全文获取类型
收费全文 | 2225篇 |
免费 | 34篇 |
国内免费 | 46篇 |
专业分类
电工技术 | 67篇 |
综合类 | 65篇 |
化学工业 | 153篇 |
金属工艺 | 595篇 |
机械仪表 | 399篇 |
建筑科学 | 136篇 |
矿业工程 | 26篇 |
能源动力 | 57篇 |
轻工业 | 6篇 |
水利工程 | 8篇 |
石油天然气 | 130篇 |
武器工业 | 13篇 |
无线电 | 52篇 |
一般工业技术 | 410篇 |
冶金工业 | 103篇 |
原子能技术 | 19篇 |
自动化技术 | 66篇 |
出版年
2024年 | 1篇 |
2023年 | 15篇 |
2022年 | 15篇 |
2021年 | 19篇 |
2020年 | 24篇 |
2019年 | 12篇 |
2018年 | 20篇 |
2017年 | 50篇 |
2016年 | 64篇 |
2015年 | 67篇 |
2014年 | 142篇 |
2013年 | 139篇 |
2012年 | 134篇 |
2011年 | 210篇 |
2010年 | 122篇 |
2009年 | 101篇 |
2008年 | 80篇 |
2007年 | 92篇 |
2006年 | 102篇 |
2005年 | 87篇 |
2004年 | 109篇 |
2003年 | 91篇 |
2002年 | 59篇 |
2001年 | 53篇 |
2000年 | 79篇 |
1999年 | 95篇 |
1998年 | 53篇 |
1997年 | 49篇 |
1996年 | 39篇 |
1995年 | 30篇 |
1994年 | 28篇 |
1993年 | 23篇 |
1992年 | 24篇 |
1991年 | 23篇 |
1990年 | 22篇 |
1989年 | 19篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有2305条查询结果,搜索用时 904 毫秒
41.
42.
针对生产刀具规格和材料品种较多的情况,就C25型摩擦焊机代替闪光对焊机应用在刀具焊接上进行了一系列工艺调试和生产应用,认为摩擦焊机焊接性能优于闪光焊机。 相似文献
43.
介绍一种引弧-燃弧-熄弧能够实时控制,实现多头自动转换的钨极氩弧点焊机。该焊机采用“无源引弧器”引弧,引入CMOS、时基、大功率开关等集成电路进行弧焊自动控制。 相似文献
44.
在辊弯成形生产线及冲压生产线中,为了提高生产效率和材料利用率,常将卷料的料头与料尾焊接在一起。作者结合自已的实践经验,对料头与料尾的焊接技术以及与此有关的料头料尾剪切齐头、对缝、压料等技术进行了探讨。 相似文献
45.
提出了双面搅拌摩擦焊这种新的焊接方法,对比研究了6K32-T4铝合金搅拌摩擦焊与双面搅拌摩擦焊接头的组织和硬度,并对双面搅拌摩擦焊焊缝进行了XRD分析。研究发现:铝合金双面搅拌摩擦焊与搅拌摩擦焊焊缝组织分区相同;双面搅拌摩擦焊焊缝的硬度略低于搅拌摩擦焊,且焊缝硬度下降区域范围更大;双面搅拌摩擦焊后焊缝依然保持为原有相组成;双面搅拌摩擦焊比搅拌摩擦焊焊接线能量更大,采用双面搅拌摩擦焊代替搅拌摩擦焊有利于提高焊接效率并消除焊缝隧道型缺陷、改善焊缝的性能。 相似文献
46.
本文介绍方波信号发生器及场效应管驱动器的原理与设计。实验证明,设计的方波信号发生器与场效应管驱动器工作稳定可靠,所研制的方波交流高频弧焊电源已成功地对薄钢板进行了焊接。 相似文献
47.
Slow displacement rate tensile tests were carried out to study sulfide stress corrosion cracking (SSCC) of PH 13-8 Mo stainless steel welds in a saturated H2S solution. The welds aged in the temperature range of 482-593 °C were susceptible to SSCC; the fracture surfaces revealed mainly quasi-cleavage fractures after notched tensile tests. However, the SSCC susceptibility in terms of the percentage loss of the notched tensile strength (NTS) of the welds was dependent on the aging treatment. The SSCC resistance and the austenite content of the welds increased with the aging temperatures. The presence of greater amounts of austenite, mainly reverted austenite, in the W1100 specimen (the weld aged at 1100 °F or 593 °C) than that in other aged specimens could account for its lower hardness and better SSCC resistance. On the other hand, the AW (as-welded) specimen containing a small amount of retained austenite films in a soft matrix exhibited a slightly improved SSCC resistance than that in the W1100 specimen. The lower hardness of the AW specimen was owing to the absence of fine coherent precipitates, leading to a reduced local stress and an enlarged plastic zone located in front of the notch in the test. With lower hardness, the local stress would also be lower and less likely to exceed some critical stress for failure in the saturated H2S solution. For the aged specimens, the hardness/strength level and the amount of reverted austenite were the important factors that affect SSCC susceptibility. 相似文献
48.
49.
本文阐述了热丝TIG焊的特点,并通过实验研究论证了这种焊接工艺应用于电站锅炉管道焊接的可行性,同时对各工艺参数的影响进行了详细介绍。 相似文献
50.
To join a medium or thick plate weldment with a full penetration, a groove is usually prepared in the space between two sections of metal. Because weld metal needs to be deposited within the groove to form the joint, it is expected that different groove type will require different heat input, which may consequently have influence on welding residual stress and deformation. Generally, different groove corresponds to different bead layout, so it can be foreseen that the groove type has a significant effect on temperature history, shape and size of heat affected zone, and region of sensitization in certain alloys such as austenitic stainless steel. The influences of groove type on residual stress, angular distortion and width of sensitization region in a SUS304 butt-welded joint were investigated by means of numerical simulation and experiment. Based on ABAQUS code, a computational approach with considering thermo-mechanical coupling behaviors, moving heat source, strain hardening and annealing effect was developed to simulate temperature profile, stress field and deformation in multi-pass joint. Welding temperature cycles, residual stress distributions and deformations in V, K and X groove joints were calculated through using the proposed computational procedure. Meanwhile, experiments were carried out to obtain residual stress distributions and angular distortions. Through comparing the numerical results and the measured data, the effectiveness and accuracy of the developed computational approach were verified. The simulation results show that groove type has a significant influence on welding residual stress distribution, angular distortion and width of sensitization region. 相似文献