全文获取类型
收费全文 | 42273篇 |
免费 | 6517篇 |
国内免费 | 3058篇 |
专业分类
电工技术 | 3039篇 |
技术理论 | 2篇 |
综合类 | 3745篇 |
化学工业 | 3307篇 |
金属工艺 | 1104篇 |
机械仪表 | 3364篇 |
建筑科学 | 1574篇 |
矿业工程 | 449篇 |
能源动力 | 975篇 |
轻工业 | 1002篇 |
水利工程 | 562篇 |
石油天然气 | 486篇 |
武器工业 | 363篇 |
无线电 | 5374篇 |
一般工业技术 | 1697篇 |
冶金工业 | 753篇 |
原子能技术 | 275篇 |
自动化技术 | 23777篇 |
出版年
2024年 | 30篇 |
2023年 | 368篇 |
2022年 | 851篇 |
2021年 | 1053篇 |
2020年 | 1005篇 |
2019年 | 827篇 |
2018年 | 932篇 |
2017年 | 805篇 |
2016年 | 951篇 |
2015年 | 928篇 |
2014年 | 4648篇 |
2013年 | 3680篇 |
2012年 | 4606篇 |
2011年 | 5361篇 |
2010年 | 4348篇 |
2009年 | 4076篇 |
2008年 | 2561篇 |
2007年 | 2042篇 |
2006年 | 1858篇 |
2005年 | 1763篇 |
2004年 | 1476篇 |
2003年 | 1393篇 |
2002年 | 1174篇 |
2001年 | 927篇 |
2000年 | 780篇 |
1999年 | 747篇 |
1998年 | 584篇 |
1997年 | 520篇 |
1996年 | 395篇 |
1995年 | 304篇 |
1994年 | 213篇 |
1993年 | 182篇 |
1992年 | 135篇 |
1991年 | 63篇 |
1990年 | 60篇 |
1989年 | 45篇 |
1988年 | 29篇 |
1987年 | 16篇 |
1986年 | 24篇 |
1985年 | 18篇 |
1984年 | 18篇 |
1983年 | 15篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Molecular dynamics simulations are used to investigate polymer networks made by either end-linking or randomly crosslinking a melt of linear precursor chains. The resulting network structures are very different, since end-linking leads to nearly ideal monodisperse networks, while random crosslinking leads to polydisperse networks, characterized by an exponential strand length distribution. Networks with average strand length 20 and 100 were generated. These networks were used to study the effects of disorder in the network connectivity on observables averaged either over the entire network or selected sub-structures. Heterogeneities in the randomly crosslinked networks cause significant differences in the localization of monomers, however, neither the localization of crosslinks nor the microscopic strain response are significantly affected. Compared to end-linked networks, randomly crosslinked networks have a slightly increased tube diameter, and as a result a slightly decreased shear modulus, but otherwise identical stress-strain behavior. For the investigated systems, we conclude that the microscopic strain response, tube diameter, and stress-strain relation are all insensitive to the heterogeneities due to the linking process by which the network were made. 相似文献
72.
73.
本文介绍了3COM Superstack ⅡSwitch 3300 的主要特性及其在局域网中的实际应用,评述了冗余网络的构造等问题。 相似文献
74.
Bingyong Yan Zuohua Tian Songjiao Shi 《International Journal of Electrical Power & Energy Systems》2008,30(5):343-360
In this paper, we propose a novel distributed robust fault detection and identification (RFDI) scheme for a class of nonlinear systems. Firstly, a detection and identification estimator—robust fault tracking approximator (RFTA) is designed for online health monitoring. A novel feature of the RFTA is that it can simultaneously detect and accurately identify the shape and magnitude of the fault and disturbance. Moreover, it takes less online training time compared with the traditional neural network based fault diagnosis schemes. For some distributed systems, a network of distributed estimators is constructed where the RFTA is embedded into each estimator. Then we use consensus filter to filter the outputs of each estimator. One of the most important merits of the consensus filter is that its outputs can dramatically improve the accuracy of fault detection and identification. Next, the stability of the distributed RFDI scheme is rigorously investigated. Finally, two numerical examples are given to illustrate the feasibility and effectiveness of the proposed approach. 相似文献
75.
The use of neural networks as global approximation tool in crashworthiness problems is here investigated. Neural networks are not only asked to return some meaningful indices of the structural behavior but also to reproduce load-time curves during crash phenomena. To contain the number of examples required for the training process, parallel subsystems of small neural networks are designed. Design points for the training process are obtained by explicit finite element analyses performed by PAMCRASH. The settlement of the points in the design domain is defined using a maximum distance concept. The procedure is applied to different typical absorption structures made of aluminum alloy: riveted tubes, honeycomb structures, longitudinal keel beam and intersection elements of helicopter subfloors. 相似文献
76.
V. Rodin Author Vitae A. Benzinou Author VitaeAuthor Vitae P. Ballet Author VitaeAuthor Vitae J. Tisseau Author VitaeAuthor Vitae 《Pattern recognition》2004,37(4):631-645
In this article, we present a parallel image processing system based on the concept of reactive agents. Our system lies in the oRis language, which allows to describe finely and simply the agents’ behaviors to detect image features. We also present a method of segmentation using a multi-agent system, and two biological applications made with oRis. The stopping of this multi-agent system is implemented through a technique issued from immunology: the apoptosis. 相似文献
77.
78.
79.
80.
国内3G网络共享问题之研究 总被引:2,自引:0,他引:2
随着国内3G时代的来临,3G网络共享问题越来越受到人们的关注。本文结合国内移动通信的现状,着重分析了3G网络共享的模式及经济效益,论述了3G网络共享的相应策略。 相似文献