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101.
102.
Shell Filling and Spin Effects in a Few Electron Quantum Dot 总被引:1,自引:0,他引:1
Tarucha S Austing DG Honda T van der Hage RJ Kouwenhoven LP 《Physical review letters》1996,77(17):3613-3616
103.
Let $\mathcal{K}$ be the family of graphs on ω1 without cliques or independent subsets of sizew 1. We prove that
- it is consistent with CH that everyGε $\mathcal{K}$ has 2ω many pairwise non-isomorphic subgraphs,
- the following proposition holds in L: (*)there is a Gε $\mathcal{K}$ such that for each partition (A, B) of ω1 either G?G[A] orG?G[B],
- the failure of (*) is consistent with ZFC.
104.
Given a directed graph G=(V,E) an independent set A⊂V is called quasi-kernel (quasi-sink) iff for each point v there is a path of length at most 2 from some point of A to v (from v to some point of A). Every finite directed graph has a quasi-kernel. The plain generalization for infinite graphs fails, even for tournaments. We study the following conjecture: for any digraph G=(V,E) there is a a partition (V0,V1) of the vertex set such that the induced subgraph G[V0] has a quasi-kernel and the induced subgraph G[V1] has a quasi-sink. 相似文献
105.
A maximal antichain A of poset P splits if and only if there is a set B ⊂ A such that for each p ∈ P either b ≤ p for some b ∈ B or p ≤ c for some c ∈ A\B. The poset P is cut-free if and only if there are no x < y < z in P such that [x,z]P = [x,y]P ∪ [y,z]P . By [1] every maximal antichain in a finite cut-free poset splits. Although this statement for infinite posets fails (see
[2])) we prove here that if a maximal antichain in a cut-free poset “resembles” to a finite set then it splits. We also show
that a version of this theorem is just equivalent to Axiom of Choice.
We also investigate possible strengthening of the statements that “A does not split” and we could find a maximal strengthening.
* This work was supported, in part, by Hungarian NSF, under contract Nos. T37846, T34702, T37758, AT 048 826, NK 62321. The
second author was also supported by Bolyai Grant. 相似文献
106.
Direct numerical solutions of scattering problems based on boundary-integral equations are computationally costly at high frequencies. A numerical method is presented that efficiently computes accurate approximations to unknown surface quantities given known surface data (an approximate Dirichlet-to-Neumann map). The method is based on a pseudo-differential impedance operator (PIO) numerically implemented using rational approximations. An example of a PIO is the so-called on-surface radiation condition (OSRC) method. For a convex obstacle, the method can be viewed as applying a parabolic equation directly on the surface of a scatterer. In contrast to past OSRCs, the use of rational approximations provides accuracy for wide scattering angles which is needed for grazing angles of incidence. Generalization to impedance operators for two-dimensional acoustic scatterers with concave parts is presented. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
107.
M. ícha Z. Hubi
ka M. Tichý M. Novk L. Soukup L. Jastrabík J. F. Behnke V. Kapi
ka K. Kapoun M. erý 《等离子体物理论文集》1996,36(5):605-611
Although the plasma-chemical processes and properties of the deposited thin film can strongly depend on the interaction of the supersonic plasma jet channel with the substrate, up to now the study of this phenomenon has not yet been done. We decided to study this interaction by means of CCD camera. The presented results indicate that the light intensity recorded close to the substrate can be used as a measure of the intensity of plasma-chemical deposition processes on the substrate surface. 相似文献
108.
Physics-based interface scattering models for the seafloor [H.-H. Essen, J. Acoust. Soc. Am. 95, 1299-1310 (1994); Gragg et al., ibid. 110, 2878-2901 (2001)] exhibit features in their predicted grazing angle dependence. These features have a strong dependence on the assumed composition and roughness of the bottom. Verifying such predictions requires data that cover a wide range of grazing angles and involve minimal sub-bottom penetration. Such measurements were performed in the frequency band 2-3.5 kHz over an exposed limestone bottom off the Carolina coast during the second Littoral Warfare Advanced Development Focused Technology Experiment of 1996 (LWAD FTE 96-2). Direct-path bottom scattering strengths were obtained in shallow water (198-310 m deep) for grazing angles from 8 degrees to 75 degrees using data fusion from multiple experimental geometries coupled with careful signal processing. The processing included corrections for the surface-reflected path, other multipaths, and characteristics of the reverberation decay observed over the pulse duration at higher grazing angles. The resulting frequency and grazing-angle dependences exhibit trends consistent with theoretical predictions, and geoacoustic parameters obtained by inversion are consistent with values expected for limestone. 相似文献
109.
110.
3,3,6,9,9-Pentamethyl-2,10-diaza-bicyclo[4.4.0]-1-decen and some of its derivatives A simple synthesis for the bicyclic amidine 1 (Scheme 3) is described. This base and the salts which were prepared from it show solubility characteristics which make the amidine a potentially useful reagent for salt formation of carboxylic acids and related proton complexes of bidentate ligands. Among the derivatives made from 1 are the sterically strongly hindered N-alkylated amidines 11 , 12 and 14 (Scheme 5), as well as the stable crystalline N1-oxidoamidine-N2-oxyl radical 2 (Scheme 6). The ability of the latter to serve as a paramagnetic chelating ligand for metal ions is illustrated by the preparation of a corresponding nickel(II) complex. The radical is also a source for the α-nitronyl-nitrosonium cation 4 which shows in its reactivity towards conjugated dienes and olefines some of the expected resemblance to singlet oxygen. 相似文献