全文获取类型
收费全文 | 25369篇 |
免费 | 1800篇 |
国内免费 | 2280篇 |
专业分类
电工技术 | 949篇 |
技术理论 | 2篇 |
综合类 | 1175篇 |
化学工业 | 880篇 |
金属工艺 | 687篇 |
机械仪表 | 1758篇 |
建筑科学 | 768篇 |
矿业工程 | 347篇 |
能源动力 | 601篇 |
轻工业 | 326篇 |
水利工程 | 171篇 |
石油天然气 | 201篇 |
武器工业 | 158篇 |
无线电 | 3516篇 |
一般工业技术 | 965篇 |
冶金工业 | 360篇 |
原子能技术 | 126篇 |
自动化技术 | 16459篇 |
出版年
2024年 | 20篇 |
2023年 | 283篇 |
2022年 | 517篇 |
2021年 | 795篇 |
2020年 | 701篇 |
2019年 | 488篇 |
2018年 | 451篇 |
2017年 | 472篇 |
2016年 | 549篇 |
2015年 | 686篇 |
2014年 | 1235篇 |
2013年 | 1320篇 |
2012年 | 1486篇 |
2011年 | 2098篇 |
2010年 | 1342篇 |
2009年 | 1434篇 |
2008年 | 1628篇 |
2007年 | 1869篇 |
2006年 | 1745篇 |
2005年 | 1669篇 |
2004年 | 1393篇 |
2003年 | 1320篇 |
2002年 | 1108篇 |
2001年 | 829篇 |
2000年 | 741篇 |
1999年 | 701篇 |
1998年 | 560篇 |
1997年 | 489篇 |
1996年 | 385篇 |
1995年 | 292篇 |
1994年 | 212篇 |
1993年 | 181篇 |
1992年 | 132篇 |
1991年 | 63篇 |
1990年 | 59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 | 14篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 5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 343 毫秒
81.
82.
83.
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
84.
Kyle A. Crawford
Osama K. Eyada PhD PE
《Computers & Industrial Engineering》1989,17(1-4):298-302The worldwide proliferation of fraudulent materials has brought about the need for a new approach to the control of purchased material quality. Nuclear power, defense, aerospace and many other industries are affected by the supply of poor quality clones that presume to be original replacement parts. Safety considerations abound as these highly defective materials are used in systems that are critical to the preservation of human lives. Commonly utilized quality assurance programs have not effectively stopped the influx of fraudulent materials. These programs fail to concentrate inspection efforts on materials and inspection attributes that would effectively prevent the acceptance of fraudulent materials. herein a solution is presented to this problem in the form of an expert system application. Information commonly available in industry is formulated into a knowledge based system wherein advisories are given to the user regarding key purchased material receipt inspection strategies. 相似文献
85.
Sung-Hoon An U-Yeol Park Kyung-In Kang Moon-Young Cho Hun-Hee Cho 《Canadian Metallurgical Quarterly》2007,21(4):259-264
Total conceptual cost estimates and the assessment of the quality of these estimates are critical in the early stages of a building construction project. In this study, the support vector machine (SVM) model for assessing the quality of conceptual cost estimates is proposed, and the application of SVM in construction areas is investigated. The results show that the SVM model assessed the quality of conceptual cost estimates slightly more accurately than the discriminant analysis model. This shows that using the SVM has potential in construction areas. In addition, the SVM model can assist clients in their evaluation of the quality of the estimated cost and the probability of exceeding the target cost, and in their decision on whether or not it is necessary to seek a more accurate estimate in the early stages of a project. 相似文献
86.
87.
Determination of vitality from a non-invasive biomedical measurement for use in fingerprint scanners
Fingerprints are the oldest and most widely used biometrics for personal identification. Unfortunately, it is usually possible to deceive automatic fingerprint identification systems by presenting a well-duplicated synthetic or dismembered finger. This paper introduces one method to provide fingerprint vitality authentication in order to solve this problem. Detection of a perspiration pattern over the fingertip skin identifies the vitality of a fingerprint. Mapping the two-dimensional fingerprint images into one-dimensional signals, two ensembles of measures, namely static and dynamic measures, are derived for classification. Static patterns as well as temporal changes in dielectric mosaic structure of the skin, caused by perspiration, demonstrate themselves in these signals. Using these measures, this algorithm quantifies the sweating pattern and makes a final decision about vitality of the fingerprint by a neural network trained by examples. 相似文献
88.
A neural network model for fault detection in conjunction with a programmable logic controller 总被引:2,自引:0,他引:2
This paper discusses the feasibility of using neural networks as a tool in the fault detection process. A neural network is integrated with a state language programmable logic controller, an important device in an automatic control system. Time series data related to time spent in a state is gathered and used as input into a neural network, for the purpose of identifying when a fault has occurred. A feedforward neural network is used to identify which (if any) of three types of faults may have occurred. Experimental results related to sensitivity and accuracy measures are presented. A brief review of related applications and research is also presented. 相似文献
89.
张鸿宾 《计算机应用与软件》1994,11(5):15-19,53
使用BP算法训练多层网络的速度很慢而且事先难于确定隐节点和隐层的适当数目。本文提出一个有效的算法,先构造决策树,然后将构造的决策树转换为神经网。文中使用一个全局准则函数控制决策树的增长,它较好地匹配了树的复杂性和训练样本量及错分率界。实验结果,本文的算法比用BP算法训练多层网络要快,而其分类精度不低于用BP算法训练的多层神经网。 相似文献
90.
提出并讨论了两种实现码分多址系统中最佳多用户检测的神经网络方法。一种基于离散Hopfield神经网络,另一种基于采用反向传播算法的多层感知器神经网络。理论分析和计算机模拟都证实了这两种神经网络方法的可行性,优越性和实用性。前者适用“固定”用户情况;后者既可用于“固定”用户吼适用于移动用户的情况,因而在未来的CDMA个人通信网中有较好的应用前景。 相似文献