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961.
We study risk-sensitive control of continuous time Markov chains taking values in discrete state space. We study both finite and infinite horizon problems. In the finite horizon problem we characterize the value function via Hamilton Jacobi Bellman equation and obtain an optimal Markov control. We do the same for infinite horizon discounted cost case. In the infinite horizon average cost case we establish the existence of an optimal stationary control under certain Lyapunov condition. We also develop a policy iteration algorithm for finding an optimal control. 相似文献
962.
This paper introduces stationary and multi-self-similar random fields which account for stochastic volatility and have type G marginal law. The stationary random fields are constructed using volatility modulated mixed moving average (MA) fields and their probabilistic properties are discussed. Also, two methods for parameterizing the weight functions in the MA representation are presented: one method is based on Fourier techniques and aims at reproducing a given correlation structure, the other method is based on ideas from stochastic partial differential equations. Moreover, using a generalized Lamperti transform we construct volatility modulated multi-self-similar random fields which have type G distribution. 相似文献
963.
We consider optimal control problems for one-dimensional diffusion processes y x (t) = y v x (t), solutions dy x (t) = g(y x (t) dt + σ(y x (t)(dw) + dv t with y x(0) = x& isinv;[a,b], the control processes v t are increasing, positive, and adapted. Several types of expected cost structures associated with each policy v(.) are adopted, e.g. discounted cost, long term average cost and time average cost. Our work is related to [2,6,12,14,16 and 21], where diffusions are allowed to evolve in the whole space, and to [13] and [20], where diffusions evolve only in bounded regions. We shall present some analytic results about value functions, mainly their characterizations, by simple dynamic programming arguments. Several simple examples are explicitly solved to illustrate the singular behaviour of our problems 相似文献
964.
We consider optimal control problems for one-dimensional diffusion processes [ILM0001] where the control processes υt are increasing, positive, and adapted. Several types of expected cost structures associated with each policy υ(.) are adopted, e.g. discounted cost, long term average cost and time average cost. Our work is related to [2,6,12,14,16 and 21], where diffusions are allowed to evolve in the whole space, and to [13] and [20], where diffusions evolve only in bounded regions. We shall present some analytic results about value functions, mainly their characterizations, by simple dynamic programming arguments. Several simple examples are explicitly solved to illustrate the singular behaviour of our problems. 相似文献
965.
Analysis of a predator-prey model with modified Leslie-Gower and Holling-type II schemes with stochastic perturbation 总被引:1,自引:0,他引:1
Chunyan Ji Daqing Jiang Ningzhong Shi 《Journal of Mathematical Analysis and Applications》2009,359(2):482-1233
In this paper, we consider a predator-prey model with modified Leslie-Gower and Holling-type II schemes with stochastic perturbation. We show there is a unique positive solution to the system with positive initial value, and mainly investigate the long time behavior of the system. Condition for the system to be extinct is given and persistent condition is established. At last, numerical simulations are carried out to support our results. 相似文献
966.
B. K. Pagnoncelli S. Ahmed A. Shapiro 《Journal of Optimization Theory and Applications》2009,142(2):399-416
We study sample approximations of chance constrained problems. In particular, we consider the sample average approximation (SAA) approach and discuss the convergence properties of the resulting problem. We discuss how one can use the SAA method
to obtain good candidate solutions for chance constrained problems. Numerical experiments are performed to correctly tune
the parameters involved in the SAA. In addition, we present a method for constructing statistical lower bounds for the optimal
value of the considered problem and discuss how one should tune the underlying parameters. We apply the SAA to two chance
constrained problems. The first is a linear portfolio selection problem with returns following a multivariate lognormal distribution.
The second is a joint chance constrained version of a simple blending problem.
B.K. Pagnoncelli’s research was supported by CAPES and FUNENSEG.
S. Ahmed’s research was partly supported by the NSF Award DMI-0133943.
A. Shapiro’s research was partly supported by the NSF Award DMI-0619977. 相似文献
967.
Joanna Petela 《Applied mathematics and computation》2009,215(2):481-494
In this paper we consider nonautonomous competitive Kolmogorov systems, which is a generalization of classical Lotka–Volterra competition model. Applying Ahmad and Lazer’s definitions of lower and upper averages of a function, we give the average conditions for the persistence, permanence and global attractivity of the system. 相似文献
968.
For Vilenkin-like system, the authors define a new operator H*f := supn |Hnf|, where Hnf is the weighted average for partial sums, and prove that H* is of type (Hp* (Gm), Lp(Gm)) for all 1/2 < p ≤∞. As a consequence, the authors prove the operator S*f := supn |Snf| is of type (p, p) for 1 < p < ∞, where Snf is the n-partial sum. 相似文献
969.
Circle graphs with girth at least five are known to be 2-degenerate [A.A. Ageev, Every circle graph with girth at least 5 is 3-colourable, Discrete Math. 195 (1999) 229-233]. In this paper, we prove that circle graphs with girth at least g≥5 and minimum degree at least two contain a chain of g−4 vertices of degree two, which implies Ageev’s result in the case g=5. We then use this structural property to give an upper bound on the circular chromatic number of circle graphs with girth at least g≥5 as well as a precise estimate of their maximum average degree. 相似文献
970.
在考虑到捕获电子效应的情况下,对求解二维Fokker-Planck方程的编程进行了反弹平均的修改,使用了交替方向隐式法来求解方程。分析和计算了在不同扩散系数和不同共振区间的情况下,捕获电子效应对驱动电流的影响。结果显示:随着逆纵横比的增加驱动电流密度有明显的下降,在磁轴附近捕获电子效应对电流驱动影响很小;提高波功率并不能很好的改善捕获电子效应对电流驱动的影响;右移共振区间提高共振电子的速度,也不能很好的改善捕获电子效应对电流驱动的影响。所得结果与理论分析基本一致。 相似文献