348
The energy spectra of free water molecules were measured at scattering angles 2θ ranging from 10.5° to 75.7°, using an angle-dispersive-type diffractometer and synchrotron radiation as an X-ray source. A silicon (111) monochrometer was used to obtain incident X-rays with the wavelengths of (1.543/n) Å (n = 1,3,4,5). Observed inelastic scattering peaks are clearly separated from eleastic ones at s values [s = (4π/λ) sin Å] larger than 8 Å?1. The increase of the separation with an increasing s value was consistent with the classical theory of the Compton shift. The total (elastic plus inelastic) intensities were obtained over a range of s = 0.74–5.0 Å?1. Experimental difference intensities Δσee and Δσne were obtained separately by combining the X-ray and high-energy electron scattering data. The experimental results are in reasonable agreement with the theoretical intensities calculated from SCF and CI molecular wave functions with a basis set of double-zeta plus polarization functions. © 1994 John Wiley & Sons, Inc. 相似文献
100.
Proteomic LC-MS systems using nanoscale liquid chromatography with tandem mass spectrometry 总被引:3,自引:0,他引:3
Ishihama Y 《Journal of chromatography. A》2005,1067(1-2):73-83
Current nano-scale liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) approaches in proteome research are reviewed from an analytical perspective. For comprehensive analysis of cellular proteins, analytical methods with higher resolution, sensitivity, and wider dynamic range are required. Miniaturized LC coupled with tandem mass spectrometry is currently one of the most versatile techniques. In this review, the current status of nanoLC-MS/MS systems as well as data management systems is addressed. In addition, the future prospects for complete proteomics are discussed. 相似文献