全文获取类型
收费全文 | 290116篇 |
免费 | 21535篇 |
国内免费 | 11144篇 |
专业分类
电工技术 | 15469篇 |
技术理论 | 31篇 |
综合类 | 17456篇 |
化学工业 | 50255篇 |
金属工艺 | 16949篇 |
机械仪表 | 18453篇 |
建筑科学 | 22908篇 |
矿业工程 | 9541篇 |
能源动力 | 7964篇 |
轻工业 | 16795篇 |
水利工程 | 4809篇 |
石油天然气 | 20273篇 |
武器工业 | 2259篇 |
无线电 | 31527篇 |
一般工业技术 | 34452篇 |
冶金工业 | 15286篇 |
原子能技术 | 2873篇 |
自动化技术 | 35495篇 |
出版年
2024年 | 1222篇 |
2023年 | 4698篇 |
2022年 | 7954篇 |
2021年 | 11518篇 |
2020年 | 8560篇 |
2019年 | 7299篇 |
2018年 | 8191篇 |
2017年 | 9241篇 |
2016年 | 8041篇 |
2015年 | 11204篇 |
2014年 | 13798篇 |
2013年 | 16472篇 |
2012年 | 17796篇 |
2011年 | 19441篇 |
2010年 | 16780篇 |
2009年 | 15936篇 |
2008年 | 15469篇 |
2007年 | 15108篇 |
2006年 | 15999篇 |
2005年 | 14174篇 |
2004年 | 9076篇 |
2003年 | 7925篇 |
2002年 | 7322篇 |
2001年 | 6501篇 |
2000年 | 7111篇 |
1999年 | 8514篇 |
1998年 | 6850篇 |
1997年 | 5827篇 |
1996年 | 5458篇 |
1995年 | 4513篇 |
1994年 | 3759篇 |
1993年 | 2631篇 |
1992年 | 2140篇 |
1991年 | 1604篇 |
1990年 | 1174篇 |
1989年 | 933篇 |
1988年 | 760篇 |
1987年 | 524篇 |
1986年 | 389篇 |
1985年 | 265篇 |
1984年 | 183篇 |
1983年 | 120篇 |
1982年 | 130篇 |
1981年 | 86篇 |
1980年 | 71篇 |
1979年 | 24篇 |
1978年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Haitao Zhang Zonghai Chen Yongji Wang Ming Li Ting Qin 《International Journal of Adaptive Control and Signal Processing》2006,20(2):53-76
Laguerre Functional Model has many advantages such as good approximation capability for the variances of system time‐delay, order and other structural parameters, low computational complexity, and the facility of online parameter identification, etc., so this model is suitable for complex industrial process control. A series of successful applications have been gained in linear and non‐linear predictive control fields by the control algorithm based on Laguerre Functional Model, however, former researchers have not systemically brought forward the theoretical analyses of the stability, robustness, and steady‐state performance of this algorithm, which are the keys to guarantee the feasibility of the control algorithm fundamentally. Aimed at this problem, we introduce the principles of the Incremental Mode Linear Laguerre Predictive Control (IMLLPC) algorithm, and then systemically propose the theoretical analyses and proofs of the stability and robustness of the algorithm, in addition, we also put forward the steady‐state performance analysis. At last, the control performances of this algorithm on two different physical industrial plants are presented in detail, and a number of experimental results validate the feasibility and superiority of IMLLPC algorithm. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
63.
STUDYONRESIDUESOF~(14)C-FENITROTHIONINMODELRICE-FISHECOSYSTEMANDFIELDRICE-FISHECOSYSTEMZhangZhongliang(张仲良);WangHuaxin(王化新);G?.. 相似文献
64.
65.
通过对铝镁合金材料的焊接特性的分析 ,总结出内外两面成型且不加管道内衬的焊接施工工艺 ,以此来提高铝镁合金管道的焊接一次合格率 相似文献
66.
Shu-han Zhang 《IEEE transactions on instrumentation and measurement》1994,43(6):929-932
A method for calculating the partial capacitance (PC) in a multiconductor system (a system of conductors) consisting of n conductors parallel to the shield axis inside earthed cylindrical shields is discussed. Formulas for the PC in SI units are given. The PC is defined as the conductor-to-conductor capacitance and conductor-to-shield capacitance. These methods and formulas are suitable for calculating the PC of Gibbings' resistors with a calculable ac/dc resistance ratio 相似文献
67.
In this paper, the CdxHg1-xTe (x=1-0.7) doped silica glass was prepared through two step sol-gel process and in-situ growth technique from tetraethoxysilane (TEOS), cadmium acetate, mercury acetate and telluric acid. The influence of various factors on the glass was studied. The structure of the microcrystals was investigated by XRD. The absorption and transmittance spectrum of the composite showed that the shift of absorption edge was in conformity with the quantum size effect. The third-order nonlinear optical susceptibility χ(3) was measured by the degenerate four wave mixing (DFWM). The values of χ(3) was in the range of 10-11-10-12 MO esu at wavelength of 1.06 μm. 相似文献
68.
简要介绍了蒸汽发生器水位控制系统的运行方式和试验方法。试验项目包括旁通阀控制试验、主给水阀控制试验和旁通阀与主给水阀的切换试验。文中给出了试验结果,即在液位扰动和核动率扰动时,蒸汽发生器液位的变化过程。经过两个月的运行和瞬态试验,证明蒸汽发生器水位控制系统满足设计要求。 相似文献
69.
重大技术装备的制造水平是一个国家综合实力的直接体现,因此从上个世纪八十年代初开始,历届国务院领导人均兼任国家重大技术装备领导小组组长,通过推进重大技术装备的发展,促进 相似文献
70.
Yanbin Luo Jianhui Zhang Alexandrov P. Fursin L. Zhao J.H. Burke T. 《Electron Device Letters, IEEE》2003,24(11):695-697
This letter reports the design and fabrication of 4H-SiC bipolar junction transistors with both high voltage (>1kV) and high dc current gain (/spl beta/=32) at a collector current level of I/sub c/=3.83A (J/sub c/=319 A/cm/sup 2/). An Al-free base ohmic contact has been used which, when compared with BJTs fabricated with Al-based base contact, shows clearly improved blocking voltage. A specific on-resistance of 17 m/spl Omega//spl middot/cm/sup 2/ has been achieved for collector current densities up to 289 A/cm/sup 2/. 相似文献