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121.
122.
1,1-Dialkylethenes are readily prepared in good yields from vinyltrialkylborates derived from trialkylboranes and trisylhydrazones of methyl ketones by treatment with iodine. 相似文献
123.
124.
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
125.
Tamejiro Hiyama Hiroyuki Saimoto Koji Nishio Masaki Shinoda Hajime Yamamoto Hitosi Nozaki 《Tetrahedron letters》1979,20(22):2043-2046
A new method is reported for constructing α-methylene-γ-butyrolactone moiety under neutral, anhydrous conditions. Olefin-dibromocarbene adducts are transformed to methyl 1-(N,N-dimethylaminomethyl)cyclopropanecarboxylates which in turn are treated with trimethylsilyl iodide and the crude products distilled to give the title compounds with high regio- and stereoselectivity. 相似文献
126.
Experimental observation of optical Ramsey interference in saturated absorption of methane in a low-pressure gas cell with
three spacially separated laser beams at 3.39 μm is reported. 相似文献
127.
Minoru Hatanaka Yu-ichi Yamamoto Hajime Nitta Toshiyasu Ishimaru 《Tetrahedron letters》1981,22(39):3883-3886
A new synthesis of the carbapen-2-em ring system, the basic nucleus of thienamycin and its relatives, is described. 相似文献
128.
This paper describes a novel, sensitive detection system for biomolecules (DNA and proteins etc.) that is integrated in a lab-on-a-chip utilizing optical compact discs (CDs) and bio-nanofibers. The new method comprises a microchannel containing CD grating that confines fragments of unique bacterial cellulose fibrils (BC), which have nanometre scale fibers and holes. A maximum of six times higher sensitivity to detect DNA was obtained with this CD and BC system compared to a conventional method. We also demonstrate an effective light-confining effect for biological application with the new method. 相似文献
129.
Nakayama M Wakihara M Kobayashi Y Miyashiro H 《The journal of physical chemistry. B》2005,109(30):14648-14653
The relationship between the Li arrangement and the electrochemical behavior has been examined as a function of composition x in electrochemically lithiated A-site deficient perovskite, Li(x)()La(1/3)NbO(3). The cell potential diagram and powder X-ray diffraction (XRD) study indicated that the Li ions are inserted into the vacant Perovskite A-site with an electrochemical reaction. In addition, the derivatives of the cell potential diagram showed three cathodic peaks, indicating a stepwise Li insertion mechanism takes place. Such a stepwise behavior would be ascribed to the changes in arrangement of inserted Li ions in the Perovskite lattice, since the XRD patterns of pristine La(1/3)NbO(3) showed that the La arrangement in La(1/3)NbO(3) was ordered along the c-axis, causing two kinds of A-site vacancies. To reveal the changes in the arrangement of Li ions, the entropy measurement of the reaction was performed by both the electrochemical and the calorimetric techniques. Moreover, the formation energy of the Perovskite structure with various Li arrangements was compared by using an ab initio calculation. The results of experiment and computation suggested that the electrochemical reaction proceeded via two kinds of superstructures of Li(1/6)La(1/3)NbO(3) and Li(1/2)La(1/3)NbO(3) due to the ordered arrangement of Li ions. 相似文献
130.
We demonstrate the generation of up to the 63rd harmonic (lambda = 12.6 nm) of a Ti:sapphire laser pulse (150 fs, 10 mJ), using a prepulse- (210-ps,24-mJ) produced boron plasma as the nonlinear medium. The influence of various parameters on the harmonic conversion efficiency was analyzed. The steep decrease in intensity for low-order harmonics (up to 19th order) was followed by a plateau. Typical conversion efficiencies were evaluated to be 10(-4) (for a 3rd harmonic) to 10(-7) (within the plateau region). Harmonic generation appeared to be efficient for the plasma that comprised neutral atoms and singly ionized boron. 相似文献