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201.
Using the effective operator formalism, the importance of ground-state correlations on photonuclear cross sections is studied. For purposes of orientation, a bound-state calculation is first performed to take into account the mixing of 2p-2h and 3p-3h configurations into the 1p-1h dipole states. Inclusion of these configurations is found to affect the energies of the 1p-1h states in opposite directions and the combined effect, including that on the transition strengths, is negligible. Most of the reduction in the absorption comes from the ground-state correlations of which the A-dependence is examined with a model interaction. We then proceed to calculate the excitation function for the reactions using effective dipole matrix elements obtained from the continuum wave functions of the coupled-channels calculation. Application to the case of 16O leads to a reduction of about 25 % in the cross sections. 相似文献
202.
203.
Feng Dang Kazumi Kato Hiroaki Imai Satoshi Wada Hajime Haneda Makoto Kuwabara 《Ultrasonics sonochemistry》2010,17(2):310-314
A new effect of ultrasonic irradiation on the formation of BaTiO3 particles was identified. Ultrasonication caused the aggregation of the original 5–10 nm BaTiO3 particles in the same crystal axis and accelerated the formation of BaTiO3 particles significantly. Furthermore, narrow size distribution was obtained for the aggregated particles under ultrasonic irradiation. 相似文献
204.
Petriellin A is a novel cyclic depsipeptide antifungal compound consisting of nine l-configured residues, one d-phenyllactic acid (PhLac) and three unknown chiral centres: two N-methyl-threonines (MeThr1 & MeThr2) and one N-methyl-isoleucine (MeIle). NMR experiments including 2D ROESY, NOESY along with structural and energy calculations predicted that the unknown chiral centres were all l-configured, which was later verified chemically. Simulated annealing, dynamics calculations and minimisation processes showed Petriellin A to have a folded "C-shaped" structure. 相似文献
205.
An efficient and regiospecific strategy to N7-substituted purines and its application to a library of trisubstituted purines 总被引:1,自引:0,他引:1
A regiospecific strategy for the preparation of N(7)-substituted purines in an efficient manner was devised. This approach to 6,7,8-trisubstituted purines relies on the cyclization reactions of suitably substituted pyrimidines (1) with either a carboxylic acid or an aldehyde. The method development for the five-step synthetic strategy outlined here was completed using 5-amino-4,6-dichloropyrimidine (4) as the starting material. The utility of this methodology was demonstrated through the preparation of a 40-membered library of 6,7,8-trisubstituted purines (3) in good yields and high purity. 相似文献
206.
Molecular dynamics simulations utilizing many-body potentials of H2O-CCl4 and H2O-vapor interfaces were carried out at different cesium and iodide ion concentrations to compare ion distribution, interfacial orientational and structural properties, and dynamics. It was found that cesium was repelled by both interfaces, and iodide was active at both interfaces, but to a much greater degree at the H2O-vapor interface. At the interface, the iodide dipole was strongly induced, orienting perpendicular to the interface for both systems, leading to stronger hydrogen bonds with water. For the H2O-CCl4 interface, though, there was a compensation between these strong hydrogen bonds and short to moderate ranged repulsion between iodide and CCl4. Hydrogen bond distance and angular distributions showed weaker water-water hydrogen bonds at both interfaces, but generally stronger water-iodide hydrogen bonds. Both translational and rotational dynamics of water were faster at the interface, while for CCl4, its translational dynamics was slower, but rotational dynamics faster at the interface. For many of the studied systems and species, translational diffusion was found to be anisotropic at both interfacial and bulk regions. 相似文献
207.
Höfft O Borodin A Kahnert U Kempter V Dang LX Jungwirth P 《The journal of physical chemistry. B》2006,110(24):11971-11976
Surface segregation of iodide, but not of fluoride or cesium ions, is observed by a combination of metastable impact electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy (UPS(HeI)) of amorphous solid water exposed to CsI or CsF vapor. The same surface ionic behavior is also derived from molecular dynamics (MD) simulations of the corresponding aqueous salt solutions. The MIES results show the propensity of iodide, but not fluoride, for the surface of the amorphous solid water film, providing thus strong evidence for the suggested presence of heavier halides (iodide, bromide, and to a lesser extent chloride) at the topmost layer of aqueous surfaces. In contrast, no appreciable surface segregation of ions is observed in methanol, neither in the experiment nor in the simulation. Furthermore, the present results indicate that, as far as the thermodynamic aspects of solvation of alkali halides are concerned, amorphous solid water and methanol surfaces behave similarly as surfaces of the corresponding liquids. 相似文献
208.
Y. Zhang X.Y. Dang J. Jin T. Yu B.Z. Li Q. He F.Y. Li Y. Sun 《Applied Surface Science》2010,256(22):6871-6875
In this combined film thickness, scanning electron microscopy (SEM), X-ray diffraction and optical properties study, we explore the effects of different stirring speeds on the growth and optical properties of ZnS film deposited by CBD method. From the disclosed changes of thickness of ZnS film, we conclude that film thickness is independent of the stirring speeds in the heterogeneous process (deposition time less than 40 min), but increases with the stirring speeds and/or deposition time increasing in the homogeneous process. Grazing incident X-ray diffraction (GIXRD) and the study of optical properties disclosed that the ZnS films grown with different stirring speeds show partially crystallized film and exhibit good transmittance (70-88% in the visible region), but the stirring speeds cannot give much effects on the structure and optical properties in the homogeneous process. 相似文献
209.
Numerical Algorithms - Recently, the condition numbers of the total least squares (TLS) problems having a unique solution have been studied at length in Zheng et al. (SIAM J. Matrix Anal. Appl. 38:... 相似文献
210.
In this paper, we establish a Lebeau–Robbiano spectral inequality for a degenerate one-dimensional elliptic operator, and we show how it can be used to study impulse control and finite-time stabilization for a degenerate parabolic equation. 相似文献