全文获取类型
收费全文 | 418篇 |
免费 | 16篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 49篇 |
金属工艺 | 5篇 |
机械仪表 | 5篇 |
建筑科学 | 12篇 |
能源动力 | 9篇 |
轻工业 | 56篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 91篇 |
一般工业技术 | 63篇 |
冶金工业 | 74篇 |
自动化技术 | 50篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 15篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 13篇 |
2013年 | 14篇 |
2012年 | 22篇 |
2011年 | 15篇 |
2010年 | 13篇 |
2009年 | 15篇 |
2008年 | 13篇 |
2007年 | 27篇 |
2006年 | 21篇 |
2005年 | 11篇 |
2004年 | 15篇 |
2003年 | 21篇 |
2002年 | 14篇 |
2001年 | 19篇 |
2000年 | 12篇 |
1999年 | 10篇 |
1998年 | 34篇 |
1997年 | 15篇 |
1996年 | 13篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1961年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有435条查询结果,搜索用时 31 毫秒
21.
This paper describes a bridge condition assessment model that is based upon the simplification of a computational technique called resolution identity of fuzzy sets. The proposed model utilizes a fuzzy weighted average to combine fuzzy bridge condition ratings. The procedure is based on the decomposition of fuzzy sets into non-fuzzy level-sets or intervals. The utility and effectiveness of this procedure are illustrated with an example of the bridge condition assessment problem. 相似文献
22.
The investigated microemulsion system consisted of methyl methacrylate, 2-hydroxyethyl methacrylate and water using sodium dodecyl sulphate as surfactant. Ethylene glycol dimethacrylate acting as a cross-linker was also incorporated to enhance the mechanical strengths of the microporous polymeric materials. The polymerization was carried out at room temperature using a reactive redox initiator comprising ammonium persulphate and N,N,N′,N′-tetramethylethylene diamine. The conductivities of the microemulsion samples were monitored during the course of polymerization. The conductivities for a bicontinuous microemulsion before and after polymerization were found to be very similar. In addition, the transformation of microstructures was also examined using a transmission as well as a field emission scanning electron microscope. It is evidenced from the micrographs that microporous polymeric materials prepared from bicontinuous microemulsion polymerization are attributed to numerous coagulations of spherical particles. A possible mechanism for the microstructural transformation is discussed based on the information of conductivity measurements and electron micrographs. © 1996 John Wiley & Sons, Inc. 相似文献
23.
Xue-ren Zhang Tong Yan Tee Jing-en Luan 《电子与封装》2006,6(2):10-15,4
<正>Packaging of MEMS ( micro-electro-mechanical system ) devices poses more challenges than conventional IC packaging, since the performance of the MEMS devices is highly dependent on packaging processes. A Land Grid Array ( LGA ) package is introduced for MEMS technology based linear multi-axis accelerometers. Finite element modeling is conducted to simulate the warpage behavior of the LGA packages. A method to correlate the package warpage to matrix block warpage has been developed. Warpage for both package and sensor substrate are obtained. Warpage predicted by simulation correlates very well with experimental measurements. Based on this validated method, detailed design analysis with different package geometrical variations are carried out to optimize the package design. With the optimized package structure, the packaging effect on accelerometer signal performance is well controlled. 相似文献
24.
A bipolar membrane combined with ferric iron reduction as an efficient cathode system in microbial fuel cells 总被引:2,自引:0,他引:2
Ter Heijne A Hamelers HV De Wilde V Rozendal RA Buisman CJ 《Environmental science & technology》2006,40(17):5200-5205
There is a need for alternative catalysts for oxygen reduction in the cathodic compartment of a microbial fuel cell (MFC). In this study, we show that a bipolar membrane combined with ferric iron reduction on a graphite electrode is an efficient cathode system in MFCs. A flat plate MFC with graphite felt electrodes, a volume of 1.2 L and a projected surface area of 290 cm2 was operated in continuous mode. Ferric iron was reduced to ferrous iron in the cathodic compartment according to Fe(3+) + e(-) --> Fe2+ (E0 = +0.77 V vs NHE, normal hydrogen electrode). This reversible electron transfer reaction considerably reduced the cathode overpotential. The low catholyte pH required to keep ferric iron soluble was maintained by using a bipolar membrane instead of the commonly used cation exchange membrane. For the MFC with cathodic ferric iron reduction, the maximum power density was 0.86 W/m2 at a current density of 4.5 A/m2. The Coulombic efficiency and energy recovery were 80-95% and 18-29% respectively. 相似文献
25.
M. Bueno J. Luong F. Terán U. Viñuela S.E. Paje 《International Journal of Pavement Engineering》2014,15(7):606-613
The road surface is one of the most important factors that have influence on the current traffic noise. Usually, for dense surfaces, impacts of the tyre on the pavement generate vibrations which are the dominant mechanisms in the tyre–road noise. In this study, the effect of muffling these vibrations, by the incorporation of crumb rubber (CR) from wasted tyres into asphalt pavements, has been evaluated acoustically. Close proximity measurements have been carried out to register the sound emission generated in the contact zone between a reference tyre and an experimental asphalt pavement with CR. The analysis of the measurements indicates that the incorporation of CR as well as the air voids content has less influence than the macrotexture of the road surface on the acoustical behaviour of this experimental asphalt pavement. 相似文献
26.
The boilers developed by the power machinery construction company Alstom for two power-generating units operating on high-moisture lignite from the Maritsa East field in Bulgaria are described. 相似文献
27.
When developing a coal-fired power unit designed for operating at supercritical steam conditions (SSCs), it is necessary not only to achieve high economic performance and the high reliability of a new power unit, but also to tackle many problems related to the efficient combustion of the solid fuel without exceeding the future standards for limitations on emissions of harmful substances into the atmosphere. The technological methods of suppression of nitrogen oxides capable of providing the permissible NO x emissions are discussed. The results of calculations are given that demonstrate the feasibility of achieving the purpose in view by means of installation of new low-NO x burners and staged injection of the fuel even on combustion of the Ekibastuz black coal high in ash content. 相似文献
28.
Electrodeionization 2: The migration of nickel ions absorbed in a flexible ion-exchange resin 总被引:2,自引:0,他引:2
The removal of nickel ions from a low cross-linked ion-exchange resin using an applied electrical potential gradient was studied. The potential gradient across a bed of ion-exchange particles, in which nickel ions were absorbed, was varied by two methods. One involved a change of cell voltage across beds of constant width, the other a change of bed width at constant cell voltage. In this way, various characteristics concerning the electrodialytic regeneration of a bed of ion-exchange particles in the nickel form were ascertained. The diffusion coefficient, current efficiency and migration rate of nickel in the bed are discussed. It is shown that the current efficiency for the removal of nickel is nearly one hundred percent when the bed is in the nickel form, and that the rate of regeneration is proportional to the cell voltage. 相似文献
29.
In this paper, an effective medium access control protocol is proposed for Ethernet passive optical networks. By combining the bandwidth guarantee polling (BGP) scheme with the strict priority queuing (SPQ) mechanism, the proposed solution can greatly mitigate the light-load penalty while supporting differentiated services. The performance of the proposed solution has been demonstrated by the simulation results. 相似文献
30.
Selvarajoo T.A.L. Ranjan R. Kin-Leong Pey Lei-Jun Tang Chih Hang Tung Wenhe Lin 《Device and Materials Reliability, IEEE Transactions on》2005,5(2):190-197
The breakdown phenomena in SiO/sub x/N/sub y/ (EOT=20 /spl Aring/) gate dielectric under a two- stage constant voltage stress in inversion mode are physically analyzed with the aid of transmission electron microscopy. The results show that dielectric-breakdown-induced epitaxy (DBIE) remains as one of the major failure defects responsible for gate dielectric breakdown evolution even for a stress voltage as low as 2.5 V. Based on the results, the same failure mechanism i.e., presence of DBIE would be responsible for the degradation in ultrathin gate dielectrics for gate voltage below 2.5 V. It is believed that DBIE will be present in MOSFETs failed at nominal operating voltage. 相似文献