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201.
4'-Substituted nucleoside analogues have been synthesized using palladium-catalyzed asymmetric allylic amination conditions. A kinetic discrimination between the diastereomeric lactol acetates (3) produced the desired aminated products (6a-d) and recovered acetate (alpha-3) in high yields and <97:3 diastereoselectivity. Epimerization of the recovered lactol acetate (alpha-3) produced a 60:40 alpha/beta mixture of (3), which could be resubjected, in principle, to the palladium-catalyzed asymmetric allylic amination conditions. 相似文献
202.
203.
Self-written waveguides in photopolymerizable resins 总被引:2,自引:0,他引:2
We study the optically induced growth and interaction of self-written waveguides in a photopolymerizable resin. We investigate experimentally how the interaction depends on the mutual coherence and the relative power of the input beams and suggest an improved analytical model that describes the growth of single waveguides and the main features of their interaction in photosensitive materials. 相似文献
204.
Hashi K Shimizu T Goto A Kiyoshi T Matsumoto S Wada H Fujito T Hasegawa K Yoshikawa M Miki T Ito S Hamada M Hayashi S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,156(2):318-321
We have developed a 920-MHz NMR system and performed the proton NMR measurement of H(2)O and ethylbenzene using the superconducting magnet operating at 21.6 T (920 MHz for proton), which is the highest field produced by a superconducting NMR magnet in the persistent mode. From the NMR measurements, it is verified that both homogeneity and stability of the magnet have a specification sufficient for a high resolution NMR. 相似文献
205.
Satoshi Shogen Masahiro Kawasaki Toshihiro Kondo Yukari Sato Kohei Uosaki 《应用有机金属化学》1992,6(6):533-536
An angle-resolved X-ray photoelectron spectroscopic study has been performed on structures of self-assembling systems, viz ferrocenylthiols on a gold (111) crystal. The angular dependence of the intensities of photoemission reveals that ferrocenyl groups are on the outermost layer, separated from the gold substrate by hydrocarbon chains of the thiol groups. 相似文献
206.
Pressure, temperature, and composition phase equilibrium diagrams of new solid solution systems of the Cd1?xMxS (M = Mg, Ca, Sr) type were investigated using the quenching method. The stable region for the rock-salt-type phase is widely extended toward the high-temperature/low-pressure region by substituting 10–20 mole% of Cd with Ca or Sr. Temperature and composition phase diagrams for each solid solution system were obtained at 2 GPa. The rock-salt-type phase stability is discussed in view of these phase relations. 相似文献
207.
Kiyoshi Hasebe Satoshi Hikima Hitoshi Yoshida 《Fresenius' Journal of Analytical Chemistry》1990,336(7):586-588
Summary An electrochemical method for the determination of l-lactic acid using the specific reaction of lactate oxidase, has been studied and applied to lactic acid beverage and yoghurt. The technique is reasonably rapid and simple to perform. The calibration curve is linear in the concentration range from 1.0 to 20 mol/l, the reproducibility (R.S.D.) at 10 mol/l l-lactic acid is 1.34% (n=6) and the detection limit is 0.29 mol/l (k=2). The method can possibly be used for monitoring l-lactate or l-lactic acid in food industries and clinical laboratories. 相似文献
208.
The electronic absorption spectra of four monosubstituted naphthalenes, α-, β-naphthols, and α-, β-naphthylamines have been investigated by means of configuration analysis with particular attention to the dependence of spectra on the position of substitution and on the electron-donating power of the substituent. The results of molecular orbital calculations based on the Pariser-Parr-Pople method are analyzed in terms of locally excited states and intramolecular charge-transfer configurations. The characteristic changes in location and polarization of the Lb, La, and Bb bands caused by substitution at the α- or β-position are adequately explained by the analysis. Two strong absorption bands of α-substituted naphthalenes, which appear in place of the Bb band of naphthalene, are shown to result from a mixing of the and states. The amino group exerts a great influence on the electronic structure of the parent molecule, so that the Bb band cannot be identified in the spectrum of β-naphthylamine. 相似文献
209.
Satoshi Ikeda 《International Journal of Theoretical Physics》1974,11(3):205-212
In this paper, a non-local field (i.e. the (x, ψ)-field) is constructed by regarding the spinor (ψ) as the internal freedom attached to each point (x). Since this field is likened to a unified field between the (x)- and (ψ)-fields, the metric is given bydσψ=gλ dx λψ. Concerning this, some conformally equivalent relations are considered. Next, Weyl's gauge field is introduced into the concept of connection in order to consider the gauge invariance. Finally, some essential features underlying our non-local field are grasped by formulating some fundamental equations of the spin curvature tensors. 相似文献
210.
Hiroyuki Inouye Yoshio Takeda Shinichi Uesato Kenichi Uobe Toshiro Hashimoto Tetsuro Shingu 《Tetrahedron letters》1980,21(11):1059-1062
Hydrangenoside A, isolated along with its three congeners from Hydrangea macrophylla, was proved to have a novel type of structure which is thought to be biosynthesized through an aldol-type condensation of secologanin with a unit formed by the shikimate-malonate route followed by decarboxylation. 相似文献