全文获取类型
收费全文 | 1576篇 |
免费 | 72篇 |
国内免费 | 156篇 |
专业分类
电工技术 | 15篇 |
综合类 | 54篇 |
化学工业 | 66篇 |
金属工艺 | 612篇 |
机械仪表 | 82篇 |
建筑科学 | 10篇 |
矿业工程 | 16篇 |
能源动力 | 253篇 |
轻工业 | 16篇 |
石油天然气 | 58篇 |
武器工业 | 18篇 |
无线电 | 18篇 |
一般工业技术 | 319篇 |
冶金工业 | 205篇 |
原子能技术 | 52篇 |
自动化技术 | 10篇 |
出版年
2024年 | 2篇 |
2023年 | 43篇 |
2022年 | 64篇 |
2021年 | 57篇 |
2020年 | 62篇 |
2019年 | 58篇 |
2018年 | 50篇 |
2017年 | 49篇 |
2016年 | 32篇 |
2015年 | 41篇 |
2014年 | 69篇 |
2013年 | 83篇 |
2012年 | 71篇 |
2011年 | 100篇 |
2010年 | 75篇 |
2009年 | 96篇 |
2008年 | 68篇 |
2007年 | 61篇 |
2006年 | 67篇 |
2005年 | 67篇 |
2004年 | 73篇 |
2003年 | 62篇 |
2002年 | 63篇 |
2001年 | 45篇 |
2000年 | 35篇 |
1999年 | 46篇 |
1998年 | 43篇 |
1997年 | 45篇 |
1996年 | 44篇 |
1995年 | 31篇 |
1994年 | 26篇 |
1993年 | 15篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 2篇 |
1984年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有1804条查询结果,搜索用时 15 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(90):38468-38476
The distribution of hydrogen entering an Fe sheet under a droplet of NaCl solution was successfully visualized using a hydrogenochromic sensor consisting of a polyaniline layer and a Ni intermediate layer. At the initial stage of corrosion, the hydrogen entry was barely confirmed. The hydrogen entry was observed as the corrosion proceeded, and the preferential hydrogen entry site corresponded to the rust-formed area. It was postulated that the hydrogen entry is promoted by the decrease in pH due to the hydrolysis reactions of Fe ions under the rust. The hydrogenochromic sensor paves the way for the visualization of the hydrogen entry into metals under corrosion conditions. 相似文献
2.
3.
《International Journal of Hydrogen Energy》2021,46(70):34970-34982
Alloy hardened steels offer excellent combination of mechanical properties, hardenability and corrosion resistance. 34CrMo4 is a medium carbon, low alloy steel widely used due to a good combination of high-strength, toughness and wear resistance. However, this steel experiences hydrogen embrittlement (HE), a complex phenomenon depending on the composition and microstructure. This work estimates de loss of the mechanical properties caused by hydrogen in electrochemically H-charged specimens in absence of mechanical stress but also, at low strain rate and constant load. H-charging for 2 and 6 h induce YS losses of about 40% and 71% and UTS losses of 39% and 59%, respectively. The synergistic effect of the stress and the H-charging process leads to a higher loss, 91%, and a faster brittle fracture even though hydrogen content is similar to those firstly H-charged and then tested in air. 相似文献
4.
5.
In order to protect bolts from corrosion, electroplating such as zinc plating is widely used. However, hydrogen can easily penetrate or diffuse into the vacancies and dislocations between the lattices of bolt steel during electroplating. As the diffused hydrogen defects inside the lattice are in gaseous form, small cracks can easily be produced due to high pressure from the hydrogen gas. In this research, in order to determine the root cause of the fracture in pole fastening screws resulting from hydrogen embrittlement in typical electric motors, additional factors that accelerate hydrogen embrittlement fracture were selectively applied, including a small fillet in the head–shank transition and excessive hardness, and parametric study was performed experimentally. 相似文献
6.
7.
8.
采用正交试验对汽轮机叶片用X20Cr13钢进行了热处理工艺研究,以获得该钢的最佳热处理工艺,并在回火后以不同的速度冷却,以揭示冷却速度对钢的回火脆性的影响。结果,X20Cr13钢的最佳热处理工艺为900℃油淬或风冷,670℃回火,风冷。 相似文献
9.
铈和磷对中碳锰钢低温回火脆性的影响 总被引:1,自引:0,他引:1
本文采用冲击试验和断口扫描电镜,俄歇谱分析等方法,研究了铈对不同磷含量的中碳锰钢低温回火脆性的影响。结果表明,磷在奥氏体晶界偏聚是导致含磷锰钢产生低温回火脆性的原因,而铈的加入,可减少磷的偏聚程度,增加回火马氏体的冲击值,从而降低中碳锰钢的回火脆性。 相似文献
10.
The influence of an aggressive environment (0.6 M, aerated NaCl solution) on short fatigue crack initiation and growth behaviour has been studied. The study involved three major test series, namely: air fatigue, corrosion fatigue, and intermittent air fatigue/corrosion fatigue. The above tests carried out under fully reversed torsional loading conditions at a frequency of 5 Hz, showed that it was the non-metallic inclusions which took part in crack initiation resulting from debonding at metal matrix/inclusion interface and pitting of inclusions in both air and corrosove environments, respectively. Short fatigue crack growth results in these two environments obtained by using plastic replication technique, indicated a large effect of microstructure i.e. prior austenite grain boundaries. The stage/stages at which the environmental contribution was dominant has been discussed by considering the results achieved from intermittent tests. However, the mechanisms involved in corrosion fatigue short crack growth have also been described in the light of results obtained from futher investigations carried out by conducting corrosion fatigue tests under applied cathodic potential conditions and tests on hydrogen pre-charged specimens under air fatigue and uniaxial tension conditions. 相似文献