全文获取类型
收费全文 | 1826篇 |
免费 | 253篇 |
国内免费 | 88篇 |
专业分类
电工技术 | 22篇 |
综合类 | 77篇 |
化学工业 | 49篇 |
金属工艺 | 571篇 |
机械仪表 | 68篇 |
建筑科学 | 6篇 |
矿业工程 | 25篇 |
能源动力 | 4篇 |
轻工业 | 12篇 |
水利工程 | 1篇 |
武器工业 | 6篇 |
无线电 | 1034篇 |
一般工业技术 | 220篇 |
冶金工业 | 44篇 |
自动化技术 | 28篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 28篇 |
2021年 | 27篇 |
2020年 | 27篇 |
2019年 | 21篇 |
2018年 | 29篇 |
2017年 | 40篇 |
2016年 | 35篇 |
2015年 | 65篇 |
2014年 | 74篇 |
2013年 | 92篇 |
2012年 | 118篇 |
2011年 | 133篇 |
2010年 | 114篇 |
2009年 | 162篇 |
2008年 | 148篇 |
2007年 | 169篇 |
2006年 | 184篇 |
2005年 | 134篇 |
2004年 | 121篇 |
2003年 | 88篇 |
2002年 | 72篇 |
2001年 | 62篇 |
2000年 | 45篇 |
1999年 | 44篇 |
1998年 | 32篇 |
1997年 | 10篇 |
1996年 | 14篇 |
1995年 | 15篇 |
1994年 | 30篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 6篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有2167条查询结果,搜索用时 15 毫秒
21.
Au-Ag-Si新型中温共晶钎料的研究 总被引:12,自引:1,他引:12
根据合金相图的基本原理,分析了Au-Ag-Si系相图,研制出熔化温度在400℃~500℃的共晶钎料合金.通过钎料合金与Ni板的润湿性测试和润湿后界面的微观组织分析.结果表明:Au-Ag-Si系钎料对于纯Ni具有良好的漫流性和润湿性,在450℃~500℃范围内,可以对Ni板进行钎焊. 相似文献
22.
23.
Understanding the Influence of Copper Nanoparticles on Thermal Characteristics and Microstructural Development of a Tin-Silver Solder 总被引:1,自引:0,他引:1
D.C. Lin T.S. Srivatsan G-X. Wang R. Kovacevic 《Journal of Materials Engineering and Performance》2007,16(5):647-654
This paper presents and discusses issues relevant to solidification of a chosen lead-free solder, the eutectic Sn-3.5%Ag,
and its composite counterparts. Direct temperature recordings for the no-clean solder paste during the simulated reflow process
revealed a significant amount of undercooling to occur prior to the initiation of solidification of the eutectic Sn-3.5%Ag
solder, which is 6.5 °C, and for the composite counterparts, it is dependent on the percentage of copper nanopowder. Temperature
recordings revealed the same temperature level of 221 °C for both melting (from solid to liquid) and final solidification
(after recalescence) of the Sn-3.5%Ag solder. Addition of copper nanoparticles was observed to have no appreciable influence
on melting temperature of the composite solder. However, it does influence solidification of the composite solder. The addition
of 0.5 wt.% copper nanoparticles lowered the solidification temperature to 219.5 °C, while addition of 1.0 wt.% copper nanoparticles
lowered the solidification temperature to 217.5 °C, which is close to the melting point of the ternary eutectic Sn-Ag-Cu solder
alloy, Sn-3.7Ag-0.9Cu. This indicates the copper nanoparticles are completely dissolved in the eutectic Sn-3.5%Ag solder and
precipitate as the Cu6Sn5, which reinforces the eutectic solder. Optical microscopy observations revealed the addition of 1.0 wt.% of copper nanoparticles
to the Sn-3.5%Ag solder results in the formation and presence of the intermetallic compound Cu6Sn5. These particles are polygonal in morphology and dispersed randomly through the solder matrix. Addition of microsized copper
particles cannot completely dissolve in the eutectic solder and projects a sunflower morphology with the solid copper particle
surrounded by the Cu6Sn5 intermetallic compound coupled with residual porosity present in the solder sample. Microhardness measurements revealed the
addition of copper nanopowder to the eutectic Sn-3.5%Ag solder resulted in higher hardness. 相似文献
24.
25.
26.
27.
28.
The shear strength and aging characteristics of 63Sn–37Pb solder bumps were characterized with variation in solder ball and
UBM pad sizes. The shear strength increased with shorter effective crack size,a
effs
which was determined with the solder ball and pad sizes. The shear strength of the solder bumps on Au/Ni/Cu and Ni/Cu did
not change significantly with reflow time. Substantial decrease in the shear strength occurred for the solder bumps formed
on Au/Ni/Cu with aging treatment, and the shear strength after aging was also related to the bump shape which was determined
with the solder ball and pad sizes. 相似文献
29.
30.
Epoxy adhesives filled with four different volume fractions of eutectic tin-bismuth solder alloy were prepared and the effect of filler content on the electrical and mechanical properties of these anisotropic electrically conductive adhesives was investigated. The results show that the adhesive containing the lowest amount of the filler alloy had the best combination of conductivity, insulation resistance and shear strength. The DSC-measurements suggested that the filler melts before the cure of the resin begins which allows the filler to wet and bond well to the conductors. This was verified by SEM/EPMA examinations. A temperature cycling test and high humidity, high temperature treatment were conducted on the best composite adhesive. The temperature variation had no effect on conductivity of the joints while humid and hot environment decreased the conductivity. 相似文献