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排序方式: 共有390条查询结果,搜索用时 11 毫秒
381.
Miyawaki A Miyauchi M Takashima Y Yamaguchi H Harada A 《Chemical communications (Cambridge, England)》2008,(4):456-458
Poly[2]rotaxane and supramolecular assembly have been prepared by modified cyclodextrins bearing an adamantyl group in an aqueous medium. 相似文献
382.
Takashima T Yamaguchi A Hashimoto K Nakamura R 《Chemical communications (Cambridge, England)》2012,48(24):2964-2966
Using carbon monoxide as a probe molecule for the oxidation state of Cu ions, we demonstrated that anchored polynuclear charge-transfer complexes consisting of Ce(III) ions and Cu(II)-substituted Keggin-type polyoxotungstates function as efficient visible-light-driven multielectron-transfer catalysts. 相似文献
383.
meta-Ethynylpyridine 18-mer associates with octyl β-D-glucopyranoside to show an induced circular dichroism (CD) band at around 337 nm in CH(2)Cl(2). The addition of copper(II) triflate and o-phenanthroline enhanced the CD band. Even when an equimolar amount of β-L-glucopyranoside was added to make the system racemic, the CD was memorized and remained for several weeks. 相似文献
384.
Fast enantiomeric analysis of a complex essential oil with an innovative multidimensional gas chromatographic system 总被引:1,自引:0,他引:1
Mondello L Casilli A Tranchida PQ Furukawa M Komori K Miseki K Dugo P Dugo G 《Journal of chromatography. A》2006,1105(1-2):11-16
The present research is focussed on the evaluation of a recently developed high performance multidimensional gas chromatographic (MDGC) system employed in the fast analysis of a series of chiral compounds contained in rosemary essential oil. The heart of the MDGC system consists in a simple transfer device for the rapid sequential re-injection of analyte "heart-cuts" from the first to the second dimension. The transfer system has no temperature restrictions, presents very low dead volumes and achieves multidimensional analysis through a pressure-balance mechanism. The MDGC set-up is characterized by two GC ovens (enabling independent temperature programming) and the possibility of mass spectrometric (MS) and/or flame ionization detection (FID). Multiple-cut conventional and fast MDGC-FID methods were developed and the results obtained compared, in order to evaluate the effectiveness of the system. In this respect, the rapid method provided the same analytical result in a greatly reduced time (approximately five times less). Furthermore, quali/quantitative data reproducibilty was very good. Fast MDGC was achieved by using micro-bore (0.1mm I.D.) columns in both dimensions. 相似文献
385.
A one-dimensional (1D) uneven peanut-shaped C(60) polymer formed from electron-beam (EB)-induced polymerization of C(60) molecules showed an anomalous increase in two characteristic infrared (IR) peak intensities, which are respectively due to the radial and tangential motion of the 1D polymer, when compared to the IR peaks of pristine C(60) films. This anomaly was analyzed on the basis of the vibrational van Hove singularity (VHS), using an extended thin-shell elastic model fully considering the effects of periodic radius modulation inherent to the 1D uneven peanut-shaped C(60) polymer. We succeeded in explaining the enhancement in the tangential peak intensity by VHS, whereas the origin to cause that in the radial peak intensity is still unclear. 相似文献
386.
387.
Tetragonal PbSnF4 was prepared by precipitation method with Pb(NO3)2 and SnF2 aqueous solutions. The product was characterized using X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XFS), and the other chemical analyses. Tetragonal PbSnF4 exhibited the highest electric conductivity of 3.2 Sm−1 at 473 K in air as a fluoride ion conductor. We have investigated the possibility of COF2 formation using CO2 and F2 in an electrochemical cell with PbSnF4 as a solid electrolyte. At same time, we tried to produce an electric power from an electrochemical cell. This CO2/F2 electrochemical cell was constructed with a tetragonal PbSnF4 disk having Au electrodes. The electromotive force was about 0.9 V at room temperature for 0.1 MPa CO2/(0.01 MPa F2 + 0.09 MPa Ar). However, the short circuit current density was 0.24 A m−2, which was quite small. This current density was so small that no fluorocarbon compound was detected after 3 h discharge using FT-IR. 相似文献
388.
Hereditary Spastic Paraplegia Protein Spartin Is an FK506-Binding Protein Identified by mRNA Display
Mayuko Tokunaga Hirokazu Shiheido Ichigo Hayakawa Akiko Utsumi Hideaki Takashima Nobuhide Doi Kenichi Horisawa Yuko Sakuma-Yonemura Noriko Tabata Hiroshi Yanagawa 《Chemistry & biology》2013,20(7):935-942
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389.
The citric acid oxidation by vanadium(V) in sulfuric acid medium at 303 K is reported. The reaction rate was determined spectrophotometrically by monitoring the formation of vanadium(IV) at 760 nm. The oxidation showed a first‐order dependence with respect to vanadium(V) concentration and fractional order with respect to citric acid concentrations, with no control and with constant ionic strength. The reaction is also first order with respect to sulfuric acid concentration with no control and of fractional order at constant ionic strength. The reaction rate is enhanced by an increase of ionic strength and increased by a decrease of the dielectric constant. The activation parameters were calculated based on the rate constants determined in the 293 to 313 K interval. The proposed oxidation mechanisms and the derived rate laws are consistent with the experimental rate laws. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 566–572, 2000 相似文献
390.
T. Nishida M. Katada J. Kubota Y. Takashima F. Ichikawa T. Fukami T. Aomine 《Hyperfine Interactions》1994,93(1):1659-1664
Phonon anomaly was observed below 140 K for the absorption area (lnA) and the isomer shift () plotted against the temperature (T) in the119Sn Mössbauer study of the Bi2Sr2Ca(Cu0.995Sn0.005)2O8–y
superconductor (glass-ceramic,T
c(on)=86 K), which was prepared by heat treatment of the glassy sample. The anomaly suggests that the softening (quenching) of the lattice vibration causes the superconducting transition, as was observed in several YBa2(Cu, Sn)3O7–y
superconductors. Fitting of the theoretical curve for the normal phonon of the combined Debye and Einstein model to the lnA versusT and versusT plots yielded
D and
E of 240 and 140 K, respectively. These results suggest that the probe (Sn4+) was located at the interstitial site close to the Cu site, and the softening of the Cu site vibration could be detected before the superconducting transition took place. Disordered structure seems to be favorable for the detection of phonon anomaly in the Bi system. 相似文献