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排序方式: 共有397条查询结果,搜索用时 31 毫秒
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P. Marage M. Aderholz P. Allport N. Armenise J. P. Baton M. Berggren D. Bertrand V. Brisson F. W. Bullock W. Burkot M. Calicchio E. F. Clayton T. Coghen A. M. Cooper-Sarkar O. Erriquez P. J. Fitch G. Gerbier J. Guy F. Hamisi P. O. Hulth G. T. Jones P. Kasper H. Klein R. P. Middleton D. B. Miller M. M. Mobayyen D. R. O. Morrison S. Natali M. Neveu S. W. O'Neale M. A. Parker P. Petiau J. Sacton R. A. Sansum E. Simopoulou C. Vallée K. Varvell A. Vayaki W. Venus H. Wachsmuth J. Wells W. Wittek BEBC WA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1986,31(2):191-197
The cross section for coherent production of a single π? meson in charged current antineutrino interactions on neon nuclei has been measured in BEBC to be (175±25) 10?40 cm2/neon nucleus, averaged over the energy spectrum of the antineutrino wide band beam at the CERN SPS; this corresponds to (0.9±0.1) % of the total charged current \(\bar v_\mu \) cross section. The distributions of kinematical variables are in agreement with theoretical predictions based on the PCAC hypothesis and the meson dominance model; in particular, theQ 2 dependence is well described by a propagator containing a massm=(1.35±0.18) GeV. The absolute value of the cross section is also in agreement with the model. This analysis thus provides a test of the PCAC hypothesis in the antineutrino energy range 5–150 GeV. 相似文献
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Abstract— The excitation spectrum for bacteriochlorophyll b fluorescence, the action spectrum for cytochrome-553 oxidation, and the action spectrum for P-985 bleaching are compared to the absorption (1-T) spectrum of a Rhodopseudomonas sp. NHTC 133 extract over the range 770 to 930 mμ. These spectra show that a minor pigment P-830 is more effective in sensitizing cytochrome oxidation and P-985 bleaching than in exciting fluorescence of Bchl b. These results are consistent with the proposal that P-830 is a form of Bchl b in special relation to the reaction center pigment P-985. 相似文献
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Spectral Properties of Fluorescein in Solvent-Water Mixtures: Applications as a Probe of Hydrogen Bonding Environments in Biological Systems 总被引:1,自引:0,他引:1
Nectarios Klonis rew H. A. Clayton Edward W. Voss Jr. William H. Sawyer 《Photochemistry and photobiology》1998,67(5):500-510
Although fluorescein is a widely used fluorescent probe in the biosciences, the effect of solvent environment on its spectral properties is poorly understood. In this paper we explore the use of fluorescein as a probe of the state of hydrogen bonding in its local environment. This application is based on the observation, originally made by Martin ( Chem. Phys. Lett . 35, 105–111, 1975), that the absorption maximum of fluorescein undergoes substantial shifts in organic solvents related to the hydrogen bonding power of the solvents. We have extended this work by studying the spectral properties of the dianion form of the probe in solvent–water mixtures. We show that the magnitude of the shift correlates with the α and β parameters of Kamlet and Taft ( J. Am. Chem. Soc . 98, 377–383; 2886–2894, 1976), which provide a scale of the hydrogen bond donor acidities and acceptor basicities, respectively, of the solvents. In solvent–water mixtures, these shifts reflect general effects of the solvents on the hydrogen bonding environment of the fluorescein through water–solvent hydrogen bonding and specific effects due to fluorescein–solvent hydrogen bonding. Indeed, both the absorption and fluorescence properties appear to be dominated by these effects indicating that the spectral shifts of the dianion can be used as an indicator of its hydrogen bonding environment. We discuss the application of fluorescein as a probe of hydrogen bonding in the microenvironment immediately surrounding the fluorophore, and we illustrate the effect with reference to the fluorescein–antifluorescein antibody complex where it appears that antibodies selected during the immune response possess binding sites that are increasingly dehydrated and hydrophobic. 相似文献
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By an appropriate choice of cation, three of the four possible aldols from the reactions of the chiral α-silyloxy ketone 1 with aldehydes may be obtained. The , lithium enolate provides 6, the , boron enolate gives 7, and the magnesium enolate affords 8. 相似文献
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Eric A. Gregory Mark R. Buckingham Dawn Z. Clayton Freda J. Wolfenden C.J.S.M. Simpson 《Chemical physics letters》1984,104(4):393-397
Rate constants for the vibrational deactivation of CD4 by the collision partners CD4, He, Ne, Ar, Kr, D2 and O2 have been measured using a laser-fluorescence technique. The results are compared with those for the deactivation of CH4 by the same collision partners and with a modified SSH type theoretical treatment. 相似文献
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