全文获取类型
收费全文 | 631篇 |
免费 | 42篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 180篇 |
金属工艺 | 7篇 |
机械仪表 | 11篇 |
建筑科学 | 11篇 |
矿业工程 | 1篇 |
能源动力 | 14篇 |
轻工业 | 46篇 |
水利工程 | 15篇 |
无线电 | 60篇 |
一般工业技术 | 105篇 |
冶金工业 | 143篇 |
原子能技术 | 10篇 |
自动化技术 | 66篇 |
出版年
2022年 | 14篇 |
2021年 | 27篇 |
2020年 | 14篇 |
2019年 | 26篇 |
2018年 | 22篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 16篇 |
2014年 | 27篇 |
2013年 | 29篇 |
2012年 | 37篇 |
2011年 | 27篇 |
2010年 | 16篇 |
2009年 | 20篇 |
2008年 | 22篇 |
2007年 | 27篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 17篇 |
2003年 | 15篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 12篇 |
1999年 | 9篇 |
1998年 | 40篇 |
1997年 | 24篇 |
1996年 | 25篇 |
1995年 | 18篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有673条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
Aicardi M. Davoli F. Giordano A. 《Selected Areas in Communications, IEEE Journal on》1989,7(2):219-225
A solution for the connection of personal computers or workstations to a central station (represented by a mainframe or a server attached to a local area network) by means of a shared radio channel is presented. Issues regarding the multiple-access protocol are discussed, and an access scheme that is based on the independent stations algorithm (ISA) is presented. The necessary modifications of the basic ISA are discussed, and the overall algorithm is analyzed and tested by simulation. An implementation that is currently being developed is briefly described, focusing on the choices made for the logical link control protocol, the transmission techniques, and the interface software 相似文献
65.
V. Alderucci E. Passalacqua N. Giordano P. L. Antonucci F. Parmigiani N. Ricci 《Journal of Applied Electrochemistry》1990,20(2):235-239
This paper reports the experimental evidence for morphological changes that occur at the electrodes of phosphoric acid fuel cells (PAFC) under very severe (OCV) conditions. In addition, the dissolution of Pt-supported crystallites in H3PO4 is demonstrated by Transmission Electron Microscopy (TEM) confirming previous results already reported in the literature. Finally, the experimental data are discussed on the basis of an analysis of the reaction rates and models for the corrosion mechanism is postulated. 相似文献
66.
Measurement is made of the first-sound generation and detection efficiencies of vibrating superleak transducers (VSTs) operated in superfluid4He. This is accomplished by using an ordinary pressure transducer to generate first sound with a VST as the detector, and by using a pressure transducer to detect the sound generated by a VST. The results are in reasonably good agreement with the current theory of VST operation. 相似文献
67.
Multihop Ad Hoc Networking: The Reality 总被引:1,自引:0,他引:1
In this article we show that, although pure general-purpose MANET (mobile ad hoc networks) does not yet exist in the real world, the multihop ad hoc networking paradigm was successfully applied in several classes of networks that are penetrating the mass market. We present as examples mesh, opportunistic, vehicular, and sensor networks, where the multi-hop ad hoc paradigm is applied in a pragmatic way to extend the Internet and/or to support well-defined application requirements. We contrast these successful areas of ad hoc networking to the lack of impact of pure general-purpose MANET, demonstrating how a more pragmatic approach is a winner 相似文献
68.
Rosario G. Garroppo Stefano Giordano Michele Pagano 《International Journal of Communication Systems》2002,15(10):851-866
The paper presents an analytical study aimed to establish a dimensioning procedure for the token bucket algorithm, used as a meter in a Differentiated Services network architecture, when a stochastic model for the multiplexed traffic is available. In the work, we propose an equivalent queueing system method to ‘on line’ estimate the linear bounded arrival processes (LBAP) parameters when a non‐zero probability of non‐conforming packets is accepted. Then, we validate our approach considering an aggregation of fluidic On‐Off processes with exponentially distributed sojourn time in each state, used to model telephone sources with voice activity detection (VAD). To test the goodness of our analytical results, we employ discrete event simulations, which have highlighted the accuracy of the proposed dimensioning procedure in a voice over IP (VoIP) scenario. Moreover, we investigate the multiplexing gain and the effect of different parameters on the LBAP characterization of the VoIP traffic, taking into account a non‐zero probability of non‐conforming packets. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
69.
Lorena?del?Rosario Cappellari Maricel?Valeria?Santoro Herminda?Reinoso Claudia?Travaglia Walter?Giordano Erika?BanchioEmail author 《Journal of chemical ecology》2015,41(2):149-158
Plant growth-promoting rhizobacteria (PGPR) generally exert their effects through enhancement of plant nutrient status and/or phytohormone production. The effects of PGPR on aromatic plant species are poorly known. We measured plant growth parameters, chlorophyll content, trichome density, stomatal density, and levels of secondary metabolites in peppermint (Mentha piperita) seedlings inoculated with PGPR strains Bacillus subtilis GB03, Pseudomonas fluorescens WCS417r, P. putida SJ04, or a combination of WCS417r?+?SJ04. The treated plants, in comparison with controls, showed increases in shoot biomass, root biomass, leaf area, node number, trichome density, and stomatal density, and marked qualitative and quantitative changes in monoterpene content. Improved knowledge of the factors that control or affect biosynthesis of secondary metabolites and monoterpene accumulation will lead to strategies for improved cultivation and productivity of aromatic plants and other agricultural crops without the use of chemical fertilizers or pesticides. 相似文献
70.
Aymeric Lepronier Thierry Achard Laurent Giordano Alphonse Tenaglia Grard Buono Herv Clavier 《Advanced Synthesis \u0026amp; Catalysis》2016,358(4):631-642
Palladium(II) acetate in association with secondary phosphine oxides provides an efficient catalytic system for [2+1] cycloadditions starting from oxanorbornene derivatives and tertiary propargyl esters giving rise to vinylidenecyclopropanes. This reaction is specific to bidentate phosphinito–phosphinous acid ligands generated from secondary phosphine oxides. The [2+1] cycloaddition was found broad in scope with a high tolerance to various functional groups. Moreover, vinylidenecyclopropanes were straightforwardly converted into oxabicyclo[3.2.1]oct‐2‐ene derivatives through a palladium‐catalyzed ring‐expansion. Finally, the oxa bridge cleavage of oxatricyclic compounds yields functionalized 7‐membered carbocycles.