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1.
Abstract When isolated mitochondria are irradiated in the presence of 50 μg/ml hematoporphyrin or hematoporphyrin derivative in the respiratory medium, the irradiation is at least twenty-fold less effective in impairing the Ca2+ pump in the absence of oxygen than in its presence. This result suggests that photosensitization by non oxygen-depending pathways has few or no effects on cell membranes, a result somewhat at variance with those observed with liposomes. 相似文献
2.
J. Gomez C. Bruneau N. Soyer A. Brault 《Journal of Analytical and Applied Pyrolysis》1985,7(4):307-313
The pyrolysis of amphetamine sulphate was studied in a laboratory flow reactor in the range 350–1000°C. The identifications and quantitative determinations of most gaseous and condensed products by means of gas chromatography and mass spectrometry made possible the suggestion of a thermal degradation scheme. The presence of sulphate in the initial molecule led to oxidation reactions in addition to the usual thermal reactions that occur during the pyrolysis of organic materials. 相似文献
3.
D. Brault C. Vever-Bizet K. Kuzelova 《Journal of photochemistry and photobiology. B, Biology》1993,20(2-3):191-195
The interactions of dicarboxylic porphyrins with membrane systems are discussed with particular emphasis on the effect of the charge of the porphyrin and the nature of the side-chains. The incorporation of hematoporphyrin or related dicarboxylic porphyrins within small unilamellar vesicles as membrane models is favored by a decrease of the pH in the range of physiological pH values. This effect might play an important role in the retention of porphyrins by tumors, which are more acidic than normal tissues. Kinetics studies also show that the partition of the porphyrin between the lipidic bilayer and the aqueous phase is governed by its release rate rather than by its incorporation rate. 相似文献
4.
Fourier transform spectra recorded using (a) natural abundance water vapor, (b) H218O-enriched water vapor, and (c) H217O-enriched water vapor are analyzed. The ratio of intensities in three spectra is used to identify 927 lines due to absorption by H218O. Intensities and self-broadening parameters are derived for these lines. Using theoretical linelists, comparisons with previously assigned H216O spectra, and automatic searches for combination differences, 747 lines are assigned. These lines belong to 14 vibrational states in the 3ν+δ and 4ν polyads. Newly determined H218O vibrational band origins include 4ν1 at 13 793.09 cm−1, 3ν1+ν3 at 13 795.40 cm−1, 2ν1+2ν3 at 14 188.82 cm−1, ν1+3ν3 at 14 276.34 cm−1, and 2ν2+2ν2+ν3 at 13 612.71 cm−1. These results are compared with data in HITRAN. 相似文献
5.
The v = 0?0 quadrupole spectrum of H2 has been recorded using a 0.005-cm?1 resolution Fourier transform spectrometer. The rotational lines S(1) through S(5) are observable in the spectra, in the region 587 to 1447 cm?1. The spectral position for S(0) was also obtained from its v = 1-0 ground-state combination difference. The high accuracy of the H2 measurements has permitted a determination of four rotational constants. These are (in cm?1) B0 = 59.33455(6); D0 = 0.045682(4); H0 = 4.854(12) × 10?5; L0 = ?5.41(12) × 10?8. The hydrogen line positions will facilitate studies of structure and dynamics in astrophysical objects exhibiting infrared H2 spectra. The absolute accuracy of frequency calibration over wide spectral ranges was verified using 10-μm CO2 and 3.39-μm CH4 laser frequencies. Standard frequencies for 5-μm CO were found to be high by 12 MHz (3.9 × 10?4 cm?1). 相似文献
6.
The reaction of singlet oxygen with four vinyl-substituted dicarboxylic porphyrins, vinyldeuteroporphyrin (VD), ethylvinyldeuteroporphyrin (EVD), hydroxyethylvinyldeuteroporphyrin (HVD) and protoporphyrin (PP) in organic solutions is investigated. The main products, the "hydroxyaldehyde" chlorin-type derivatives, are formed with a concentration-dependent photochemical quantum yield that reaches a maximum of 7.4 +/- 1.6 x 10(-3). However, owing to the high turnover of singlet-oxygen production, these chlorin-type compounds are easily prepared photochemically with a chemical yield of 70% and little side product formation. In chemical ionization mass spectrometry, these compounds display an unusual fragmentation with a loss of 16 mass units. This is attributed to the loss of the oxygen bound to the saturated carbon of the modified pyrrole unit. All these compounds sensitize the formation of singlet oxygen with a yield around 0.8. They interact with singlet oxygen with rate constants of 5 x 10(6)-9 x 10(6) M-1 s-1, lower than those measured for vinyl porphyrins. These data are likely to help in the characterization of photoproducts of vinyl porphyrins relevant to photodynamic therapy (PP, HVD). As exemplified with VD and EVD, they also point out the reaction of singlet oxygen as an efficient route to chlorin-type photosensitizers. 相似文献
7.
We generalize previous stochastic classical trajectory-ghost atom calculations for describing palladium deposition onto the Ni(111) surface between 0.1 and 0.5 monolayers. The growth evolves through two-dimensional islands. The islands are formed following the downward funneling mechanism. Surface temperature does not affect the island growth. 相似文献
8.
Linda R. Brown Robert A. Toth Robert H. Hunt James W. Brault 《Journal of Molecular Spectroscopy》1981,89(2):528-541
As part of a comprehensive effort to compile line parameters of methane from 2400 to 3200 cm?1, the P and R branches of the ν2 + ν3 ? ν2 band of CH4 at 3010 cm?1 were assigned through upper state J = 9. The process utilized the analysis of ν2 + ν3 at 4544 cm?1 by J. C. Hilico, J. Degni, J. P. Champion, and G. Guelachvili (J. Mol. Spectrosc.81, 277–302 (1980)) and the ν2 levels derived from the infrared spectrum by Margolis (in preparation) to predict the positions of the hot band. Experimentally determined lower-state energies were used to confirm assignments, and line intensities of the 300 transitions assigned are observed on the order of 10?3 cm?2 atm?1 or less. 相似文献
9.
Linda R. Brown Robert A. Toth Alan G. Robiette Jens-Erik Lolck Robert H. Hunt James W. Brault 《Journal of Molecular Spectroscopy》1982,93(2):317-350
Line assignments, positions, strengths, and experimentally determined upper states are reported for the ν1 and ν2 + ν4 infrared bands of 12CH4. The bands have been analyzed using infrared spectra recorded with different optical densities and temperatures at 0.02- and 0.01-cm?1 resolution using a four-passed grating spectrometer at Florida State University and a Fourier transform spectrometer at Kitt Peak National Observatory. Both ν1 and ν2 + ν4 lines are assigned through J′ = 14. For J′ ≥ 10, the upper state of the vibrationally infrared inactive ν1 band interacts strongly with ν2 + ν4 and is observed in the infrared spectrum with line strengths on the order of 10?3 cm?2 atm?1. The upper-state energies and transition intensities are calculated from the molecular constants and transition moment matrix elements obtained through a simultaneous analysis of ν1, ν3, ν2 + ν4, 2ν4, and 2ν2. 相似文献
10.
Reaction of the free-radical diphenylpicrylhydrazyl (DPPH(.)) with Trolox (TrOH) was investigated in buffered hydroalcoholic media by using a stopped-flow system. DPPH was reduced to the hydrazine analogue DPPH-H with a measured stoichiometry of about 2. DPPH-H was characterized by an acid-base equilibrium (pKa = 8.6). Time-resolved absorption spectra recorded with an excess of either TrOH or DPPH indicated that no significant amount of the TrO radical was accumulated. The TrO radical formed in a first step further reacted quickly with DPPH(.). For 1 : 1 ethanol-buffer mixtures at pH 7.4, the bimolecular rate constants of the first and second steps were 1.1 x 10(4) M(-1) s(-1) and 2 x 10(6) M(-1) s(-1), respectively. A significant increase of the measured rate constant was observed for ethanol-buffer solutions as compared to ethanol. The rate was also increased at higher pH. A deuterium isotopic effect of 2.9 was measured. These data are discussed with regards to mechanisms involving either electron or proton exchange as rate determining steps in the reaction of DPPH with Trolox. The importance of solvent acidity control in investigation of antioxidant properties is outlined. 相似文献