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821.
Rodríguez L Lima JC Pina F Cacciapaglia R Di Stefano S Ruggi A 《The journal of physical chemistry. A》2011,115(2):123-127
The photophysical properties of two atropisomeric naphthalenophanes (1 and 2) have been studied. Their structure only differs in the relative arrangement, syn (1) or anti (2), of the two aromatic units. The compounds emission is mainly excimeric and is strongly quenched in the presence of oxygen. Comparison of emission intensities obtained from steady state and from decay times provides clear evidence of the formation of ground state charge transfer complexes between oxygen and the naphthalenophanes 1 and 2. The calculated values for the association constants are on the order of 10(3) M(-1) (ethanol, room temperature) for both naphthalenophanes. 相似文献
822.
Di Fabio G D'Onofrio J Chiapparelli M Hoorelbeke B Montesarchio D Balzarini J De Napoli L 《Chemical communications (Cambridge, England)》2011,47(8):2363-2365
A series of d((5')TGGGAG(3')) sequences, 5'-conjugated with a variety of aromatic groups through phosphodiester linkages, were synthesized, showing CD spectra diagnostic of parallel-stranded, tetramolecular G-quadruplex structures. When tested for anti-HIV-1 and HIV-2 activity, potent inhibition of HIV-1 infection in CEM cell cultures was found, associated with high selectivity index values. Surface Plasmon Resonance assays revealed specific binding to HIV-1 gp120 and gp41. 相似文献
823.
Highly spectral dependent enhancement of upconversion emission with sputtered gold island films 总被引:1,自引:0,他引:1
We report a five-fold overall enhancement of upconversion emission in NaYF(4)?:?Yb/Er nanocrystals when coupled with gold island films. Spectroscopic studies show that the enhancement factors are highly dependent on the exact spectral positions and excitation power density, with a largest enhancement factor of more than 12 observed at selected spectral positions, which may be attributed to different upconversion processes involved. 相似文献
824.
Di Fiore A Maresca A Alterio V Supuran CT De Simone G 《Chemical communications (Cambridge, England)》2011,47(42):11636-11638
N-substituted benzenesulfonamides, incorporating the N-amino-, N-hydroxy- and N-methoxy-moieties at the sulfonamide zinc binding group, have been investigated as CAIs by means of inhibition and structural studies, unraveling interesting aspects related to their inhibition mechanism. 相似文献
825.
Givelet C Sun J Xu D Emge TJ Dhokte A Warmuth R 《Chemical communications (Cambridge, England)》2011,47(15):4511-4513
Several dynamic hexaimine cryptophanes, that are built up from two triformylcyclotribenzylene cavitands and three diamino linkers and spontaneously assemble in water in the presence of a suitable templating guest, are reported. X-ray structure, kinetics and thermodynamics of assembly and molecular recognition properties are discussed. 相似文献
826.
The lack of authentic standards limits the quantitative analysis of herbal drugs in biological samples. This present work demonstrated a practicable assay of herbs and their metabolites independent of the availability of authentic standards. A liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method for the qualitative and quantitative determination of the metabolites after oral administration of Evodiae fructus and Zuojinwan preparation in rat urine has been developed. Urine samples extracted with a protein precipitation procedure were separated on a C(18) column using a mixture of water (containing 0.1% formic acid) and acetonitrile (30:70, v/v) as mobile phase. The detection was performed by MS with electrospray ionization interface in positive selected reaction monitoring (SRM) mode. One urine sample after administration was selected as 'standard'. The method validation was carried out according to a conventional method that was calibrated by authentic standards. The fully validated method was applied to the pharmacokinetic study of the metabolites in rat urine. The results could provide evidence to explain the combination of Coptidis rhizoma and Evodiae fructus in terms of elimination. 相似文献
827.
828.
Becker SM Scheuermann M Sepelák V Eichhöfer A Chen D Mönig R Ulrich AS Hahn H Indris S 《Physical chemistry chemical physics : PCCP》2011,13(43):19624-19631
We studied the electrochemical insertion of Li in mechanochemically prepared Zn(2)SnO(4). The mechanism of the electrochemical reaction was investigated by using X-ray diffraction, nuclear magnetic resonance spectroscopy, and M?ssbauer spectroscopy. Changes in the morphology of the Zn(2)SnO(4) particles were studied by in situ scanning electron microscopy. The results were compared with mixtures of SnO(2) + ZnO and with Zn(2)SnO(4) prepared by conventional solid-state synthesis and showed that the mechanochemically prepared Zn(2)SnO(4) exhibits the best cyclic stability of these samples. 相似文献
829.
Yu-Shu Wu Bitao Lai Jennifer L. Miskimins Perapon Fakcharoenphol Yuan Di 《Transport in Porous Media》2011,88(2):205-223
Recent laboratory studies and analyses (Lai et al. Presented at the 2009 Rocky Mountain Petroleum Technology Conference, 14–16
April, Denver, CO, 2009) have shown that the Barree and Conway model is able to describe the entire range of relationships between flow rate and
potential gradient from low- to high-flow rates through porous media. A Buckley and Leverett type analytical solution is derived
for non-Darcy displacement of immiscible fluids in porous media, in which non-Darcy flow is described using the Barree and
Conway model. The comparison between Forchheimer and Barree and Conway non-Darcy models is discussed. We also present a general
mathematical and numerical model for incorporating the Barree and Conway model in a general reservoir simulator to simulate
multiphase non-Darcy flow in porous media. As an application example, we use the analytical solution to verify the numerical
solution for and to obtain some insight into one-dimensional non-Darcy displacement of two immiscible fluids with the Barree
and Conway model. The results show how non-Darcy displacement is controlled not only by relative permeability, but also by
non-Darcy coefficients, characteristic length, and injection rates. Overall, this study provides an analysis approach for
modeling multiphase non-Darcy flow in reservoirs according to the Barree and Conway model. 相似文献
830.
The aerodynamic unstable critical wind velocity for three-dimensional open cable-membrane structures is investigated. The
geometric nonlinearity is introduced into the dynamic equilibrium equations of structures. The disturbances on the structural
surface caused by the air flow are simulated by a vortex layer with infinite thickness in the structures. The unsteady Bernoulli
equation and the circulation theorem are applied in order to express the aerodynamic pressure as the function of the vortex
density. The vortex density is then obtained with the vortex lattice method considering the coupling boundary condition. From
the analytical expressions of the unstable critical wind velocities, numerical results and some useful conclusions are obtained.
It is found that the initial curvature of open cable-membrane structures has clear influence on the critical wind velocities
of the structures. 相似文献