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排序方式: 共有619条查询结果,搜索用时 46 毫秒
61.
Takamitsu Otake Yoshie Aoyagi Takashi Yarita Masahiko Numata 《Analytical and bioanalytical chemistry》2010,397(6):2569-2577
Fish certified reference material (CRM), NMIJ CRM 7404-a, for the analysis of polychlorinated biphenyls (PCBs) and organochlorine
pesticides (OCPs) was developed by the National Metrology Institute of Japan, part of the National Institute of Advanced Industrial
Science and Technology. Fish samples (Japanese seabass) used for the preparation of the CRM were collected from Tokyo Bay,
and the edible part was freeze-dried, pulverized, sieved, homogenized, and sterilized by γ-irradiation. This sample is in
the form of a powder comprising approximately 10 g stored in a brown glass bottle. The certification was carried out using
multiple analytical methods such as pressurized liquid extraction, Soxhlet extraction, saponification, and homogenization
to ensure the reliability of analytical results; the certified values of target PCBs (PCB 28, PCB 70, PCB 105, PCB 153, and
PCB 170) and OCPs (trans-nonachlor, dieldrin, p,p′-DDE, p,p′-DDT, and p,p′-DDD) were 1.05–14.0 μg kg−1 and 1.57–18.0 μg kg−1 for PCBs and OCPs, respectively. This is the first fish powder CRM in which PCBs and OCPs were determined by isotope dilution
mass spectrometry. 相似文献
62.
Hiroyuki Okamura Hiroki SakaeKeiji Kidani Naoki HirayamaNoboru Aoyagi Takumi SaitoKojiro Shimojo Hirochika NaganawaHisanori Imura 《Polyhedron》2012,31(1):748-753
The extraction constant and the two-phase stability constant (KD,Mβ3) of tris(2-thenoyltrifluoroacetonato)europium(III) between 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][Tf2N]) as an ionic liquid and an aqueous phase were determined by considering the extraction equilibria including anionic tetrakis(2-thenoyltrifluoroacetonato)europate(III). Specific solute-solvent interactions between the neutral Eu(III) chelate and [C4mim][Tf2N] molecules were revealed from the relationships between the distribution constant of the enol form of 2-thenoyltrifluoroacetone (Htta) as a proton chelate and the distribution constant (KD,M) of the neutral Eu(III) chelate because the [C4mim][Tf2N] system gave the high KD,Mβ3 value compared with those in conventional molecular solvents such as benzene and 1,2-dichloroethane. The coordination environment of Eu3+ in the neutral Eu(III) chelate in [C4mim][Tf2N] was investigated by time-resolved laser-induced fluorescence spectroscopy and infrared absorption spectroscopy. Both methods consistently indicated that not only the Eu(III) chelate extracted but also Eu(tta)3(H2O)3 synthesized as a solid crystal were almost completely dehydrated in [C4mim][Tf2N] saturated with water. Consequently, the higher KD,M or extractability of the neutral Eu(III) chelate in the [C4mim][Tf2N] system can be ascribed to the dehydration of the Eu(III) chelate, which is caused by the specific solvation with [C4mim][Tf2N] molecules. 相似文献
63.
Electronic structure of the interface between a bathocuproine (BCP) molecule and metal surface was studied by density functional theory. The bond energy of BCP with metal surface increased with decreasing work function of metals, that is, Au, Ag, Al, Mg, and Ca in this order. The charge transfer also increased with decreasing metal work function. It was analyzed that the Fermi level and the lowest unoccupied molecular orbital of BCP are composed of both BCP and metal orbital component, and electron transport properties across the BCP and metal is discussed based on these analyses. 相似文献
64.
Katsuhiro Inomata Yoichi Sasaki Takuhei Nose 《Journal of Polymer Science.Polymer Physics》2002,40(17):1904-1912
We have investigated the morphology and packing manner of graft copolymers consisting of rigid‐rod‐like poly(γ‐benzyl L ‐glutamate) (PBLG) main chains and grafted diblock copolymers of amorphous poly(propylene glycol) (PPG) and crystalline poly(ethylene glycol) (PEG). The results of differential scanning calorimetry and wide‐angle X‐ray scattering measurements for graft copolymers with higher side‐chain volume fractions suggest that the rodlike main chains and crystallized PEG chains exist in segregated domains. Small‐angle X‐ray scattering profiles for these samples show diffraction intensity maxima accompanied by higher order peaks, the positions of which suggest the formation of an ordered layered structure. From these observations, the graft copolymers are estimated to form repeated layered structure consisting of segregated PBLG, PPG, and PEG layers. A proposed model for molecular packing of the graft copolymers is consistent with the experimental observation that the repeating distance for the layered structure decreases with an increase in the volume fraction of side chains. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1904–1912, 2002 相似文献
65.
66.
Masataka Sugimoto Takumi Koizumi Takashi Taniguchi Kiyohito Koyama Katsuhiro Saito Daigo Nonokawa Tsuyoshi Morita 《Journal of Polymer Science.Polymer Physics》2009,47(22):2226-2237
Melt rheological behaviors of hyperbranched‐polystyrene (PS) copolymerized by dendric macromonomer technique are presented. The time–temperature superposition principle was applicable to the hyperbranched‐PS. The branched‐PS showed slightly lower zero‐shear viscosity in comparison with linear PS regardless of a presence of a number of branches expected from the dendric macromonomer technique. Although the influence of use of multimethacryloyl macromonomer in the polymerization process was marginal for linear viscoelastic regime, nonlinear shear and uniaxial elongational flows showed distinct differences between linear and branched‐PS. The strain dependence of the damping function became weak as increase of macromonomer content. The branched‐PS exhibited the growing elongational viscosity function comparing with linear PS. This prominent effect on the elongational flow behavior can be explained by the molecular architecture of the branched‐PS. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2226–2237, 2009 相似文献
67.
Dr. Shintaro Ishida Dr. Takashi Abe Dr. Fumiya Hirakawa Tomoyuki Kosai Katsuhiro Sato Prof. Dr. Mitsuo Kira Prof. Dr. Takeaki Iwamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15100-15103
A persistent dialkylsilanone was synthesized by the dehydrobromination of a dialkylbromosilanol with tris(trimethylsilyl)silyl potassium in solution at ?80 °C: It was characterized by NMR and IR spectroscopy, and was tested in several reactions. In 29Si NMR spectrum in [D8]toluene, the signal due to the unsaturated silicon nuclei was observed at 128.7 ppm. Reactions of the dialkylsilanone with water and mesitonitrile oxide gave a silanediol and a [2+3] cycloadduct, respectively. The silanone remains intact in [D8]toluene below ?80 °C for at least two days, while it undergoes unprecedented isomerization to give a siloxysilene by means of 1,3‐silyl migration at higher temperatures. 相似文献
68.
Frontispiece: Entropy‐Driven 1,2‐Type Friedel–Crafts Reaction of Phenols with N‐tert‐Butoxycarbonyl Aldimines
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69.
70.
Progress toward the total synthesis of hederacines A and B is described. Our approach involves an allylic cyanate-to-isocyanate rearrangement, eneyne ring-closing metathesis, and a transannular reaction between the C-5 amino group and the C-12 position of the perhydroazuleno[5,6-b]furanone intermediate. 相似文献