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131.
FORCING BONDS OF A BENZENOID SYSTEM 总被引:1,自引:0,他引:1
FORCINGBONDSOFABENZENOIDSYSTEMZHANGFUJI(DepartmentofMathematics,XiamenUniversity,Xiamen850046,China)LIXUELIANG(DepartmentofAp... 相似文献
132.
Trees with revenues are a generalization of standard trees. In a tree with revenues, players have to pay for their connections to the root, but a player can also earn some revenue from being connected to the root. In this paper, we present an algorithm for calculating the nucleolus. 相似文献
133.
Richard T. Wong 《Mathematical Programming》1984,28(3):271-287
The Steiner tree problem on a directed graph (STDG) is to find a directed subtree that connects a root node to every node
in a designated node setV. We give a dual ascent procedure for obtaining lower bounds to the optimal solution value. The ascent information is also
used in a heuristic procedure for obtaining feasible solutions to the STDG. Computational results indicate that the two procedures
are very effective in solving a class of STDG's containing up to 60 nodes and 240 directed/120 undirected arcs.
The directed spanning tree and uncapacitated plant location problems are special cases of the STDG. Using these relationships,
we show that our ascent procedure can be viewed as a generalization ofboth the Chu-Liu-Edmonds directed spanning tree algorithm and the Bilde-Krarup-Erlenkotter ascent algorithm for the plant location
problem. The former comparison yields a dual ascent interpretation of the steps of the directed spanning tree algorithm. 相似文献
134.
Servet Martínez Daniel Remenik Jaime San Martín 《Journal of Theoretical Probability》2007,20(3):561-579
We study an approximation of a Markov process associated to the boundary of an infinite rooted tree. This approximation is
constructed by projecting the infinitesimal generator of the original process (defined on the boundary) onto the spaces associated
to the filtration spanned by the successive levels of the rooted tree.
S. Martínez and J. San Martín acknowledge the support by Nucleus Millenium Information and Randomness P04-069-F.
D. Remenik current address: Center for Applied Mathematics, Cornell University, 657 Rhodes Hall, Ithaca, NY 14853. The author acknowledges the partial
support by Nucleus Millenium Information and Randomness P01-005 for his work in his undergraduate thesis at Universidad de
Chile. 相似文献
135.
We answer a question of Jockusch by constructing a hyperimmune-free minimal degree below a 1-generic one. To do this we introduce a new forcing notion called arithmetical Sacks forcing. Some other applications are presented.The first author was supported in part by the Marsden Fund of New Zealand.The second author was supported by a postdoctoral fellowship from the New Zealand Institute for Mathematics and its Applications, NSF of China No.10471060 and No.10420130638. 相似文献
136.
137.
Proper approximation of the force terms, especially the bed slope term, is of crucial importance to simulating shallow water flows in lattice Boltzmann (LB) models. However, there is little discussion on the schemes of adding force terms to LB models for shallow water equations (SWEs). In this study, we evaluate the performance of forcing schemes coupled with different LB models (LABSWE and MLBSWE) in simulating shallow water flows over complex topography and try to find out their intrinsic characteristics and applicability. Three cases are adopted for evaluation, including a stationary case, a one-dimensional tidal wave flow over an irregular bed, and a steady flow over a two-dimensional seamount. The simulating results are compared with analytical solutions or the results produced by the finite difference method. For LABSWE, all the forcing schemes, except for the weighting factor method, fail to produce accurate solutions for the test cases; this is probably due to the mismatch between the bed slope term in source terms and the quadratic depth term of the equilibrium distribution functions in these forcing schemes. For MLBSWE, all the forcing schemes are capable of simulating flows over the complex topography accurately; furthermore, those schemes taking into account the collision effect τ to eliminate the momentum induced by forces provide more accurate solutions with quicker convergence as the lattice size decreases. In this view, MLBSWE can bring more flexibility in treating the force terms and thus can be a better tool to simulate shallow water flows over complex topography in practical application. 相似文献
138.
Tom X.-P. Zhao Hongbin Yu Istvan Laszlo William C. Conant 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(7):1162-1186
A two-step approach is proposed to derive component aerosol direct radiative forcing (ADRF) at the top of atmosphere (TOA) over global oceans from 60°S to 60°N for clear-sky condition by combining Terra CERES/MODIS-SSF shortwave (SW) flux and aerosol optical thickness (AOT) observations with the fractions of component AOTs from the GSFC/GOCART model. The derived global annual mean component ADRF is +0.08±0.17 W/m2 for black carbon, −0.52±0.24 W/m2 for organic carbon, −1.10±0.42 W/m2 for sulfate, −0.99±0.37 W/m2 for dust, −2.44±0.84 W/m2 for sea salt, and −4.98±1.67 W/m2 for total aerosols. The total ADRF has also been partitioned into anthropogenic and natural components with a value of −1.25±0.43 and −3.73±1.27 W/m2, respectively. The major sources of error in the estimates have also been discussed. The analysis adds an alternative technique to narrow the large difference between current model-based and observation-based global estimates of component ADRF by combining the satellite measurement with the model simulation. 相似文献
139.
Dominique Barth 《Discrete Mathematics》2006,306(5):469-477
A n-vertex graph is said to be decomposable if for any partition (λ1,…,λp) of the integer n, there exists a sequence (V1,…,Vp) of connected vertex-disjoint subgraphs with |Vi|=λi. In this paper, we focus on decomposable trees. We show that a decomposable tree has degree at most 4. Moreover, each degree-4 vertex of a decomposable tree is adjacent to a leaf. This leads to a polynomial time algorithm to decide if a multipode (a tree with only one vertex of degree greater than 2) is decomposable. We also exhibit two families of decomposable trees: arbitrary large trees with one vertex of degree 4, and trees with an arbitrary number of degree-3 vertices. 相似文献
140.
Kyoji Saito 《Advances in Mathematics》2007,212(2):645-668
For any tree Γ, we introduce Γ-cones consisting of chambers and enumerate the number of chambers contained in two particular (called principal) Γ-cones. The problem is equivalent to the combinatorial problem of the enumeration of linear extensions of two bipartite orderings on a tree Γ. We characterize the principal Γ-cones among other Γ-cones by the strict maximality of the number of their chambers, and give a formula for this maximal (called principal) number by a finite sum of hook length formulae. We explain the formula through the simplicial block decomposition of principal Γ-cones. The results have their origin and application in the study of the topology related to Coxeter groups and Artin groups. 相似文献