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971.
The host compound 2,2′-bis(hydroxydiphenylmethyl)-1,1′-binaphthyl displays a remarkably constant conformation, which is governed chiefly by an intramolecular O–H…O hydrogen bond. Its inclusion compound with chloroform has been characterised and the dehydration product affords the corresponding oxepine with significantly different conformation. 相似文献
972.
Giancarlo De Santis Luigi Fabbrizzi Maurizio Licchelli Carlo Mangano Piersandro Pallavicini Antonio Poggi 《Supramolecular chemistry》2013,25(3-4):239-250
Abstract The synthetic approach to supramolecular systems containing one or more metallocyclam subunits is reviewed. In particular, the template synthesis of azacyclam complexes has been used to design supramolecular coordination compounds displaying multi-electron redox activity. Moreover, it is shown that whenever the supramolecular design requires a component able to provide a fast and reversible redox change, a metallocyclam subunit should be used. Finally, the design of supramolecular systems in which a light-emitting fragment (anthracene) has been linked to a metallocyclam subunit has been considered. In particular, anthracene fluorescence can be switched on/off through the CuI/CuII redox couple inside a tetra-thia-macrocyclic environment, via an electron transfer mechanism. 相似文献
973.
Unsymmetrical Binding Modes of the HOPNO Inhibitor of Tyrosinase: From Model Complexes to the Enzyme
Dr. Constance Bochot Dr. Elisabeth Favre Dr. Carole Dubois Dr. Benoit Baptiste Prof. Luigi Bubacco Prof. Pierre‐Alain Carrupt Gisèle Gellon Dr. Renaud Hardré Prof. Dominique Luneau Dr. Yohann Moreau Dr. Alessandra Nurisso Dr. Marius Réglier Prof. Guy Serratrice Dr. Catherine Belle Dr. Hélène Jamet 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3655-3664
The deciphering of the binding mode of tyrosinase (Ty) inhibitors is essential to understand how to regulate the tyrosinase activity. In this paper, by combining experimental and theoretical methods, we studied an unsymmetrical tyrosinase functional model and its interaction with 2‐hydroxypyridine‐N‐oxide (HOPNO), a new and efficient competitive inhibitor for bacterial Ty. The tyrosinase model was a dinuclear copper complex bridged by a chelated ring with two different complexing arms (namely (bis(2‐ethylpyridyl)amino)methyl and (bis(2‐methylpyridyl)amino)methyl). The geometrical asymmetry of the complex induces an unsymmetrical binding of HOPNO. Comparisons have been made with the binding modes obtained on similar symmetrical complexes. Finally, by using quantum mechanics/molecular mechanics (QM/MM) calculations, we studied the binding mode in tyrosinase from a bacterial source. A new unsymmetrical binding mode was obtained, which was linked to the second coordination sphere of the enzyme. 相似文献
974.
Stefano Cianchetta Barbara Di Maggio Pier Luigi Burzi Stefania Galletti 《Applied biochemistry and biotechnology》2014,173(2):609-623
Biological pretreatment of lignocellulosic biomass by fungi can represent a low-cost and eco-friendly alternative to physicochemical methods to facilitate enzymatic hydrolysis. However, fungal metabolism can cause cellulose loss and it is therefore necessary to use the appropriate fungal strain-biomass type combination. In this work, the effects of biological pretreatments carried out by five different fungi on enzymatic hydrolysis of wheat straw were investigated. The best results were obtained with a Ceriporiopsis subvermispora strain, which minimized weight and cellulose losses and gave the highest net sugar yield (calculated with respect to the holocellulose content of the untreated straw), up to 44 % after a 10-week pretreatment, more than doubling the yields obtained with the other isolates. Moreover, prolonging the pretreatment from 4 up to 10 weeks produced a 2-fold increase, up to 60 %, in digestibility (sugar yield, calculated considering the holocellulose content of the pretreated material). The hemicellulose content of the pretreated material resulted inversely correlated with digestibility, and it could thus be utilized as an index of the pretreatment efficacy. Finally, a correlation was also found between digestibility and the difference between the absorbance values at 290 and 320 nm of pretreated wheat straw extracts. 相似文献
975.
Antonella Accardo Paola Ringhieri Noemi Szekely Vitaly Pipich Alessandra Luchini Luigi Paduano Diego Tesauro 《Colloid and polymer science》2014,292(5):1121-1127
Nanostructures are gaining interest in drug release applications. Amphiphilic molecules can give, in water solution, a variety of nanostructures as well as thermodynamically stable mesophases three-dimensional inverse cubic structures. These mesophases are attractive candidates for biomedical applications containing extensive water channel networks and could act as very efficient delivery systems of drugs or contrast agents. In order to discover, optimize, and develop these systems, we have performed a deep physicochemical characterization by dynamic light scattering and small-angle neutron scattering of nanoparticles of monoolein (MO) and Pluronic PF127, containing different amounts (1, 5, 10, and 20 %) of the synthetic amphiphilic gadolinium complex (C18)2DTPA(Gd). Nanoparticle size is found in the 70–400 nm range for all investigated systems; the morphology of the aggregates is driven by the main constituents MO/PF127 and is a mixture of multilayer vesicles and bicontinuous aggregates. Nanostructures are also able to encapsulate doxorubicin (drug-loading content between 70 and 90 % for the different systems) acting as a potential theranostic for simultaneous cancer therapy and MRI visualization. 相似文献
976.
In this paper the authors present a derivation of a back-scatter rotational Large Eddy Simulation model,which is the extension of the Baldwin&Lomax model to nonequilibrium problems.The model is particularly designed to mathematically describe a fluid filling a domain with solid walls and consequently the differential operators appearing in the smoothing terms are degenerate at the boundary.After the derivation of the model,the authors prove some of the mathematical properties coming from the weighted energy estimates,which allow to prove existence and uniqueness of a class of regular weak solutions. 相似文献
977.
M. Wesołowski W. Strupiński M. Motyka G. Sęk E. Dumiszewska P. Caban A. Jasik A. Wójcik K. Pierściński D. Pierścińska 《Opto-Electronics Review》2011,19(2):140-144
The antimonide laser heterostructures growth technology using MBE epitaxy is currently well-developed, while MOVPE method
is still being improved. It is known that the principal problem for MOVPE is the oxygen and carbon contamination of aluminium
containing waveguides and claddings. The solution would be to apply a proper aluminium precursor. In this study we present
the results of metal-organic epitaxy of In- and Al-containing layers and quantum well structures composing antimonide lasers
devices. Special emphasis was put on the aluminium precursor and its relation to AlGaSb and AlGaAsSb materials properties.
The crystalline quality of the layers grown with two different Al precursors was compared, very good structural quality films
were obtained. The results suggested a substantial influence of precursors pre-reactions on the epitaxial process. The oxygen
contamination was measured by SIMS, which confirmed its dependence on the precursor choice. We also optimised the GaSb substrate
thermal treatment to deposit high quality GaSb homoepitaxial layers. Quaternary InGaAsSb layers were obtained even within
the predicted miscibility gap, when arsenic content reached high above 10% values. InGa(As)Sb/AlGa(As)Sb quantum wells were
grown and their optical properties were characterised by photoluminescence and photoreflectance spectroscopy. Type-I quantum
wells showed a fundamental optical transition in the 1.9–2.1 μm range at room temperature. The epitaxial technology of the
structures was subjected to an optimisation procedure. The investigated layers and heterostructures can be considered for
application in laser devices. 相似文献
978.
979.
Holzmann M Bernu B Pierleoni C McMinis J Ceperley DM Olevano V Delle Site L 《Physical review letters》2011,107(11):110402
We calculate the off-diagonal density matrix of the homogeneous electron gas at zero temperature using unbiased reptation Monte Carlo calculations for various densities and extrapolate the momentum distribution and the kinetic and potential energies to the thermodynamic limit. Our results on the renormalization factor allow us to validate approximate G0W0 calculations concerning quasiparticle properties over a broad density region (1≤r(s)?10) and show that, near the Fermi surface, vertex corrections and self-consistency aspects almost cancel each other out. 相似文献
980.
Luigi Capozza 《Hyperfine Interactions》2011,200(1-3):27-30
Backward angle measurements with the A4 setup at Mainz have been performed and are ongoing. Differently as with the forward measurements severe background issues had to be faced, due to ??-events generated by the ?? 0 decay. Hardware upgrades as well as data analysis improvements were needed. For the latest a detailed study of the background by means of Monte Carlo simulations has been undertaken. Its major features together with the basic ansaetze of the ??-background handling are presented in this contribution. 相似文献