全文获取类型
收费全文 | 3278篇 |
免费 | 252篇 |
国内免费 | 20篇 |
专业分类
电工技术 | 41篇 |
综合类 | 25篇 |
化学工业 | 669篇 |
金属工艺 | 91篇 |
机械仪表 | 126篇 |
建筑科学 | 55篇 |
能源动力 | 246篇 |
轻工业 | 386篇 |
水利工程 | 28篇 |
石油天然气 | 27篇 |
无线电 | 386篇 |
一般工业技术 | 703篇 |
冶金工业 | 197篇 |
原子能技术 | 37篇 |
自动化技术 | 533篇 |
出版年
2024年 | 6篇 |
2023年 | 91篇 |
2022年 | 145篇 |
2021年 | 272篇 |
2020年 | 191篇 |
2019年 | 187篇 |
2018年 | 254篇 |
2017年 | 208篇 |
2016年 | 172篇 |
2015年 | 129篇 |
2014年 | 171篇 |
2013年 | 276篇 |
2012年 | 169篇 |
2011年 | 195篇 |
2010年 | 139篇 |
2009年 | 111篇 |
2008年 | 87篇 |
2007年 | 78篇 |
2006年 | 66篇 |
2005年 | 41篇 |
2004年 | 42篇 |
2003年 | 33篇 |
2002年 | 30篇 |
2001年 | 29篇 |
2000年 | 17篇 |
1999年 | 17篇 |
1998年 | 60篇 |
1997年 | 37篇 |
1996年 | 28篇 |
1995年 | 28篇 |
1994年 | 27篇 |
1993年 | 25篇 |
1992年 | 15篇 |
1991年 | 15篇 |
1990年 | 8篇 |
1989年 | 20篇 |
1988年 | 19篇 |
1987年 | 16篇 |
1986年 | 11篇 |
1985年 | 15篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 12篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1975年 | 4篇 |
1974年 | 6篇 |
排序方式: 共有3550条查询结果,搜索用时 15 毫秒
1.
Naqvi Nuzhat Abbasi Aliya Tabassum Hussain Rasheed Khan M. Aihab Ahmad Basheer 《Wireless Personal Communications》2018,103(2):1563-1585
Wireless Personal Communications - This paper presents a Multilayer Partially Homomorphic Encryption Text Steganography, an invisible approach for covert communication. Existing text-based schemes... 相似文献
2.
Mudassar Hussain Turgut Meydan Jerome A. Cuenca Yevgen Melikhov Ghulam Mustafa Ghulam Murtaza Yasir Jamil 《Ceramics International》2018,44(6):5909-5914
A series of co-precipitated Zn1?xCoxGdyFe2?yO4 spinel ferrites (x = 0.0–0.5, y = 0.00–0.10) sintered at 1000 °C were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), vibrating sample magnetometery (VSM) and microwave cavity perturbation (MCP). XRD patterns and FTIR spectra reveal formation of the spinel phase along with few traces of GdFeO3 second phase. The lattice constant decreases with an increasing amount of CoGd ions due to the segregation of Gd3+on the grain boundaries and due to replacement of lager Zn2+ ions with smaller Co2+ ions. SEM shows grain size to decrease with the increase of CoGd contents due to grain growth inhibition by the second phase. VSM results show remanence and saturation magnetization to exhibit an increasing trend due to Co substitution on octahedral sites and presence of a second phase. The coercivity increases with the increase of CoGd contents due to anisotropic nature of Co. MCP shows the complex magnetic permeability to increase with CoGd concentration while the complex permittivity decreases. 相似文献
3.
Multimedia Tools and Applications - Disc herniation is considered as a very common spine abnormality resulting in severe pain in back and legs. Besides it has great impact on economy of suffering... 相似文献
4.
Abidi Syed Muhammad Raza Xu Yonglin Ni Jianyue Wang Xiangmeng Zhang Wu 《Multimedia Tools and Applications》2020,79(47-48):35583-35617
Multimedia Tools and Applications - Film industries all over the world are producing several hundred movies rapidly and grabbing the attraction of people of all ages. Every movie producer is of... 相似文献
5.
Rehena Nasrin Saddam Hossain Ishrat Zahan Khandker Farid Uddin Ahmed Hussain Fayaz 《亚洲传热研究》2020,49(8):4204-4225
This numerical study reveals the heat transfer performance of hybrid/single nanofluids inside a lid-driven sinusoidal trapezoidal-shaped enclosure. The right and left inclined surfaces of the trapezium have been considered as insulated, whereas the bottom sinusoidal wavy and the flat top surfaces of the enclosure as hot and cold, respectively. The governing partial differential equations of fluid's velocity and temperature have been resolved by applying the finite element method. The implications of Prandtl number (4.2-6.2), Richardson number (0.1-10.0), undulation number (0-3), nanoparticles volume fraction (0%-3%), and nanofluid/base fluid (water, water–copper (Cu), water–Cu–carbon nanotube, water–Cu–copper oxide (CuO), water–Cu–TiO2, and water–Cu–Al2O3) on the velocity and temperature profiles have been studied. Simulated findings have been represented by means of streamlines, isothermal lines, and average Nusselt number of above-mentioned hybrid nanofluids for varying the governing parameters. The comparison of heat transfer rates using hybrid nanofluids and pure water has been also shown. The heat transfer rate is increased about 15% for varying Richardson number from 0.1 to 10.0. Blending of two nanoparticles suspension in base fluid has a higher heat transfer rate—approximately 5% than a mononanoparticle. Moreover, a higher average Nusselt number is obtained by 14.7% using the wavy surface than the flat surface of the enclosure. Thus, this study showed that applying hybrid nanofluid may be beneficial to obtain expected thermal performance. 相似文献
6.
7.
8.
Moiduddin Khaja Mian Syed Hammad Ahmed Naveed Ameen Wadea Al-Khalefah Hisham Mohammed Muneer khan Umer Usama 《The International Journal of Advanced Manufacturing Technology》2020,106(9):3831-3847
The International Journal of Advanced Manufacturing Technology - The restoration of mandibular defects, especially large deformities is regarded as the most challenging surgical procedure owing to... 相似文献
9.
Yassen Mahmood T. Hussan Mohammed R. Hammas Hussain A. Al-Saedi Hussam Ali Jawad K. 《Wireless Personal Communications》2019,104(2):649-662
Wireless Personal Communications - The design of a fractal based slot antenna, to serve the dual-band communication applications, is proposed in this paper. The structure of the proposed antenna is... 相似文献
10.
Maktabdar Oghaz Mahdi Maarof Mohd Aizaini Rohani Mohd Foad Zainal Anazida Shaid Syed Zainudeen Mohd 《Neural computing & applications》2019,31(6):1835-1853
Neural Computing and Applications - Texture analysis is devised to address the weakness of color-based image segmentation models by considering the statistical and spatial relations among the group... 相似文献