全文获取类型
收费全文 | 3278篇 |
免费 | 341篇 |
国内免费 | 178篇 |
专业分类
化学 | 150篇 |
晶体学 | 8篇 |
力学 | 285篇 |
综合类 | 46篇 |
数学 | 2154篇 |
物理学 | 1154篇 |
出版年
2023年 | 27篇 |
2022年 | 67篇 |
2021年 | 60篇 |
2020年 | 54篇 |
2019年 | 63篇 |
2018年 | 62篇 |
2017年 | 91篇 |
2016年 | 108篇 |
2015年 | 70篇 |
2014年 | 170篇 |
2013年 | 209篇 |
2012年 | 120篇 |
2011年 | 203篇 |
2010年 | 196篇 |
2009年 | 182篇 |
2008年 | 211篇 |
2007年 | 252篇 |
2006年 | 199篇 |
2005年 | 159篇 |
2004年 | 177篇 |
2003年 | 157篇 |
2002年 | 116篇 |
2001年 | 92篇 |
2000年 | 90篇 |
1999年 | 95篇 |
1998年 | 69篇 |
1997年 | 71篇 |
1996年 | 46篇 |
1995年 | 57篇 |
1994年 | 37篇 |
1993年 | 29篇 |
1992年 | 32篇 |
1991年 | 28篇 |
1990年 | 17篇 |
1989年 | 18篇 |
1988年 | 20篇 |
1987年 | 19篇 |
1986年 | 9篇 |
1985年 | 20篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1973年 | 3篇 |
排序方式: 共有3797条查询结果,搜索用时 15 毫秒
81.
We construct a quantum circuit to produce a task-oriented partially entangled state and use it as the quantum channel for controlled joint remote state preparation. Unlike most previous works, where the parameters of the quantum channel are given to the receiver who can accomplish the task only probabilistically by consuming auxiliary resource, operation and measurement, here we give them to the supervisor. Thanks to the knowledge of the task-oriented quantum channel parameters, the supervisor can carry out proper complete projective measurement, which, combined with the feed-forward technique adapted by the preparers, not only much economizes (simplifies) the receiver's resource (operation) but also yields unit total success probability. Notably, such apparent perfection does not depend on the entanglement degree of the shared quantum channel. Our protocol is within the reach of current quantum technologies. 相似文献
82.
Theo Steininger Jait Dixit Philipp Frank Maksim Greiner Sebastian Hutschenreuter Jakob Knollmüller Reimar Leike Natalia Porqueres Daniel Pumpe Martin Reinecke Matev raml Csongor Varady Torsten Enßlin 《Annalen der Physik》2019,531(3)
NIFTy , “Numerical Information Field Theory,” is a software framework designed to ease the development and implementation of field inference algorithms. Field equations are formulated independently of the underlying spatial geometry allowing the user to focus on the algorithmic design. Under the hood, NIFTy ensures that the discretization of the implemented equations is consistent. This enables the user to prototype an algorithm rapidly in 1D and then apply it to high‐dimensional real‐world problems. This paper introduces NIFTy 3, a major upgrade to the original NIFTy framework. NIFTy 3 allows the user to run inference algorithms on massively parallel high performance computing clusters without changing the implementation of the field equations. It supports n‐dimensional Cartesian spaces, spherical spaces, power spaces, and product spaces as well as transforms to their harmonic counterparts. Furthermore, NIFTy 3 is able to handle non‐scalar fields, such as vector or tensor fields. The functionality and performance of the software package is demonstrated with example code, which implements a mock inference inspired by a real‐world algorithm from the realm of information field theory. NIFTy 3 is open‐source software available under the GNU General Public License v3 (GPL‐3) at https://gitlab.mpcdf.mpg.de/ift/NIFTy/tree/NIFTy_3 . 相似文献
83.
84.
85.
Julia Calatayud Juan Carlos Corts Marc Jornet 《Mathematical Methods in the Applied Sciences》2019,42(18):7259-7267
In this paper, we address the problem of approximating the probability density function of the following random logistic differential equation: P′(t,ω)=A(t,ω)(1?P(t,ω))P(t,ω), t∈[t0,T], P(t0,ω)=P0(ω), where ω is any outcome in the sample space Ω. In the recent contribution [Cortés, JC, et al. Commun Nonlinear Sci Numer Simulat 2019; 72: 121–138], the authors imposed conditions on the diffusion coefficient A(t) and on the initial condition P0 to approximate the density function f1(p,t) of P(t): A(t) is expressed as a Karhunen–Loève expansion with absolutely continuous random coefficients that have certain growth and are independent of the absolutely continuous random variable P0, and the density of P0, , is Lipschitz on (0,1). In this article, we tackle the problem in a different manner, by using probability tools that allow the hypotheses to be less restrictive. We only suppose that A(t) is expanded on L2([t0,T]×Ω), so that we include other expansions such as random power series. We only require absolute continuity for P0, so that A(t) may be discrete or singular, due to a modified version of the random variable transformation technique. For , only almost everywhere continuity and boundedness on (0,1) are needed. We construct an approximating sequence of density functions in terms of expectations that tends to f1(p,t) pointwise. Numerical examples illustrate our theoretical results. 相似文献
86.
87.
We discuss the motion of substance in a channel containing nodes of a network. Each node of the channel can exchange substance with: (i) neighboring nodes of the channel, (ii) network nodes which do not belong to the channel, and (iii) environment of the network. The new point in this study is that we assume possibility for exchange of substance among flows of substance between nodes of the channel and: (i) nodes that belong to the network but do not belong to the channel and (ii) environment of the network. This leads to an extension of the model of motion of substance and the extended model contains previous models as particular cases. We use a discrete-time model of motion of substance and consider a stationary regime of motion of substance in a channel containing a finite number of nodes. As results of the study, we obtain a class of probability distributions connected to the amount of substance in nodes of the channel. We prove that the obtained class of distributions contains all truncated discrete probability distributions of discrete random variable which can take values . Theory for the case of a channel containing infinite number of nodes is presented in Appendix A. The continuous version of the discussed discrete probability distributions is described in Appendix B. The discussed extended model and obtained results can be used for the study of phenomena that can be modeled by flows in networks: motion of resources, traffic flows, motion of migrants, etc. 相似文献
88.
Ion Grama Ronan Lauvergnat Émile Le Page 《Stochastic Processes and their Applications》2019,129(7):2485-2527
Let be a branching process in a random environment defined by a Markov chain with values in a finite state space . Let be the probability law generated by the trajectories of starting at We study the asymptotic behaviour of the joint survival probability , as in the critical and strongly, intermediate and weakly subcritical cases. 相似文献
89.
Let be the first return time to of sums of increments given by a functional of a stationary Markov chain. We determine the asymptotic behavior of the survival probability, for an explicit constant . Our analysis is based on a connection between the survival probability and the running maximum of the time-reversed process, and relies on a functional central limit theorem for Markov chains. As applications, we recover known clustering results for the 3-color cyclic cellular automaton and the Greenberg–Hastings model, and we prove a new clustering result for the 3-color firefly cellular automaton. 相似文献
90.