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121.
Beniamino Cappelletti Montano Antonio De Nicola 《Journal of Geometry and Physics》2007,57(12):2509-2520
We present a compared analysis of some properties of 3-Sasakian and 3-cosymplectic manifolds. We construct a canonical connection on an almost 3-contact metric manifold which generalises the Tanaka–Webster connection of a contact metric manifold and we use this connection to show that a 3-Sasakian manifold does not admit any Darboux-like coordinate system. Moreover, we prove that any 3-cosymplectic manifold is Ricci-flat and admits a Darboux coordinate system if and only if it is flat. 相似文献
122.
Giovanni Di Nicola Cristiano Di Nicola Matteo Moglie Marco Pacetti 《Journal of Thermal Analysis and Calorimetry》2012,108(2):621-625
This study presents a new formula for the surface tension prediction of alkenes. As a first step, an analysis of the available
data of the experimental surface tension data for alkenes was performed. The experimental data were collected, after a careful
literature survey, for the following pure fluids: propene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-tetradecene, and 1-pentadecene.
Then, the experimental data were regressed with the most reliable semi-empirical correlating methods based on the corresponding
state theory existing in the literature. As a final step, an analysis of the available data of the experimental surface tension
data for alkenes was performed starting from the two recently proposed equations for the prediction of the surface tension
of refrigerants based on the corresponding states principle. To minimize the deviation between the predicted data and the
experimental data and to find the optimal equation coefficients for experimental data regression, a (μ + λ)-evolution strategy
was adopted. The analysis showed that the equation that gave the best results for the prediction of the surface tension of
alkenes was the one with a very limited number of parameters. The finally proposed equation is very simple and gives a noticeable
improvement with respect to the existing equations. It is based on the corresponding state principle, containing the acentric
factor, the critical temperature, and pressure. 相似文献
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Shan She Weimin Xuan Nicola L. Bell Robert Pow Eduard Garrido Ribo Zoe Sinclair De-Liang Long Leroy Cronin 《Chemical science》2021,12(7):2427
The precise control over the formation of complex nanostructures, e.g. polyoxometalates (POMs), at the sub-nanoscale is challenging but critical if non-covalent architectures are to be designed. Combining biologically-evolved systems with inorganic nanostructures could lead to sequence-mediated assembly. Herein, we exploit oligopeptides as multidentate structure-directing ligands via metal-coordination and hydrogen bonded interactions to modulate the self-assembly of POM superstructures. Six oligopeptides (GH, AH, SH, G2H, G4H and G5H) are incorporated into the cavities of Molybdenum Blue (MB) POM nanowheels. It is found that the helicity of the nanowheel can be readily switched (Δ to Λ) by simply altering the N-terminal amino acid on the peptide chain rather than their overall stereochemistry. We also reveal a delicate balance between the Mo-coordination and the hydrogen bonds found within the internal cavity of the inorganic nanowheels which results in the sequence mediated formation of two unprecedented asymmetrical nanowheel frameworks: {Mo122Ce5} and {Mo126Ce4}.Peptide sequence can be used to control the self-assembly and structures of nanoscale molybdenum blue polyoxometalate (POM) wheel-shaped clusters. 相似文献
128.
Giona Kilcher Lei Wang Nicola Tirelli 《Journal of polymer science. Part A, Polymer chemistry》2008,46(6):2233-2249
Episulfide polymerization offers a number of features that are uncommon in other ring‐opening anionic mechanisms. Besides the negligible sensitivity to water, the most distinctive and novel one is likely to be the role of disulfides, which may act both at the levels of chain transfer and end‐capping, producing polymers that feature both terminal and internal disulfides. In this article, we have qualitatively studied the kinetics of chain transfer and measured the thiolate–disulfide exchange equilibrium constants. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2233–2249, 2008 相似文献
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We have simulated short channel carbon nanotube field-effect transistors with asymmetric source and drain contacts using a coupled mode space approach within the non-equilibrium Green's function framework. The simulated results show that the asymmetric conduction properties under positive and negative drain-to-source voltages are caused by the asymmetric Schottky barriers to carriers at the source and drain contacts. Under negative drain-to-source voltages, hole and electron conduction are dominated by thermionic emission and tunneling through the Schottky barrier, respectively, leading to the different subthreshold behaviors of the hole and electron conduction. With increasing channel length, short channel effects can be suppressed effectively and ON/OFF ratio can be improved. 相似文献