全文获取类型
收费全文 | 7571篇 |
免费 | 530篇 |
国内免费 | 318篇 |
专业分类
化学 | 1261篇 |
晶体学 | 55篇 |
力学 | 797篇 |
综合类 | 54篇 |
数学 | 4554篇 |
物理学 | 1698篇 |
出版年
2024年 | 7篇 |
2023年 | 64篇 |
2022年 | 116篇 |
2021年 | 152篇 |
2020年 | 214篇 |
2019年 | 221篇 |
2018年 | 192篇 |
2017年 | 185篇 |
2016年 | 212篇 |
2015年 | 215篇 |
2014年 | 380篇 |
2013年 | 862篇 |
2012年 | 395篇 |
2011年 | 456篇 |
2010年 | 429篇 |
2009年 | 508篇 |
2008年 | 489篇 |
2007年 | 485篇 |
2006年 | 362篇 |
2005年 | 244篇 |
2004年 | 246篇 |
2003年 | 227篇 |
2002年 | 225篇 |
2001年 | 166篇 |
2000年 | 153篇 |
1999年 | 121篇 |
1998年 | 135篇 |
1997年 | 116篇 |
1996年 | 111篇 |
1995年 | 83篇 |
1994年 | 85篇 |
1993年 | 78篇 |
1992年 | 57篇 |
1991年 | 48篇 |
1990年 | 58篇 |
1989年 | 20篇 |
1988年 | 34篇 |
1987年 | 42篇 |
1986年 | 21篇 |
1985年 | 23篇 |
1984年 | 30篇 |
1983年 | 10篇 |
1982年 | 16篇 |
1981年 | 23篇 |
1980年 | 21篇 |
1979年 | 17篇 |
1978年 | 20篇 |
1977年 | 18篇 |
1976年 | 15篇 |
1975年 | 6篇 |
排序方式: 共有8419条查询结果,搜索用时 15 毫秒
991.
Etienne Adam 《Stochastic Processes and their Applications》2018,128(9):2905-2922
We classify the possible behaviors of a class of one-dimensional stochastic recurrent growth models. In our main result, we obtain nearly optimal bounds for the tail of hitting times of some compact sets. If the process is an aperiodic irreducible Markov chain, we determine whether it is null recurrent or positive recurrent and in the latter case, we obtain a subgeometric convergence of its transition kernel to its invariant measure. We apply our results in particular to state-dependent Galton–Watson processes and we give precise estimates of the tail of the extinction time. 相似文献
992.
Sascha Bachmann Matthias Reitzner 《Stochastic Processes and their Applications》2018,128(10):3327-3352
Concentration bounds for the probabilities and are proved, where is a median or the expectation of a subgraph count associated with a random geometric graph built over a Poisson process. The lower tail bounds have a Gaussian decay and the upper tail inequalities satisfy an optimality condition. A remarkable feature is that the underlying Poisson process can have a.s. infinitely many points.The estimates for subgraph counts follow from tail inequalities for more general local Poisson U-statistics. These bounds are proved using recent general concentration results for Poisson U-statistics and techniques involving the convex distance for Poisson processes. 相似文献
993.
We develop a dynamic structural model for the wealth of individual mortgagors in a mortgage pool. We model the process of default and prepayment and, by taking a limit as the pool size goes to infinity, derive a stochastic partial differential equation (SPDE) which can be used to describe the evolution of the loss process from the pool. We prove existence and uniqueness of solutions to this SPDE and show how our model is able to capture, in a flexible way, the prices of credit risky tranches of mortgage-backed securities under different market conditions. 相似文献
994.
This work is concerned with identifying a space-dependent source function from noisy final time measured data in a time-fractional diffusion wave equation by a variational regularization approach. We provide a regularity of direct problem as well as the existence and uniqueness of adjoint problem. The uniqueness of the inverse source problem is discussed. Using the Tikhonov regularization method, the inverse source problem is formulated into a variational problem and a conjugate gradient algorithm is proposed to solve it. The efficiency and robust of the proposed method are supported by some numerical experiments. 相似文献
995.
Quasi-projective synchronization analysis for delayed stochastic quaternion-valued neural networks via state-feedback control strategy
下载免费PDF全文
![点击此处可从《Journal of Applied Analysis & Computation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this paper, we explore the complete synchronization and quasi-projective synchronization in a class of stochastic delayed quaternion-valued neural networks, utilizing a state-feedback control scheme. The studied neural networks into real-valued networks are short of known decomposing, by designing a very general nonlinear controller, according to the quaternion form It\^{o} formula with a number of inequality techniques in the configuration of quaternion domain, we obtained a quasi-projective synchronization criterion for drive-response networks. Moreover, we estimate the error margin for quasi-projective synchronization. At last, the theoretical results are confirmed by a numerical simulation. 相似文献
996.
《Operations Research Letters》2020,48(5):584-586
In recent years, a range of measures of “partial” stochastic dominance have been introduced. These measures attempt to determine the extent to which one distribution is dominated by another. We assess these measures from intuitive, axiomatic, computational and statistical perspectives. Our investigation leads us to recommend a measure related to optimal transport as a natural default. 相似文献
997.
We investigate the optimal reinsurance problem under the criterion of maximizing the expected utility of terminal wealth when the insurance company has restricted information on the loss process. We propose a risk model with claim arrival intensity and claim sizes distribution affected by an unobservable environmental stochastic factor. By filtering techniques (with marked point process observations), we reduce the original problem to an equivalent stochastic control problem under full information. Since the classical Hamilton–Jacobi–Bellman approach does not apply, due to the infinite dimensionality of the filter, we choose an alternative approach based on Backward Stochastic Differential Equations (BSDEs). Precisely, we characterize the value process and the optimal reinsurance strategy in terms of the unique solution to a BSDE driven by a marked point process. 相似文献
998.
This paper investigates the open-loop equilibrium reinsurance-investment (RI) strategy under general stochastic volatility (SV) models. We resolve difficulties arising from the unbounded volatility process and the non-negativity constraint on the reinsurance strategy. The resolution enables us to derive the existence and uniqueness result for the time-consistent mean variance RI policy under both situations of constant and state-dependent risk aversions. We apply the general framework to popular SV models including the Heston, the 3/2 and the Hull–White models. Closed-form solutions are obtained for the aforementioned models under constant risk aversion, and the non-leveraged models under state-dependent risk aversion. 相似文献
999.
Recently, the actuarial professions in various countries have adopted an innovative two-dimensional approach to projecting future mortality. In contrast to the conventional approach, the two-dimensional approach permits mortality improvement rates to vary with not only age but also time. Despite being an important breakthrough, the currently used two-dimensional mortality improvement scales are subject to several limitations, most notably a heavy reliance on subjective judgments and a lack of measures of uncertainty. In view of these limitations, in this paper we introduce a new model known as the heat wave model, in which short- and long-term mortality improvements are treated respectively as ‘heat waves’ that taper off over time and ‘background improvements’ that always exist. Using the heat wave model, one can derive two-dimensional mortality improvement scales that entail minimal subjective judgment and include measures of the uncertainty. 相似文献
1000.
《Operations Research Letters》2020,48(6):777-783
In the lines of our previous approach to devise proximal algorithms for nonsmooth convex optimization by applying Nesterov fast gradient concept to the Moreau–Yosida regularization of a convex function, we develop three new proximal algorithms for nonsmooth convex optimization. In these algorithms, the errors in computing approximate solutions for the Moreau–Yosida regularization are not fixed beforehand, while preserving the complexity estimates already established. We report some preliminary computational results to give a first estimate of their performance. 相似文献