全文获取类型
收费全文 | 10261篇 |
免费 | 688篇 |
国内免费 | 408篇 |
专业分类
电工技术 | 2813篇 |
技术理论 | 1篇 |
综合类 | 284篇 |
化学工业 | 1096篇 |
金属工艺 | 338篇 |
机械仪表 | 571篇 |
建筑科学 | 222篇 |
矿业工程 | 57篇 |
能源动力 | 1107篇 |
轻工业 | 87篇 |
水利工程 | 29篇 |
石油天然气 | 23篇 |
武器工业 | 36篇 |
无线电 | 1490篇 |
一般工业技术 | 1075篇 |
冶金工业 | 149篇 |
原子能技术 | 64篇 |
自动化技术 | 1915篇 |
出版年
2024年 | 25篇 |
2023年 | 146篇 |
2022年 | 198篇 |
2021年 | 265篇 |
2020年 | 284篇 |
2019年 | 243篇 |
2018年 | 222篇 |
2017年 | 349篇 |
2016年 | 403篇 |
2015年 | 479篇 |
2014年 | 661篇 |
2013年 | 626篇 |
2012年 | 635篇 |
2011年 | 917篇 |
2010年 | 698篇 |
2009年 | 741篇 |
2008年 | 721篇 |
2007年 | 731篇 |
2006年 | 610篇 |
2005年 | 493篇 |
2004年 | 347篇 |
2003年 | 376篇 |
2002年 | 264篇 |
2001年 | 186篇 |
2000年 | 124篇 |
1999年 | 116篇 |
1998年 | 93篇 |
1997年 | 67篇 |
1996年 | 56篇 |
1995年 | 74篇 |
1994年 | 59篇 |
1993年 | 29篇 |
1992年 | 24篇 |
1991年 | 35篇 |
1990年 | 20篇 |
1989年 | 16篇 |
1988年 | 13篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
41.
42.
Hybrid Approach for Addressing Uncertainty in Risk Assessments 总被引:3,自引:0,他引:3
Dominique Guyonnet Bernard Bourgine Didier Dubois Hélène Fargier Bernard C?me Jean-Paul Chilès 《Canadian Metallurgical Quarterly》2003,129(1):68-78
Parameter uncertainty is a major aspect of the model-based estimation of the risk of human exposure to pollutants. The Monte Carlo method, which applies probability theory to address model parameter uncertainty, relies on a statistical representation of available information. In recent years, other uncertainty theories have been proposed as alternative approaches to address model parameter uncertainty in situations where available information is insufficient to identify statistically representative probability distributions, due in particular to data scarcity. The simplest such theory is possibility theory, which uses so-called fuzzy numbers to represent model parameter uncertainty. In practice, it may occur that certain model parameters can be reasonably represented by probability distributions, because there are sufficient data available to substantiate such distributions by statistical analysis, while others are better represented by fuzzy numbers (due to data scarcity). The question then arises as to how these two modes of representation of model parameter uncertainty can be combined for the purpose of estimating the risk of exposure. This paper proposes an approach (termed a hybrid approach) which combines Monte Carlo random sampling of probability distribution functions with fuzzy calculus. The approach is applied to a real case of estimation of human exposure, via vegetable consumption, to cadmium present in the surficial soils of an industrial site located in the north of France. The application illustrates the potential of the proposed approach, which allows the uncertainty affecting model parameters to be represented in a way that is consistent with the information at hand. Also, because the hybrid approach takes advantage of the “rich” information provided by probability distributions, while retaining the conservative character of fuzzy calculus, it is believed to hold value in terms of a “reasonable” application of the precautionary principle. 相似文献
43.
一种基于混沌的随机数发生器设计及其IC实现 总被引:1,自引:1,他引:0
在密码学、仿真学以及集成电路测试等许多领域 ,随机数起着重要的作用。在密码学中 ,通常要求所使用的随机数具有不可预测性。基于混沌现象 ,使用开关电容技术 ,用集成电路实现了一种硬件随机数发生器。测试结果表明 ,其产生的序列具有不可预测性 ,可以满足密码学的应用要求。 相似文献
44.
Seung-Hwan Kim Seung-Bok Choi Sung-Ryong Hong M.-S.Moon-Sik Han 《International Journal of Mechanical Sciences》2004,46(1):269-157
This paper presents vibration control of a flexible beam structure using a hybrid mount which consists of elastic rubber and piezoelectric stack actuator. After identifying stiffness and damping properties of the rubber and piezoelectric elements, a mechanical model of the hybrid mount is established. The mount model is then incorporated with the beam structure, and the governing equation of motion is obtained in a state space. A sliding mode controller is designed in order to actively attenuate the vibration of the beam structure subjected to high-frequency and small magnitude excitations. The controller is experimentally realized and measured control responses such as acceleration of the beam structure and force transmission through the hybrid mount are evaluated and presented in both frequency and time domains. 相似文献
45.
The High Field Project at Dresden/Rossendorf: A Pulsed 100 T/10 ms Laboratory at an Infrared Free-Electron-Laser Facility 总被引:1,自引:0,他引:1
T. Herrmannsdörfer H. Krug F. Pobell S. Zherlitsyn H. Eschrig J. Freudenberger K. H. Müller L. Schultz 《Journal of Low Temperature Physics》2003,133(1-2):41-59
This article describes the project to build a pulsed magnetic field user laboratory at the Forschungszentrum Rossendorf near Dresden. Using a 50 MJ/24 kV capacitor bank, pulsed fields and rise times of 100 T/10 ms, 70 T/100 ms, and 60 T/1 s should be achieved. The laboratory will be built next to a free-electron-laser-facility for the middle and far infrared (5 to 150 µm, 2 ps, cw). We describe the work which has been performed until now to start the construction of the laboratory in 2003: coil concepts and computer simulations, materials development for the high field coils, and design of the capacitor bank modules. In addition, a pilot laboratory has been set up where fields up to 62 T/15 ms have been obtained with a 1 MJ/10 kV capacitor module. It is used to gain experience in the operation of such a facility and to test various parts of it. In this test laboratory special devices have been developed for measurements of magnetization and magnetoresistance, and have been successfully used to investigate various materials including semiconductors and Heavy Fermion compounds. In particular, metamagnetic transitions in intermetallic compounds and the irreversibility field of a high-T
c superconductor have been determined. Shubnikov–de Haas oscillations have been observed in the semimetallic compound CeBiPt. Resistance relaxation has been observed to start less than 1second after the field pulse. It could be shown for the first time that nuclear magnetic resonance (NMR) is detectable in pulsed fields. 相似文献
46.
47.
开关电流技术:一种新的模拟抽样数据处理方法 总被引:1,自引:0,他引:1
开关电流(SI)技术是一种新的模拟抽样数据处理技术,介绍了开关电流电路的基本单元结构,讨论了目前开关电流技术中存在的问题及其解决方法。对开关电流技术与开关电容技术的一些基本特征进行了比较,SI技术不仅结构简单,而且与标准CMOS工艺兼容,可望替代开关电容电路。 相似文献
48.
本文提出了激光功能微调技术在高精度混合集成电路上的应用,讨论了关键技术问题,并以实例具体说明。该技术的应用为研制高精度混合集成电路开辟了新途径。 相似文献
49.
A demonstrative study for the wind and solar hybrid power system 总被引:1,自引:0,他引:1
In March 1995, a small scale wind and solar hybrid power system was installed at Ashikaga Institute of Technology. Until now, the authors have acquired the data of the output of the hybrid power plant along with wind speed, wind direction, and the solar radiation, in order to demonstrate a complementary relationship between solar energy and wind energy.After nine months operation of the system, the authors confirmed that there exists a complementary relationship between solar energy and wind energy. We also found, however, that the power output by wind does not have much prospect compared to that by solar cell especially in summer season in Ashikaga area. 相似文献
50.
片式阻容元件的现状和发展方向 总被引:1,自引:1,他引:0
在国外的片式元器件(SMD)中,片式阻容元件发展最快,主要表现为片式化率迅速上升,尺寸越来越小,性能越来越好,包装形式多样化和生产管理不断改进。本文综述了国外阻容元件在这些方面的进展,指出了我国的差距,提出了我国如何发展的措施。 相似文献