全文获取类型
收费全文 | 8868篇 |
免费 | 846篇 |
国内免费 | 689篇 |
专业分类
化学 | 3514篇 |
晶体学 | 40篇 |
力学 | 232篇 |
综合类 | 96篇 |
数学 | 4802篇 |
物理学 | 1719篇 |
出版年
2024年 | 9篇 |
2023年 | 58篇 |
2022年 | 145篇 |
2021年 | 218篇 |
2020年 | 224篇 |
2019年 | 250篇 |
2018年 | 210篇 |
2017年 | 311篇 |
2016年 | 354篇 |
2015年 | 280篇 |
2014年 | 498篇 |
2013年 | 823篇 |
2012年 | 515篇 |
2011年 | 551篇 |
2010年 | 499篇 |
2009年 | 555篇 |
2008年 | 607篇 |
2007年 | 635篇 |
2006年 | 435篇 |
2005年 | 396篇 |
2004年 | 287篇 |
2003年 | 310篇 |
2002年 | 272篇 |
2001年 | 279篇 |
2000年 | 215篇 |
1999年 | 200篇 |
1998年 | 154篇 |
1997年 | 138篇 |
1996年 | 110篇 |
1995年 | 125篇 |
1994年 | 109篇 |
1993年 | 89篇 |
1992年 | 83篇 |
1991年 | 76篇 |
1990年 | 33篇 |
1989年 | 42篇 |
1988年 | 39篇 |
1987年 | 30篇 |
1986年 | 30篇 |
1985年 | 43篇 |
1984年 | 25篇 |
1983年 | 18篇 |
1982年 | 27篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 23篇 |
1978年 | 10篇 |
1977年 | 13篇 |
1975年 | 8篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 984 毫秒
111.
Su-Yun Huang Chuhsing Kate Hsiao Ching-Wei Chang 《Annals of the Institute of Statistical Mathematics》2003,55(3):655-670
The article provides a refinement for the volume-corrected Laplace-Metropolis estimator of the marginal likelihood of DiCiccioet al. The correction volume of probability α in DiCiccioet al. is fixed and suggested to take the value α=0.05. In this article α is selected based on an asymptotic analysis to minimize
the mean square relative error (MSRE). This optimal choice of α is shown to be invariant under linear transformations. The
invariance property leads to easy implementation for multivariate problems. An implementation procedure is provided for practical
use. A simulation study and a real data example are presented. 相似文献
112.
Keith Jonathan M. Kroese Dirk P. Bryant Darryn 《Methodology and Computing in Applied Probability》2004,6(1):29-53
A recent development of the Markov chain Monte Carlo (MCMC) technique is the emergence of MCMC samplers that allow transitions between different models. Such samplers make possible a range of computational tasks involving models, including model selection, model evaluation, model averaging and hypothesis testing. An example of this type of sampler is the reversible jump MCMC sampler, which is a generalization of the Metropolis–Hastings algorithm. Here, we present a new MCMC sampler of this type. The new sampler is a generalization of the Gibbs sampler, but somewhat surprisingly, it also turns out to encompass as particular cases all of the well-known MCMC samplers, including those of Metropolis, Barker, and Hastings. Moreover, the new sampler generalizes the reversible jump MCMC. It therefore appears to be a very general framework for MCMC sampling. This paper describes the new sampler and illustrates its use in three applications in Computational Biology, specifically determination of consensus sequences, phylogenetic inference and delineation of isochores via multiple change-point analysis. 相似文献
113.
This paper deals with the analysis of an M/M/c queueing system with setup times. This queueing model captures the major characteristics of phenomena occurring in production
when the system consists in a set of machines monitored by a single operator. We carry out an extensive analysis of the system
including limiting distribution of the system state, waiting time analysis, busy period and maximum queue length.
AMS subject classification: 90B22, 60K25 相似文献
114.
Pierre Gaspard 《Journal of statistical physics》2004,117(3-4):599-615
A concept of time-reversed entropy per unit time is introduced in analogy with the entropy per unit time by Shannon, Kolmogorov, and Sinai. This time-reversed entropy per unit time characterizes the dynamical randomness of a stochastic process backward in time, while the standard entropy per unit time characterizes the dynamical randomness forward in time. The difference between the time-reversed and standard entropies per unit time is shown to give the entropy production of Markovian processes in nonequilibrium steady states. 相似文献
115.
N. Fazeli F. Afshar Taromi 《Journal of polymer science. Part A, Polymer chemistry》2003,41(1):135-142
The basis of the two‐step in–in method is as follows: star polymers with poly(divinyl benzene) cores, synthesized by the arm‐first method, include many unreacted double bonds in their core, and these double bonds can be attacked by the carbanions of some monomers such as styrene and dienes. In this work, linear polyisoprene chains were used to attack the double bonds existing in the poly(divinyl benzene) cores of polystyrene star polymers, so that a heteroarm star polymer with polystyrene and polyisoprene arms was synthesized. It was later well characterized with size exclusion chromatography, light scattering, viscometry, UV spectroscopy, dynamic mechanical thermal analysis, and 1H NMR. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 135–142, 2003 相似文献
116.
给出了随机环境中马氏链的特征数和状态的定义,讨论了状态间的传递性,自反性,对称性,是经典马氏链相应结果的一般化.并运用位势方法研究了状态间的关系,它们在极限理论的研究中非常有用. 相似文献
117.
We focus on continuous Markov chains as a model to describe the evolution of credit ratings. In this work it is checked whether a simple, tridiagonal type of generator provides a good approximation to a general one. Three different tridiagonal approximations are proposed and their performance is checked against two generators, corresponding to a volatile and a stable period, respectively. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
118.
Consider a queueing system where customers arrive at a circle according to a homogeneous Poisson process. After choosing their positions on the circle, according to a uniform distribution, they wait for a single server who travels on the circle. The server's movement is modelled by a Brownian motion with drift. Whenever the server encounters a customer, he stops and serves this customer. The service times are independent, but arbitrarily distributed. The model generalizes the continuous cyclic polling system (the diffusion coefficient of the Brownian motion is zero in this case) and can be interpreted as a continuous version of a Markov polling system. Using Tweedie's lemma for positive recurrence of Markov chains with general state space, we show that the system is stable if and only if the traffic intensity is less than one. Moreover, we derive a stochastic decomposition result which leads to equilibrium equations for the stationary configuration of customers on the circle. Steady-state performance characteristics are determined, in particular the expected number of customers in the system as seen by a travelling server and at an arbitrary point in time. 相似文献
119.
120.
主要研究相互粒子系统中概率测度的负相关.我们得到判定概率测度是负相关的一个充分必要条件.最后证明了具有负相关的概率测度的线性组合及乘积测度仍是负相关的. 相似文献