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排序方式: 共有115条查询结果,搜索用时 62 毫秒
1.
Separation of fluorescent oligosaccharide derivatives by microcolumn techniques based on electrophoresis and liquid chromatography. 总被引:1,自引:0,他引:1
Various aldose oligosaccharides can be quantitatively derivatized into primary amines for subsequent reaction with fluorogenic reagents, such as 3-(4-carboxybenzoyl)-2-quinolinecarboxaldehyde or 3-benzoyl-2-naphthaldehyde. Capillary electrophoresis (CE) and microcolumn liquid chromatography (LC), coupled with laser-induced fluorescence detection, were evaluated as a means of separating complex oligosaccharide mixtures. Whereas microcolumn LC and open-tubular CE appear confined in their utility to relatively small oligosaccharides, unprecedented results were obtained with polyacrylamide gel-filled capillaries on hydrolyzed malto-oligosaccharides and enzymatically degraded samples of chondroitin sulfate and hyaluronic acid. 相似文献
2.
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
3.
Masaaki Fujimatsu Tadao Natsuume Hirotaka Hirata Yasuhiko Shirota Shigekazu Kusabayashi Hiroshi Mikawa 《Journal of polymer science. Part A, Polymer chemistry》1970,8(11):3349-3357
Copolymerizations of N-vinylcarbazole with both isobutyl vinyl ether and N-vinyl-pyrrolidone initiated by some organic electron acceptors have been investigated for the purpose of elucidating the propagation mechanism in the charge-transfer polymerization. Copolymerizations of the same system catalyzed by authentic cationic catalysts have also been made for comparison. The results indicate that the propagation mechanism of the charge-transfer polymerization studied is catio ie. 相似文献
4.
We have prepared novel room temperature ionic liquids (RTILs) with trimethylsilylmethyl (TMSiM)-substituted imidazolium cations and compared the properties of these liquids with those for which the TMSiM group is replaced by the analogous neopentyl group. The ionic liquids are prepared with both tetrafluoroborate (BF(4)(-)) and bis(trifluoromethylsulfonyl)imide (NTf(2)(-)) anions paired with the imidazolium cations. At 22 degrees C, the TMSiM-substituted imidazolium ILs have shear viscosities that are reduced by a factor of 1.6 and 7.4 relative to the alkylimidazolium ILs for the NTf(2)(-) and BF(4)(-) anions, respectively. To understand the effect of silicon substitution on the viscosity, the charge densities have been calculated by using density functional theory electronic structure calculations. The ultrafast intermolecular, vibrational, and orientational dynamics of these RTILs have been measured by using femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy (OHD-RIKES). The intermolecular dynamical spectrum provides an estimate of the strength of interactions between the ions in the RTILs, and provides a qualitative explanation for the observed reduction in viscosity for the silicon-substituted RTILs. 相似文献
5.
Koichiro Shirota Ichirou Yamaguchi Kiyoshi Kanie Tomiki Ikeda Tamejiro Hiyama Ichiro Kobayashi 《Liquid crystals》2013,40(5):555-558
The optical properties of two kinds of photochromic antiferroelectric liquid crystal (AFLC) containing an azo group have been examined. Depending on the substituting group at the chiral centre, these AFLCs showed different photoinduced phase transitions by Ar+ laser light irradiation. This phase transition has led to a new form of optical switching controlled by a bias voltage. In addition, it was found that these AFLCs caused an azimuthal photoalignment effect regulated by linearly polarized Ar+ laser light irradiation. These phenomena were applied to image storage. 相似文献
6.
Kunio Yubuta Teruhisa Hongo Kazutaka G. Nakamura Masae Kikuchi 《Solid State Communications》2007,143(3):127-130
Microstructure of MnF2 subjected to by shock compression at 4.4 GPa was examined using transmission electron microscopy (TEM). Lamellar structure consisting of twin-related domains of rutile-structure and intergrowth of α- PbO2-type phase is observed in the electron diffraction pattern and TEM images. The crystallographic relationship between rutile and α- PbO2-type phases can be expressed as and . 相似文献
7.
Peerawas Kongsong Waritha Jantaporn Mahamasuhaimi Masae 《Surface and interface analysis : SIA》2020,52(8):486-492
TiO2 nanowire-nanoparticle hetero-structured films were prepared via a sol–gel method and coated on glass substrates by dipping method for photocatalytic activity. In this study 0, 1, 3, and 5 mol% of Ni doped were studied. One-dimensional TiO2 nanowires (NWs) were prepared by hydrothermal treatment with TiO2 nanoparticles (NPs) which are commercially available. XRD, FESEM, DRS, and XPS were used to characterize the prepared nanowire-nanoparticle hetero-structures films. 3%Ni doped TiO2 hetero-structured film (TNi3) had the highest photocatalytic activity on the degradation of methylene blue (MB). TNi3 films provided about 4.3 times of degradation rate compared to undoped TiO2 (T). It revealed that TNi3 film resulted in shifting the absorption wavelength towards narrowing the energy band gap and small crystallite size. Therefore, the TNi3 film exhibited a photocatalytic activity on the degradation of MB under visible light irradiation greater than undoped film. 相似文献
8.
We report the quality anisotropic intermolecular vibrational spectra within the frequency range 0.5-800 cm(-1) of four C(3v) CXY(3) molecular liquids, CHCl(3), CHBr(3), CFBr(3), and CBrCl(3), by means of femtosecond optical-heterodyne-detected Raman-induced Kerr effect spectroscopy. The results show that the first moment of the intermolecular vibrational spectrum is proportional to the square root of the value of the surface tension divided by the liquid density. This implies that the intermolecular vibrational spectrum reflects the bulk properties of the liquids. To understand the molecular-level aspects of the intermolecular vibrational spectra of the liquids, the spectra are compared with the molecular properties such as molecular weight, rotational constants, and bimolecular interaction energy. Overall, the first moment of the spectrum moderately correlates to the inverse square roots of both the molecular weight and the fast rotational constant. Therefore, the molecular properties are responsible for the intermolecular vibrational spectrum. Plots of the first moment of the intermolecular vibrational spectrum vs the square root of the value of the simple bimolecular interaction energy divided by the molecular surface area and the molecular weight show a linear correlation in the case of the oblate symmetric top molecular liquids, CHCl(3), CHBr(3), and CFBr(3). However, CBrCl(3), which is a prolate symmetric top molecular liquid, does not show the same correlation for the oblate molecular liquids. 相似文献
9.
Eriko Ohshima Keiji KusabaSinji Onodera Masae Kikuchi 《Journal of Physics and Chemistry of Solids》2002,63(3):419-423
High-pressure phase transition of Ta2NiO6 with the trirutile-type structure was investigated from the viewpoint of crystal chemistry. A new quenchable high-pressure phase was found in the pressure range higher than 7 GPa and 900°C. The high-pressure phase has an orthorhombic cell (a=4.797(1) Å, b=5.153(2) Å and c=14.85(1) Å and space group; Abm2), and it is more dense by 9.6% than the trirutile-structured phase. Infrared spectra of the trirutile-type phase and the high-pressure phase show that Ni2+ ions in the high-pressure phase are still in octahedral sites. The crystal structure of the high-pressure phase is considered as a cation-ordering trifluorite-type structure, which can be stabilized by a crystal field effect of Ni2+ ions. 相似文献
10.
Yongqiang Liu Alfarius E. Nugroho Asami Nakata Nahoko Uchiyama Osamu Shirota Haji Akber Aisa 《Tetrahedron letters》2010,51(50):6584-6587
Two novel elemanolide dimers, vernodalidimers A (1) and B (2), possessing a rare tricyclic ortho ester moiety, were isolated from the seeds of Vernonia anthelmintica. Their structures were elucidated by 1D and 2D NMR data and CD spectra. Vernodalidimers A (1) and B (2) exhibited potent cell growth inhibitory activity against HL-60 cells (IC50 0.72 and 0.47 μM, respectively). 相似文献