全文获取类型
收费全文 | 92864篇 |
免费 | 7644篇 |
国内免费 | 6328篇 |
专业分类
化学 | 20224篇 |
晶体学 | 272篇 |
力学 | 6816篇 |
综合类 | 984篇 |
数学 | 57840篇 |
物理学 | 20700篇 |
出版年
2023年 | 862篇 |
2022年 | 1071篇 |
2021年 | 1806篇 |
2020年 | 2356篇 |
2019年 | 2520篇 |
2018年 | 2068篇 |
2017年 | 2263篇 |
2016年 | 2358篇 |
2015年 | 2073篇 |
2014年 | 3869篇 |
2013年 | 7390篇 |
2012年 | 4121篇 |
2011年 | 4996篇 |
2010年 | 4623篇 |
2009年 | 5860篇 |
2008年 | 6240篇 |
2007年 | 6417篇 |
2006年 | 5255篇 |
2005年 | 4328篇 |
2004年 | 3670篇 |
2003年 | 3851篇 |
2002年 | 3545篇 |
2001年 | 2900篇 |
2000年 | 2480篇 |
1999年 | 2254篇 |
1998年 | 2099篇 |
1997年 | 1852篇 |
1996年 | 1541篇 |
1995年 | 1219篇 |
1994年 | 1112篇 |
1993年 | 944篇 |
1992年 | 846篇 |
1991年 | 663篇 |
1990年 | 513篇 |
1989年 | 398篇 |
1988年 | 389篇 |
1987年 | 378篇 |
1986年 | 388篇 |
1985年 | 570篇 |
1984年 | 465篇 |
1983年 | 274篇 |
1982年 | 480篇 |
1981年 | 631篇 |
1980年 | 560篇 |
1979年 | 613篇 |
1978年 | 481篇 |
1977年 | 363篇 |
1976年 | 316篇 |
1974年 | 103篇 |
1973年 | 181篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
1.
The authors consider the short time existence for Ricci-Bourguignon flow on manifolds with boundary. If the initial metric has constant mean curvature and satisfies some compatibility conditions, they show the short time existence of the Ricci-Bourguignon flow with constant mean curvature on the boundary. 相似文献
2.
Khoder Makkawi Nourdine Ait-Tmazirte Maan El Badaoui El Najjar Nazih Moubayed 《Entropy (Basel, Switzerland)》2021,23(4)
When applying a diagnostic technique to complex systems, whose dynamics, constraints, and environment evolve over time, being able to re-evaluate the residuals that are capable of detecting defaults and proposing the most appropriate ones can quickly prove to make sense. For this purpose, the concept of adaptive diagnosis is introduced. In this work, the contributions of information theory are investigated in order to propose a Fault-Tolerant multi-sensor data fusion framework. This work is part of studies proposing an architecture combining a stochastic filter for state estimation with a diagnostic layer with the aim of proposing a safe and accurate state estimation from potentially inconsistent or erroneous sensors measurements. From the design of the residuals, using α-Rényi Divergence (α-RD), to the optimization of the decision threshold, through the establishment of a function that is dedicated to the choice of α at each moment, we detail each step of the proposed automated decision-support framework. We also dwell on: (1) the consequences of the degree of freedom provided by this α parameter and on (2) the application-dictated policy to design the α tuning function playing on the overall performance of the system (detection rate, false alarms, and missed detection rates). Finally, we present a real application case on which this framework has been tested. The problem of multi-sensor localization, integrating sensors whose operating range is variable according to the environment crossed, is a case study to illustrate the contributions of such an approach and show the performance. 相似文献
3.
Frank Nielsen 《Entropy (Basel, Switzerland)》2021,23(4)
We generalize the Jensen-Shannon divergence and the Jensen-Shannon diversity index by considering a variational definition with respect to a generic mean, thereby extending the notion of Sibson’s information radius. The variational definition applies to any arbitrary distance and yields a new way to define a Jensen-Shannon symmetrization of distances. When the variational optimization is further constrained to belong to prescribed families of probability measures, we get relative Jensen-Shannon divergences and their equivalent Jensen-Shannon symmetrizations of distances that generalize the concept of information projections. Finally, we touch upon applications of these variational Jensen-Shannon divergences and diversity indices to clustering and quantization tasks of probability measures, including statistical mixtures. 相似文献
4.
This paper proposes a method for solving optimisation problems involving piecewise quadratic functions. The method provides a solution in a finite number of iterations, and the computational complexity of the proposed method is locally polynomial of the problem dimension, i.e., if the initial point belongs to the sufficiently small neighbourhood of the solution set. Proposed method could be applied for solving large systems of linear inequalities. 相似文献
5.
Dariusz Marek Adam Domaski Joanna Domaska Jakub Szygua Tadeusz Czachrski Jerzy Klamka 《Entropy (Basel, Switzerland)》2021,23(5)
In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature. 相似文献
6.
We address the problem of telegraphic transport in several dimensions. We review the derivation of two and three dimensional telegrapher’s equations—as well as their fractional generalizations—from microscopic random walk models for transport (normal and anomalous). We also present new results on solutions of the higher dimensional fractional equations. 相似文献
7.
A mean-field type model with random growth and reset terms is considered. The stationary distributions resulting from the corresponding master equation are relatively easy to obtain; however, for practical applications one also needs to know the convergence to stationarity. The present work contributes to this direction, studying the transient dynamics in the discrete version of the model by two different approaches. The first method is based on mathematical induction by the recursive integration of the coupled differential equations for the discrete states. The second method transforms the coupled ordinary differential equation system into a partial differential equation for the generating function. We derive analytical results for some important, practically interesting cases and discuss the obtained results for the transient dynamics. 相似文献
8.
9.
10.
针对“仓店一体化”模式下提供限时送达服务的新零售仓店,研究多拣货员、多客户、配送方式为带限时送达约束的路径优化分批配送情形下的订单拣选与配送集成调度问题。以最小化订单最大履行时间和配送成本为目标,构建了混合整数非线性规划模型,并设计两阶段启发式算法(H-2)进行求解,最后通过数值实验对算法进行验证与分析。数值实验结果表明,H-2具有较高的求解质量;相较于传统调度算法(TS)在效率提升、资源节约以及客户满意度提高方面具有更优的表现,进而为新零售仓店管理者提供决策支持。 相似文献