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51.
PHOTODYNAMIC INHIBITION OF ESCHERICHIA COLI DNA POLYMERASE I BY 8-METHOXYPSORALEN PLUS NEAR ULTRAVIOLET IRRADIATION 总被引:1,自引:0,他引:1
Abstract— Morphological abnormality due to the UV irradiation of sperm and its modification by photoreactivation (PR) were studied in the sea urchin, Hemicentrotus pukherrimus. When sperm was UV-irradiated and allowed to fertilize unirradiated eggs, the effect of the UV was manifested as an abnormal morphology of embryos in the gastrula or later stages. The UV-induced morphological abnormality was prevented by photoreactivation when the fertilized eggs were illuminated with visible light. In the experiments on a stage-dependent change of PR effectiveness, it was found that an illumination sufficed to effect a nearly complete PR when applied up to the onset of the first DNA synthetic phase, while the PR effectiveness declined thereafter. Illumination after the completion of DNA synthesis had little effect for PR. 相似文献
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S. Rasool Azari Mohammad S. Rahmanifar Maher F. El-Kady Abolhassan Noori Mir F. Mousavi Richard B. Kaner 《Journal of the Iranian Chemical Society》2017,14(12):2579-2590
Aqueous supercapacitors based on neutral solutions have the advantages of high-ionic conductivity, being environmentally friendly, safe, and low cost. However, the operating potential window for most aqueous electrolytes is far lower than that of organic electrolytes that are commonly used in commercial supercapacitors. In this work, we report on the fabrication of a wide potential window, high-energy aqueous asymmetric supercapacitor, without sacrificing power, by using a nanostructured LiMn2O4/reduced graphene oxide (LMO–rGO) nanocomposite. We synthesized the uniformly distributed LMO in the LMO–rGO nanocomposite using a co-precipitation route followed by a low-temperature hydrothermal treatment. In a three-electrode cell setup, the specific capacitance of the LMO–rGO nanocomposite electrode at 1 A/g (1.2 mA/cm2) is 268.75 F/g (258 mF/cm2), which shows a dramatic improvement over the sum of the specific capacitances of pristine LMO (162.5 F/g) and pure rGO (29.94 F/g) electrodes in their relative ratios, when used alone. This finding suggests a synergistic coupling of LMO and rGO in the nanocomposite. We also assembled the LMO–rGO nanocomposite, as the positive electrode, with activated carbon, as the negative electrode, into an asymmetric cell configuration. The device shows an ultra-wide potential window of 2.0 V in a neutral aqueous Li2SO4 electrolyte, with a maximum energy density of 29.6 Wh/kg (which approaches the commercial lead-acid batteries), power density of up to 7408 W/kg, and an excellent cycle life (5% loss after 6000 cycles). These findings confirm that an LMO–rGO nanocomposite is a promising material to meet the demands of real world energy storage. 相似文献
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DFT (B3PW91) and CASSCF calculations have been carried out to study the relative α migratory abilities of H and F in alkyl transition metal complexes. It is shown that the activation energy is considerably lower to migrate H than F, whereas the energies of reaction are similar for the two reactions. A study of the electron configurations and the orbitals describing these configurations shows that the high activation energy for F is due to a 4-electron repulsion between an F lone pair and the occupied Ru=C π orbital. 相似文献
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M. Müllenborn R. F. Jarvis Jr. B. G. Yacobi R. B. Kaner C. C. Coleman N. M. Haegel 《Applied Physics A: Materials Science & Processing》1993,56(4):317-321
We report the characterization of solution-synthesized CdTe and HgTe nanocrystals by X-ray diffraction, transmission electron microscopy, and photoluminescence. Methanol solutions of sodium telluride and cadmium iodide or mercury iodide, respectively, are reacted to precipitate the nanocrystalline metal tellurides, while the sodium iodide byproduct remains in solution. The existence of crystalline CdTe, HgTe, and ternary HgCdTe compounds has been demonstrated by powder X-ray diffraction after a post-synthesis sintering process. Precipitated crystallites from this synthesis were analyzed by transmission electron microscopy, which revealed that crystal diameters can vary from approximately 1 nm to 100 nm and that crystals are stoichiometric within the detection limit of the electron microprobe technique. Narrow size ranges can be selected and investigated due to an in-situ separation process in the electron microscope. Photoluminescence is found at energies above the bulk exciton energy for CdTe and is attributed to near-band-gap recombination which is blue-shifted due to quantum confinement. Both low defect luminescence and dark field imaging suggest a high crystalline quality. A comparative characterization by photoluminescence, transmission electron microscopy, and X-ray diffraction evaluates the effects of heat treatments during and after synthesis. 相似文献
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Laith Al-Mashat Richard B. Kaner Henry D. Tran Kourosh Kalantar-zadeh Wojtek Wlodarski 《Procedia Chemistry》2009,1(1):220-223
Here we report on a layered Surface Acoustic Wave (SAW) gas sensor featuring polyethylaniline nanofibers as the active layer. A rapidly-mixed reaction was employed to synthesize polyethylaniline nanofibers. The product was deposited on a microfabricated ZnO/36° YX LiTaO3 SAW transducer. Scanning Electron Microscopy (SEM) and Ultraviolet-visible spectroscopy (UV-vis) were utilized to characterize the nanomaterials. The novel sensor was tested towards different concentrations of hydrogen at room temperature. It was observed that the sensor maintained a stable baseline with good repeatability. Hence, the sensor is expected to be potentially attractive for industrial applications. 相似文献
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The behaviour of the spins of the photoexcited ions and its nearest antiferromagnetic neighbours in a two-sublattice antiferromagnet with isotropic Heisenberg interaction in the saturated paramagnetism region has been theoretically studied. It has been shown that the magnetic moments of the ions may be oriented in this region noncollinear to the magnetic field in the case whether the exchange integral in the excited state is larger than in the ground state or there is strong uniaxial single-ion “easy plane” anisotropy in the excited state. The exciton-magnon transitions intensity may, as a result, also alter in the saturated paramagnetism region. 相似文献