全文获取类型
收费全文 | 45080篇 |
免费 | 9509篇 |
国内免费 | 1900篇 |
专业分类
电工技术 | 2742篇 |
综合类 | 4357篇 |
化学工业 | 3964篇 |
金属工艺 | 12735篇 |
机械仪表 | 6731篇 |
建筑科学 | 2475篇 |
矿业工程 | 980篇 |
能源动力 | 741篇 |
轻工业 | 1155篇 |
水利工程 | 670篇 |
石油天然气 | 2021篇 |
武器工业 | 475篇 |
无线电 | 2595篇 |
一般工业技术 | 4392篇 |
冶金工业 | 1904篇 |
原子能技术 | 289篇 |
自动化技术 | 8263篇 |
出版年
2024年 | 173篇 |
2023年 | 528篇 |
2022年 | 987篇 |
2021年 | 1013篇 |
2020年 | 1140篇 |
2019年 | 1208篇 |
2018年 | 1411篇 |
2017年 | 1608篇 |
2016年 | 1708篇 |
2015年 | 1381篇 |
2014年 | 5186篇 |
2013年 | 4388篇 |
2012年 | 5067篇 |
2011年 | 5421篇 |
2010年 | 4551篇 |
2009年 | 4171篇 |
2008年 | 2150篇 |
2007年 | 2042篇 |
2006年 | 2001篇 |
2005年 | 1576篇 |
2004年 | 1563篇 |
2003年 | 1230篇 |
2002年 | 996篇 |
2001年 | 955篇 |
2000年 | 815篇 |
1999年 | 621篇 |
1998年 | 510篇 |
1997年 | 452篇 |
1996年 | 389篇 |
1995年 | 322篇 |
1994年 | 211篇 |
1993年 | 140篇 |
1992年 | 139篇 |
1991年 | 111篇 |
1990年 | 85篇 |
1989年 | 79篇 |
1988年 | 60篇 |
1987年 | 34篇 |
1986年 | 10篇 |
1985年 | 13篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1959年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
81.
本文通过焊接试验对奥氏体不锈钢绕带容器环板与绕带焊接工艺进行了研究分析,并得出了合理的焊接方法和工艺参数。 相似文献
82.
We analyze the wear resistance of plasma coatings for a constant work of friction. The dependences of the wear resistance
of the coatings are obtained for a broad range of loading conditions. It is shown that the minimum sensitivity to loading
conditions is exhibited by the molybdenum coatings. It is also established that the wear resistance of the coatings decreases
as the amplitude of displacements increases and the cyclic frequency of the tests decreases due to the intensification of
fatigue processes on the surfaces. The comparative characteristics of coatings are presented.
__________
Translated from Problemy Prochnosti, No. 5, pp. 94–100, September–October, 2007. 相似文献
83.
自动焊技术在涩宁兰输气管道X70钢试验段上的应用 总被引:6,自引:0,他引:6
通过涩宁兰输气管道X70钢试验段的施工,进一步探索和完善自动焊接技术在高强钢管道焊接中的应用。文章介绍了该试验段施工的焊接设备、焊材和焊接工艺,可为同类焊接工程提供借鉴。 相似文献
84.
通过对CO2气体保护焊在高炉炉壳组装与焊接工艺的使用,有效地控制了焊接变形及防止焊缝裂纹,阐明提高焊接质量要从多元角度出发,有机整体地考虑问题,在结论中进一步从成本,焊接质量及培训等方面分析证明推广CO2气体保护焊的必要性。 相似文献
85.
A variable friction model that relates the parameters of sheet metal drawing to the local lubrication conditions taking place during the deformation, has been integrated to a finite element program. Variable friction coefficients for the contacting surfaces are determined from the friction model, which uses the related parameters obtained at each time step of the finite element program as inputs. A number of numerical runs have been performed and the strains are compared with the experimental results for circular blanks. A good agreement is obtained between the numerical and experimental results for the variable friction model used. 相似文献
86.
The effect of Zr on reduction of hardness and microstructure in an FS weld of equal channel angular-pressed Al alloy was investigated. Zr addition to Al suppressed dynamic recovery in the thermomechanically affected zone and enabled retention of the high hardness of the ECA-pressed material throughout the weld. 相似文献
87.
M. E. Stevenson S. L. Lowrie R. D. Bowman B. A. Bennett 《Journal of Failure Analysis and Prevention》2002,2(4):55-60
Cold cracking of structural steel weldments is a well-characterized, well-documented, and well-understood failure mechanism.
Extensive effort has been put forth to recognize the welding and materials selection parameters that are conducive to cold
cracking; however, these engineering efforts have not fully eliminated the occurrence of such failures. This article describes
cold cracking failure specifically related to the construction industry. This particular failure was successfully identified
prior to final erection of the structural member, and the weld was successfully reworked. These actions potentially prevented
a serious catastrophic event that could have occurred have occurred either later in the construction process or possibly during
the use of the building. Individual welding parameters, such as electrode/wire selection, joint design, and pre/postheating,
played a role in the failure, and a number of human factors relating to the actual fabrication practices also contributed
to the failure process. 相似文献
88.
89.
A new technique, namely, the open-die backward extrusion test technique, was developed as an alternative method to the ring compression test in order to quantitatively evaluate the coefficient of friction, μ, at the die/workpiece interface. This technique relates the percentage deformation in height of the specimen to the percentage increase in extruded height of the specimen. In this study, the open-die backward extrusion tests (ODBET) were simulated for different aspect ratios, (H/D), and different die geometries, (d/D), by utilizing an elastic-plastic finite element code (ANSYS) in order to obtain the friction calibration curves (FCCs). The results indicated that the extruded height is related to the friction conditions at the die/workpiece interface. Therefore, ODBET can be used to generate FCCs to determine the coefficient of friction at the die/workpiece interface in large deformation processes. 相似文献
90.
钢骨架塑料复合管既有钢管的耐压又有塑料管的耐腐蚀性,且易于敷设,使用寿命长,本文结合实际施工中的应用。介绍其要点。 相似文献