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991.
The identification of (3, 4-dihydro-2H-pyran-5-yl)-oxo-acetic acid methyl ester has been realized by combination of two dimensional HETCOR and HMBC techniques. 13C and 1H chemical shifts asignements are described. 相似文献
992.
Patricia Sakon Williams Frederick J. Troendle Kunisi S. Venkatasubban Robert Rothchild 《光谱学快报》2013,46(7):1229-1251
The 200 MHz 1H NMR spectra of the analgesic, famprofazone, 1, have been studied in CDCl3 solution at ambient temperatures with the achiral lanthanide shift reagent (LSR) tris (6, 6, 7, 7, 8, 8, 8-heptaf luoro-2, 2-dimethyl-3, 5-octanedionato) europium (III), Eu(FOD)3, 2, for spectral simplification, and with the chiral LSR, tris [3-(heptafluoropropylhydroxymethylene) - (+) camphorato] europium (III), Eu (HFC)3, 3. Lanthanide induced shift (LIS) magnitudes suggested predominant LSR binding at the carbonyl oxygen. Substantial enantiomeric shift differences were observed for several nuclei of 1 with added 3 which could permit direct determinations of enantiomeric excess. 相似文献
993.
Sahar Al Akoum-Ebrik Mohamed Ansar Rahima Mouhoub Claude Vaccher Marie-Pierre Vaccher Nathalie Flouquet 《光谱学快报》2013,46(5):925-944
The enantiomeric composition and absolute configuration of 4-Amino-3-(benzo[b]furan-2-yl)-Butanoic Acids and of 4-Amino-3-(thien-2-yl)-Butanoic Acids 1 may be accurately determined by 1H and 13C nuclear magnetic resonance analysis of the corresponding derivatives 3 prepared by reaction with chiral reagents. Correlation with HPLC is signaled. 相似文献
994.
Abstract The infrared spectrum of 3-bromo-1,3-dinitroazetidine was interpreted with the aid of normal coordinate calculations. A seventy-two parameter modified valence field was used in those calculations, and the observed wave numbers were fit with an average error of 2.5 cm?1. An assignment of the bands in terms of symmetry coordinates is given. Many of the force constants were transferred to 1-acetyl-3,3-dinitroazetidine to aid in normal coordinate calculations for that compound. 相似文献
995.
The use of neutral surfactant polyoxyethylene (9) dodecyl ether (AEO9) and polyoxyethylene (10) hexylphenol ether (TX-10) as an additive to enhance the chemiluminescence of peroxyoxalate reaction using bis(2-butoxycarbonyl-3,4,6-trichlorophenyl) oxalate (BBTPO) and hydrogen peroxide as the energy source in organic media with 9,10-diphenylanthracene as a fluorophore had been investigated. The oxidation of BBTPO in both AEO9 and TX-10 inverted micelles produced significantly improved intensity and efficiency of the chemiluminescence relative to that in normal organic media. It was found that in AEO9 and TX-10 inverted micellar media the enhancement of chemiluminescence was mainly due to the improvement of the reaction excitation efficiencies, but only slightly contributed by the increase of the fluorescence efficiency. 相似文献
996.
A. A. El-bindary 《光谱学快报》2013,46(3):383-395
The dissociation constant of l-acetyl-2-(coumariniminecarboxamide-3-yl) hydrazine (ACCH) has been determined potentiometrically in 0.1 M KC1 and 40% (v/v) ethanol-water mixture. The stepwise stability constants of the formed complexes of Mn2+, Co2+, Ni2+, Cu2+, Zn2+ and UO2 2+ with ACCH have been determined. The stability constants were found to UO2 2+ > Cu2+> Zn2+ > Ni2+ < CO2+ < Mn2+. The effect of temperature on the dissociation of ACCH and the stability of its formed complexes were studied. The corresponding thermodynamic functions were also determined and discussed. The spectral data of ACCH were investigated in pure organic solvents as well as in Britton Robinson buffer solutions of varying pH values. The dissociation constant pKH 1 of ACCH and the overall stability constants logβ of their complexes were determined in 20% (v/v) ethanol-water mixture at 298K. 相似文献
997.
B. Rellinghaus D. Lindackers M. Köckerling P. Roth E. F. Wassermann 《Phase Transitions》2013,86(4-5):347-354
Tin oxide nanoparticles with sizes in the range 5-30 nm are generated within a low pressure flame reactor setup in the gas phase. We study the effect of preparation parameters such as precursor concentration, flame to substrate distance, and post-deposition annealing procedures on the morphology and crystal structure of the particles utilizing transmission electron microscopy and X-ray diffraction in order to characterize the particle formation process. The structural investigations indicate that monoxide particles form from SnO monomers within the flame. These primary particles need to be further oxidized and thermally annealed to transform into single phase rutile type SnO 2 nanoparticles. 相似文献
998.
The effect of hydrostatic pressure on the dielectric response of Pb(Mg1/3Nb2/3)O3 relaxor single crystal was studied. An increase in the dispersion of the dielectric anomaly, characteristic of the relaxors, was observed: pressure-induced downward shift of the temperature T m of permittivity maximum at 1 kHz amounts to dT m /dp = ? 3.8 K/100 MPa, whereas that measured at 1 MHz equals ? 3.3 K/100 MPa. Analysis of the dielectric response of the highly polarizable Pb(Mg1/3Nb2/3)O3 shows that hydrostatic pressure results in a decrease of the correlation radius r c of polar nanodomains, as well as their activation energy. 相似文献
999.
The transition between insulator and metal conductor states, induced by oxygen non-stoichiometry, was studied for NaNbO3 : Mn crystals. Conditions for an optimal reduction were determined on the basis of TGA tests. The temperature dependencies of the resistance measured on the macroscale showed that the transition from thermally activated to metallic features depends on the level of oxygen deficiency. The LC-AFM measurement exhibited non-homogeneous electric resistance on the nanoscale. We ascribed the local insulator–metal transition to changeover in the electronic state of the Nb ions occurring in filaments. The Mn dopant stabilised the induced oxygen non-stoichiometry and the metallic conduction down to room temperature. 相似文献
1000.
We present the results for thermal expansion coefficients of Sn2P2S6 crystals determined both in the crystallographic system and the system based on eigenvectors of thermal expansion tensor. Peculiarities of temperature evolution of the indicative surface of thermal expansion tensor for Sn2P2S6 are discussed, including the region of their ferroelectric phase transition. 相似文献