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61.
We study the class of functions computed by constant-depth polynomial-size arithmetic circuits of unbounded fan-in addition and multiplication gates. No model-theoretic characterization for arithmetic circuit classes is known so far. Inspired by Immerman's characterization of the Boolean circuit class , we remedy this situation and develop such a characterization of . Our characterization can be interpreted as follows: Functions in are exactly those functions counting winning strategies in first-order model checking games. A consequence of our results is a new model-theoretic characterization of , the class of languages accepted by constant-depth polynomial-size majority circuits. 相似文献
62.
63.
Skwara B Góra RW Zaleśny R Lipkowski P Bartkowiak W Reis H Papadopoulos MG Luis JM Kirtman B 《The journal of physical chemistry. A》2011,115(37):10370-10381
The potential energy surface (PES) of Ti@C(28) has been revisited, and the stationary points have been carefully characterized. In particular, the C(2v) symmetry structure considered previously turns out to be a transition state lying 2.3 kcal/mol above the ground state of C(3v) symmetry at the MP2/6-31G(d) level. A large binding energy of 181.3 kcal/mol is found at the ROMP2/6-31G(d) level. Topological analysis of the generalized Ti@C(28) density reveals four bond paths between Ti and carbon atoms of the host. The character of all four contacts corresponds to a partially covalent closed shell interaction. UV-vis, IR, and Raman spectra are calculated and compared with C(28)H(4). The dipole moment and the static electronic and double harmonic vibrational (hyper)polarizabilities have been obtained. Distortion of the fullerene cage due to encapsulation leads to nonzero diagonal components of the electronic first hyperpolarizability β, and to an increase in the diagonal components of the electronic polarizability α and second hyperpolarizability γ. However, introduction of the Ti atom causes a comparable or larger reduction in most cases due to localized bonding interactions. At the double harmonic level, the average vibrational β is much larger than its electronic counterpart, but the opposite is true for α and for the contribution to γ that has been calculated. There is also a very large anharmonic (nuclear relaxation) contribution to β which results from a shallow PES with four minima separated by very low barriers. Thus, the vibrational γ (and α) may, likewise, become much larger when anharmonicity is taken into account. 相似文献
64.
Heribert Offermanns 《Nachrichten aus der Chemie》2013,61(2):123-126
65.
Stewart F. Parker Keith Refson Susan M. Tavender Peter Albers Bernd Hannebauer Matthias Janik Arndt Müller Jürgen Martens Martin Watzke Kenneth Shankland Charlotte Leech Heribert Offermanns 《Journal of Raman spectroscopy : JRS》2009,40(6):703-708
The product of the Asinger reaction between elemental sulfur, n‐butylamine and acetophenone is 8‐(n‐butylaminophenylmethyliden)‐1,2,3,4,5,6,7‐heptathiocane which contains a CS7 ring. A combination of infrared, Raman and inelastic neutron scattering spectroscopies with periodic density functional theory calculations is used to provide a complete assignment of the vibrational spectra of this unusual species. The similarity between the Raman spectra of the compound and that of elemental sulfur is particularly striking. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
66.
We study the Dirac operator D
0 in an external potential V, coupled to a quantized radiation field with energy H
f and vector potential A. Our result is a Chernoff-type theorem, i.e., we prove, for the operator D
0+α · A+V +λ H
f with λ ∈{0, 1}, that the essential self-adjointness is not affected by the behavior of V at ∞.
相似文献
67.
Docentka Dr. Ludmila Eckertová Dozent Dr. Heribert Jahrreiss 《Zeitschrift für Physik A Hadrons and Nuclei》1968,211(1):89-106
The origin and the behaviour of surface charges on the inner walls of differently sized diodes has been investigated by the authors previously. Now, a quantitative treatment is given for the time dependence of the anode current as well as of the potential of an electrode on the outside of the diodes which is characteristic for this method of investigation. The comparison between the results of the calculations and the experimental data shows the models to be adequate on which the calculations are based. 相似文献
68.
Klaus G. Heumann und Heribert Seewald 《Fresenius' Journal of Analytical Chemistry》1987,329(4):485-486
Ohne Zusammenfassung
Simultaneous determination of boron, chloride, bromide, and iodide in water samples by isotope dilution mass spectrometry相似文献
69.
70.
We develop a new path integral formulation of QCD in radial and axial gauges. This formalism yields free propagators which are free of gauge poles. We find that radial gauges are ghost free. In axial gauges ghosts cannot generally be excluded from the formalism due to the need to fix the residual gauge freedom. 相似文献