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921.
Ohne Zusammenfassung 相似文献
922.
(2,4-Pentadienyl)- and (2,4-hexadienyl)trimethylsilanes, prepared from the corresponding pentadienylpotassiums and trimethylchlorosilane, react smoothly with various electrophiles such as acetals, aldehydes and acid halides to give pentadienylation products, with regiospecific transposition of the pentadienyl group. 相似文献
923.
924.
Kayori Shimada Marina A. Lusenkova Keisuke Sato Takeshi Saito Shigetomo Matsuyama Hisae Nakahara Shinichi Kinugasa 《Rapid communications in mass spectrometry : RCM》2001,15(4):277-282
Mass discrimination effects in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) were quantitatively investigated using equiweight and equimolar mixtures of uniform polystyrene (PS) oligomers. Uniform PS oligomers were separated by preparative super-critical fluid chromatography (SFC) from commercial standard PS samples. The separated PS oligomers, with degrees of polymerization n = 2–25, have absolutely no molecular weight distributions. Equiweight and equimolar mixtures of uniform PS oligomers were accurately prepared by weighing by microbalance, and their spectra were recorded using a MALDI-TOF mass spectrometer. In the lower molecular weight region (less than about 103) the oligomers with lower molecular weights give lower mass spectral intensities, with no correlation with laser power. In contrast, higher laser powers yield a decrease of mass spectral intensities in the higher molecular weight region. These results clearly show that mass discrimination effects occur at lower and higher molecular weights depending on the laser power, and provide quantitative information about the discrimination. Using the data on equiweight and equimolar mixtures of PS oligomers, it was possible to calibrate the MALDI-TOF mass spectral data for an analysis of molecular weight distribution of a standard monodisperse PS sample with number-averaged molecular weight of 103, and to compare it with the molecular weight distribution measured by analytical SFC. The result from the calibrated MALDI-TOF mass spectrum, however, does not agree perfectly with that from the SFC results, because undetectable peaks in MALDI-TOF mass spectra at lower and higher molecular weights could not be included in the calibration of peak intensities. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
925.
The microwave spectrum of HNO has been observed and analyzed. Both a-type and b-type transitions have been measured. The rotational constants obtained are A = 553903.0 ± 2.7 MHz, B = 42308.52 ± 0.10 MHz, and C = 39169.46 ± 0.10 MHz. In the analysis of the spectrum, centrifugal distortion corrections are tentatively taken into account by using the centrifugal distortion constants determined by Dalby. The quadrupole coupling constants for nitrogen in HNO are determined to be χaa = 0.36 ± 0.56 MHz, χbb = ? 5.46 ± 0.30 MHz, and χcc = 5.10 ± 0.26 MHz. The dipole moment and its components determined from the Stark effect measurement are μtotal = 1.67 ± 0.03 D, μa = 1.03 ± 0.01 D, and μb = 1.31 ± 0.02 D. The microwave spectrum of DNO has been reanalyzed by taking into account the centrifugal distortion effect. The inertia defects for HNO and DNO have been calculated. The results are limited in precision by the lack of reliable force constants. 相似文献
926.
927.
Sadayuki Ueha Naoki Kobayashi Takahiro Saito Jumpei Tsujiuchi 《Optics Communications》1980,34(3):340-344
In order to measure vibration amplitudes by speckle photography in quasi real-time, the feasibility of using thermoplastic photographic material for recording a speckle pattern image is studied experimentally to be proved true. An optimum recording condition of the material is also obtained. 相似文献
928.
P. Feller M. Fukushima N. Horikawa R. Kajikawa K. Mori T. Nakanishi T. Ohshima C.O. Pak M. Saito S. Suzuki Y. Tarui T. Yamaki T. Matsuda K. Mizushima N. Tokuda 《Nuclear Physics B》1976,104(2):219-244
A phenomenological partial-wave analysis on γp → π+n and πOp reactions has been performed in the energy range 0.25–1.2 GeV with available data, laying special emphasis on the polarization and asymmetry data. A good fit has been obtained. 相似文献
929.
The frequency spectrum of tungsten field emission current instability when H2 and CO are adsorbed is measured. The power spectrum density slope W(f) versus f is found to be different for both cases. The slopes are about ?1 and ?1.5 for H2 and CO adsorption, respectively. The dependency of frequency spectra on the crystal planes is also measured. The amplitude of W(f) is found to be largest for (310) and lowest for (112). 相似文献
930.