全文获取类型
收费全文 | 2017篇 |
免费 | 137篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 31篇 |
综合类 | 1篇 |
化学工业 | 512篇 |
金属工艺 | 38篇 |
机械仪表 | 46篇 |
建筑科学 | 87篇 |
矿业工程 | 3篇 |
能源动力 | 72篇 |
轻工业 | 300篇 |
水利工程 | 35篇 |
石油天然气 | 11篇 |
无线电 | 223篇 |
一般工业技术 | 334篇 |
冶金工业 | 152篇 |
原子能技术 | 25篇 |
自动化技术 | 288篇 |
出版年
2024年 | 8篇 |
2023年 | 37篇 |
2022年 | 68篇 |
2021年 | 101篇 |
2020年 | 76篇 |
2019年 | 80篇 |
2018年 | 72篇 |
2017年 | 98篇 |
2016年 | 82篇 |
2015年 | 60篇 |
2014年 | 100篇 |
2013年 | 157篇 |
2012年 | 130篇 |
2011年 | 165篇 |
2010年 | 119篇 |
2009年 | 111篇 |
2008年 | 116篇 |
2007年 | 81篇 |
2006年 | 64篇 |
2005年 | 47篇 |
2004年 | 41篇 |
2003年 | 34篇 |
2002年 | 30篇 |
2001年 | 22篇 |
2000年 | 24篇 |
1999年 | 14篇 |
1998年 | 47篇 |
1997年 | 46篇 |
1996年 | 28篇 |
1995年 | 15篇 |
1994年 | 8篇 |
1993年 | 13篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有2158条查询结果,搜索用时 15 毫秒
1.
2.
3.
Castro Mateus B. Souza Raphael R. N. Junior Agord M. P. Lima Eduardo R. Manera Leandro T. 《Analog Integrated Circuits and Signal Processing》2021,109(3):647-656
Analog Integrated Circuits and Signal Processing - This paper presents the complete design of a phase locked loop-based clock synthesizer for reconfigurable analog-to-digital converters. The... 相似文献
4.
5.
Gomes A. C. S. A. Costa L. C. Brito D. C. Frana R. J. Marques Mnica R. C. 《Polymer Bulletin》2020,77(4):1969-1981
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with... 相似文献
6.
7.
Martin F. Falcone F. Bonache J. Marques R. Sorolla M. 《Microwave and Wireless Components Letters, IEEE》2003,13(12):511-513
A novel compact stop band filter consisting of a 50 /spl Omega/ coplanar waveguide (CPW) with split ring resonators (SRRs) etched in the back side of the substrate is presented. By aligning SRRs with the slots, a high inductive coupling between line and rings is achieved, with the result of a sharp and narrow rejection band in the vicinity of the resonant frequency of the rings. In order to widen the stop band of the filter, several ring pairs tuned at equally spaced frequencies within the desired gap are cascaded. The frequency response measured in the fabricated prototype device exhibits pronounced slopes at either side of the stop band and near 0 dBs insertion loss outside that band. Since SRR dimensions are much smaller than signal wavelength, the proposed filters are extremely compact and can be used to reject frequency parasitics in CPW structures by simply patterning properly tuned SRRs in the back side metal. Additional advantages are easy fabrication and compatibility with MMIC or PCB technology. 相似文献
8.
9.
Marcos de Carvalho Barcellos Alcino Palermo de Aguiar Mônica Regina Marques Palermo de Aguiar Luiz Claudio de Santa Maria 《Polymer Bulletin》2005,55(1-2):61-70
Summary This article deals with the handy synthesis of sulfonyl resins, which were produced by the treatment of a commercial sulfonic resin (Lewatit VPOC1812® based at divinylbenzene (DVB) and styrene (STY). The preliminary chemical modification was based on the reaction of the Lewatit VPOC1812® with thionyl chloride aiming to produce the sulfonyl chloride groups. The best conditions to obtain the sulfonyl chloride groups were: SOCl2/SO3H (molar ratio) =13 at 79 °C during 72 h. The resin chlorinated was afterward treated with urea, thiourea or guanidine. The functionalized resins with urea, thiourea or guanidine were produced with 56, 68 and 93% yield, respectively. The commercial and modified resins were characterized by apparent density, swelling degree, elemental analysis (CHNS), FTIR, optical microscopy (OM) and scanning electron microscopy (SEM). 相似文献
10.
Marques N.A. Kamon M. Silveira L.M. White J.K. 《Advanced Packaging, IEEE Transactions on》2004,27(4):569-580
As very large scale integration (VLSI) circuit speeds and density continue to increase, the need to accurately model the effects of three-dimensional (3-D) interconnects has become essential for reliable chip and system design and verification. Since such models are commonly used inside standard circuit simulators for time or frequency domain computations, it is imperative that they be kept compact without compromising accuracy, and also retain relevant physical properties of the original system, such as passivity. In this paper, we describe an approach to generate accurate, compact, and guaranteed passive models of RLC interconnects and packaging structures. The procedure is based on a partial element equivalent circuit (PEEC)-like approach to modeling the impedance of interconnect structures accounting for both the charge accumulation on the surface of conductors and the current traveling in their interior. The resulting formulation, based on nodal or mixed nodal and mesh analysis, enables the application of existing model order reduction techniques. Compactness and passivity of the model are then ensured with a two-step reduction procedure where Krylov-subspace moment-matching methods are followed by a recently proposed, nearly optimal, passive truncated balanced realization-like algorithm. The proposed approach was used for extracting passive models for several industrial examples, whose accuracy was validated both in the frequency domain as well as against measured time-domain data. 相似文献