全文获取类型
收费全文 | 35066篇 |
免费 | 2361篇 |
国内免费 | 2107篇 |
专业分类
电工技术 | 1910篇 |
技术理论 | 7篇 |
综合类 | 5204篇 |
化学工业 | 2853篇 |
金属工艺 | 1033篇 |
机械仪表 | 2659篇 |
建筑科学 | 2389篇 |
矿业工程 | 1435篇 |
能源动力 | 699篇 |
轻工业 | 1119篇 |
水利工程 | 563篇 |
石油天然气 | 996篇 |
武器工业 | 339篇 |
无线电 | 2750篇 |
一般工业技术 | 2819篇 |
冶金工业 | 1561篇 |
原子能技术 | 341篇 |
自动化技术 | 10857篇 |
出版年
2024年 | 76篇 |
2023年 | 280篇 |
2022年 | 619篇 |
2021年 | 703篇 |
2020年 | 737篇 |
2019年 | 469篇 |
2018年 | 402篇 |
2017年 | 540篇 |
2016年 | 695篇 |
2015年 | 899篇 |
2014年 | 1841篇 |
2013年 | 1781篇 |
2012年 | 2089篇 |
2011年 | 2126篇 |
2010年 | 2144篇 |
2009年 | 1966篇 |
2008年 | 1870篇 |
2007年 | 2376篇 |
2006年 | 2221篇 |
2005年 | 2072篇 |
2004年 | 1709篇 |
2003年 | 1712篇 |
2002年 | 1465篇 |
2001年 | 1377篇 |
2000年 | 1244篇 |
1999年 | 1026篇 |
1998年 | 847篇 |
1997年 | 756篇 |
1996年 | 635篇 |
1995年 | 550篇 |
1994年 | 474篇 |
1993年 | 295篇 |
1992年 | 261篇 |
1991年 | 213篇 |
1990年 | 153篇 |
1989年 | 138篇 |
1988年 | 110篇 |
1987年 | 83篇 |
1986年 | 69篇 |
1985年 | 74篇 |
1984年 | 86篇 |
1983年 | 74篇 |
1982年 | 62篇 |
1981年 | 32篇 |
1980年 | 29篇 |
1979年 | 24篇 |
1978年 | 9篇 |
1977年 | 18篇 |
1961年 | 12篇 |
1956年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Hatto F. Jacobi 《国际钢铁研究》2003,74(11-12):667-678
Improvements of solidification processing in conventional or near net shape casting depend on sophisticated methods of macroscopic examination of central unsoundness and inhomogeneity of the cast material. As long as remarkable deviations referring to the quality features exist between the slab centre and the bulk material such methods should be looked after. Two semi‐macroscopic methods of segregation analysis are discussed in this paper: firstly, the potential of the emission spectral analysis combined with sectioning of a sample and secondly, the computer aided micro‐probe analysis. Both methods are restricted to small local areas. The proneness of elements and steel grades with respect to micro‐ and macrosegregation as well as distribution‐ and segregation coefficients are determined. The effect of a diffusion anneal on homogenisation of segregation is studied. Last not least the precipitation of sulphides, phosphides or carbonitrides is estimated. Ultrasonic detection of the central unsoundness of conventional slabs or thin slabs is a new approach towards a quantitative macroscopic examination. The sample size is 400 mm x 300 mm x 30 mm. To achieve a low ultrasonic noise using a 5 MHz‐transducer the samples are heat treated for grain refinement. “Dog bone porosity”, macroscopic topographical misfit between the upper and lower solidifying shells, periodical corner cracks or systematic transverse centre cracks are detected. Obviously, segregations do not reflect the ultrasonic beam. However, it can be presumed that an interrelation exists between porosity and segregation, although these might be locally apart from each other. This new ultrasonic test of the central unsoundness of continuous cast (c.c.) slabs gives valuable arguments to machine builders and maintenance people to decide on the right concepts for strand guidance, support rollers and secondary cooling. Soft reduction can be optimized and variations in casting speed counteracted by dynamic means. R&D service of this kind can help steelmakers when decisions are impending to build new casting machines or revamp old ones. 相似文献
62.
Presents an obituary for Douglas W. Bray, the inventor of the modern-day assessment center, a method used by thousands of organizations around the world to identify the best people for critical roles and to guide individuals in optimizing their talents. Bray's death in Englewood, New Jersey, on May 9, 2006, ended the extraordinary career of a pioneer in industrial/organizational (I/O) psychology who optimized the interplay of research and application. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
63.
由于在机器人导航等领域新的图像装置不符合透视规则,无法运用传统的透视位置估计方法,采用吴氏零点分解方法,给出非透视3点问题的解析解.利用新图像装置的几何条件,建立了非透视3点方程系统. 相似文献
64.
着重阐述了河北冶金实验厂8MN快锻液压机电控系统的选择过程。经过反复考察,论证,对比,最终所选的压机电控系统为目前国产快锻液压机中自动化水平最高的锻造设备。 相似文献
65.
66.
Not all Group Support Systems are identical, as is demonstrated by their software implementations. We discuss two existing implementations of group support tools and the process models underlying them. We demonstrate that fundamental to both processes is the merging or integration of individual data. Based on this and other empirical research, the Shared Context Model (SCM) of cooperative work is adopted and we show that it supports existing processes and others. We expect that groups will find merging their work easier with the SCM. This model is presented and embedded in the architecture and implementation of four group tools. Because these tools are destined to be used by dispersed groups, synchronously or asynchronously, an object-based communication and control mechanism is incorporated. Finally, as graphics and multi-tasking have been shown to be increasingly important, the tools are implemented in Microsoft Windows for personal computers attached to local area networks. 相似文献
67.
空调器用盘式电机的计算机模拟 总被引:1,自引:0,他引:1
介绍线绕盘式永磁直流电流电动机的结构特点,设计原则和有关的主要设计公式,并进行电机的计算机模拟。模拟运行结果与样机实测数据基本相符。 相似文献
68.
70.
柴石滩水库坝后电站装机容量3×20MW,水库库容4.37亿,坝高103.2m,电站采用计算机监控为主简易常规监控为辅的方式。本文介绍了电站计算机监控系统网络结构及系统软硬件配置以及监控系统功能、特点,简易常规监控方式。电站监控系统采用招标方式已定了生产厂家和系统方案。 相似文献