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Abstract The formation of protein aggregates after pressure treatment was investigated by Fourier Transform Infrared Spectroscopy (FTIR). The results show that the pressure unfolded protein ends in a conformation, after the release of the pressure, which has an increased tendency to aggregate, even at temperatures lower than the denaturation temperature of the untreated protein. After pressure pretreatment the infrared spectrum shows the same intermolecular antiparallel β-structure features as observed after a temperature treatment that gives rise to protein gelation. on the other hand, this structure can be destabilized by applying moderate pressures, which are significantly lower than the corresponding denaturation pressure. 相似文献
94.
RAMAIYER VENKATRAMAN JÓZEF S. KWIATKOWSKI GRZEGORZ BAKALARSKI JERZY LESZCZYNSKI 《Molecular physics》2013,111(6):371-386
The molecular parameters (geometries, rotational constants, dipole moments) and vibrational IR spectra (harmonic wavenumbers, absolute intensities) of bromomethanes (CH3Br, CH2Br2, CHBr3, CBr4) are predicted by a density functional theory with the hybrid Becke3-LYP functional (DFT) and post-Hartree-Fock methods (MP2, CCSD(T)) using a 6-311G(2d,2p)-type basis set. The MP2 calculations are carried out with different numbers of frozen core orbitals to find how the number of bromine orbitals used for electron correlation influences the predicted molecular parameters and IR spectra of the species in question. Three options were used: (a) all electrons (full), with both the core and valence orbitals considered; (b) partial frozen core option (pfc), when the orbitals up to 3p of bromine were frozen; and (c) full frozen core option (ffc), when all core orbitals up to 3d were frozen. The CCSD(T) calculations for geometric parameters were carried out with both the pfc and ffc options, while for the prediction of the IR spectra only the ffc option was used. In addition, the calculations at the DFT and MP2(pfc) levels with inclusion of f functions on carbon and bromine atoms in bromomethanes (and also the CCSD(T)(pfc) calculations for CH3Br) were carried out to predict the changes in the geometric parameters and/or vibrational IR spectra of the molecules upon inclusion of f functions The geometries of bromomethanes (particularly the CBr bond lengths) are predicted better by the DFT and CCSD(T) calculations when the f functions (in particular on bromine atom) are included, while the MP2 calculations without f functions are good enough for correct predictions of the molecular geometries. The molecular parameters and vibrational IR spectra of bromomethanes in question and their deuterated species predicted by the DFT, MP2(ffc) and CCSD(T)(ffc) with the 6-311G(2d,2p) basis set agree well with the available experimental data. 相似文献
95.
Photocatalytic CO2 reduction to C1 fuels is considered to be an important way for alleviating increasingly serious energy crisis and environmental pollution. Due to the environment-friendly, simple preparation, easy formation of highly-stable metal-nitrogen(M-Nx) coordination bonds, and suitable band structure, polymeric carbon nitride-based single-atom catalysts(C3N4-based SACs) are expected to become a potential for CO2 reduction under visible-light irradiation. In this review, we summarize the recent advancement on C3N4-based SACs for photocatalytic CO2 reduction to C1 products, including the reaction mechanism for photocatalytic CO2 reduction to C1 products, the structure and synthesis methods of C3N4-based SACs and their applications toward photocatalytic CO2 reduction reaction(CO2RR) for C1 production. The current challenges and future opportunities of C3N4-based SACs for photoreduction of CO2 are also discussed. 相似文献
96.
Lennon Ó Náraigh 《The Journal of mathematical sociology》2020,44(1):42-64
ABSTRACTWe introduce a model based on Ordinary Differential Equations to describe how two mutually exclusive groups progress through a career hierarchy, whether in a single organization, or in an entire economic sector. The intended application is to gender imbalance at the top of the academic hierarchy in European Universities; however, the model is entirely generic and may be applied in other contexts also. Previous research on gender imbalance in European universities has focused on large-scale statistical studies. Our model represents a point of departure, as it is deterministic (i.e., based on Ordinary Differential Equations). The model requires a precise definition of the progression rates for the different groups through the hierarchy; these are key parameters governing the dynamics of career progression. The progression rate for each group can be decomposed into a product: the proportion of group members at a low level in the hierarchy who compete for promotion to the next level a given year, multiplied by the in-competition success rate for the group in question. Either of these two parameters can differ across the groups under consideration; this introduces a group asymmetry into the organization’s composition. We introduce a glass-ceiling index to summarize this asymmetry succinctly. Using case studies from the literature, we demonstrate how the mathematical framework can pinpoint the proximate cause of the glass ceiling in European academia. 相似文献
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Summary A volume-preserving symplectic map is proposed to describe the magnetic field lines when the Taylor equilibriumis perturbed
in a generic way. The standard scenario is observed by varying the perturbation strength, but the statistical properties in
the chaotic regions are not simple due to the presence of boundaries and remnants of invariant structures. Simpler models
of volume-preserving maps are proposed. The slowly modulated standard map captures the basic topological and statistical features.
The diffusion is analytically described for large perturbations (above the break-up of the last KAM torus) in terms of correlation
functions and for small perturbations using the adiabatic theory, provided that the modulation is sufficiently slow. 相似文献
100.
Dr. Óscar Gutiérrez‐Sanz Dr. Paolo Natale Dr. Ileana Márquez Dr. Marta C. Marques Sonia Zacarias Dr. Marcos Pita Dr. Inês A. C. Pereira Dr. Iván López‐Montero Dr. Antonio L. De Lacey Dr. Marisela Vélez 《Angewandte Chemie (International ed. in English)》2016,55(21):6216-6220
ATP, the molecule used by living organisms to supply energy to many different metabolic processes, is synthesized mostly by the ATPase synthase using a proton or sodium gradient generated across a lipid membrane. We present evidence that a modified electrode surface integrating a NiFeSe hydrogenase and a F1F0‐ATPase in a lipid membrane can couple the electrochemical oxidation of H2 to the synthesis of ATP. This electrode‐assisted conversion of H2 gas into ATP could serve to generate this biochemical fuel locally when required in biomedical devices or enzymatic synthesis of valuable products. 相似文献