全文获取类型
收费全文 | 858806篇 |
免费 | 11556篇 |
国内免费 | 2612篇 |
专业分类
电工技术 | 14734篇 |
综合类 | 3274篇 |
化学工业 | 126280篇 |
金属工艺 | 37487篇 |
机械仪表 | 28429篇 |
建筑科学 | 20671篇 |
矿业工程 | 5905篇 |
能源动力 | 21257篇 |
轻工业 | 64529篇 |
水利工程 | 10434篇 |
石油天然气 | 18601篇 |
武器工业 | 79篇 |
无线电 | 93358篇 |
一般工业技术 | 174476篇 |
冶金工业 | 140213篇 |
原子能技术 | 19156篇 |
自动化技术 | 94091篇 |
出版年
2021年 | 6857篇 |
2020年 | 5329篇 |
2019年 | 6938篇 |
2018年 | 26756篇 |
2017年 | 25991篇 |
2016年 | 22569篇 |
2015年 | 8792篇 |
2014年 | 13803篇 |
2013年 | 36198篇 |
2012年 | 24625篇 |
2011年 | 39337篇 |
2010年 | 32504篇 |
2009年 | 32634篇 |
2008年 | 34164篇 |
2007年 | 35486篇 |
2006年 | 22459篇 |
2005年 | 22791篇 |
2004年 | 21368篇 |
2003年 | 20736篇 |
2002年 | 18477篇 |
2001年 | 17055篇 |
2000年 | 15902篇 |
1999年 | 16125篇 |
1998年 | 38677篇 |
1997年 | 27928篇 |
1996年 | 21410篇 |
1995年 | 17178篇 |
1994年 | 15351篇 |
1993年 | 15186篇 |
1992年 | 11582篇 |
1991年 | 11136篇 |
1990年 | 10941篇 |
1989年 | 10623篇 |
1988年 | 10102篇 |
1987年 | 9180篇 |
1986年 | 8984篇 |
1985年 | 10168篇 |
1984年 | 9293篇 |
1983年 | 8708篇 |
1982年 | 7945篇 |
1981年 | 8061篇 |
1980年 | 7781篇 |
1979年 | 7703篇 |
1978年 | 7675篇 |
1977年 | 8422篇 |
1976年 | 10665篇 |
1975年 | 6773篇 |
1974年 | 6504篇 |
1973年 | 6552篇 |
1972年 | 5587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.
Zenkour A. M. Abouelregal A. E. 《Journal of Engineering Physics and Thermophysics》2022,95(3):651-661
Journal of Engineering Physics and Thermophysics - The generalized nonlocal thermoelastic model in the context of Eringen’s nonlocal elasticity is applied to investigate the... 相似文献
5.
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
6.
Kuznetsov I. V. Budin O. N. Shchepin A. S. Kalenova M. Yu. Mel’nikova I. M. Saprykin R. V. Al’zhev N. I. 《Inorganic Materials》2022,58(6):651-660
Inorganic Materials - We have studied the effect of annealing on the chemical and physical properties of mineral-like host matrices for immobilization of the rare-earth–actinide fraction from... 相似文献
7.
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
8.
Yusupov M. R. Umurakova K. E. Gantsev A. V. Akhmetov A. F. 《Chemistry and Technology of Fuels and Oils》2022,58(3):449-453
Chemistry and Technology of Fuels and Oils - This article considers the alternatives for treatment of the raffinate produced at a unit for the extraction of benzene-containing fractions and the... 相似文献
9.
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
10.
Khaled Al-Farhany Mohammed A. Alomari Ahmed Al-Saadi Ali Chamkha Hakan F. Öztop Wael Al-Kouz 《亚洲传热研究》2022,51(2):1691-1710
In the current work, numerical simulations are achieved to study the properties and the characteristics of fluid flow and heat transfer of (Cu–water) nanofluid under the magnetohydrodynamic effects in a horizontal rectangular canal with an open trapezoidal enclosure and an elliptical obstacle. The cavity lower wall is grooved and represents the heat source while the obstacle represents a stationary cold wall. On the other hand, the rest of the walls are considered adiabatic. The governing equations for this investigation are formulated, nondimensionalized, and then solved by Galerkin finite element approach. The numerical findings were examined across a wide range of Richardson number (0.1 ≤ Ri ≤ 10), Reynolds number (1 ≤ Re ≤ 125), Hartmann number (0 ≤ Ha ≤ 100), and volume fraction of nanofluid (0 ≤ φ ≤ 0.05). The current study's findings demonstrate that the flow strength increases inversely as the Reynolds number rises, which pushes the isotherms down to the lower part of the trapezoidal cavity. The Nuavg rises as the Ri rise, the maximum Nuavg = 10.345 at Ri = 10, Re = 50, ϕ = 0.05, and Ha = 0; however, it reduces with increasing Hartmann number. Also, it increase by increasing ϕ, at Ri = 10, the Nuavg increased by 8.44% when the volume fraction of nanofluid increased from (ϕ = 0–0.05). 相似文献