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排序方式: 共有311条查询结果,搜索用时 9 毫秒
41.
42.
Kenji Yoshii Yasuhiro Yoneda Ignace Jarrige Tatsuo Fukuda Yasuo Nishihata Chikashi Suzuki Yoshiaki Ito Takahito Terashima Shinzo Yoshikado Sei Fukushima 《Journal of Physics and Chemistry of Solids》2014
We have studied the electronic properties of the ferroelectric barium titanate BaTiO3 using two complementary bulk-sensitive spectroscopic probes, resonant X-ray emission spectroscopy (RXES) and X-ray absorption spectroscopy in the partial fluorescence mode (PFY-XAS) at the Ba-L3 and Ti-K absorption edges. Contrary to a previous study, we found no fine structure in the pre-edge area of the PFY-XAS spectrum at the Ba-L3 edge, and no temperature-induced spectral change was observed between room temperature and 150 °C. This result is not supportive of the possible presence of the displacement around Ba2+ at the Curie temperature. RXES spectra were measured at the Ti-K edge for BaTiO3, along with SrTiO3 and La-doped metallic SrTiO3. The photon energy of the emission peak is found to be nearly constant throughout the absorption edge for all three compounds. We deduce the Ti 3d states to have a delocalized character, in contrast with the Ba 5d states, a property which is consistent with the proposed scenario of the formation of electric dipoles in BaTiO3. 相似文献
43.
Tan HH Makino A Sudesh K Greimel P Kobayashi T 《Angewandte Chemie (International ed. in English)》2012,51(2):533-535
At a glance: The stereochemical configuration of the diglycerophosphate backbone of the endosome-specific lipid bis(monoacylglycero)phosphate (BMP, see picture) was determined by (1)H?NMR spectroscopy. Enantiomeric discrimination was facilitated by introduction of D-camphor ketals as chiral shift reagents, and enantiopure synthetic BMP analogues were prepared as reference materials. Natural BMP exhibited the unusual sn-1,1' diglycerophosphate backbone. 相似文献
44.
Ikeda M Fukuda K Tanida T Yoshii T Hamachi I 《Chemical communications (Cambridge, England)》2012,48(21):2716-2718
A boronic acid-appended fluorescent receptor was incorporated into self-assembled nanofibers containing a hydrophobic FRET-paired dye to develop a gel-based fluorocolorimetric sensor for polyols. We demonstrated that the gel-based sensor is capable of detecting polyols such as catechol and dopamine not only under semi-wet conditions, but also under dry conditions using a paper platform. 相似文献
45.
Derek Yiren Ong Zhihao Yen Asami Yoshii Julia RevilloImbernon Ryo Takita Shunsuke Chiba 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):5046-5051
New protocols for controlled reduction of carboxamides to either alcohols or amines were established using a combination of sodium hydride (NaH) and zinc halides (ZnX2). Use of a different halide on ZnX2 dictates the selectivity, wherein the NaH‐ZnI2 system delivers alcohols and NaH‐ZnCl2 gives amines. Extensive mechanistic studies by experimental and theoretical approaches imply that polymeric zinc hydride (ZnH2)∞ is responsible for alcohol formation, whereas dimeric zinc chloride hydride (H?Zn?Cl)2 is the key species for the production of amines. 相似文献
46.
Saya Nakabayashi Katsunori Nagano Makoto Nakamura Junya Togawa Asami Kurokawa 《Adsorption》2011,17(4):675-686
The aim of this study is the development of a new adsorbent for the desiccant material which can be regenerated by the domestic
exhaust heat by using natural mesoporous material, Wakkanai siliceous shale. To improve this shale’s performance to adsorb/desorb
the water vapor, lithium chloride, calcium chloride or sodium chloride was supported into the mesopores by impregnating with
each chloride solution. Especially sodium chloride was effective to increase the water vapor adsorption amount 5–7 times of
that of natural shale in the relative humidity range from 50 to 70%. Moreover, the appropriate impregnating concentrations
were determined as 5wt% from the relationship between the maximum water vapor adsorption amount and the mesopore volume. Based
on these results, a new desiccant filter has been developed by impregnated original paper with lithium chloride and sodium
chloride. This paper contained shale powder in the synthetic fibers. The dehumidification performance of this filter was evaluated
under the simulated summer condition in Tokyo. From the cyclic adsorption/regeneration test, this shale and chlorides filter
could adsorb and desorb 60 g/h water vapor repeatedly at the regeneration temperature of 40°C. On the other hand, a silica
gel filter and a zeolite filter adsorbed and desorbed only 10 g/h and 25 g/h, respectively. These results suggested that the
shale impregnated with the chlorides has the best dehumidification ability as a new desiccant material. Further, the desiccant
filter made from the shale will achieve the effective use of the low temperature exhaust heat. 相似文献
47.
Satoshi Anezaki Yoshitaka Yamaguchi Masatoshi Asami 《Journal of organometallic chemistry》2011,696(11-12):2399-2405
New o-xylylene-linked bis(benzimidazolium) salts were synthesized in six-steps from C2-symmetric chiral 1,4-diol, 1,2-bis(1-hydroxypropyl)benzene, as a starting material. The silver complex of bis(benzimidazol-2-ylidene) was obtained on treatment of bis(benzimidazolium) salt with silver oxide. The reaction of the silver bis-NHC with [PdCl2(PhCN)2] afforded the bis-NHC complex of palladium. The X-ray diffraction studies on Pd complexes revealed that these complexes have distorted square planar geometry around the Pd center coordinating the NHC ligand in mutually cis-position. The arene ring of o-xylylene unit hanged over the Pd center and thus these complexes showed C1-symmetric structures. The variable temperature NMR spectroscopy revealed that these Pd complexes showed fluxional behavior between C1- and C2-symmetric structures in solution state. 相似文献
48.
The current status of the R & D activities is presented on electron beam processing of polymers being carried out at TRCRE. Topics included are sterilization of medical products, graft polymers for selective separation or absorbents and curing of liquid prepolymer-monomer systems. 相似文献
49.
K Kameo Y Asami K Ogawa T Matsunaga S Saito K Tomisawa K Sota 《Chemical & pharmaceutical bulletin》1989,37(5):1260-1267
2-Acetylthio-3-benzoylpropionic acid derivatives having two benzene rings or condensed-ring moieties were prepared, and tested for hypolipidemic activity in normal rats. Some of these compounds were active. 2-Acetylthio-3-[4-(phenylthio)benzoyl]propionic acid (10) and its derivatives seemed to have the most potent hypocholesterolemic activities. Compound 10 showed strong activity, especially in cholesterol-fed rats. 相似文献
50.
K Yoshii A Kaihara Y Tsumura S Ishimitsu Y Tonogai 《Journal of AOAC International》2001,84(3):910-917
A liquid chromatographic (LC) method was developed for the determination of emamectin and its metabolites (8,9-Z-isomer, N-demethylated, N-formylated, and N-methylformylated emamectin) in various crops. The analytes were extracted with acetone, cleaned up on cartridge columns (C18 and NH2), derivatized with trifluoroacetic anhydride and 1-methylimidazole, and determined by LC with fluorescence detection. Because radish inhibited the formation of the fluorescent derivatives, an additional Bond Elut PRS cartridge was used in the cleanup of Japanese radish samples. During sample preparation, N-formylated emamectin partially degraded to emamectin B1b and emamectin B1a, and the 8,9-Z-isomer partially degraded to N-demethylated emamectin. Therefore, emamectin and its metabolites were determined as total emamectin, i.e., their sum was estimated as emamectin benzoate. Their recoveries from most crops were approximately 80-110% with the developed method. The detection limits for the analytes in vegetables were 0.1-0.3 parts per trillion (ppt). The results for these compounds were confirmed by LC/mass spectrometry (LC/MS; electrospray ionization mode). Because the fluorescent derivative of emamectin was undetectable by LC/MS, the results for the analyte were confirmed by using a sample solution without derivatization. Limits of detection by LC/MS were similar to the fluorescence detection limits, 0.1-0.3 ppt in vegetables. In addition to the emamectins, milbemectin, ivermectin, and abamectin were also determined by the developed method. 相似文献