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211.
Matsuda T Watanabe K Kamitanaka T Harada T Nakamura K 《Chemical communications (Cambridge, England)》2003,(10):1198-1199
The immobilized resting-cell of Geotrichum candidum was used as a catalyst for the reduction of a ketone in a semi-continuous flow process using supercritical carbon dioxide for the first time; it was also applied for the asymmetric reduction of a ketone and resulted in excellent enantioselectivity (ee > 99%) and a higher space-time yield than that of the corresponding batch process. 相似文献
212.
[reaction: see text] 1,1,3,3-Tetramethylguanidine (TMG)(1), a nitrogen organic base, is a convenient and useful reagent for chemoselective deprotection of both silyl and acetyl groups on acidic hydroxyl groups such as phenol and carboxylic acid without affecting aliphatic silyl and acetyl groups. The chemoselectivity is dependent on the acidity of the hydroxyl group. 相似文献
213.
214.
We earlier proposed an analytical and prospective method for evaluating projection optical lithography. In this paper, we apply it to more complicated cases, such as optimizing transparency of a half tone phase-shifting mask and considering the resolution enhancement technique which uses both multiple exposure and non-linear resist. We also apply it to the evaluation of isolated line patterns using 1:2 line-and-space patterns.Presented at the International Commission for Optics Topical Meeting, Kyoto, 1994. 相似文献
215.
Sterically hindered trialkylalanes, such as triisobutylalane, react with olefins at or below room temperature under the influence of a catalytic amount of Cl2ZrCp2 to effect hydroalumination of the olefins. The reaction can tolerate certain hetero-functional groups, such as OH, SPh, and Br, which tend to interfere with previously reported hydroalumination procedures. 相似文献
216.
Experimentally observed paramagnetic susceptibility of CeB6 is fitted by using an anisotropic exchange interaction, which is written by the bases of the crystal field eigenstates, Γ7, the ground state, and Γ8. It is shown that the antiferromagnetic exchange interaction within Γ8 is largest and fairly long range. The next important interaction is that which is also antiferromagnetic and mixes between Γ7 and Γ8. This is similar with the usual singlet ground state problem but is more complicated because the ground state is doublet. It is argued that various unusual properties of CeB6 seem to be explained by this interaction. 相似文献
217.
The as-grown shape of the cylindric tilt grain boundary (GB) in Mo bicrystals grown by the floating zone method has been studied with the electron backscattering diffraction method. The seed crystals were misoriented such that the coincidence site lattice (CSL) with lowest possible inverse density of coincidence sites, a Sigma=3 was grown. The flat (100)(Sigma3CSL) facets were observed forming smooth edges (no slope discontinuity) with rounded rough GB portions. Rough GBs curve away from the plane of the (100)(Sigma3CSL) facet as x(beta) with beta=1.69+/-0.07 on one side and beta=1.72+/-0.07 on the other side. Therefore, GB roughening belongs to the Pokrovsky-Talapov universality class. Slope discontinuities between two rounded rough GB portions were also observed. This is the first experimental observation of such first-order rough-to-rough ridges predicted by the Davidson-den-Nijs model. 相似文献
218.
Competitive nitrations of two pairs of aromatic substrates were carried out in order to clarify the effect of several methods of mixing on the observed relative rates. The experimental results indicate that a commercially available four-jet mixer for rapid reaction could not achieve homogeneous mixing in the competitive nitration of aromatic substrates in aqueous sulfuric acid. 相似文献
219.
Methamphetamine (MPA), being a stimulant drug, reacts with tetrabromophenolphthalein ethyl ester (TBPEH) to form a red-violet ion associate, TBPEHMPA, in 1,2-dichloroethane (DCE) at pH 9. The maximum absorption wavelength was at 570 nm. After measuring, yellow TBPEH with DCE could be regenerated by mixing with the buffer solution at pH 3. The regenerated TBPEH/DCE could be reused as an ion association reagent and extracting solvent. In addition, the reagent regeneration could be performed by the on-line flow injection system and the cyclic flow injection analysis system was demonstrated for the determination of MPA without consumption of ion association reagent and organic solvent. The calibration curve was linear in the range of 0.5-3.5 × 10−5 M with good repeatability. The sample throughput was 20 h−1. 相似文献
220.
Hydrogen uptake in boron nitride nanotubes at room temperature 总被引:2,自引:0,他引:2
Ma R Bando Y Zhu H Sato T Xu C Wu D 《Journal of the American Chemical Society》2002,124(26):7672-7673
Hydrogen uptake capacities of 1.8 and 2.6 wt % were obtained on BN multiwalled nanotubes and bamboo-like nanotubes, respectively, under approximately 10 MPa at room temperature. The preliminary results show that chemical interactions mainly take place between hydrogen and BN. Taking into consideration the uniform semiconducting electronic property and ultimate stable chemical and thermal stability, BN nanotubes may exhibit some interesting possibilities in storing hydrogen. This will also provide some viewpoints on designing the carbon-based hydrogen storage system. 相似文献