全文获取类型
收费全文 | 23181篇 |
免费 | 332篇 |
国内免费 | 122篇 |
专业分类
电工技术 | 497篇 |
综合类 | 64篇 |
化学工业 | 3165篇 |
金属工艺 | 939篇 |
机械仪表 | 657篇 |
建筑科学 | 545篇 |
矿业工程 | 67篇 |
能源动力 | 599篇 |
轻工业 | 1832篇 |
水利工程 | 212篇 |
石油天然气 | 179篇 |
武器工业 | 1篇 |
无线电 | 2586篇 |
一般工业技术 | 4067篇 |
冶金工业 | 6130篇 |
原子能技术 | 419篇 |
自动化技术 | 1676篇 |
出版年
2021年 | 149篇 |
2020年 | 114篇 |
2019年 | 157篇 |
2018年 | 229篇 |
2017年 | 229篇 |
2016年 | 255篇 |
2015年 | 177篇 |
2014年 | 296篇 |
2013年 | 819篇 |
2012年 | 507篇 |
2011年 | 774篇 |
2010年 | 558篇 |
2009年 | 621篇 |
2008年 | 715篇 |
2007年 | 745篇 |
2006年 | 629篇 |
2005年 | 718篇 |
2004年 | 587篇 |
2003年 | 634篇 |
2002年 | 675篇 |
2001年 | 670篇 |
2000年 | 599篇 |
1999年 | 614篇 |
1998年 | 2158篇 |
1997年 | 1402篇 |
1996年 | 1043篇 |
1995年 | 718篇 |
1994年 | 618篇 |
1993年 | 640篇 |
1992年 | 358篇 |
1991年 | 344篇 |
1990年 | 341篇 |
1989年 | 343篇 |
1988年 | 292篇 |
1987年 | 267篇 |
1986年 | 245篇 |
1985年 | 275篇 |
1984年 | 215篇 |
1983年 | 200篇 |
1982年 | 185篇 |
1981年 | 217篇 |
1980年 | 202篇 |
1979年 | 164篇 |
1978年 | 152篇 |
1977年 | 277篇 |
1976年 | 386篇 |
1975年 | 127篇 |
1974年 | 109篇 |
1973年 | 117篇 |
1972年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
U. Schmoch 《Scientometrics》1993,26(1):193-211
The use of references of patent search reports as transfer indications needs a good theoretical understanding of the underlying examination procedures. On this background, different patent indicators based on sample patents and on respective references can be established and combined to a network which gives an interesting insight into the complex process of knowledge transfer from science to technology. 相似文献
102.
103.
104.
105.
Tauber D. Nagar R. Livne A. Eisenstein G. Koren U. Raybon G. 《Photonics Technology Letters, IEEE》1992,4(3):238-240
The authors report on the noise characteristics of InGaAs/InGaAsP multiple-quantum-well optical amplifiers operating near 1.5 μm. A noise figure of 4.4 dB is reported, verifying the predicted low-noise properties of quantum-well amplifiers 相似文献
106.
Today patients want to change their Christian names not so much for social support but in order to obtain sex change operations. For this reason among others we caution against casual and careless evaluations and plead for conscientiousness and thoroughness. The spectrum of 16 evaluation cases in the year 1995 is presented. Following this and looking for guiding principles, the most important aspects are discussed: the dilatable frame of the written law, the examiner's diagnostic process, the duty of being well informed, reconstruction of development as the first goal of examination, real-life self-testing and therapy, the obligation to report one's own findings, change of Christian name and indication of operation, evaluation for gender changing, problems of the judge-expert relationship and of future development. 相似文献
107.
On overview on the state of the art and future trends in physics-based electron device modelling for the computer-aided design of monolithic microwave ICs is provided. After a review of the main physics-based approaches to microwave modeling, special emphasis is placed on innovative developments relevant to circuit-oriented device performance assessment, such as efficient physics-based noise and parametric sensitivity analysis. The use of state-of-the-art physics-based analytical or numerical models for circuit analysis is discussed, with particular attention to the role of intermediate behavioral models in linking multidimensional device simulators with circuit analysis tools. Finally, the model requirements for yield-driven MMIC design are discussed, with the aim of pointing out the advantages of physics-based statistical device modeling; the possible use of computationally efficient approaches based on device sensitivity analysis for yield optimization is also considered 相似文献
108.
The authors demonstrate the application of a commercially available SiGe heterojunction bipolar transistor monolithic microwave integrated circuit technology to active mixers in future communication systems at 5.7 GHz and above. This technology can be used to realise circuits with less than 50 mW power consumption, conversion gains above 15 dB and small double sideband noise figures of 3.6 and 9.4 dB for 5.7 and 11.2 GHz Gilbert cell mixer circuits, respectively 相似文献
109.
Handschin E. Hoffmann W. Reyer F. Stephanblome T. Schlucking U. Westermann D. Ahmed S.S. 《Power Systems, IEEE Transactions on》1994,9(1):533-539
The synthesis of the structure of the power system stabiliser (PSS) and its parametrization are based entirely on methods of linear system theory. Thus the desired effect of the PSS is limited to a bounded area around one system operating point. The use of a controller based on fuzzy set theory introduces an event controlled excitation of the synchronous machine taking into account the power system operation. The desired response of the fuzzy controller is given by a set of rules which are obtained from the limits of the voltage regulator and the undesired performance of the conventional excitation control. A fuzzy controller has been developed for which simulation results are provided. These results support the concept of a fuzzy controller for the purpose of excitation control. They show that a well designed fuzzy controller is superior to a fast excitation control with an additional PSS 相似文献
110.
The UV instruments described in part I of this paper have been applied for measurements of solar global UV radiation in three different wavelength regions (310–320 nm, 315–391 nm, and 296–388 nm). UV radiation values obtained since 1985 are analyzed. Different types of regression equations were compared as to how much information on UV radiation is contained in total global radiation measurements (400–2800 nm). Applying those regression equations allows us to estimate UV radiation from measurements of total global radiation, which are readily available. 相似文献