全文获取类型
收费全文 | 6740篇 |
免费 | 629篇 |
国内免费 | 266篇 |
专业分类
电工技术 | 395篇 |
综合类 | 338篇 |
化学工业 | 1081篇 |
金属工艺 | 337篇 |
机械仪表 | 464篇 |
建筑科学 | 489篇 |
矿业工程 | 224篇 |
能源动力 | 147篇 |
轻工业 | 574篇 |
水利工程 | 110篇 |
石油天然气 | 556篇 |
武器工业 | 41篇 |
无线电 | 754篇 |
一般工业技术 | 824篇 |
冶金工业 | 442篇 |
原子能技术 | 70篇 |
自动化技术 | 789篇 |
出版年
2024年 | 30篇 |
2023年 | 116篇 |
2022年 | 227篇 |
2021年 | 327篇 |
2020年 | 240篇 |
2019年 | 200篇 |
2018年 | 197篇 |
2017年 | 194篇 |
2016年 | 200篇 |
2015年 | 295篇 |
2014年 | 301篇 |
2013年 | 399篇 |
2012年 | 389篇 |
2011年 | 432篇 |
2010年 | 362篇 |
2009年 | 330篇 |
2008年 | 409篇 |
2007年 | 382篇 |
2006年 | 353篇 |
2005年 | 292篇 |
2004年 | 188篇 |
2003年 | 146篇 |
2002年 | 148篇 |
2001年 | 137篇 |
2000年 | 175篇 |
1999年 | 204篇 |
1998年 | 197篇 |
1997年 | 139篇 |
1996年 | 118篇 |
1995年 | 100篇 |
1994年 | 99篇 |
1993年 | 84篇 |
1992年 | 61篇 |
1991年 | 34篇 |
1990年 | 24篇 |
1989年 | 27篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1971年 | 3篇 |
1969年 | 1篇 |
排序方式: 共有7635条查询结果,搜索用时 421 毫秒
41.
42.
43.
Grantham K. H. Pang 《International Journal of Adaptive Control and Signal Processing》1991,5(1):63-86
A multivariable control system design approach in the frequency domain is presented. The issue of control system redesign in an adaptive control scheme is discussed. Expert system techniques have been used for the automated design of controllers for multivariable systems. Design knowledge has been represented using rules, facts and objects. The design process consists of a sequence of operations obtained by heuristics and experience in the the design techniques. An automated design session of a multivariable plant using the expert system demonstrates that the expert system appears to work well in its prototype implementation. 相似文献
44.
45.
Excessive intermetallic compound (IMC) growth in solder joints will significantly decrease the reliability of the joints.
IMC growth is known to be influenced by numerous factors during the component fabrication process and in service. It is reported
that, other than temperature and holding time, stress can also influence the IMC growth behavior. However, no existing method
can be used to study the effect of stress state on IMC growth in a controlled manner. This paper presents a novel method to
study the effect of stress on interfacial IMC growth between Sn-Ag-Cu solder and a Cu substrate coated with electroless Ni
immersion Au (ENIG). A C-ring was used and in-plane bending induced tensile and compressive stresses were applied by tightening
the C-ring. Results revealed that in-plane compressive stress led to faster IMC growth as compared with in-plane tensile stress. 相似文献
46.
文章概述了人类能源利用从柴薪、煤到石油、天然气的探索与转变历程,着重对天然气利用在解决城市燃料和空气污染、提高发电效率、推动分布式发电、生产合成氨和合成甲醇、推动燃料电池转向氢能经济时代等方面的优越性进行了阐述。 相似文献
47.
48.
49.
Wei-Cheng Tian Pang S.W. Chia-Jung Lu Zellers E.T. 《Journal of microelectromechanical systems》2003,12(3):264-272
The design, fabrication, and testing of a preconcentrator-focuser (PCF), consisting of a thick micromachined Si heater packed with a small quantity of a granular adsorbent material are described. The PCF is developed to capture and concentrate vapors for subsequent focused thermal desorption and analysis in a micro gas chromatograph. The microheater contains an array of high-aspect-ratio, etched-Si heating elements, 520 /spl mu/m (h)/spl times/50 /spl mu/m (w)/spl times/3000 /spl mu/m (l), bounded by an annulus of Si and thermally isolated from the remaining substrate by an air gap. This structure is sandwiched between Pyrex glass plates with inlet/outlet ports that accept capillary tubes for sample flow and is sealed by anodic bonding (bottom) and rapidly annealed glass/metal/Si solder bonding (top). The large microheater surface area allows for high adsorption capacity and efficient, uniform thermal desorption of vapors captured on the adsorbent within the structure. The adsorbent consists of roughly spherical granules, /spl sim/200 /spl mu/m in diameter, of a high-surface-area, graphitized carbon. Key design considerations, fabrication technologies, and results of performance tests are presented with an emphasis on the thermal desorption characteristics of several representative volatile organic compounds as a function of volumetric flow rates and heating rates. Preconcentration factors as high as 5600 and desorbed peak widths as narrow as 0.8 s are achieved from 0.25-L samples of benzene at modest heating rates. The effects of operating variables on sensitivity, chromatographic resolution, and detection limits are assessed. Testing of this PCF with a micromachined separation column and integrated sensor array is discussed briefly. 相似文献
50.
德国慕尼黑国际博览集团是享誉全球的国际化大型博览公司,是世界上最重要的十大展览公司之一。自2002年始与上海新国际博览中心共同组织了两年一届的中国国际工程机械、建材机械、工程车辆及设备博览会(BAUMA CHINA)。2004年该博览会吸引了来自27个国家的738个参展商,展会场地达10万平方米,观众来自100个国家约5万多人(国外观众占21%)。鉴于中国使用工程机械、建材机械较多的交通运输业、建筑业、能源建设、水利水电建设等行业都保持了很高的发展速度,中国工程机械市场将是一个持续和不断成长的市场。2006年11月21—24日将在上海新国际… 相似文献