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51.
Umebayashi Y Mroz B Asada M Fujii K Matsumoto K Mune Y Probst M Ishiguro S 《The journal of physical chemistry. A》2005,109(21):4862-4868
Solvation structure of the zinc(II) ion in N,N-dimethylpropionamide (DMPA) was studied by Raman spectroscopy at varying temperature and by quantum mechanical calculations. No significant ion-pair formation was found for the Zn(ClO4)2 solution in the molality range m(Zn) < 1.5 mol kg(-1), and the solvation number of the zinc(II) ion was determined to be 4, indicating that 6-coordination of DMPA is sterically hindered. Interestingly, DMPA molecules are under equilibrium between planar cis and nonplanar staggered conformers, and the latter is more preferred in the coordination sphere, while the reverse is the case in the bulk. The DeltaG degrees , DeltaH degrees , and TDeltaS degrees values of conformational change from planar cis to nonplanar staggered in the coordination sphere were obtained to be -0.9, -8.5, and -7.5 kJ mol(-1), respectively. Density functional theory (DFT) calculations show that the planar cis conformer is more favorable than the nonplanar staggered one in the 1:2 cluster, as is the case for a single DMPA molecule and H(DMPA)+, indicating that there hardly occurs solvent-solvent interaction through the metal ion in the Zn2+-DMPA 1:2 cluster. On the other hand, the SCF energy of [Zn(planar cis-DMPA)4-n(nonplanar staggered DMPA)n]2+ (n = 0-4) decreases with increasing n, implying that the nonplanar staggered conformer is preferred in the solvate ion. It is thus concluded that solvent-solvent interaction through space, or solvation steric effect, plays a crucial role in the conformational equilibrium in the coordination sphere of the four-solvate metal ion. 相似文献
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53.
The retarded transverse current-current response functions of an ideal two-dimensional electron gas at zero temperature are calculated. Introducing a new approximation scheme which allows one to take account of the reaction of the electromagnetic field to the induced current, i.e. the influence of the electronic induced current on the dynamics of the electromagnetic field, within the framework of the conventional linear response theory in a self-consistent way, a possible form of the dispersion relation for the transverse plasmon in the system is obtained. It is found that the energy of the transverse plasmon has a gap at k=0, if the thickness of the system is finite, in contrast to the longitudinal case. 相似文献
54.
Sylwia Mozia Ewa Borowiak-Paleń Barbara Grzmil Masahiro Toyoda Antoni W. Morawski 《Journal of Physics and Chemistry of Solids》2010,71(3):263-26
Titanate nanotubes (TNTs) were prepared from TiO2 P25 via hydrothermal method. The reaction temperature was 130 or 140 °C and the reaction time was 24 or 48 h. The samples were characterized by transmission electron microscopy, X-ray diffraction, thermogravimetry and N2 adsorption as well as Raman, FTIR-DRS and UV-vis/DR spectroscopy. The obtained samples exhibited similar properties, regardless of the preparation temperature and time. The most notable difference between properties of TNTs prepared under different conditions was observed in case of BET surface area, which was increasing from 386 to 478 m2/g along with increasing the reaction time and temperature. Based on TEM, XRD and TG measurements we have suggested that the structure of TNTs was H2Ti2O4(OH)2. The TEM and Raman spectroscopy measurements showed that the obtained products contained also low amount of anatase phase. The TNTs exhibited no photoactivity towards degradation of model azo dye Acid Red 18. However, TNTs were successfully applied for photocatalytic generation of CH4 and H2 in a solution of acetic acid. The amount of methane produced with application of TNTs synthesized at 140 °C was about 2.5 times higher than that generated with use of TiO2 P25. To the best of our knowledge this is a first report on the photocatalytic generation of hydrocarbons using TNTs in the current state of the art. 相似文献
55.
Tsuyoshi Kijima Hiroyuki Sushida Yuhsuke Hara Ryuhsuke Shiraishi Mitsunori Yada Masato Machida 《Molecular Crystals and Liquid Crystals》2013,570(2):193-198
Abstract A series of new layered cuprates with the composition MI2+xBi2Sr2CaCu2O8+y (x=0.6–0.9; M=Mn, Fe, Co, Cu, Zn) have been synthesized by the reaction of Bi2Sr2CaCu2O8 with each transition metal under an atmosphere of iodine at 400°C. The new cuprates, lamellar in shape, are crystallized in a tetragonal unit cell with the lattice parameters of a = 5.393–5.402 Å and c = 43.32–43.96 Å. A structure model for these cuprates are proposed in which the monoiodide anions are intercalated in the Bi2O2 layer to form a bilayer accompanying 3d metal cations. All of the intercalated cuprates are non-superconducting to be as high as 0.74–2.52 MΩ · cm in resistivity at room temperature. 相似文献
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57.
Shuntaro Chiba Yasushi Okuno Teruki Honma Mitsunori Ikeguchi 《Journal of computational chemistry》2019,40(29):2577-2585
We propose a novel force-field-parametrization procedure that fits the parameters of potential functions in a manner that the pair distribution function (DF) of molecules derived from candidate parameters can reproduce the given target DF. Conventionally, approaches to minimize the difference between the candidate and target DFs employ radial DFs (RDF). RDF itself has been reported to be insufficient for uniquely identifying the parameters of a molecule. To overcome the weakness, we introduce energy DF (EDF) as a target DF, which describes the distribution of the pairwise energy of molecules. We found that the EDF responds more sensitively to a small perturbation in the pairwise potential parameters and provides better fitting accuracy compared to that of RDF. These findings provide valuable insights into a wide range of coarse graining methods, which determine parameters using information obtained from a higher-level calculation than that of the developed force field. © 2019 The Authors. Journal of Computational Chemistry published by Wiley Periodicals, Inc. 相似文献
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59.
p-GaAs/n-GaAs thin film concentrator solar cells were fabricated by Peeled Film Technology. This is the first paper that reports the concentration characteristics of thin film solar cells. The energy conversion efficiency of thin film solar cells at a concentration ratio of 109 is 9.4% and the output power density is 0.82 W/cm2 · n-Ga1?xAlxAs/p-GaAs heterojunction thin film solar cells were also fabricated. The initial heterojunction thin film solar cell with a Al mole fraction of 0.5 showed an efficiency of up to 13.5% (AM 1.5). It is proposed that Multi-Peeled Film Technology will give numerous GaAs thin films by selective etching of (GaAl)As/GaAs multi-layered structures. 相似文献
60.
H. Matsumura K. Masumoto A. Toyoda N. Kinoshita 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(3):733-738
Highly selective and sensitive γ-ray detection was performed by coincidence and anticoincidence event analysis after list-mode
data acquisition using an HPGe spectrometer equipped with NaI(Tl) and plastic scintillation detectors. In order to obtain
the most suitable detection of specific nuclides, coincidence or anticoincidence spectra could be freely constructed by extracting
events with particular time and energy correlations. Although the detector arrangement of this system was the same as that
of a typical Compton suppression spectrometer, background counts were drastically reduced and γ-rays of particular nuclides
could be selectively detected by using γ-γ, γ-X, γ-X-X, and γ-β+ coincidences. 相似文献