全文获取类型
收费全文 | 99508篇 |
免费 | 8019篇 |
国内免费 | 5529篇 |
专业分类
电工技术 | 5600篇 |
技术理论 | 6篇 |
综合类 | 6939篇 |
化学工业 | 13952篇 |
金属工艺 | 6322篇 |
机械仪表 | 5400篇 |
建筑科学 | 6188篇 |
矿业工程 | 2069篇 |
能源动力 | 2782篇 |
轻工业 | 10293篇 |
水利工程 | 2152篇 |
石油天然气 | 3413篇 |
武器工业 | 756篇 |
无线电 | 11860篇 |
一般工业技术 | 14321篇 |
冶金工业 | 6458篇 |
原子能技术 | 1192篇 |
自动化技术 | 13353篇 |
出版年
2024年 | 476篇 |
2023年 | 1412篇 |
2022年 | 2878篇 |
2021年 | 3723篇 |
2020年 | 2959篇 |
2019年 | 2323篇 |
2018年 | 2662篇 |
2017年 | 3021篇 |
2016年 | 2809篇 |
2015年 | 3878篇 |
2014年 | 5067篇 |
2013年 | 6878篇 |
2012年 | 6911篇 |
2011年 | 7877篇 |
2010年 | 6877篇 |
2009年 | 6585篇 |
2008年 | 6560篇 |
2007年 | 6184篇 |
2006年 | 5471篇 |
2005年 | 4480篇 |
2004年 | 3293篇 |
2003年 | 2812篇 |
2002年 | 2820篇 |
2001年 | 2462篇 |
2000年 | 1868篇 |
1999年 | 1654篇 |
1998年 | 1985篇 |
1997年 | 1466篇 |
1996年 | 1304篇 |
1995年 | 829篇 |
1994年 | 668篇 |
1993年 | 570篇 |
1992年 | 449篇 |
1991年 | 382篇 |
1990年 | 262篇 |
1989年 | 255篇 |
1988年 | 192篇 |
1987年 | 135篇 |
1986年 | 96篇 |
1985年 | 81篇 |
1984年 | 60篇 |
1983年 | 53篇 |
1982年 | 52篇 |
1981年 | 48篇 |
1980年 | 44篇 |
1979年 | 25篇 |
1978年 | 16篇 |
1977年 | 16篇 |
1976年 | 25篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
1.
2.
H. L. Du S. R. Rose Z. D. Xiang P. K. Datta X. Y. Li 《Materialwissenschaft und Werkstofftechnik》2003,34(4):421-426
The oxidation/sulphidation behaviour of a Ti‐46.7Al‐1.9W‐0.5Si alloy with a TiAl3 diffusion coating was studied in an environment of H2/H2S/H2O at 850oC. The kinetic results demonstrate that the TiAl3 coating significantly increased the high temperature corrosion resistance of Ti‐46.7Al‐1.9W‐0.5Si. The SEM, EDX, XRD and TEM analysis reveals that the formation of an Al2O3 scale on the surface of the TiAl3‐coated sample was responsible for the enhancement of the corroison resistance. The Ti‐46.7Al‐1.9W‐0.5Si alloy was also modified by Nb ion implantation. The Nb ion implanted and as received sampels were subjected to cyclic oxidation in an open air at 800oC. The Nb ion implantation not only increased the oxidation resistance but also substantially improved the adhesion of scale to the substrate. 相似文献
3.
Shi-Jin Ding Hang Hu Lim H.F. Kim S.J. Yu X.F. Chunxiang Zhu Li M.F. Byung Jin Cho Chan D.S.H. Rustagi S.C. Yu M.B. Chin A. Dim-Lee Kwong 《Electron Device Letters, IEEE》2003,24(12):730-732
For the first time, we successfully fabricated and demonstrated high performance metal-insulator-metal (MIM) capacitors with HfO/sub 2/-Al/sub 2/O/sub 3/ laminate dielectric using atomic layer deposition (ALD) technique. Our data indicates that the laminate MIM capacitor can provide high capacitance density of 12.8 fF//spl mu/m/sup 2/ from 10 kHz up to 20 GHz, very low leakage current of 3.2 /spl times/ 10/sup -8/ A/cm/sup 2/ at 3.3 V, small linear voltage coefficient of capacitance of 240 ppm/V together with quadratic one of 1830 ppm/V/sup 2/, temperature coefficient of capacitance of 182 ppm//spl deg/C, and high breakdown field of /spl sim/6 MV/cm as well as promising reliability. As a result, the HfO/sub 2/-Al/sub 2/O/sub 3/ laminate is a very promising candidate for next generation MIM capacitor for radio frequency and mixed signal integrated circuit applications. 相似文献
4.
Towards intelligent dressing 总被引:1,自引:0,他引:1
Egana I. Mendikute A. Urionaguena X. Alberdi H. 《IEEE instrumentation & measurement magazine》2006,9(3):38-43
The aim of this article is to state the principles of an intelligent monitoring and control system for the grinding machine, comprising the dressing process as well as grinding stability. 相似文献
5.
This paper provides an overview of the main aspects of modern fluorescence microscopy. It covers the principles of fluorescence and highlights the key discoveries in the history of fluorescence microscopy. The paper also discusses the optics of fluorescence microscopes and examines the various types of detectors. It also discusses the signal and image processing challenges in fluorescence microscopy and highlights some of the present developments and future trends in the field. 相似文献
6.
Simultaneous determination of six ephedrines in urine sample has been achieved by high performance liquid chromatography on a Lichrospher RP-18 column, using methylamphetamine as internal standard. The 6 ephedrines are well separated in 25 minutes with resolution better than 1.8. This method has high recovery, selectivity and reproducibility, and the linearity is satisfactory from 1.5 micrograms/ml to 25 micrograms/ml with correlation coefficients better than 0.999. 相似文献
7.
8.
Douay M. Xie W.X. Taunay T. Bernage P. Niay P. Cordier P. Poumellec B. Dong L. Bayon J.F. Poignant H. Delevaque E. 《Lightwave Technology, Journal of》1997,15(8):1329-1342
A comprehensive survey of photosensitivity in silica glasses and optical fiber is reviewed. Recent work on understanding the mechanisms contributing to germanium or aluminum doped fiber photosensitivity is discussed within the framework of photoelastic densification models 相似文献
9.
This article deals with the kinetics of two-step anionic polymerization by way of a non-steady state method. Several molecular parameters can be evaluated using the formulae developed. A bimodal molecular weight distribution function for the resulting polymer is derived from the set of kinetic differential equations, which is in agreement with the experimental data reported. 相似文献