全文获取类型
收费全文 | 273694篇 |
免费 | 3517篇 |
国内免费 | 1293篇 |
专业分类
电工技术 | 4725篇 |
综合类 | 515篇 |
化学工业 | 38233篇 |
金属工艺 | 11056篇 |
机械仪表 | 8275篇 |
建筑科学 | 6192篇 |
矿业工程 | 1573篇 |
能源动力 | 6877篇 |
轻工业 | 22027篇 |
水利工程 | 3016篇 |
石油天然气 | 5774篇 |
武器工业 | 43篇 |
无线电 | 33329篇 |
一般工业技术 | 55844篇 |
冶金工业 | 50860篇 |
原子能技术 | 7488篇 |
自动化技术 | 22677篇 |
出版年
2021年 | 2026篇 |
2019年 | 2056篇 |
2018年 | 3574篇 |
2017年 | 3668篇 |
2016年 | 3896篇 |
2015年 | 2484篇 |
2014年 | 4344篇 |
2013年 | 11956篇 |
2012年 | 7060篇 |
2011年 | 9698篇 |
2010年 | 7528篇 |
2009年 | 8744篇 |
2008年 | 9090篇 |
2007年 | 9129篇 |
2006年 | 7800篇 |
2005年 | 7246篇 |
2004年 | 7149篇 |
2003年 | 6896篇 |
2002年 | 6413篇 |
2001年 | 6521篇 |
2000年 | 6042篇 |
1999年 | 6425篇 |
1998年 | 15982篇 |
1997年 | 11303篇 |
1996年 | 8579篇 |
1995年 | 6797篇 |
1994年 | 5956篇 |
1993年 | 6006篇 |
1992年 | 4360篇 |
1991年 | 4142篇 |
1990年 | 4043篇 |
1989年 | 3994篇 |
1988年 | 3703篇 |
1987年 | 3343篇 |
1986年 | 3353篇 |
1985年 | 3696篇 |
1984年 | 3430篇 |
1983年 | 3181篇 |
1982年 | 3003篇 |
1981年 | 3008篇 |
1980年 | 2997篇 |
1979年 | 2802篇 |
1978年 | 2845篇 |
1977年 | 3122篇 |
1976年 | 4079篇 |
1975年 | 2407篇 |
1974年 | 2366篇 |
1973年 | 2377篇 |
1972年 | 2011篇 |
1971年 | 1769篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Chhipa Mayur Kumar Madhav B. T. P. Suthar Bhuvneshwer Janyani Vijay 《Photonic Network Communications》2022,44(1):30-40
Photonic Network Communications - In the present work, a high-speed optical encoder is proposed based on two-dimensional photonic crystal ring resonator using coupled mode theory and resonance... 相似文献
2.
Venhryn Yu. I. Popovych I. D. Serednytski A. S. Kolomys O. F. Luchechko A. P. Strelchuk V. V. 《Journal of Materials Science: Materials in Electronics》2022,33(14):10715-10722
Journal of Materials Science: Materials in Electronics - The ZnO and TiO2 nanopowders have been prepared by means of the pulsed laser reactive ablation of metallic (Zn, Ti) targets. The Structural,... 相似文献
3.
Raju E. Jayaprakash P. Hegde Tejaswi Ashok Vinitha G. Kumaresan S. 《Journal of Materials Science: Materials in Electronics》2022,33(1):167-176
Journal of Materials Science: Materials in Electronics - A mixed solution of 2-aminopyridine and succinic acid, with a 1:1 molar ratio, was kept at room temperature to develop a 2-aminopridinium... 相似文献
4.
Wireless Personal Communications - In a communication system, ultra-wideband (UWB) is the most promising solution because of its high speed, high data rate, and short-range communication. However,... 相似文献
5.
Kalinina E. V. Kudoyarov M. F. Nikitina I. P. Dementyeva E. V. Zabrodskii V. V. 《Semiconductors》2022,56(3):184-188
Semiconductors - The results of the effect of irradiation with Ar ions on the structural, electrophysical, and optical characteristics of ultraviolet Cr/4H-SiC photodetectors in the spectral range... 相似文献
6.
Yogeswararao G. Malmathanraj R. Palanisamy P. 《Multimedia Tools and Applications》2022,81(27):38735-38755
Multimedia Tools and Applications - The quality and quantity of agricultural products are significantly affected by plant diseases. The plant diseases could be mitigated if identified at an early... 相似文献
7.
Parkhomenko M. P. Kalenov D. S. Eremin I. S. Fedoseev N. A. Kolesnikova V. M. 《Journal of Communications Technology and Electronics》2022,67(9):1127-1133
Journal of Communications Technology and Electronics - A modified resonator method for determining the complex permittivity of materials based on the theory of small perturbations where a resonator... 相似文献
8.
Christopher J. Marvel Qirong Yang Scott D. Walck Kelvin Y. Xie Kristopher D. Behler Jerry C. LaSalvia Masashi Watanabe Richard A. Haber Martin P. Harmer 《Journal of the American Ceramic Society》2022,105(5):2990-3007
Compositional analysis of boron carbide on nanometer length scales to examine or interpret atomic mechanisms, for example, solid-state amorphization or grain-boundary segregation, is challenging. This work reviews advancements in high-resolution microanalysis to characterize multiple generations of boron carbide. First, ζ-factor microanalysis will be introduced as a powerful (scanning) transmission electron microscopy ((S)TEM) analytical framework to accurately characterize boron carbide. Three case studies involving the application of ζ-factor microanalysis will then be presented: (1) accurate stoichiometry determination of B-doped boron carbide using ζ-factor microanalysis and electron energy loss spectroscopy, (2) normalized quantification of silicon grain-boundary segregation in Si-doped boron carbide, and (3) calibration of a scanning electron microscope X-ray energy-dispersive spectroscopy (XEDS) system to measure compositional homogeneity differences of B/Si-doped arc-melted boron carbides in the as-melted and annealed conditions. Overall, the improvement and application of advanced analytical tools have helped better understand processing–microstructure–property relationships and successfully manufacture high-performance ceramics. 相似文献
9.
Rukomoynikov A. A. Yuminov I. P. Khamitov A. I. Garifullin I. Sh. Agliullin Ya. F. 《Russian Engineering Research》2022,42(9):916-919
Russian Engineering Research - Systems are considered for the dehydration of petroleum so as to separate water–petroleum emulsions. In particular, the low-temperature microwave (UHF)... 相似文献
10.