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排序方式: 共有437条查询结果,搜索用时 580 毫秒
1.
Etsuro Yoshimura Mariko Akashi Tomonari Umemura Kin-ichi Tsunoda 《Analytical sciences》2004,20(2):373-374
27Al NMR spectra of an equimolar (10 mM) Al(III)-citrate system were obtained at different temperatures. The linewidths of the signals decreased in the spectra recorded at elevated temperatures, which enabled us to unequivocally identify the resonance lines. From the spectrum recorded at 65 approximately C, a mononuclear Al(III)-citrate complex was identified at a solution pH of 3.0 in addition to trinuclear Al(III)-citrate complex, which dominated at pH 4.0. 相似文献
2.
Yoshimi Egawa Mariko Hagita Ken-ichi Kawarabayashi Hong Wang 《Discrete Mathematics》2003,270(1-3):115-125
Let d, k and n be three integers with k3, d4k−1 and n3k. We show that if d(x)+d(y)d for each pair of nonadjacent vertices x and y of a graph G of order n, then G contains k vertex-disjoint cycles converting at least min{d,n} vertices of G. 相似文献
3.
Toshiaki Asakai Ryota Minegishi Norie Inaba Yutaka Ishimura Mariko Murayama Tatsuhiko Tanaka 《Analytical sciences》2006,22(3):461-463
The drying conditions for primary standards of volumetric analysis have a significant effect on the titration results due to changes in the purity, stability and homogeneity. Amidosulfuric acid, a strong acid used as a reference material for volumetric analysis in Japan, was dried in a vacuum desiccator or heated at different temperatures, and then measured by Karl-Fischer titration, thermogravimetry/mass spectroscopy (TG-MS), ion chromatography and coulometric titration. The optimum drying conditions were at 50 degrees C for 24 h with crushing. 相似文献
4.
Synthesis and hypotensive activity of benzopyran derivatives 总被引:1,自引:0,他引:1
M Shiratsuchi K Kawamura T Akashi M Fujii H Ishihama Y Uchida 《Chemical & pharmaceutical bulletin》1987,35(2):632-641
5.
Mariko Kusabe Hiromitsu Kozuka Satoru Abe Hiroshi Suzuki 《Journal of Sol-Gel Science and Technology》2007,44(2):111-118
Hydroxypropylcellulose (HPC)–titania hybrid thin films were prepared by sol–gel method where titanium tetraisopropoxide Ti(OC3H7
i
)4 was hydrolyzed under acidic conditions in the presence of HPC, followed by dip-coating and drying at 120 °C for 24 h. The
viscosity average molecular weight of HPC was 55,000–70,000 or 110,000–150,000, and the TiO2/(HPC + TiO2) mass ratio ranged from 0 to 1, which was calculated on the assumption that all Ti(OC3H7
i
)4 is converted into TiO2. The films were 0.35–1.0 μm thick, transparent in visible region and opaque in ultraviolet (UV) region, where the optical
absorption coefficient in UV region increased with increasing titania content. The refractive index increased with increasing
titania content, ranging from 1.6 to 1.8 for the hybrid thin films. The pencil hardness increased from 6B to 5H, the durability
in hot water significantly increased and the contact angle of water on films increased from 35° to 89° with increasing titania
content. Crack-free films could be deposited on organic polymer substrates irrespective of titania or HPC contents, where
cracking did not occur at higher HPC contents even when the substrate was bent. 相似文献
6.
Nanometer-sized metallic palladium particles can be synthesized by hydrogen reduction of Pd2+ ions dissolved in the water core of a water-in-CO2 microemulsion. The Pd nanoparticles, stabilized by the micromeulsion and uniformly dispersed in the supercritical fluid phase, are effective catalysts for hydrogenation of olefins. Examples of rapid and efficient hydrogenation of water-soluble and CO2-soluble olefins catalyzed by the Pd nanoparticles in supercritical CO2 are given. 相似文献
7.
[structure: see text] The structure of gelsemoxonine, isolated from Gelsemium elegans Benth., was revised to be a novel oxindole alkaloid having an azetidine unit. A new alkaloid, 14,15-dihydroxygelsenicine, which was presumed to be a biosynthetic precursor of gelsemoxonine, was also isolated. 相似文献
8.
Toshiyuki Uryu Toshiyuki Seki Tokiji Kawamura Akashi Funamoto Kei Matsuzaki 《Journal of polymer science. Part A, Polymer chemistry》1976,14(12):3035-3044
The stereoregularity of polystyrene prepared by anionic polymerization was determined by means of 13C-NMR spectroscopy. The stereoregularity changed with such polymerization conditions as catalyst, solvent, and temperature. Sodium naphthalene as catalyst gave a syndiotactic-rich polystyrene of 66–68% syndiotactic dyads independently of solvent and temperature, while potassium and cesium naphthalenes as catalyst produced polystyrenes with different stereoregularities ranging from syndiotactic-rich to isotactic-rich configurations, depending on solvent and temperature. The mechanism of anionic polymerization which caused the difference in stereoregularity was discussed from the viewpoint of growing ionic species. 相似文献
9.
Seiji Miyano Osamu Yamashita Kunihiro Sumoto Keiyu Shima Mariko Hayashimatsu Fumio Satoh 《Journal of heterocyclic chemistry》1987,24(1):271-274
The method for preparing 7a-substituted hexahydro-1H-pyrrolizines 2 from 1,2,3,5,6,7-hexahydropyrrol-izinium Perchlorate (3) was investigated, by which introduction of a wide variety of functionalities on C(7a) could be achieved easily. 相似文献
10.
Summary In the aqueous solutions of poly(N-vinylacetamide) in the presence of Na2SO4 or (NH4)2SO4, the intrinsic viscosities were small and the Huggins constants were large compared with those in water. Similar but much
less effects were observed for NaF. Opposite effects were found, however, for NaSCN. The poor solvent quality of aqueous sulfate
solutions was significantly improved by the addition of guanidine hydrochloride to 3 M or higher. Urea was much less effective
in improving the solvent quality. The different M28.8neffects observed between urea and GdnHCl may be explained by their different
binding affinities to amide group. Solubilization of PNVA flocculates induced by the presence of 0.8 M Na2SO4 took place by adding urea to 1 M, although only small changes were detected in the viscosity behavior accompanying the addition
of 1 M urea.
Received: 12 June 1997 Accepted: 4 August 1997 相似文献