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951.
无向图G的L(3,2,1)-标号是指从顶点集V(G)到非负整数集Z*的一个映射,满足:对i=1,2,3,只要dG(x,y)=i,则f(x)-f(y)|≥4-i.若一个L(3,2,1)-标号中的所有像元素都不超过整数k,则称之为k-L(3,2,1)-标号.图G的L(3,2,1)-标号数,记作3λ(G),是使得图G存在k-L(3,2,1)-标号的最小整数k.文中给出了路、圈、树等特殊图的L(3,2,1)-标号数,并给出了一般图的L(3,2,1)-标号数的一个上界. 相似文献
952.
作业车间调度是一类求解困难的组合优化问题,本文在考虑遗传算法早熟收敛问题和禁忌搜索法自适应优点的基础上,将遗传算法和禁忌搜索法相结合,提出了一种基于遗传和禁忌搜索的混合算法,并用实例对该算法进行了仿真研究.结果表明,该算法有很好的收敛精度,是可行的,与传统的算法相比较,有明显的优越性. 相似文献
953.
In a seminal paper, Martin Clark (Communications Systems and Random Process Theory, Darlington, 1977, pp. 721–734, 1978) showed how the filtered dynamics giving the optimal estimate of a Markov chain observed in Gaussian noise can be expressed
using an ordinary differential equation. These results offer substantial benefits in filtering and in control, often simplifying
the analysis and an in some settings providing numerical benefits, see, for example Malcolm et al. (J. Appl. Math. Stoch.
Anal., 2007, to appear).
Clark’s method uses a gauge transformation and, in effect, solves the Wonham-Zakai equation using variation of constants.
In this article, we consider the optimal control of a partially observed Markov chain. This problem is discussed in Elliott
et al. (Hidden Markov Models Estimation and Control, Applications of Mathematics Series, vol. 29, 1995). The innovation in our results is that the robust dynamics of Clark are used to compute forward in time dynamics for a simplified
adjoint process. A stochastic minimum principle is established. 相似文献
954.
Jean-Philippe Chancelier Marouen Messaoud Agnès Sulem 《Mathematical Methods of Operations Research》2007,65(2):239-259
The aim of this paper is to solve the fixed point problems:
where
is a finite set, L is contractive and B is a nonexpansive operator and
where
and
are general control sets, the operators L
w
are contractive and operators B
z
are nonexpansive. For these two problems, we give conditions which imply existence and uniqueness of a solution and provide
a policy iteration algorithm which converges to the solution. The proofs are slightly different for the two problems since
the set of controls is finite for (1) while it is not necessary the case for problem (2). Equation (2) typically arises in
numerical analysis of quasi variational inequalities and variational inequalities associated to impulse or singular stochastic
control. 相似文献
955.
Fabrice Guillemin Bruno Sericola 《Methodology and Computing in Applied Probability》2007,9(4):521-540
Motivated by queueing systems playing a key role in the performance evaluation of telecommunication networks, we analyze in
this paper the stationary behavior of a fluid queue, when the instantaneous input rate is driven by a continuous-time Markov
chain with finite or infinite state space. In the case of an infinite state space and for particular classes of Markov chains
with a countable state space, such as quasi birth and death processes or Markov chains of the G/M/1 type, we develop an algorithm
to compute the stationary probability distribution function of the buffer level in the fluid queue. This algorithm relies
on simple recurrence relations satisfied by key characteristics of an auxiliary queueing system with normalized input rates.
相似文献
956.
In the space of summable sequences we give an example of a one-dimensional affine subspace C such that the best Lp-approximations of 0 from C fail to converge as p↓1. We thus give an answer to this problem of convergence in infinite measure spaces. 相似文献
957.
Weak and strong convergence theorems for strict pseudo-contractions in Hilbert spaces 总被引:1,自引:0,他引:1
Giuseppe Marino 《Journal of Mathematical Analysis and Applications》2007,329(1):336-346
Let C be a closed convex subset of a real Hilbert space H and assume that T is a κ-strict pseudo-contraction on C with a fixed point, for some 0?κ<1. Given an initial guess x0∈C and given also a real sequence {αn} in (0,1). The Mann's algorithm generates a sequence {xn} by the formula: xn+1=αnxn+(1−αn)Txn, n?0. It is proved that if the control sequence {αn} is chosen so that κ<αn<1 and , then {xn} converges weakly to a fixed point of T. However this convergence is in general not strong. We then modify Mann's algorithm by applying projections onto suitably constructed closed convex sets to get an algorithm which generates a strong convergent sequence. This result extends a recent result of Nakajo and Takahashi [K. Nakajo, W. Takahashi, Strong convergence theorems for nonexpansive mappings and nonexpansive semigroups, J. Math. Anal. Appl. 279 (2003) 372-379] from nonexpansive mappings to strict pseudo-contractions. 相似文献
958.
Qiqing Yu George Y. C. Wong Menggang Yu 《Annals of the Institute of Statistical Mathematics》2007,59(4):675-695
We consider the estimation problem with classical case-cohort data. The case-cohort design was first proposed by Prentice
(Biometrics 73:1–11, 1986). Most studies focus on the Cox regression model. In this paper, we consider the linear regression
model. We propose an estimator which extends the Buckley–James estimator to the classical case-cohort design. In order to
derive the BJE, there is an additional problem of finding the generalized maximum likelihood estimator (GMLE) of the underlying
distribution functions. We propose a self-consistent algorithm for the GMLE. We also justify that the GMLE is consistent and
asymptotically normally distributed under certain regularity conditions. We further present some simulation results on the
asymptotic properties of the BJE and apply our procedure to a data set used in the literature. 相似文献
959.
V. N. Temlyakov 《Advances in Computational Mathematics》2007,26(4):431-449
We study convergence and rate of convergence of expansions of elements in a Banach space X into series with regard to a given dictionary
. For convenience we assume that
is symmetric:
implies
. The primary goal of this paper is to study representations of an element f∈X by a series
In building such a representation we should construct two sequences: {g
j
(f)}
j=1∞
and {c
j
(f)}
j=1∞
. In this paper the construction of {g
j
(f)}
j=1∞
will be based on ideas used in greedy-type nonlinear approximation. This explains the use of the term greedy expansion. We use a norming functional
of a residual f
m−1
obtained after m−1 steps of an expansion procedure to select the mth element
from the dictionary. This approach has been used in previous papers on greedy approximation. The greedy expansions in Hilbert
spaces are well studied. The corresponding convergence theorems and estimates for the rate of convergence are known. Much
less is known about greedy expansions in Banach spaces. The first substantial result on greedy expansions in Banach spaces
has been obtained recently by Ganichev and Kalton. They proved a convergence result for the L
p
, 1<p<∞, spaces. In this paper we find a simple way of selecting coefficients c
m
(f) that provides convergence of the corresponding greedy expansions in any uniformly smooth Banach space. Moreover, we obtain
estimates for the rate of convergence of such greedy expansions for
– the closure (in X) of the convex hull of
.
This research was supported by the National Science Foundation Grant DMS 0200187 and by ONR Grant N00014-91-J1343. 相似文献
960.