全文获取类型
收费全文 | 91805篇 |
免费 | 7942篇 |
国内免费 | 4180篇 |
专业分类
电工技术 | 5768篇 |
技术理论 | 2篇 |
综合类 | 5874篇 |
化学工业 | 14213篇 |
金属工艺 | 5080篇 |
机械仪表 | 5336篇 |
建筑科学 | 6824篇 |
矿业工程 | 1900篇 |
能源动力 | 2712篇 |
轻工业 | 7192篇 |
水利工程 | 1839篇 |
石油天然气 | 3988篇 |
武器工业 | 677篇 |
无线电 | 12159篇 |
一般工业技术 | 11781篇 |
冶金工业 | 4688篇 |
原子能技术 | 1040篇 |
自动化技术 | 12854篇 |
出版年
2024年 | 380篇 |
2023年 | 1399篇 |
2022年 | 2627篇 |
2021年 | 3646篇 |
2020年 | 2544篇 |
2019年 | 2135篇 |
2018年 | 2379篇 |
2017年 | 2836篇 |
2016年 | 2497篇 |
2015年 | 3457篇 |
2014年 | 4504篇 |
2013年 | 5733篇 |
2012年 | 6126篇 |
2011年 | 6846篇 |
2010年 | 5951篇 |
2009年 | 5721篇 |
2008年 | 5678篇 |
2007年 | 5434篇 |
2006年 | 5207篇 |
2005年 | 4252篇 |
2004年 | 2882篇 |
2003年 | 2398篇 |
2002年 | 2405篇 |
2001年 | 2057篇 |
2000年 | 1948篇 |
1999年 | 1971篇 |
1998年 | 1849篇 |
1997年 | 1592篇 |
1996年 | 1432篇 |
1995年 | 1204篇 |
1994年 | 932篇 |
1993年 | 768篇 |
1992年 | 619篇 |
1991年 | 467篇 |
1990年 | 389篇 |
1989年 | 305篇 |
1988年 | 253篇 |
1987年 | 185篇 |
1986年 | 154篇 |
1985年 | 140篇 |
1984年 | 101篇 |
1983年 | 75篇 |
1982年 | 68篇 |
1981年 | 59篇 |
1980年 | 51篇 |
1979年 | 35篇 |
1978年 | 32篇 |
1977年 | 32篇 |
1976年 | 54篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
61.
62.
Min-Shiang Hwang Chih-Wei Lin Cheng-Chi Lee 《Electronics letters》2002,38(23):1429-1431
An authenticated multiple-key agreement protocol is proposed. The protocol is not only secure against the unknown-key attack but also more efficient than other protocols. 相似文献
63.
Using AuGeNiCr multilayered metals as the wafer bonding medium, long-wavelength GaInAsP/InP vertical cavity surface emitting lasers employing Al-oxide/Si as the upper and lower distributed Bragg reflectors were fabricated on Si substrate with the bonding interface formed outside the vertical cavity surface emitting laser cavity. Laser emission at 1.545 μm was measured under pulsed operations near room temperature. The low-temperature metallic bonding process demonstrates a great potential in device fabrication 相似文献
64.
Coplanar waveguide-fed uniplanar bow-tie antenna 总被引:3,自引:0,他引:3
Yu-De Lin Syh-Nan Tsai 《Antennas and Propagation, IEEE Transactions on》1997,45(2):305-306
The design of coplanar waveguide (CPW)-fed bow-tie antenna for the 2.4-GHz ISM band is described. A coplanar waveguide-to-coplanar strips (CPW-to-CPS) balun is used to obtain the balanced feed line for the printed bow-tie. An analysis method based on the mixed potential integral equation method is used to characterize the input characteristics of the bow-tie antenna. The numerical results obtained are in good agreement with the experimental data. Through experiments with bow-tie antennas of various extended angles, the bow-tie antenna with a 90° extended angle exhibits the widest bandwidth in the desired frequency band which has a bandwidth of 17% for a VSWR <1.5:1 相似文献
65.
Color image retrieval based on hidden Markov models 总被引:1,自引:0,他引:1
In this correspondence, a new approach to retrieving images from a color image database is proposed. Each image in the database is represented by a two-dimensional pseudo-hidden Markov model (2-D PHMM), which characterizes the chromatic and spatial information about the image. In addition, a flexible pictorial querying method is used, by which users can paint the rough content of the desired images in a query picture. Image matching is achieved by comparing the query picture with each 2-D PHMM in the database. Experimental results show that the proposed approach is indeed effective. 相似文献
66.
Horng-Dar Lin 《Circuits and Devices Magazine, IEEE》1995,11(4):25-31
Identifies the basic technological components of multimedia communications. Among these technologies, multimedia processing and transmission already benefit heavily from VLSI advances. in fact, these two technologies could not have matured without special-purpose VLSI chips. We have examined basic processing required in these technologies and some VLSI architectures. The focus has been on standard-compliant VLSI chips, because the eventual goal of communications is to allow everyone to reach others without constraints. There are still a number of evolving standards, which means that we might witness yet another wave of VLSI chips for multimedia communications 相似文献
67.
本文用计算机数字模拟方法研究了电活性分子多层Z型L-B膜修饰电极的循环伏安行为。计算了电极与修饰L-B膜分子第一层之间的电荷转移速度常数K_o,L-B膜分子层间的电荷转移速度常数k_i;对峰电位差△E_p及阳极峰面积Q的影响,以及在不同条件下各层分子的氧化态分数随扫描时间的变化。为研究和设计电活性分子修饰电极的实际体系提供了大量数据和信息。 相似文献
68.
本文提出新型布线算法,集李氏迷宫法与线搜索法的长处为一体,以饱和带法进行动态排序,以线搜索法确定借孔位置,然后用李氏法进行单层布线,获得最佳路径,从而达到线型好,布通率高的效果。 相似文献
69.
On the magnetic-wall approximation for their slots, shielded coplanar waveguides (SCPWs) and semienclosed CPWs (SECPWs) are analyzed through an intensive use of elliptic function transformation. CAD-oriented formulas for the quasi-TEM parameters of SCPWs and SECPWs, including their coupled versions, are derived. The comparison of the results calculated here with previous ones show 2% accuracy for formulas in the practical situation where the slots are not too wide, e.g., s / (s + 2w) ≥ 0.2 for an SCPW. © 1994 John Wiley & Sons, Inc. 相似文献
70.