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101.
In the study of wave radiation by oscillators moving in a fluid considerable interest attaches to the question of the effect which the radiation has on the nature of the motion of the source. The main task here is to clarify the conditions under which the component of the radiation reaction force connected with the radiation of anomalous Doppler harmonics prevails over the component of the reaction force in the region in which normal Doppler frequencies are radiated. The latter results in a buildup in the oscillations of an oscillator moving in a dispersing medium [1, 2]. In the present study the authors obtain in the dipole approximation expressions for the reaction force of radiation (wave resistance) of a mass source of the oscillator type [2] when it excites surface waves in an incompressible fluid of finite depth, and internal waves in a smoothly stratified fluid. The thresholds are also found for the occurrence of radiation instability with respect to gravitational waves, and is found that with respect to internal waves radiation instability is nonthreshold in character in the Boussinesq approximation.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 168–171, January–February, 1986.The authors are grateful to, E. V. Teodorovich for discussing the results and for his useful comments, and to A. I. Notik for performing numerical calculations. 相似文献
102.
Dubberley SR Ignatov SK Rees NH Razuvaev AG Mountford P Nikonov GI 《Journal of the American Chemical Society》2003,125(3):642-643
A series of hydridosilyl complexes of tantalum, Cp(ArN)Ta(PMe3)(H)(SiClnR3-n) (n = 0-3), was prepared and studied by 29Si NMR, X-ray diffraction, and DFT calculations. An unprecedented increase of the J(Si-H) coupling constant between the hydride and silyl ligands from 14 Hz for n = 0 to 50 Hz n = 3 was observed, which however, according to DFT calculations, does not correspond to stronger bonding interaction between silicon and hydride ligands, with the strongest interaction being for n = 1. 相似文献
103.
Jan ?echal Jind?ich Mach Stanislav Voborný Petr Kostelník Petr Bábor Ji?í Spousta Tomáš Šikola 《Surface science》2007,601(9):2047-2053
Results for deposition and thermal annealing of gallium on the Si(1 0 0)-(2 × 1) surface achieved by synchrotron radiation photoelectron spectroscopy (SR-PES) and low energy electron diffraction (LEED) are presented. In addition to deposition of Ga on a clean surface, the influence of water adsorption on the arrangement of gallium atoms was also studied. The results on Ga deposition at a higher temperature (490 °C) are consistent with a Ga ad-dimer model showing equivalent bond arrangement of all Ga atoms for coverages up to 0.5 ML. The deposition onto a surface with adsorbed water at room temperature led to a disordered gallium growth. In this case gallium atoms bind to silicon dimers already binding fragments of adsorbed water. A subsequent annealing of these layers leads to a surface structure similar to the Ga-(2 × 2), however, it is less ordered, probably due to the presence of silicon oxides formed from water fragments. 相似文献
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Stanislav Shkarin 《Journal of Mathematical Analysis and Applications》2010,367(2):713-856
We give a short proof of existence of disjoint hypercyclic tuples of operators of any given length on any separable infinite dimensional Fréchet space. Similar argument provides disjoint dual hypercyclic tuples of operators of any length on any infinite dimensional Banach space with separable dual. 相似文献
106.
Stanislav Standara Petr Kulhánek Radek Marek Michal Straka 《Journal of computational chemistry》2013,34(22):1890-1898
The isotropic 129Xe nuclear magnetic resonance (NMR) chemical shift (CS) in Xe@C60 dissolved in liquid benzene was calculated by piecewise approximation to faithfully simulate the experimental conditions and to evaluate the role of different physical factors influencing the 129Xe NMR CS. The 129Xe shielding constant was obtained by averaging the 129Xe nuclear magnetic shieldings calculated for snapshots obtained from the molecular dynamics trajectory of the Xe@C60 system embedded in a periodic box of benzene molecules. Relativistic corrections were added at the Breit–Pauli perturbation theory (BPPT) level, included the solvent, and were dynamically averaged. It is demonstrated that the contribution of internal dynamics of the Xe@C60 system represents about 8% of the total nonrelativistic NMR CS, whereas the effects of dynamical solvent add another 8%. The dynamically averaged relativistic effects contribute by 9% to the total calculated 129Xe NMR CS. The final theoretical value of 172.7 ppm corresponds well to the experimental 129Xe CS of 179.2 ppm and lies within the estimated errors of the model. The presented computational protocol serves as a prototype for calculations of 129Xe NMR parameters in different Xe atom guest–host systems. © 2013 Wiley Periodicals, Inc. 相似文献
107.
Prof. David M. Hodgson Dr. Stanislav Man 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(35):9731-9737
Starting from readily available (S)‐styrene oxide an asymmetric synthesis is described of the naturally occurring anti‐HIV spirolactone (?)‐hyperolactone C, which possesses adjacent fully substituted stereocenters. The key step involves a stereocontrolled RhII‐catalysed oxonium ylide formation–[2,3] sigmatropic rearrangement of an α‐diazo‐β‐ketoester bearing allylic ether functionality. From the resulting furanone, an acid‐catalysed lactonisation and dehydrogenation gives the natural product. 相似文献
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