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排序方式: 共有122条查询结果,搜索用时 15 毫秒
81.
Yoshiro Kususe Suguru Yoshida Koji Fujita Hirofumi Akamatsu Masafumi Fukuzumi Shunsuke Murai Katsuhisa Tanaka 《ChemInform》2016,47(32):no-no
Polycrystalline EuNbO3 samples are prepared by solid state reaction of stoichiometric amounts of Eu2O3 and Nb2O3 (air, 1400 °C, 1 d) to form Eu3NbO7 which in a second step is sintered with stoichiometric amounts of NbO2 and Nb (Mo foil enwrapped in evacuated silica tubes, 1200 °C, 12 h). 相似文献
82.
Suguru ItoAkira Hayashi Hirotomo KomaiHitoshi Yamaguchi Yoshihiro KubotaMasatoshi Asami 《Tetrahedron》2011,67(11):2081-2089
A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity. 相似文献
83.
84.
Treatment of arylketene bis(methylthio)acetal monoxide with trifluoromethanesulfonic anhydride leads to ring-closure to afford 2-methylthiobenzo[b]thiophene in high yield. The reaction is useful for synthesizing multisubstituted benzo[b]thiophenes. 相似文献
85.
Liquid-crystalline (LC) physical gels are a new class of dynamically functional materials consisting of liquid crystals and fibrous aggregates of molecules that are called "gelators". Liquid-crystalline physical gels, which are macroscopically soft solids, exhibit induced or enhanced electro-optical, photochemical, electronic properties due to the combination of two components that form phase-separated structures. In this tutorial review, we describe the materials design and structure-property relationships of the LC physical gels. The introduction of self-assembled fibers into nematic liquid crystals leads to faster responses in twisted nematic (TN) mode and high contrast switching in light scattering mode. Furthermore, the LC physical gels can be exploited as a new type of materials for electro-optical memory. This function is achieved by the control of reversible aggregation processes of gelators under electric fields in nematic liquid crystals. Electronic properties such as hole mobilities are improved by the introduction of fibrous aggregates into triphenylene-based columnar liquid crystals. The incorporation of photochromic azobenzenes or electroactive tetrathiafulvalenes into the chemical structures of gelators leads to the preparation of ordered functional materials. 相似文献
86.
Suguru Ito Kenji TanumaKohei Matsuda Akira HayashiHirotomo Komai Yoshihiro KubotaMasatoshi Asami 《Tetrahedron》2014
A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both aldehydes and acetals with silyl enol ethers or ketene silyl acetals to give the corresponding aldol adducts in moderate to high yields. The remarkable high catalytic activity of Al-MCM-41 over amorphous silica-alumina and aluminum-free mesoporous silicate was observed in the reaction. The solid acid catalyst could be recovered easily by filtration and the recovered catalyst was reusable in the same reactions without a significant loss of catalytic activity. 相似文献
87.
Partitioning sample collection/solvent extraction cartridge packed with octadecyl‐derivatized macroporous silica particles for the analysis of sesquiterpenes in air samples 下载免费PDF全文
Ikuo Ueta Moe Onikata Suguru Mochizuki Koji Fujimura Tomohiro Sasaki Junji Aoki Tsuneaki Maeda 《Journal of separation science》2015,38(22):3891-3896
A novel sampling device based on the partition of target analytes to the extraction medium was developed for the determination of sesquiterpenes in air samples. The extraction medium was prepared by the chemical derivatization of a specially prepared macroporous silica, with a specific surface area of 2.0 m2/g. Taking advantage of the sample extraction, which was mainly based on the partition of sesquiterpenes between air and a C18‐bonded phase, the extracted analytes were rapidly and quantitatively desorbed just by passing a small amount of desorption solvent for subsequent analysis by gas chromatography with mass spectrometry. Several experimental conditions, such as the sampling volume and temperature, were systematically evaluated. Under optimized conditions, desorption of the extracted analytes was completed within 1 min with a desorption efficiency of more than 99.9%, achieved using 5 mL of acetone for all the evaluated sesquiterpenes. The applicability of the developed device was confirmed by the determination of several sesquiterpenes from coniferous trees. Although further improvements of the device are required for collecting large volumes or high‐temperature air samples, the potential of the developed sampling device was confirmed by determining traces of semivolatile organic compounds in air samples. 相似文献
88.
Masayoshi Nakano Ryohei Kishi Suguru Ohta Hideaki Takahashi Shin-ichi Furukawa Kizashi Yamaguchi 《Physica B: Condensed Matter》2005,370(1-4):110-120
We investigate the long-time dynamics of two-component dilute gas Bose–Einstein condensates with relatively different two-body interactions and Josephson couplings between the two components. Although in certain parameter regimes the quantum state of the system is known to evolve into macroscopic superposition, i.e., Schrödinger cat state, of two states with relative atom number differences between the two components, the Schrödinger cat state is also found to repeat the collapse and revival behavior in the long-time region. The dynamical behavior of the Pegg–Barnett phase difference between the two components is shown to be closely connected with the dynamics of the relative atom number difference for different parameters. The variation in the relative magnitude between the Josephson coupling and intra- and inter-component two-body interaction difference turns out to significantly change not only the size of the Schrödinger cat state but also its collapse–revival period, i.e., the lifetime of the Schrödinger cat state. 相似文献
89.
Jun Zhe Min Suguru Hatanaka Toshimasa Toyo’oka Shinsuke Inagaki Ruri Kikura-Hanajiri Yukihiro Goda 《Analytical and bioanalytical chemistry》2009,395(5):1411-1422
A simultaneous determination method based on ultra-performance liquid chromatography (UPLC) with fluorescence (FL) detection
and electrospray-ionization time-of-flight mass spectrometry (ESI-TOF-MS) was developed for 16 “designated substances” (Shitei-Yakubutsu)
controlled by the Pharmaceutical Affairs Law in Japan. These substances were first labeled with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole at 60 °C for 2 h in 0.1 M borax (pH 9.3). The resulting fluorophores
were well separated by reversed-phase chromatography using an Acquity UPLC™ BEH C18 column (1.7 μm, 100 mm × 2.1 mm i.d.) by isocratic elution with a mixture of water and acetonitrile–methanol (20:80) containing
0.1% formic acid. The separated derivatives were sensitively detected by both FL and TOF-MS. However, the determination of
several designated substances by FL detection showed interference from endogenous substances in biological samples. Therefore,
the determination in real samples was carried out by a combination of UPLC separation and ESI-TOF-MS detection. The structures
of the designated substances were identified from the protonated-molecular ions [M+H]+ obtained from the TOF-MS measurement. The calibration curves obtained from the peak area ratios of the internal standard
(I.S.), i.e., 3-phenyl-1-propylamine, and the designated substances versus the injection amounts showed good linearity. The
limits of detection
( \textS/N = 3 ) \left( {{\text{S/N}} = 3} \right) and the limits of quantification
( \textS/N = 10 ) \left( {{\text{S/N}} = 10} \right) in 0.1 mL of human plasma and urine for the present method were 0.30–150 pmol and 1.0–500 pmol, respectively. Good accuracy
and precision (according to intraday and interday assays) were also obtained with the present procedure. This method was applied
to analyses of human plasma, urine and real products.
相似文献
90.
Morita Y Maki S Ohmoto M Kitagawa H Okubo T Mitani T Nakasuji K 《Organic letters》2002,4(13):2185-2188
[structure: see text] A novel TTF-based donor with a uracil moiety, TTF-(1-n-butyluracil-5-yl) (TnbU), was synthesized. Crystal structures of both TnbU and the charge-transfer complex of TnbU-hydrogen cyananilate possess complementary double hydrogen bonds through uracil moieties and pi-stacking dimer structures between TTF skeletons. Furthermore, the TnbU-TCNQ charge-transfer complex shows a high electrical conductivity underlying the partial charge-transfer accompanied by a hydrogen-bonding interaction, which was substantiated in terms of the measurements of the IR, electronic spectra, and conductivity. 相似文献