全文获取类型
收费全文 | 11606篇 |
免费 | 119篇 |
国内免费 | 140篇 |
专业分类
电工技术 | 138篇 |
综合类 | 7篇 |
化学工业 | 759篇 |
金属工艺 | 467篇 |
机械仪表 | 85篇 |
建筑科学 | 75篇 |
矿业工程 | 17篇 |
能源动力 | 66篇 |
轻工业 | 123篇 |
水利工程 | 27篇 |
石油天然气 | 22篇 |
无线电 | 427篇 |
一般工业技术 | 454篇 |
冶金工业 | 123篇 |
原子能技术 | 127篇 |
自动化技术 | 8948篇 |
出版年
2024年 | 3篇 |
2023年 | 24篇 |
2022年 | 84篇 |
2021年 | 107篇 |
2020年 | 44篇 |
2019年 | 65篇 |
2018年 | 61篇 |
2017年 | 41篇 |
2016年 | 70篇 |
2015年 | 44篇 |
2014年 | 291篇 |
2013年 | 275篇 |
2012年 | 847篇 |
2011年 | 3163篇 |
2010年 | 1214篇 |
2009年 | 1092篇 |
2008年 | 748篇 |
2007年 | 637篇 |
2006年 | 500篇 |
2005年 | 618篇 |
2004年 | 557篇 |
2003年 | 617篇 |
2002年 | 300篇 |
2001年 | 18篇 |
2000年 | 13篇 |
1999年 | 29篇 |
1998年 | 93篇 |
1997年 | 42篇 |
1996年 | 28篇 |
1995年 | 5篇 |
1994年 | 15篇 |
1993年 | 15篇 |
1992年 | 12篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 10篇 |
1986年 | 17篇 |
1985年 | 15篇 |
1984年 | 29篇 |
1983年 | 19篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1962年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Pavel Strunz Debashis Mukherji Přemysl Beran Ralph Gilles Lukas Karge Michael Hofmann Markus Hoelzel Joachim Rösler Gergely Farkas 《Metals and Materials International》2018,24(5):934-944
An addition of boron largely increases the ductility in polycrystalline high-temperature Co–Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ε (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co–17Re–23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ε to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co–17Re–23Cr–1.2Ta–2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0–1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content. 相似文献
4.
5.
The inter-comparative analysis of the deterministic safety potential of innovative molten salt systems with critical and sub-critical cores is presented for both fast and thermal neutron spectra. The analysis includes two aspects: the choice of an initial level of sub-criticality and the study of multiple unprotected transients which have been simulated on the basis of one-point kinetics and two-point thermo-hydraulic schemes considering realistic feedback effects. Our preliminary results show that even small levels of sub-criticality (2–3 dollars) of cores can improve their safety characteristics significantly. 相似文献
6.
Navab SinghAuthor Vitae Moitreyee Mukherjee-RoyAuthor VitaeSohan Singh MehtaAuthor Vitae 《Microelectronics Journal》2003,34(4):237-245
The patterning of contact holes by selecting out-of-focus image plane (defocus) using attenuated phase shift masks (APSM) has been studied. Defocus is found to enhance the image modulation at low partial coherence for contact holes with negative local average of mask function. Semi-dense holes up to 130 nm in 8% APSM have been printed by 0.5 μm defocus at a partial coherence of 0.31 using KrF scanner with highest numerical aperture of 0.68. However, these holes were closed with in-focus imaging. Defocus is also found to be beneficial for patterning the pitches that have extensive side lobes with in-focus imaging. 相似文献
7.
D. G. Pavel’ev N. V. Demarina Yu. I. Koshurinov A. P. Vasil’ev E. S. Semenova A. E. Zhukov V. M. Ustinov 《Semiconductors》2004,38(9):1105-1110
Characteristics of ohmic InGaAs contacts in planar diodes based on semiconductor superlattices with a small-area active region
(1–10 μm2) are studied. The diodes were formed on the basis of short (18 or 30 periods) heavily doped (1018 cm−3) GaAs/AlAs superlattices with a miniband width of 24.4 meV. The reduced resistance of the ohmic contact was equal to 2×10−7 Ω cm2 at room temperature. It is shown that the properties of fabricated planar diodes make it possible to use these diodes later
on in semiconductor devices that operate in the terahertz frequency region in a wide temperature range (4–300 K).
__________
Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 38, No. 9, 2004, pp. 1141–1146.
Original Russian Text Copyright ? 2004 by Pavel’ev, Demarina, Koshurinov, Vasil’ev, Semenova, Zhukov, Ustinov. 相似文献
8.
Monique Pavel 《Annals of Mathematics and Artificial Intelligence》1994,10(1-2):193-204
We present a short and rather informal account concerning a problem we posed in earlier work, recall our conjecture at the time, and report on our answer today. Specifically, our purpose is to draw attention to fiberwise topology as a possible mathematical tool for formalizing multi-colored images and other complex signals met in pattern recognition (P.R.), to provide some information concerning the mathematical background of the fiber topological machinery, and indicate how to use it. For a detailed technical study as well as a tentative hierarchical classification of topological images in growing order of complexity and the corresponding topological processing methods, the readers may consult Pavel [5]. The paper ends by mentioning some artificial intelligence (A.I.) aspects of the fiberwise imagery. 相似文献
9.
Adaptive motion control using neural network approximations 总被引:1,自引:0,他引:1
In this paper, we present a new adaptive technique for tracking control of mechanical systems in the presence of friction and periodic disturbances. Radial Basis Functions (RBFs) are used to compensate for the effects of nonlinearly occurring parameters in the friction and periodic disturbance model. Theoretical analysis, such as stability and transient performance, is provided. Furthermore, the performance of the adaptive RBF controller and its non-adaptive counterpart are compared. 相似文献
10.