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排序方式: 共有159条查询结果,搜索用时 15 毫秒
1.
Shigeyasu Kuroda Mitsunori Oda Shengli Zuo Mayumi Kyogoku Ryuta Miyatake 《Tetrahedron letters》2004,45(43):8119-8122
A new cyclobutene-fused 1,6-methano[10]annulene was synthesized by pyrolysis of the sulfone and sulfinate adducts of 3,4-bis(methylene)-1,6-methano[10]annulene and its physical and chemical properties were disclosed. 相似文献
2.
Mitsunori Oda Yosuke Fukuchi Satoshi Ito Nguyen Chung Thanh Shigeyasu Kuroda 《Tetrahedron letters》2007,48(52):9159-9162
Reactions of pyrrolidine with 2 equiv of aldehydes without any catalyst in a pressurized vessel at 140–200 °C yielded 1,3-disubstituted pyrroles. -Branched aldehydes gave fairly good yields of the corresponding products by this method, which provides a facile non-oxidative procedure for synthesizing 1,3-dialkylpyrroles from inexpensive pyrrolidine and aldehydes. 相似文献
3.
A new analytical method of designing two-aspherical-mirror anastigmats was developed and applied to searching solution groups
of soft X-ray microscopes of a large misalignment tolerance. The two-mirror anastigmat configurations were expressed by a
practical variable related to pupil obstruction limiting the system throughput. Axial coma and other aberrations caused by
a slight decenter of the system were then formulated to represent sensitivity to misalignment. These formulations enabled
a global survey of solution groups as demonstrated by a designing example of soft X-ray microscopes with a magnification m = −1/50, which resulted in four solutions more insensitive to misalignment than a standard Schwarzschild optics in the soft
X-ray region. Some solutions were also found to have much larger fields of view suitable for high resolution imaging as confirmed
by computer ray tracing. 相似文献
4.
Mitsunori Nara 《Journal of Differential Equations》2007,237(1):61-76
The long time behavior of a curve in the whole plane moving by a curvature flow is studied. Studying the Cauchy problem, we deal with moving curves represented by entire graphs on the x-axis. Here the initial curves are given by bounded functions on the x-axis. It is proved that the solution converges uniformly to the solution of the Cauchy problem of the heat equation with the same initial value. The difference is of order O(t−1/2) as time goes to infinity. The proof is based on the decay estimates for the derivatives of the solution. By virtue of the stability results for the heat equation, our result gives the sufficient and necessary condition on the stability of constant solutions that represent stationary lines of the curvature flow in the whole plane. 相似文献
5.
Ammoniacal copper quat (ACQ) compound wood preservative is comprised of copper and quaternary ammonium compounds with benzalkonium chloride (BAC) as the active ingredient. Solid-phase extraction (SPE) followed by liquid chromatography with ultraviolet detection (LC-UV) was developed for quantitative determination of BAC in treated wood. Five species of wood were used, Japanese cedar (Cryptomeria japonica), Japanese larch (Larix leptolepis), Yezo spruce (Picea jezoensis), Sakhalin fir (Abies sachalinensis), and western hemlock (Tsuga heterophylla). BAC used in the present study was composed of 66% C12, 33% C14 and less than 1% C16. BAC was added to each wood species (500 mg) then extracted with HCl-ethanol (20 ml) and quantitatively determined with LC-UV (262 nm). Wood extractives from the heartwood of each species, except western hemlock, interfered with quantitative determination of BAC, but SPE with an Oasis MCX cartridge was effective in preventing this. Using the present methods, BAC homologue peaks were clearly confirmed without interference. Recoveries from wood ranged from 92 to 101% and the limit of quantitation was approximately 240 microg/g wood for the C12 and C14 homologues. 相似文献
6.
A new entry for the synthesis of 3-alkyl substituted 5-vinyloxazolidin-2-one derivatives 2 from cis-2-butenylene-1,4-dicarbonate 1 and primary amines mediated by palladium-phosphine catalysts is described. The scope and limitation, a plausible mechanism, and an asymmetric version of the reaction are also discussed. 相似文献
7.
Mitsunori Honda Yuichi Yamamoto Hideki Tsuchida Masahito Segi Tadashi Nakajima 《Tetrahedron letters》2005,46(38):6465-6468
Treatment of cyclopropylsilylmethanols derived from cyclopropyl silyl ketones with acid catalyst gives the corresponding silyl-substituted homoallyl derivatives in high yields with good stereoselectivity, independent of the substituents on the cyclopropyl ring. Cyclopropylsilylmethanols having a n-, s-butyl or phenyl group on the carbinyl carbon react to afford the E-homoallyl derivatives selectively. On the other hand, the reaction of cyclopropylsilylmethanols having a tert-butyl group gives Z-isomers exclusively. The following protiodesilylation of the resulting homoallyl derivatives proceeds with retention of configuration. 相似文献
8.
R- and S-epimerization at the 3(1) position of bacteriochlorophyll (BChl) c and the formation of rod-like aggregates in chlorosomes of green sulfur bacteria were markedly affected in Chlorobium (Cb.) tepidum and Cb. limicola by cultivation under various light intensities (photon fluence rate). The stronger the light, the higher the ratio of the S-epimer to the R-epimer for each homolog of BChl c in the bacteria. S[P,E] BChl cF and S[I,E] BChl cF were found to be the major S-epimers in Cb. tepidum and Cb. limicola, respectively. R[P,E] BChl cF decreased markedly compared to R[E,E] BChl cF in Cb. tepidum, whereas no observable change in the ratio of R[P,E]/R[E,E] was detected for Cb. limicola. With increase in light intensity the Qy absorption maximum of the bacteria shifted to shorter wavelengths. In vitro spectroscopic studies of the aggregates showed a marked difference in the formation of aggregates from R- and S-epimers of BChl c; the S-epimers formed aggregates much more slowly than did the R-epimers. These results suggest that the ratio of the epimers of BChl c might significantly affect the aggregation of BChl in the chlorosome. We propose different roles for the R- and S-epimers in chlorosomes of Cb. limicola and Cb. tepidum. 相似文献
9.
Umebayashi Y Fujimori T Sukizaki T Asada M Fujii K Kanzaki R Ishiguro S 《The journal of physical chemistry. A》2005,109(40):8976-8982
Raman spectra of liquid 1-ethyl-3-methylimidazolium (EMI+) salts, EMI(+)BF4-, EMI(+)PF6-, EMI(+)CF3SO3-, and EMI(+)N(CF3SO2)2-, were measured over the frequency range 200-1600 cm(-1). In the range 200-500 cm(-1), we found five bands originating from the EMI+ ion at 241, 297, 387, 430, and 448 cm(-1). However, the 448 cm(-1) band could hardly be reproduced by theoretical calculations in terms of a given EMI+ conformer, implying that the band originates from another conformer. This is expected because the EMI+ involves an ethyl group bound to the N atom of the imidazolium ring, and the ethyl group can rotate along the C-N bond to yield conformers. The torsion energy for the rotation was then theoretically calculated. Two local minima with an energy difference of ca. 2 kJ mol(-1) were found, suggesting that two conformers are present in equilibrium. Full geometry optimizations followed by normal frequency analyses indicate that the two conformers are those with planar and nonplanar ethyl groups against the imidazolium ring plane, and the nonplanar conformer is favorable. It elucidates that bands at 241, 297, 387, and 430 cm(-1) mainly originate from the nonplanar conformer, whereas the 448 cm(-1) band does originate from the planar conformer. Indeed, the enthalpy for conformational change from nonplanar to planar EMI+ experimentally obtained by analyzing band intensities of the conformers at varying temperatures is practically the same as that evaluated by theoretical calculations. We thus conclude that the EMI+ ion exists as either a nonplanar or planar conformer in equilibrium in its liquid salts. 相似文献
10.
Optical resolution of new quinolone drugs by capillary electrophoresis with ligand-exchange and host-guest interactions 总被引:3,自引:0,他引:3
A method for the optical resolution of new quinolone drugs (NQs) by capillary electrophoresis has been investigated. The NQs were adequately resolved using a γ-cyclodextrin (γ-CD)-Zn(II)-
-phenylalanine (
-Phe) solution as the running solution. The resolution depended on the components of the running solution and their concentrations. When
-Phe was used instead of
-Phe, inversion of the migration order of the enantiomers was observed. The resolution mechanism is considered to be due to a ligand-exchange interaction of the NQs with Zn(II) and
-Phe, in combination with a host-guest interaction of those with γ-CD. 相似文献