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1.
We show that the open period of a CS2 light gate, triggered by a picosecond optical pulse, depends on the optical pathlength through the CS2. An alternative to the light gate is suggested for time resolved spectroscopy. The working principle is based on scattering induced in CS2. We have found that the broadband emission from H2O or D2O excited by a 5300 Å picosecond pulse is also of picosecond duration, but the blue part is delayed with respect to the red. From this delay time the lifetime of the ground state vibrational levels may be measured directly. 相似文献
2.
Alan Rigter Jan PM Langeveld Drophatie Timmers-Parohi Jorg G Jacobs Peter LJM Moonen Alex Bossers 《BMC biochemistry》2007,8(1):6
Background
The common event in transmissible spongiform encephalopathies (TSEs) or prion diseases is the conversion of host-encoded protease sensitive cellular prion protein (PrPC) into strain dependent isoforms of scrapie associated protease resistant isoform (PrPSc) of prion protein (PrP). These processes are determined by similarities as well as strain dependent variations in the PrP structure. Selective self-interaction between PrP molecules is the most probable basis for initiation of these processes, potentially influenced by chaperone molecules, however the mechanisms behind these processes are far from understood. We previously determined that polymorphisms do not affect initial PrPC to PrPSc binding but rather modulate a subsequent step in the conversion process. Determining possible sites of self-interaction could elucidate which amino acid(s) or amino acid sequences contribute to binding and further conversion into other isoforms. To this end, ovine – and bovine PrP peptide-arrays consisting of 15-mer overlapping peptides were probed with recombinant sheep PrPC fused to maltose binding protein (MBP-PrP). 相似文献3.
4.
We have monitored the spectra and kinetics of μ-oxo iron (III) tetraphenyl porphyrin. The spectral changes between 460 nm
and 770 nm were observed after excitation with 25 ps fwhm, 355 nm pulse. Kinetic studies from — 100 ps to 4 ns suggest that
after the immediate formation of the excited states a transient species is formed which we assign to the π-caion radical-ferrous
porphyrin pair. This pair decays with a time constant of 600 ps ± 100 ps leaving a small amount of disproportionation reaction
photoproducts. The spectra and kinetics of the transients, were not altered by concentration (0.15 OD – 1.0 OD at 571 nm),
solvent or addition of oxygen. 相似文献
5.
We have measured directly by time-resolved spectroscopy the transient spectra and kinetics of the methylene blue (MB) excited singlet and triplet state as a function of pH from a few picoseconds to several microseconds. The data show that the acidic triplet state (3)MBH(2+) is the protonated analogue of the basic (3)MB(+). It is also shown that the singlet oxygen formation quantum yield is much higher in basic than in acidic media. The transient spectra and their kinetics suggest that because pH exerts a large influence in singlet oxygen and radical formation, it may also be important in bacteria inactivation. Therefore, we performed experiments, which showed that the rate of gram-positive and gram-negative bacteria inactivation at pH 9 is 3-25 times higher than the rate at pH 5. 相似文献
6.
Metal/superconductor/semiconductor (Ag/Hg-1212/CdSe) hetero-nanostructures have been fabricated using pulse-electrodeposition
technique and are characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy
(SEM) studies. The junction capacitance of Ag/Hg-1212, Hg-1212/CdSe and Ag/Hg-1212/CdSe heterojunctions is measured in dark
and under laser irradiation at room temperature. The nature of the junction formed and built-in-junction potentials were determined.
The increase in carrier concentration across the junction due to photo-irradiation has been observed. 相似文献
7.
One of the innovative technological directions for the high-temperature superconductors has been persued by fabricating the
heteroepitaxial multilayer structures such as superconductor-semiconductor heterostructures. In the present investigation,
metal/superconductor/semiconductor (Ag/Tl-2223/CdSe) hetero-nanostructures have successfully been fabricated using dc electrodeposition
technique and were characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy
(SEM) studies. The measurement of junction capacitance as a function of biasing voltage was used for the estimation of junction
built-in-potential (V
D) and to study the charge distribution in a heterojunction. The Mott-Schottky plots were measured for each junction in dark
and under the photo-irradiation. The effect of laser irradiation on C-V characteristics of hetero-nanostructure has been studied. 相似文献
8.
Abstract—Picosecond absorption spectroscopy was used to determine the intramolecular energy relaxation processes occurring in Ni(II). Pd(II), Pt(II), and Zn(II) protoporphyrin IX dimethyl ester. Picosecond data on the rate of ground state repopulation and the kinetics of a transient intermediate made it possible to determine the lifetimes of the excited singlet state of Ni, Pd, and Zn porphyrins as 10±2ps, 19±3ps, and 2.6±0.5 ps, respectively, and<8 ps for Pt porphyrin. On the basis of these data. the nonfluorescent and nonphosphorescent property of Ni porphyrin can be interpreted in terms of internal conversion to a lower lying singlet d-d level which is not the case for the strongly phosphorescent Pd and Pt porphyrins. 相似文献
9.
J. Malkin K. D. Straub A. S Dvornikov P. M. Rentzepis 《Research on Chemical Intermediates》1993,19(2):159-189
The photochemistry, kinetics and spectra of several spiropyran molecules have been studied. The transient species of the photochromic reactions and precursors have been identified and the rate of formation and decay measured. We also present means for the utilization of spiropyrans in writing and accessing information in 3D volume optical memory. 相似文献
10.
Very extensive vibrationally unrelaxed florescence is observed following dye-laser excitation of single vibronic levels of naphthazarine. The rates and pathways of its vibrational relaxation are examined by means of picosecond emission spectroscopy. Analysis of its vibrational and electronic spectra establishes a C2v symmetry for free naphthazarine. 相似文献