全文获取类型
收费全文 | 6818篇 |
免费 | 533篇 |
国内免费 | 657篇 |
专业分类
电工技术 | 405篇 |
综合类 | 423篇 |
化学工业 | 494篇 |
金属工艺 | 201篇 |
机械仪表 | 311篇 |
建筑科学 | 46篇 |
矿业工程 | 49篇 |
能源动力 | 124篇 |
轻工业 | 426篇 |
水利工程 | 18篇 |
石油天然气 | 106篇 |
武器工业 | 68篇 |
无线电 | 2920篇 |
一般工业技术 | 1634篇 |
冶金工业 | 73篇 |
原子能技术 | 143篇 |
自动化技术 | 567篇 |
出版年
2024年 | 24篇 |
2023年 | 79篇 |
2022年 | 128篇 |
2021年 | 157篇 |
2020年 | 166篇 |
2019年 | 167篇 |
2018年 | 141篇 |
2017年 | 204篇 |
2016年 | 215篇 |
2015年 | 186篇 |
2014年 | 355篇 |
2013年 | 392篇 |
2012年 | 396篇 |
2011年 | 460篇 |
2010年 | 368篇 |
2009年 | 399篇 |
2008年 | 379篇 |
2007年 | 485篇 |
2006年 | 512篇 |
2005年 | 451篇 |
2004年 | 407篇 |
2003年 | 334篇 |
2002年 | 282篇 |
2001年 | 235篇 |
2000年 | 218篇 |
1999年 | 171篇 |
1998年 | 115篇 |
1997年 | 91篇 |
1996年 | 88篇 |
1995年 | 55篇 |
1994年 | 54篇 |
1993年 | 53篇 |
1992年 | 52篇 |
1991年 | 51篇 |
1990年 | 35篇 |
1989年 | 26篇 |
1988年 | 28篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1961年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有8008条查询结果,搜索用时 15 毫秒
1.
2.
3.
L. Sheeney‐Haj‐Ichia S. Pogorelova Y. Gofer I. Willner 《Advanced functional materials》2004,14(5):416-424
Three different configurations of Au‐nanoparticle/CdS‐nanoparticle arrays are organized on Au/quartz electrodes for enhanced photocurrent generation. In one configuration, Au‐nanoparticles are covalently linked to the electrode and the CdS‐nanoparticles are covalently linked to the bare Au‐nanoparticle assembly. The resulting photocurrent, φ = 7.5 %, is ca. 9‐fold higher than the photocurrent originating from a CdS‐nanoparticle layer that lacks the Au‐nanoparticles, φ = 0.8 %. The enhanced photocurrent in the Au/CdS nanoparticle array is attributed to effective charge separation of the electron–hole pair by the injection of conduction‐band electrons from the CdS‐ to the Au‐nanoparticles. Two other configurations involving electrostatically stabilized bipyridinium‐crosslinked Au/CdS or CdS/Au nanoparticle arrays were assembled on the Au/quartz crystal. The photocurrent quantum yields in the two systems are φ = 10 % and φ = 5 %, respectively. The photocurrents in control systems that include electrostatically bridged Au/CdS or CdS/Au nanoparticles by oligocationic units that lack electron‐acceptor units are substantially lower than the values observed in the analogous bipyridinium‐bridged systems. The enhanced photocurrents in the bipyridinium‐crosslinked systems is attributed to the stepwise electron transfer of conduction‐band electrons to the Au‐nanoparticles by the bipyridinium relay bridge, a process that stabilizes the electron–hole pair against recombination and leads to effective charge separation. 相似文献
4.
Chih-Wea Wang Chi-Feng Wu Jin-Fu Li Cheng-Wen Wu Tony Teng Kevin Chiu Hsiao-Ping Lin 《Journal of Electronic Testing》2002,18(6):637-647
In this paper we propose a novel built-in self-test (BIST) design for embedded SRAM cores. Our contribution includes a compact and efficient BIST circuit with diagnosis support and an automatic diagnostic system. The diagnosis module of our BIST circuit can capture the error syndromes as well as fault locations for the purposes of repair and fault/failure analysis. In addition, our design provides programmability for custom March algorithms with lower hardware cost. The combination of the on-line programming mode and diagnostic system dramatically reduces the effort in design debugging and yield enhancement. We have designed and implemented test chips with our BIST design. Experimental results show that the area overhead of the proposed BIST design is only 2.4% for a 128 KB SRAM, and 0.65% for a 2 MB one. 相似文献
5.
6.
Kwang Soo Lee In Soo Park & Dong Sun Lee 《International Journal of Food Science & Technology》1996,31(1):7-13
The aim of this study was to design a modified atmosphere package for a mixed vegetable salad consisting of 75 g of cut carrot, 55 g of cut cucumber, 20 g of sliced garlic and 50 g of whole green pepper. Respiration data of all the components were combined with film permeability data to predict package atmospheres and design optimal packages for experimental testing for improved shelf-life of the produce. The optimal package avoided minimum O2 and maximum CO2 tolerance limits, and chilling injury temperatures for any component. A pouch form package made of 27 mm low density polyethylene developed a modified atmosphere of 2.0–2.1% O2 and 5.5–5.7% CO2 , which was beneficial for all components and provided better quality retention than other test packages. 相似文献
7.
8.
J. Okabayashi M. Watanabe H. Toyao T. Yamaguchi J. Yoshino 《Journal of Superconductivity and Novel Magnetism》2007,20(6):443-446
We have investigated the current pulse width dependence on current-driven magnetization reversal in double-barrier structures
using GaMnAs-based magnetic tunneling junctions (MTJ) in order to clarify the origin of low threshold current density for
current-driven magnetization reversal. Comparing with the case of single-barrier MTJ, the pulse-width dependence reveals that
threshold current density is reduced by double-barrier MTJ. We confirmed that the threshold current density in the order of
104 A/cm2 is estimated considering the effect of current pulse width. 相似文献
9.
A. Hori 《Thin solid films》2007,515(10):4480-4483
Electroluminescence (EL) spectral intensity in the high-brightness blue and green InGaN single-quantum-well (SQW) diodes has been comparatively studied over a wide temperature range and as a function of injection current. When the necessary forward bias conditions to get a certain current level are different, it is found that the anomalous EL quenching previously observed below 100 K for the SQW diodes strongly changes and shows a striking difference between the blue and green SQW diodes. This unusual EL evolution pattern is attributed to both internal and external fields, suggesting the importance of the internal piezoelectric field effects on the efficient carrier capture processes by localized tail states within the SQW under the presence of high-density misfit dislocations. 相似文献
10.
星间激光通信技术进展与趋势 总被引:3,自引:3,他引:0
较详细地评述了目前国外卫星间光通信技术研究的现状.根据关键单元技术的进展情况,总结了未来星间光通信系统的发展趋势。 相似文献