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981.
Two-beam coupling gain and speed of Cr-doped strontium barium niobate in the visible and near-infrared spectral regions are measured. It is found that the sample still exhibits the appreciable photorefractive gain in the near-infrared spectrum. Photorefractive parameters such as effective trap density, effective electrooptic coefficient and mobility · recombination-time product are obtained from the measurement. The photorefractive spectra of the coupling gain and speed in the sample are compared with those of Cr-doped KNSBN. 相似文献
982.
983.
H. Sakamoto M. Nakamura H. Sakaguchi H. Ogawa S. Kobayashi S. Kato N. Matsuoka K. Hatanaka T. Noro 《Physics letters. [Part B]》1985,155(4):227-231
The polarization transfer coefficients Kyy′ of the break-up spectra in the reactions 12C, 58Ni, 209Bi(, X) were measured at 56 MeV. In the forwardd angles (13.5° and 20.0°), the Kyy′ data at the break-up peak are nearly equal to (the spectator model prediction) and they decrease at both sides of the peak. The deviation due to the deuteron D-state is estimated, using PWBA and DWBA. 相似文献
984.
985.
An emission spectrometric detector is used in the determination of metal acetylacetonates. Spectra are excited in the plasma of a 2450 MHz electrodeless discharge. Measuring the intensities of the atomic emission lines of aluminium, beryllium and chromium after gas chromatography provides a highly sensitive and selective method for the determination of the acetylacetonates of these metals. Detection limits are 100 ng for aluminium, 0.01 ng for beryllium and 1 ng for chromium. An analytical procedure is proposed for beryllium down to 10 ppm in aluminium. 相似文献
986.
Mino T Sato Y Saito A Tanaka Y Saotome H Sakamoto M Fujita T 《The Journal of organic chemistry》2005,70(20):7979-7984
[Chemical reaction: See text] Chiral fluorous aminophosphine 4c bearing two fluorous ponytails was prepared from (S)-prolinol and applied to palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (7) with a dialkyl malonate-BSA-LiOAc system with high enantioselectivities (up to 97% ee). Results indicated that the chiral fluorous palladium catalyst from ligand 4c was easily separated from the reaction mixture by simple solid/liquid separation and could be reused up to five times. 相似文献
987.
The (+)-enantiomer of modafinil [(RS)-2-(diphenylmethylsulfinyl)acetamide], a novel wake-promoting agent, was clarified to be S-configuration by X-ray crystal structure analysis. The crystal consists of two crystallographically independent conformers that are different at the torsion angles around the sulfinylacetamide moiety, and this results from the molecular packing requirement to form a two-dimensional hydrogen-bonding network via neighboring amide groups in the crystal. The crystal structure is characterized by the formation of alternative hydrophobic and hydrophilic layers, which are formed among the symmetry-translated assemblies of diphenylmethyl and sulfinylacetamide moieties, respectively. The spatial orientation between the diphenyl and amide groups is believed to be important for the activity of modafinil. 相似文献
988.
Yoshiharu Kimura Akihiro Tanaka Mamoru Nango Nobuhiko Kuroki Yasuji Ihara 《Journal of polymer science. Part A, Polymer chemistry》1984,22(2):407-417
The catalytic activities of N-decanoyl-L -histidine and its methyl ester and of dipeptide derivatives containing an L -histidine residue toward the stereoselective hydrolysis of enantiomeric substrates have been studied at pH 7.30 (in 0.01M Bis-tris buffer) and 25°C in the presence of poly(ethyleneimine) derivatives. The dipeptide catalyst revealed greatest stereoselectivity in a quaternized poly(ethyleneimine) derivative. A comparison of catalytic effects on both the rate constants and stereoselectivities of N-decanoyl-L -histidine and its methyl ester elucidates the cooperative effects of carboxyl groups in the polymer domains. The structure of the substrates influenced both the rate constants and stereoselectivities in polymer domains. 相似文献
989.
Akihiro Wakisaka Shunsuke Mochizuki Hitomi Kobara 《Journal of solution chemistry》2004,33(6-7):721-732
Microscopic structures of 1-butanol (1-BuOH)–water mixtures in the presence and absence of salts are studied through the mass spectrometric analysis of clusters generated from the fragmentation of liquid droplets. The analysis of cluster structures provides information on the phase separation of 1-BuOH–water mixtures from the microscopic viewpoint. In a saturated solution of 1-BuOH in water, 1-BuOH exists as hydrated 1-BuOH clusters and self-associated 1-BuOH clusters. With further addition of 1-BuOH, a 1-BuOH rich phase is generated. When the salt (LiCl, NaCl, MgCl2, etc.) coexists in the 1-BuOH–water mixtures, the cation is preferentially solvated by the 1-BuOH to form M +(1-BuOH) m or M 2+(1-BuOH) m clusters: M + = Li+, Na+, Mg2+ = Mg2+, etc., m = 1, 2, 3, ... Since the formation of M +(1-BuOH) m corresponds to an increase of the self-associated 1-BuOH clusters in water, the presence of the salt induces the phase separation at lower 1-BuOH concentrations. 相似文献
990.
Hiroshi Tanaka Takeo Yoshioka Yasutaka Shimauchi Akihiro Yoshimoto Tomoyuki Ishikura Hiroshi Naganawa Tomio Takeuchi Hamao Umezawa 《Tetrahedron letters》1984,25(31):3355-3358
(±)-2-Acetoxy-4,11-dideoxy-10-oxo-β-rhodomycinone [(±)-6a] was synthesized from the tricyclic quinone (1) by a short efficient route in an overall yield of about 54%. Reaction of (±)-6a with protected daunosamine followed by reduction and deprotection provided the optically active α-glycosidated anthracycline (II) with the 7S,9R,10R-configuration. Furthermore, the amino and aromatic hydroxy groups of II were methylated. 相似文献