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991.
Yoshio Hamashima Sadao Yamamoto Shoichiro Uyeo Mitsuru Yoshioka Masayuki Murakami Hisao Ona Yasuhiro Nishitani Wataru Nagata 《Tetrahedron letters》1979,20(28):2595-2598
Reaction of 2β-unsubstituted or functionalized-methyl 6-epipenicillin sulfoxides with tervalent phosphorus compounds gave azetidinone-epi-oxazolines , important intermediates in synthesis of 7α-methoxy-1-oxacephems. Preparation of the 2β-functionalized-methyl substrates is described also. 相似文献
992.
Poisson statistics is a nature consequence of a distribution of solubilized molecules among micellar aggregates. With postulates of non-cooperativity and thermodynamic considerations, relationships for extent of solute fractionation between the micellar phase and the aqueous phase are derived, as are expressions for the handling of experimental data from the quenching of photoluminescence probes of micellar aggregates. 相似文献
993.
Masayuki Kawakami Kiyoshi Mizuno Satoru Kunii Tadao Kasuya Hirochika Enokiya Kiyoshi Kume 《Journal of magnetism and magnetic materials》1982,30(2):201-208
The 11B nuclear magnetic resonance in a dense Kondo system CeB6 has been observed by the spin echo technique below 4.2 K at fixed frequencies of 2.5, 6.5, 13.33 and 18.00 MHz, which correspond to magnetic fields of 1.83, 4.76, 9.76 and 13.18 KOe for the free 11B nucleus, respectively. The spectra in the phase II appeared to have two peaks in the magnetic field applied in the [111] direction, the spacing of which was found to be very small in zero external field and increased monotonically (up to 0.11 kOe at 2.6 K) with increasing field. On the other hand, the spectra in the phase III were complex. Especially, the spectra observed for [111] at 6.5 MHz were found to spread over 1.9 KOe and to have several peaks. From comparison between the experiments and the dipolar field calculation based on the recent neutron diffraction measurements, possible magnetic structures were examined for the phases II and III. 相似文献
994.
Peptide mimics derived from the first extracellular loop of CCR5 bearing non-peptide spacers in place of Ala-Ala-Ala sequence in the peptide moiety were synthesized, and the effects of these compounds on the inhibition against HIV-1 were examined. Compound 2b having m-aminophenoxyacetic acid derivative as a non-peptide spacer significantly inhibited HIV-1. 相似文献
995.
Tsuji E Ando K Kunitomo J Yamashita M Ohta S Kohno S Ohishi Y 《Organic & biomolecular chemistry》2003,1(18):3139-3141
Novel 3-acetoacetylaminobenzo[b]furan derivatives with a modified triene system at the 3-position were prepared through acylation of the 3-aminobenzo[b]furans with 5-methylisoxazole-4-carboxylic acid chloride followed by basic cleavage of the isoxazole ring and several of these compounds showed moderate cysteinyl leukotriene receptor 2 antagonistic activity. 相似文献
996.
997.
998.
It was found that a one-dimensional rodlike structure of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) in water acts as a powerful template for electrochemical polymerization of ethylenedioxathiophene (EDOT) and pyrrole on an ITO electrode. Examination using CV and UV-vis spectroscopic examinations established that J-aggregated TPPS molecules are entrapped in the resultant poly(EDOT) and poly(pyrrole) films. SEM observation established that these monomers are electrochemically oxidized to grow up to a nanosized rodlike structure, reflecting the aggregation structure of TPPS. [structure: see text] 相似文献
999.
Solid-state 13C and 1H spin diffusion NMR analyses of the microfibril structure for bacterial cellulose 总被引:1,自引:0,他引:1
Masuda K Adachi M Hirai A Yamamoto H Kaji H Horii F 《Solid state nuclear magnetic resonance》2003,23(4):198-212
To obtain further information about the cause for the rather large splitting of the C4 resonance line into the downfield (C4D) and upfield (C4U) lines in CP/MAS 13C NMR spectra for native cellulose, 13C and 1H spin diffusion measurements have been conducted by using different types of bacterial cellulose samples. In 13C spin diffusion measurements, the C4D resonance line is selectively inverted by the Dante π pulse sequence and the 13C spin diffusion is allowed to proceed from the C4D carbons to other carbons including the C4U carbons with use of the 13C4-enriched bacterial cellulose sample. The analysis based on the simple spin diffusion theory for the process experimentally observed reveals that the C4U carbons may be located at distances less than about 1 nm from the C4D carbons. In 1H spin diffusion measurements, poly(vinyl alcohol) (PVA) films in which ribbon assemblies of bacterial cellulose are dispersed are employed and the 1H spin diffusion process is examined from the water-swollen PVA continuous phase to the dispersed ribbon assemblies by the 13C detection through the 1H–13C CP technique. As a result, it is found that the C4D and C4U carbons are almost equally subjected to the 1H spin diffusion from the PVA phase, indicating that the C4U carbons are not localized in some limited area, e.g. in the surfacial region, but are distributed in the whole area in the microfibrils. These experimental results suggest that the C4U carbons may exist as structural defects probably due to conformational irregularity associated with disordered hydrogen bonding of the CH2OH groups in the microfibrils. 相似文献
1000.
To examine a simulation method for vertical sound localization, and to clarify which peaks and notches in head-related transfer functions (HRTFs) play a role as spectral cues, localization tests in the median plane were carried out using a parametric HRTF model, which is recomposed only of extracted spectral peaks and notches. The results show that the parametric HRTF recomposed using the first and second notches (N1 and N2) and the first peak (P1) provides almost the same localization accuracy as the measured HRTFs. Observations of the spectral peaks and notches indicate that N1 and N2 change remarkably as the source elevation changes, whereas P1 does not depend on the source elevation. In conclusion, N1 and N2 can be regarded as spectral cues, and the hearing system could utilize P1 as the reference information to analyze N1 and N2. 相似文献