全文获取类型
收费全文 | 17315篇 |
免费 | 2157篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 1364篇 |
综合类 | 404篇 |
化学工业 | 8584篇 |
金属工艺 | 260篇 |
机械仪表 | 397篇 |
建筑科学 | 686篇 |
矿业工程 | 168篇 |
能源动力 | 100篇 |
轻工业 | 1807篇 |
水利工程 | 119篇 |
石油天然气 | 68篇 |
无线电 | 340篇 |
一般工业技术 | 2894篇 |
冶金工业 | 209篇 |
原子能技术 | 32篇 |
自动化技术 | 2045篇 |
出版年
2023年 | 623篇 |
2022年 | 320篇 |
2021年 | 671篇 |
2020年 | 664篇 |
2019年 | 580篇 |
2018年 | 557篇 |
2017年 | 383篇 |
2016年 | 618篇 |
2015年 | 778篇 |
2014年 | 818篇 |
2013年 | 1399篇 |
2012年 | 543篇 |
2011年 | 426篇 |
2010年 | 784篇 |
2009年 | 925篇 |
2008年 | 436篇 |
2007年 | 393篇 |
2006年 | 293篇 |
2005年 | 271篇 |
2004年 | 224篇 |
2003年 | 217篇 |
1998年 | 186篇 |
1997年 | 133篇 |
1996年 | 199篇 |
1995年 | 187篇 |
1994年 | 157篇 |
1993年 | 219篇 |
1992年 | 156篇 |
1991年 | 124篇 |
1990年 | 155篇 |
1989年 | 177篇 |
1988年 | 137篇 |
1987年 | 161篇 |
1986年 | 182篇 |
1985年 | 166篇 |
1984年 | 168篇 |
1983年 | 175篇 |
1982年 | 156篇 |
1981年 | 202篇 |
1980年 | 165篇 |
1979年 | 169篇 |
1977年 | 150篇 |
1976年 | 149篇 |
1975年 | 205篇 |
1974年 | 188篇 |
1973年 | 369篇 |
1972年 | 212篇 |
1971年 | 153篇 |
1970年 | 144篇 |
1968年 | 153篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Dr. K. Whybrew J. K. Raine G. R. Dunlop H. Overbye 《The International Journal of Advanced Manufacturing Technology》1993,8(2):111-113
An articulated geometry which overcomes the problem of loss of traction in differentially steered skid tractor automatic guided vehicles is described. 相似文献
72.
73.
T. Jing M. Sc. Ir. P. H. F. Moshuis Prof. Dr. Ir. F. H. Kreuger 《Electrical Engineering (Archiv fur Elektrotechnik)》1991,74(4):315-319
Contents Surface charge accumulation and its decay at a GIS spacer are studied at atmospheric conditions employing a two step-calibration method. The results show that the accumulation saturates within 30 minutes; the dominant mechanism of surface charge accumulation is the drift of charged particles via air, while that of the decay is surface conduction. The characteristics are similar at both polarities.
Sättigungskonzentration und Abklingverhalten der Oberflächenladung an einem mit Gleichspannung beanspruchten Abstandshalter unter atmosphärischen Bedingungen
Übersicht Die Konzentration und das Abklingen von Oberflächenladungen an einem GIS Abstandshalter wurden unter atmosphärischen Bedingungen mit Hilfe eines zweistufigen Kalibrierungsverfahrens untersucht. Die Ergebnisse zeigen eine Sättigung der Ladungskonzentration innerhalb von 30 Minuten. Als Hauptursache der Ladungskonzentration ist die Drift geladener Teilchen in Luft anzusehen, während das Abklingen auf die Oberflächenleitung zurückzuführen ist. Ähnliche Charakteristiken ergeben sich mit beiden Polaritäten.相似文献
74.
Three-dimensional, turbulent fluid flow analysis with computational methods has emerged as a viable tool in the design process
of engine components for passenger cars. If applied in the early stages of the component development such analysis can help
reduce the product development time drastically, and may support the design engineer to evaluate several competing design
aspects before product completion. However the grid generation for complex geometries still poses a difficult and time consuming
taks which strongly influences the accuracy of the numerical solution. The present paper studies the numerical solution of
the flow in an inlet-manifold of a five-cylinder engine with two intake-ports for each cylinder. A fast and reliable grid
generation technique is discussed in detail. The finite volume based Navier-Stokes solver with schemes of first and second
order accuracy for the convective terms is used. Numerical results at several mass flow rates and different boundary conditions
at the intake ports are compared with measurements. Finally, the computational results are discussed with respect to their
applicability to support the design process of an inlet-manifold. 相似文献
75.
IT/Business alignment 总被引:3,自引:2,他引:1
Dr. Alexander Teubner 《WIRTSCHAFTSINFORMATIK》2006,48(5):368-371
76.
77.
Dr. A. N. Danilenko V. Yu. Vetrov A. P. Dmitrochenko A. L. Leontiev E. E. Braudo V. B. Tolstoguzov 《Molecular nutrition & food research》1992,36(2):105-111
Thermodynamic properties of aqueous solutions of both native and modified legumin of broad beans (Vicia faba L.) have been examined. A restricted trypsin-induced proteolysis was used to modify protein structure. Evaluation of protein affinity to ficoll in aqueous solutions showed that modified protein possessed higher hydrophilicity. Thermodynamic properties of diluted solutions were used to predict the phase behaviour in concentrated systems containing protein and ficoll. At specific concentrations of native legumin, the system can separate in two phases, whereas in the case of modified protein the single-phase behaviour of the system was predicted for any concentrations of both components. The experimental data obtained in concentrated systems confirmed predictions of thermodynamic analysis of diluted solutions. 相似文献
78.
A. Stelzer Univ.-Ass. Ing. Dipl.-Ing. Dr. techn. A. Springer A. Univ.-Prof. Dipl.-Ing. Dr. techn. 《e & i Elektrotechnik und Informationstechnik》2003,120(3):98-101
This contribution reviews the research work performed at the Johannes Kepler University of Linz, Austria, on the development of oscillators for the microwave and millimeter wave frequency range. This work, performed by the Microelectronics Institute and the Institute for Communications and Information Engineering, covers the range from low GHz frequencies up to 61 GHz and is devoted to applications like mobile communications and sensing. The active devices are based on gallium arsenide (GaAs), silicon germanium (SiGe), and Silicon (Si) and include Gunn-devices, bipolar transistors, and CMOS-technology. 相似文献
79.
80.
Our emphasis in this paper has been on the knowledge-based and cognitive issues pertinent for improved interactions between workers and manufacturing computer systems. We believe that these techniques are as necessary and applicable to manufacturing as to any other vocation, especially as the difference in collar color of shop people becomes less noticeable in their increasing role as knowledge workers. 相似文献