全文获取类型
收费全文 | 408篇 |
免费 | 97篇 |
国内免费 | 17篇 |
专业分类
化学 | 40篇 |
晶体学 | 4篇 |
力学 | 83篇 |
综合类 | 12篇 |
数学 | 190篇 |
物理学 | 193篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 5篇 |
2017年 | 16篇 |
2016年 | 25篇 |
2015年 | 16篇 |
2014年 | 21篇 |
2013年 | 26篇 |
2012年 | 36篇 |
2011年 | 24篇 |
2010年 | 28篇 |
2009年 | 22篇 |
2008年 | 34篇 |
2007年 | 20篇 |
2006年 | 26篇 |
2005年 | 21篇 |
2004年 | 15篇 |
2003年 | 19篇 |
2002年 | 13篇 |
2001年 | 16篇 |
2000年 | 17篇 |
1999年 | 16篇 |
1998年 | 2篇 |
1997年 | 13篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有522条查询结果,搜索用时 593 毫秒
1.
2.
In this paper, we analyze the manufacturing lead time in a production system with BMAP (Batch Markovian Arrival process) input and post-operation operated under the N-policy. We use the factorization principle to derive the waiting time distribution (hence the manufacturing lead time) and the mean performance measures. A numerical example is provided. 相似文献
3.
4.
Lubomír Kubáček 《Mathematica Slovaca》2007,57(1):59-82
In some situations estimates of unknown parameters must be corrected by additional measurements. It is in principle no problem
to calculate the corrected estimates, however, it is of more interest to find formulae for correction itself. The formulae
enable us to design an additional experiment and to judge its usefulness.
The aim of the paper is to find such formulae for several situations.
Supported by the grant of the Council of Czech Government MSM 6 198 959 214. 相似文献
5.
Adaptive Constrained Control of Unknown Strict Feedback Nonlinear Systems With Dead Zone Input北大核心CSCD 下载免费PDF全文
研究了具有死区输入的预设约束未知高阶严格反馈非线性系统的控制问题,提出了一种基于免疫函数的自抗扰预设漏斗约束自适应控制策略。首先,针对系统内部的未知问题,采用免疫函数与扩张状态观测器结合对系统内部未知项进行观测;其次,通过Lyapunov方法与漏斗控制相结合设计控制器,使得跟踪误差能够维持在预先设定的漏斗约束范围内;同时,利用双曲正切函数速率变化快这一特性设计自适应控制律,引入指令滤波器避免反步法中重复求导问题,分析证明了闭环系统所有信号的有界性。仿真实例表明了控制方法的有效性。 相似文献
6.
In the study, a series of C_(30)-C_(32) lanostane homologs have been identified from Eogene source rocks and crude oils of Biyang depression in Henan Province, China. Based upon the geochemical investigations and simulating experiments, the idea that the generation of lanostane may mainly be related to the specific original organic inputs and low maturity has been proposed. 相似文献
7.
8.
Green solvent approach for printable large deformation thermoplastic elastomer based piezoresistive sensors and their suitability for biomedical applications 下载免费PDF全文
Bruna F. Gonçalves Pedro Costa Juliana Oliveira Sylvie Ribeiro Vitor Correia Gabriela Botelho Senentxu Lanceros‐Mendez 《Journal of Polymer Science.Polymer Physics》2016,54(20):2092-2103
Composites based on biocompatible thermoplastic elastomer styrene‐ethylene/butylene‐styrene (SEBS) as matrix and multi‐walled carbon nanotubes (MWCNT) as nanofillers show excellent mechanical and piezoresistive properties from low to large deformations. The MWCNT/SEBS composites have been prepared following a green solvent approach, to extend their range of applicability to biomedical applications. The obtained composites with 2, 4, and 5 wt % MWCNT content provide suitable piezoresistive response up to 80% deformation with a piezoresistive sensibility near 2.7, depending on the applied strain and MWCNT content. Composite sensors were also developed by spray and screen printing and integrated with an electronic data acquisition system with RF communication. The possibility to accurately control the composites properties and performance by varying MWCNT content, viscosity, and mechanical properties of the polymer matrix, shows the large potential of the system for the development of large deformation printable piezoresistive sensors. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2092–2103 相似文献
9.
10.
Switching adaptive controllers to control fractional‐order complex systems with unknown structure and input nonlinearities 下载免费PDF全文
This article investigates the chaos control problem for the fractional‐order chaotic systems containing unknown structure and input nonlinearities. Two types of nonlinearity in the control input are considered. In the first case, a general continuous nonlinearity input is supposed in the controller, and in the second case, the unknown dead‐zone input is included. In each case, a proper switching adaptive controller is introduced to stabilize the fractional‐order chaotic system in the presence of unknown parameters and uncertainties. The control methods are designed based on the boundedness property of the chaotic system's states, where, in the proposed methods the nonlinear/linear dynamic terms of the fractional‐order chaotic systems are assumed to be fully unknown. The analytical results of the mentioned techniques are proved by the stability analysis theorem of fractional‐order systems and the adaptive control method. In addition, as an application of the proposed methods, single input adaptive controllers are adopted for control of a class of three‐dimensional nonlinear fractional‐order chaotic systems. And finally, some numerical examples illustrate the correctness of the analytical results. © 2014 Wiley Periodicals, Inc. Complexity 21: 211–223, 2015 相似文献