全文获取类型
收费全文 | 105780篇 |
免费 | 18993篇 |
国内免费 | 3108篇 |
专业分类
电工技术 | 4753篇 |
技术理论 | 4篇 |
综合类 | 4335篇 |
化学工业 | 27979篇 |
金属工艺 | 4090篇 |
机械仪表 | 5461篇 |
建筑科学 | 6364篇 |
矿业工程 | 1315篇 |
能源动力 | 2871篇 |
轻工业 | 11967篇 |
水利工程 | 1543篇 |
石油天然气 | 2695篇 |
武器工业 | 484篇 |
无线电 | 15646篇 |
一般工业技术 | 20327篇 |
冶金工业 | 3624篇 |
原子能技术 | 919篇 |
自动化技术 | 13504篇 |
出版年
2024年 | 251篇 |
2023年 | 1015篇 |
2022年 | 1885篇 |
2021年 | 2926篇 |
2020年 | 3223篇 |
2019年 | 4653篇 |
2018年 | 4782篇 |
2017年 | 5297篇 |
2016年 | 5765篇 |
2015年 | 6409篇 |
2014年 | 7012篇 |
2013年 | 8968篇 |
2012年 | 7089篇 |
2011年 | 7308篇 |
2010年 | 6934篇 |
2009年 | 6528篇 |
2008年 | 6117篇 |
2007年 | 5575篇 |
2006年 | 5248篇 |
2005年 | 4494篇 |
2004年 | 3718篇 |
2003年 | 3541篇 |
2002年 | 3788篇 |
2001年 | 3187篇 |
2000年 | 2769篇 |
1999年 | 1958篇 |
1998年 | 1441篇 |
1997年 | 1134篇 |
1996年 | 979篇 |
1995年 | 819篇 |
1994年 | 707篇 |
1993年 | 544篇 |
1992年 | 395篇 |
1991年 | 322篇 |
1990年 | 244篇 |
1989年 | 208篇 |
1988年 | 160篇 |
1987年 | 115篇 |
1986年 | 81篇 |
1985年 | 73篇 |
1984年 | 48篇 |
1983年 | 25篇 |
1982年 | 30篇 |
1981年 | 32篇 |
1980年 | 21篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 16篇 |
1975年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
A route to synthesize ZSM‐5 crystals with a bimodal micro/mesoscopic pore system has been developed in this study; the successful incorporation of the mesopores within the ZSM‐5 structure was performed using tetrapropylammonium hydroxide (TPAOH)‐impregnated mesoporous materials containing carbon nanotubes in the pores, which were encapsulated in the ZSM‐5 crystals during a solid rearrangement process within the framework. Such mesoporous ZSM‐5 zeolites can be readily obtained as powders, thin films, or monoliths. 相似文献
74.
Jin Tae Kim Keun Byoung Yoon Choon-Gi Choi 《Photonics Technology Letters, IEEE》2004,16(7):1664-1666
A novel fabrication process using a hot embossing technique has been developed for micromechanical passive alignment of polymer planar lightwave circuit (PLC) devices. With only one step of embossing, single-mode waveguide straight channels and micropedestals for passive aligning are simultaneously defined on a polymer thin film with an accuracy of /spl plusmn/0.5 /spl mu/m. This process reduces the steps for fabricating alignment structures. A fabricated polymer PLC chip and fibers are combined on a v-grooved silicon optical bench (SiOB) in a flip-chip manner. The process provides a coupling loss as low as 0.67 dB per coupling face and a cost-effective packaging solution for various polymer PLC devices. 相似文献
75.
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
76.
Jeong-Soo Lee Yang-Kyu Choi Daewon Ha Balasubramanian S. Tsu-Jae King Bokor J. 《Electron Device Letters, IEEE》2003,24(3):186-188
The hydrogen annealing process has been used to improve surface roughness of the Si-fin in CMOS FinFETs for the first time. Hydrogen annealing was performed after Si-fin etch and before gate oxidation. As a result, increased saturation current with a lowered threshold voltage and a decreased low-frequency noise level over the entire range of drain current have been attained. The low-frequency noise characteristics indicate that the oxide trap density is reduced by a factor of 3 due to annealing. These results suggest that hydrogen annealing is very effective for improving device performance and for attaining a high-quality surface of the etched Si-fin. 相似文献
77.
T. Choi J.‐H. Jang C.K. Ullal M.C. LeMieux V.V. Tsukruk E.L. Thomas 《Advanced functional materials》2006,16(10)
The probing of the micromechanical properties within a two‐dimensional polymer structure with sixfold symmetry fabricated via interference lithography reveals a nonuniform spatial distribution in the elastic modulus “imprinted” with an interference pattern in work reported by Tsukruk, Thomas, and co‐workers on p. 1324. The image prepared by M. Lemieux and T. Gorishnyy shows how the interference pattern is formed by three laser beams and is transferred to the solid polymer structure. The elastic and plastic properties within a two‐dimensional polymer (SU8) structure with sixfold symmetry fabricated via interference lithography are presented. There is a nonuniform spatial distribution in the elastic modulus, with a higher elastic modulus obtained for nodes (brightest regions in the laser interference pattern) and a lower elastic modulus for beams (darkest regions in the laser interference pattern) of the photopatterned films. We suggest that such a nonuniformity and unusual plastic behavior are related to the variable material properties “imprinted” by the interference pattern. 相似文献
78.
H.W. Choi C.W. Jeon M.D. Dawson 《Photonics Technology Letters, IEEE》2004,16(1):33-35
The fabrication and performance of an InGaN light-emitting diode (LED) array based on a microring device geometry is reported. This design has been adopted in order to increase the surface area for light extraction and to minimize losses due to internal reflections and reabsorption. Electrical characteristics of these devices are similar to those of a conventional large-area LED, while the directed light extraction proves to be superior. In fact, these devices are found to be more efficient when operated at higher currents. This may be attributed to improved heat sinking due to the large surface area to volume ratio. The potential applications of these devices are also discussed. 相似文献
79.
80.
Polyaryloxydiphenylsilanes were prepared from phosphorus‐containing diols and diphenydichlorolsilane through solution polymerization. With a stoichiometric imbalance in feed monomers, the resulting polymers exhibited moderate melting points and good processing properties. The polymers prepared showed initial decomposition temperatures above 340 °C, excellent thermal stability, high char yields at 850 °C and very high limited oxygen index values of 56–59. The polymers' char yields and their (P + Si) contents showed linear relationships. © 2003 Society of Chemical Industry 相似文献