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991.
Redundant constraints in linear inequality systems can be characterized as those inequalities that can be removed from an
arbitrary linear optimization problem posed on its solution set without modifying its value and its optimal set. A constraint
is saturated in a given linear optimization problem when it is binding at the optimal set. Saturation is a property related
with the preservation of the value and the optimal set under the elimination of the given constraint, phenomena which can
be seen as weaker forms of excess information in linear optimization problems. We say that an inequality of a given linear
inequality system is uniformly saturated when it is saturated for any solvable linear optimization problem posed on its solution
set. This paper characterizes the uniform saturated inequalities and other related classes of inequalities.
This work was supported by the MCYT of Spain and FEDER of UE, Grant BFM2002-04114-C02-01. 相似文献
992.
Each year, the US Air Force Academy graduates nearly 1000 young men and women. To support the decision of which cadets will be classified into which career fields, we describe a linear programming formulation with appealing computational properties that enable it as the core of a decision support tool. We explore methods for measuring and balancing cadets' class standing, Air Force career field requirements, and cadets' career field preferences in the context of this model. Our computational experiments demonstrate the improvement of this method over previous classification approaches, yielding more than 10% increase in the number of cadets assigned to their top career field choice and yielding nearly a 100% reduction in the number of cadets not receiving any of their career field choices. We also explore alternative methods for measuring cadets' career field preferences and demonstrate the positive effect of the new measurement scheme on the overall classification. Because of the short running time of this model, it will serve as a flexible, real-time component of the Academy's classification process. 相似文献
993.
Some Conditions for Matrices over an Incline To Be Invertible and General Linear Group on an Incline 总被引:2,自引:0,他引:2
Song Chol HAN Hong Xing LI 《数学学报(英文版)》2005,21(5):1093-1098
Inclines are the additively idempotent semirings in which products are less than or equal to either factor. In this paper, some necessary and sufficient conditions for a matrix over L to be invertible are given, where L is an incline with 0 and 1. Also it is proved that L is an integral incline if and only if GLn(L) = PLn (L) for any n (n 〉 2), in which GLn(L) is the group of all n × n invertible matrices over L and PLn(L) is the group of all n × n permutation matrices over L. These results should be regarded as the generalizations and developments of the previous results on the invertible matrices over a distributive lattice. 相似文献
994.
Recently, Zhang, Tapia, and Dennis (Ref. 1) produced a superlinear and quadratic convergence theory for the duality gap sequence in primal-dual interior-point methods for linear programming. In this theory, a basic assumption for superlinear convergence is the convergence of the iteration sequence; and a basic assumption for quadratic convergence is nondegeneracy. Several recent research projects have either used or built on this theory under one or both of the above-mentioned assumptions. In this paper, we remove both assumptions from the Zhang-Tapia-Dennis theory.Dedicated to the Memory of Magnus R. Hestenes, 1906–1991This research was supported in part by NSF Cooperative Agreement CCR-88-09615 and was initiated while the first author was at Rice University as a Visiting Member of the Center for Research in Parallel Computation.The authors thank Yinyu Ye for constructive comments and discussions concerning this material.This author was supported in part by NSF Grant DMS-91-02761 and DOE Grant DE-FG05-91-ER25100.This author was supported in part by AFOSR Grant 89-0363, DOE Grant DE-FG05-86-ER25017, and ARO Grant 9DAAL03-90-G-0093. 相似文献
995.
The mixed form of the areal groundwater flow equations is solved with a least-squares finite element procedure (LESFEM). Hydraulic head and x- and y-directed fluxes are state variables. Physical parameters and state variables are approximated using a bilinear basis. Grid refinements and irregular domain boundaries are implemented on rectangular meshes. Residuals are constructed at collocation points for conservation of mass and Darcy's law. Boundary condition residuals are constructed at discrete points along the boundary. The residuals are weighted, squared and summed. A set of algebraic equations is formed by taking the derivatives of the weighted sum of the squares of the residuals with respect to each unknown parameter in the approximation for the state variable and setting them to zero. Proper choice of a potential scaling parameter and residual weights is essential for the effective application of the algorithm. Test problem results demonstrate that the method is effective for both transient and steady state cases. The LESFEM algorithm generates a C°-continuous velocity field. The continuous velocity field and the rectangular mesh simplify the implementation of algorithms that require tracking. In addition, rectangular meshes simplify mesh and boundary generation. 相似文献
996.
A finite element method for the analysis of nearshore current, which is one of the principal currents in coastal seas, is presented in this paper. Because the nearshore current is induced by the variable distribution of the surface waves, it is necessary to analyse two main characteristics of the wave, i.e. direction and height. The current can be computed using the resulting wave characteristics. The present method makes it possible to employ procedures for which the same methods of solution are applicable for all basic equations of wave direction, height and current flow. The linear interpolation function is used for the discretization of spatial variables and a selective lumping two step explicit scheme is employed for the numerical integration in time. The numerical solutions obtained are compared with analytical, experimental and observed ones. From these comparative studies, it is concluded that the present finite element method provide a useful tool for the analysis of nearshore current. 相似文献
997.
本文讨论了零边值半线性椭圆方程的多重正解,其中使用没有(PS)条件的山路引理及对最佳Sobolev嵌入常数的分析,证明了至少两个解的存在性. 相似文献
998.
对查尔酮类共轭体系的电子光谱,CNDO/2计算及线性关系文献中已作了全面报道。本文用林惠心等在徐光宪改进的HMO法基础上提出的改进HMO法(即MHMO法),对查尔酮类共轭体系进行了计算,结果λ_计和λ_实基本一致,线性关系良好。 相似文献
999.
1000.
This paper reports on an experimental study of the distribution of the length of simplex paths for the Optimal Assignment
Problem. We study the distribution of the pivot counts for a version of the simplex method that with essentially equal probabilities
introduces any variable with negative reduced cost into the basis.
In this situation the distribution of the pivot counts turns out to be normally distributed and independent of the actual
cost coefficients, provided these are sufficiently spread out. Further, the mean and standard deviation grow only moderately
with the size of the problem, namely asd
1.8, andd
1.5 respectively for ad×d problem, implying in particular that the pivot counts concentrate around the mean with growingd.
The usual simplex method on the other hand gives a growth ofd
1.6. Hence a large part of the favourable polynomial growth experienced on practical problems may be attributed to the fact that
the simplex paths are rather short on the average, at least for assignment problems. 相似文献