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61.
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63.
Günter Ewald 《Mathematische Zeitschrift》1961,75(1):395-418
Ohne ZusammenfassungHabilitationsschrift Mainz 1960, I. Teil (vgl. folgende Arbeit). 相似文献
64.
E. Blasius und W. Klein 《Fresenius' Journal of Analytical Chemistry》1985,322(3):348-349
Zusammenfassung Ein einfaches dünnschicht-chromatographisches Verfahren zur Erkennung und Charakterisierung von Kronenethern wird vorgestellt. Es beruht auf der Komplexbildung der Kronenether mit Alkalisalzen. Als Laufmittel dient Chloroform/Aceton. Der Nachweis erfolgt durch Fluorescenzlöschung und durch Ioddampf.
Herrn Prof. Dr. H. Monien zum 60. Geburtstag gewidmet 相似文献
Detection of crown ethers by two-dimensional thin-layer chromatography
Summary A simple thin-layer chromatography method for the detection and characterisation of crown ethers is presented. It is based on the formation of crown ether complexes with akali salts. Chloroform/acetone is employed as solvent. Fluorescence quenching or iodine vapour is used for the detection.
Herrn Prof. Dr. H. Monien zum 60. Geburtstag gewidmet 相似文献
65.
Vanhaelewyn GC Pauwels E Callens FJ Waroquier M Sagstuen E Matthys PF 《The journal of physical chemistry. A》2006,110(6):2147-2156
Beta-D-fructose single crystals were in situ X-irradiated at 80 K and measured using electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR) and ENDOR-induced EPR (EIE) techniques at Q-band (34 GHz) microwave frequencies. The measurements revealed the presence of at least four carbon-centered radicals stable at 80 K. By means of ENDOR angular variations in the three principal crystallographic planes, six proton hyperfine coupling tensors could be determined and were assigned to four different radicals by the aid of EIE. Two of the radicals exhibit only beta-proton hyperfine couplings and reveal almost identical EIE spectra. For the other two radicals, the major hyperfine splitting originates from a single alpha-proton hyperfine coupling and their EIE spectra were also quite similar. The similarity of the EIE spectra and hyperfine tensors led to the assumption that there are only two essentially different radical structures. The radical exhibiting only beta-proton hyperfine couplings was assigned to a C3 centered radical arising from H3 abstraction and the other radical suggested to be an open-ring species with a disrupted C2-C3 bond and a double C2-O2 bond. A possible formation mechanism for the latter open-ring radical is presented. By means of cluster density functional theory (DFT) calculations, the structures of the two radicals were determined and a fairly good agreement between the calculated and experimental hyperfine tensors was found. 相似文献
66.
Iacono ST Budy SM Ewald D Smith DW 《Chemical communications (Cambridge, England)》2006,(46):4844-4846
New fluorovinylene aromatic ether polymers, possessing dual reactivity, have been successfully prepared via the step-growth polymerization of commercial bis(trifluorovinyl) aromatic ethers and bisphenols. 相似文献
67.
68.
The influence of substitutionally dissolved Al in ferritic Fe–4.75 at.% Al alloy on the nucleation and growth of γ′ iron nitride (Fe4N1? x ) was investigated upon nitriding in NH3/H2 gas mixtures. The nitrided specimens were characterised employing optical microscopy, scanning electron microscopy, transmission electron microscopy, electron probe microanalysis and X-ray diffraction. As compared to the nitriding of pure ferrite (α-Fe), where a layer of γ′ develops at the surface, upon nitriding ferritic Fe–4.75 at.% Al an unusual morphology of γ′ plates develops at the surface, which plates deeply penetrate the substrate. In the diffusion zone, nano-sized precipitates of γ′ and of metastable, cubic (NaCl-type) AlN occur, having, with the ferrite matrix, a Nishiyama–Wassermann orientation relationship and a Bain orientation relationship, respectively. The γ′ plates contain a high density of stacking faults and fine ε iron nitride (Fe2N1? z ) precipitates, although the formation of ε iron nitride is not expected for the employed nitriding parameters. On the basis of dedicated nitriding experiments it is shown that the unusual microstructural development is a consequence of the negligible solubility of Al in γ′ and the obstructed precipitation of the thermodynamically stable, hexagonal (wurtzite-type) AlN in ferrite. 相似文献
69.
Prasad A Dana SK Karnatak R Kurths J Blasius B Ramaswamy R 《Chaos (Woodbury, N.Y.)》2008,18(2):023111
Recently, the phase-flip bifurcation has been described as a fundamental transition in time-delay coupled, phase-synchronized nonlinear dynamical systems. The bifurcation is characterized by a change of the synchronized dynamics from being in-phase to antiphase, or vice versa; the phase-difference between the oscillators undergoes a jump of pi as a function of the coupling strength or the time delay. This phase-flip is accompanied by discontinuous changes in the frequency of the synchronized oscillators, and in the largest negative Lyapunov exponent or its derivative. Here we illustrate the phenomenology of the bifurcation for several classes of nonlinear oscillators, in the regimes of both periodic and chaotic dynamics. We present extensive numerical simulations and compute the oscillation frequencies and the Lyapunov spectra as a function of the coupling strength. In particular, our simulations provide clear evidence of the phase-flip bifurcation in excitable laser and Fitzhugh-Nagumo neuronal models, and in diffusively coupled predator-prey models with either limit cycle or chaotic dynamics. Our analysis demonstrates marked jumps of the time-delayed and instantaneous fluxes between the two interacting oscillators across the bifurcation; this has strong implications for the performance of the system as well as for practical applications. We further construct an electronic circuit consisting of two coupled Chua oscillators and provide the first formal experimental demonstration of the bifurcation. In totality, our study demonstrates that the phase-flip phenomenon is of broad relevance and importance for a wide range of physical and natural systems. 相似文献
70.
Jan Blasius Johannes Ingenmey Eva Perlt Michael vonDomaros Oldamur Hollczki Barbara Kirchner 《Angewandte Chemie (International ed. in English)》2019,58(10):3212-3216
We demonstrate for formic and acetic acid dissolved in water as examples that the binary quantum cluster equilibrium (bQCE) approach can predict acid strengths over the whole range of acid concentrations. The acid strength increases in a complex rather than a simple way with increasing mole fraction of the acid from 0 to 0.7, reflecting the complex interplay between the dissociated ions or conjugate bases available as compared to the acid and water molecules. Furthermore, our calculated ion concentrations meet the experimental maximum of the conductivity with excellent agreement for acetic acid and satisfactorily for the formic acid/water mixture. As only a limited number of simple quantum‐chemical calculations are required for the prediction, bQCE is clearly a valuable approach to access these quantities also in non‐aqueous solutions. It is a highly valuable asset for predicting ionization processes in highly concentrated solutions, which are relevant for biological and chemical systems, as well as technological processes. 相似文献