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111.
Toyohiko Aoyama Yoshiro Sato Tooru Suzuki Hideaki Shirai 《Journal of organometallic chemistry》1978,153(2):193-207
1-Substituted 4,4-dimethyl-1,2,3,4-tetrahydrobenzo[b]1,4-azasilines (X) and 1-substituted 3,3-dimethyl-1,2,3,4-tetrahydrobenzo[e]-1,3-azasilines (XIII) were synthesized by the intramolecular benzyne reaction of the corresponding N-substituted 2-(3-chlorophenyl)dimethylsilylethylamines (IX) and N-substituted (3-chlorobenzyl)dimethylsilylmethylamines (XII). 相似文献
112.
In order to elucidate the mechanism of oxide-ion conductivity for (Ba0.5-xSrxLa0.5)(In1-yMy)2O5.5 (M=Y or Ga, 0<x<0.2, 0<y<0.2) solid-solution system, the electrical conductivity was measured as a function of oxygen partial pressure and temperature,
and the results were investigated in terms of a dopant content and unit cell free volume. The system was confirmed to be an
oxide-ion conductor from the oxygen partial pressure dependence on electrical conductivity. The oxide-ion conductivity increased
with increasing the unit cell free volume at first. However, it showed a maximum at a value of free volume, and then decreased.
The decreasing conductivity vs. the volume would be related to the crystal symmetry change.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
113.
Kazuhiko Takai Tooru Kuroda Shigeki Nakatsukasa Koichiro Oshima Hitosi Nozakil 《Tetrahedron letters》1985,26(45):5585-5588
Alkynyl halides are reduced by chromium(II) chloride in DMF to give unisolable alkynylchromium compounds which add selectively to an aldehyde moiety without affecting the coexisting ketone group of the substrate. 相似文献
114.
Kakinuma K. Yamamura H. Haneda H. Atake T. 《Journal of Thermal Analysis and Calorimetry》1999,57(3):737-743
The structural characterization, thermogravimetric analysis and electrical properties for solid solution system, (Ba1–xLax)2In2O5+x with perovskite-type structure were investigated. X-ray diffraction showed that the orthorhombic phase was in the range of 0.0<x0.3, the tetragonal phase 0.3<x0.5, and the cubic phase 0.5<x. The sharp transition of electrical conductivity shifted to a lower temperature with increasing x and disappeared at the phase boundary between the orthorhombic and tetragonal phases. This perovskite-related oxide exhibited a pure oxide-ion conduction over the oxygen partial pressure range of 1 atm to 10–3.5 atm, and the electrical conductivity reached the value of 1.610–1 (S cm–1) at 1073 K, which was nearly equal to that of the yttria stabilized zirconia. These properties were successfully explained in terms of disordered oxygen ions.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
115.
Supramolecular design for multivalent interaction: maltose mobility along polyrotaxane enhanced binding with concanavalin A 总被引:1,自引:0,他引:1
High molecular mobility of maltose-conjugated alpha-cyclodextrins (alpha-CDs) along a poly(ethylene glycol) (PEG) chain due to the mechanically locked structure of polyrotaxanes enhanced multivalent interactions between maltose and concanavalin A (Con A). When maltose groups are conjugated with alpha-CDs that were threaded onto a PEG capped with benzyloxycarbonyl l-tyrosine (polyrotaxane), Con A-induced hemagglutination was greatly inhibited by polyrotaxanes with a certain threading % of alpha-CDs. Such an inhibitory effect was significantly superior to the other type of conjugates, in which poly(acrylic acid) was used as a backbone for maltose conjugation. The spin-spin relaxation time (T2) of the maltose C(1) proton in the polyrotaxane at a typical alpha-CD threading % was significantly larger than that of any other conjugate, which was well related to the inhibitory effect. Therefore, we concluded that the high mobility of maltose groups along the polyrotaxane structure contributes to enhanced Con A recognition. 相似文献
116.
Vapor pressure measurements in carrier gas containing ligand vapor using the transpiration technique
The vapor pressures of 1,1,1-trifluoro-2,4-pentanedionates were measured in 0.1–10 mm Hg using the transpiration technique with helium or helium containing the ligand vapor as carrier gas. The injection chamber of a gas chromatograph equipped with a ligand vapor generator was used. The vapor pressure of bis(1,1,1-trifluoro-2,4-pentanedionato)nickel(II) was measured for the first time, stabilized in ligand vapor atmosphere. The vapor pressures of standard samples (naphthalene and benzoic acid) agreed well with previously reported values. 相似文献
117.
Reaction of 1,3-dimethylthymine epoxide with amines afforded cis and trans adducts, stereostructures of which were elucidated and treatment of trans adduct with boron trifluoride etherate afforded cis adduct; mechanism for the isomerization is presented. 相似文献
118.
An efficient synthesis of methyl (2R,3S)-3-(4-methoxyphenyl)glycidate (-)-2, a key intermediate for diltiazem (1), has been developed on the basis of the highly enantioselective Mukaiyama aldol reaction of p-anisaldehyde (4a) with alpha,alpha-dichloro ketene silyl acetal 5. Thus, the reaction using a stoichiometric amount of chiral oxazaborolidinone catalyst 12a proceeded to excellent yield (83%) and high enantioselectivity (96% ee), together with the chiral ligand 13a in nearly quantitative recovery. The reaction using a substoichiometric amount of 12e (20 mol %) also proceeded to excellent yield (88%), with somewhat lower enantioselectivity (77% ee). The aldol product 3a thus obtained was easily converted to (-)-2 in excellent yield (80%) and high optical purity (>99% ee). The highly enantioselective Mukaiyama aldol reaction with 5 catalyzed by 12a proved to be applicable to various aldehydes. An efficient preparation of 5 from inexpensive starting materials was also described. 相似文献
119.
Takai S. Nakanishi T. Tojo T. Kawaji H. Atake T. Esaka T. 《Journal of Thermal Analysis and Calorimetry》2002,69(3):805-811
Heat capacity measurements were carried out on Pb1-xLaxWO4+x/2 (x=0.2) and Pb1-xLa2x/3WO4 (x=0.2, 0.5) solid solutions prepared by sintering and mechanical alloying (MA) methods. For all the solid solutions, sintered
samples showed slightly larger heat capacity around 100 K in comparison with MA samples, which was presumably caused by the
excitation of mobile oxide ion motion. For sintered scheelite-type structured PbWO4s, high-temperature synthesis introduced oxide ion interstitials even for the Pb1-xLa2x/3WO4 system, which resulted in the excess heat capacity at low temperature for excitation. On the other hand, for the samples
prepared by room-temperature MA technique, oxide ion seemed to occupy the regular sites rather than interstitial ones and
excess heat capacities were not observed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
120.
Zaitsu K Katagi M Kamata H Kamata T Shima N Miki A Iwamura T Tsuchihashi H 《Journal of mass spectrometry : JMS》2008,43(4):528-534
A reliable and accurate GC-MS method was developed that allows both mass spectrometric and chromatographic discrimination of the six aromatic positional isomers of trimethoxyamphetamine (TMA). Regardless of the trifluoroacetyl (TFA) derivatization, chromatographic separation of all the investigated isomers was achieved by using DB-5 ms capillary columns (30 m x 0.32 mm i.d.), with run times less than 15 min. However, the mass spectra of the nonderivatized TMAs, except 2,4,6-trimethoxyamphetmine (TMA-6), showed insufficient difference for unambiguous discrimination. On the other hand, the mass spectra of the TFA derivatives of the six isomers exhibited fragments with significant intensity differences, which allowed the unequivocal identification of all the aromatic positional isomers investigated in the present study. This GC-MS technique in combination with TFA derivatization, therefore, is a powerful method to discriminate these isomers, especially useful to distinguish the currently controlled 3,4,5-trimethoxyamphetmine (TMA-1) and 2,4,5-trimethoxyamphetmine (TMA-2) from other uncontrolled TMAs. 相似文献