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51.
At weak force range the two-well Duffing equation has a closed bifurcation region in theparameter plane, inside which there are many different periodic windows. By means ofone-dimensional and two-dimensional symbolic dynamics, these periodic windows and thedynamical behavior of chaotic attractors are analyzed systematically. 相似文献
52.
53.
Daisuke Takano Matsumi Doe Yoshiki Morimoto Takamasa Kinoshita Kazuo Yoshihara 《Journal of heterocyclic chemistry》1999,36(1):221-224
The first synthesis of (-)-meridinol and (-)-3-epimeridinol was accomplished from (S)-malic acid. This synthesis unambiguously established the absolute stereochemistry of meridinol. 相似文献
54.
Shuntaro Mataka Kouichiro Shigaki Tsuyoshi Sawada Yoshihara Mitoma Masahiko Taniguchi Thies Thiemann Kazuya Ohga Naoyoshi Egashira 《Angewandte Chemie (International ed. in English)》1998,37(18):2532-2534
Through clever bridging of orthocyclophanes (in this case by acetalization), molecules such as 1 can be formed with four benzene rings in a stacked face-to-face arrangement. UV/Vis spectroscopic and electrochemical properties of 1 are governed by π–π through-space interactions within the molecule. 相似文献
55.
56.
Dobashi T Nobe M Yoshihara H Yamamoto T Konno A 《Langmuir : the ACS journal of surfaces and colloids》2004,20(16):6530-6534
Curdlan dissolved in aqueous sodium hydroxide was dialyzed to aqueous calcium chloride to form a gel. Transparent and turbid concentric layers observed in the gel cross section perpendicular to the long axis of the dialysis tube were identified as liquid crystalline gels with refractive index gradient and amorphous gels, respectively. The thickness of each layer was proportional to the diameter of the dialysis tube, and the gelation proceeded in proportion to the root of time. The unique pattern formation was attributed to the change of curdlan conformation and calcium-induced cross-linking resulting from a diffusion of calcium cations and hydroxide anions through the dialysis tube. It is suggested that the orderedness of the curdlan molecules decreases by the increase of the curvature of the concentric liquid crystal layers as the layer comes toward the center of the dialysis tube. 相似文献
57.
Yoshihara T Druzhinin SI Zachariasse KA 《Journal of the American Chemical Society》2004,126(27):8535-8539
The planar rigidized molecule fluorazene (FPP) undergoes fast reversible intramolecular charge transfer (ICT) in the excited state, with a reaction time of 12 ps in the polar solvent ethyl cyanide at -45 degrees C. The ICT state of FPP has a dipole moment mu(e)(ICT) of 13 D, much larger than that of the locally excited state LE (1 D). The ICT behavior of FPP is similar to that of its flexible counterpart N-phenylpyrrole (PP), for which mu(e)(ICT) = 12 D. These results show that intramolecular charge transfer to a planar ICT state can occur efficiently. In designing ICT systems capable of rapid switching, it is therefore important to realize that large amplitude motions such as those necessary for the formation of a twisted intramolecular charge transfer (TICT) state are not required. 相似文献
58.
在氮气的氛围下用γ辐照的方法在聚四氟乙烯多孔膜上接枝苯乙烯 马来酸酐、苯乙烯 甲基丙烯酸二甲氨基乙酯二元单体 .并且研究了剂量、剂量率、溶液中单体的浓度和二元单体的摩尔比等条件对接枝率的影响 .探讨了两种单体的竞聚率对接枝率、接枝膜的组成及性能的影响 .结果表明 ,苯乙烯 马来酸酐二元体系对接枝率有协同效应 ,苯乙烯 甲基丙烯酸二甲氨基乙脂二元体系对接枝率表现为加合效应 .制备的二元接枝的聚四氟乙烯多孔膜可以进一步磺化来制备用于质子交换膜燃料电池的质子交换膜 . 相似文献
59.
设计了含改性松香无苯环的环氧固化体系和无松香的对照体系,分别是无松香体系Ⅰ:丁二醇二缩水甘油醚(BDGE)和甲基六氢苯酐(MeHHPA);无规体系Ⅱ:丙烯酸松香(AR)、BDGE和MeHHPA;有规体系Ⅲ:丙烯酸松香基环氧树脂(ARE,由AR和BDGE预聚而来)和MeHHPA。对三体系的固化反应应用动态示差扫描量热仪(DSC)进行了研究,利用KAS法求得不同转化率下的表观活化能,通过整个反应过程反应活化能的变化,得到了三体系反应的内在机理,结果发现松香基的引入及引入顺序都对固化反应产生影响。 相似文献
60.
Yamada H Kumauchi M Hamada N Zheng XG Park IH Masuda K Yoshihara K Tokunaga F 《Photochemistry and photobiology》2006,82(6):1422-1425
We report a unique lambdamax shift of the absorption maximum of a photoactive yellow protein (PYP) analogue reconstituted with a fluorinated chromophore (F-PYP). The difference in lambdamax between the free chromophore and the protein was significantly larger than that with the native chromophore. We concluded that the unusual lambdamax shift is caused by the electronegative character of the fluorine atom and not by steric hindrance. This result suggests that formation of a hydrogen bond between the fluorine atom and one or more amino acid residues could neutralize its electron-withdrawing character. The properties of analogues of PYP with brominated and methylated chromophore could be explained as an effect of steric hindrance. 相似文献