全文获取类型
收费全文 | 1288篇 |
免费 | 97篇 |
国内免费 | 239篇 |
专业分类
电工技术 | 40篇 |
综合类 | 80篇 |
化学工业 | 139篇 |
金属工艺 | 750篇 |
机械仪表 | 83篇 |
建筑科学 | 50篇 |
矿业工程 | 12篇 |
能源动力 | 16篇 |
轻工业 | 18篇 |
水利工程 | 7篇 |
石油天然气 | 98篇 |
武器工业 | 5篇 |
无线电 | 17篇 |
一般工业技术 | 190篇 |
冶金工业 | 102篇 |
原子能技术 | 13篇 |
自动化技术 | 4篇 |
出版年
2024年 | 3篇 |
2023年 | 9篇 |
2022年 | 49篇 |
2021年 | 42篇 |
2020年 | 41篇 |
2019年 | 45篇 |
2018年 | 37篇 |
2017年 | 76篇 |
2016年 | 72篇 |
2015年 | 55篇 |
2014年 | 61篇 |
2013年 | 85篇 |
2012年 | 95篇 |
2011年 | 101篇 |
2010年 | 75篇 |
2009年 | 95篇 |
2008年 | 57篇 |
2007年 | 70篇 |
2006年 | 65篇 |
2005年 | 61篇 |
2004年 | 62篇 |
2003年 | 62篇 |
2002年 | 46篇 |
2001年 | 54篇 |
2000年 | 38篇 |
1999年 | 36篇 |
1998年 | 20篇 |
1997年 | 20篇 |
1996年 | 23篇 |
1995年 | 14篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1992年 | 15篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有1624条查询结果,搜索用时 15 毫秒
121.
Ma GeZuo XiurongHong LiangJi YinglunDong JunyuanWang Huihui 《金属学报》2018,(4):527-536
X70 pipeline steel with thick specifications (40.5 mm) for 3500 m deep sea reached the international advanced level in the wall thickness and service depth. Due to the high heat input during the welding process, the corrosion resistance of inside welding and outside welding would vary depending on the microstructure differences. The corrosion resistance of the welded joints of X70 pipeline for deep sea was studied by the immersion test, the weight loss test, the electrochemical test in this work. The components of the passive film were analyzed by XRD and the microstructure was observed by SEM. The results show that the corrosion resistance of the weld metal is the best. The corrosion resistance of the heat affected zone follows. The corrosion resistance of the base metal is the worst. And for the same area, the corrosion resistance of the inside welding is better than that of the outside welding. The formation of dense Fe3O4 passivation film can effectively slow down the progress of the reaction, and the corrosion products of Fe2O3, FeOOH and Fe(OH)(3) which are loose in the outer layer, have no protective effect on the matrix. The microstructure of the weld metal with the best corrosion resistance is mostly the intragranular nucleation ferrite and martensite-austenite (M-A) constituent is fine and uniform. The microstructure gradient of the heat affected zone is the largest, the M-A constituent is coarse and the corrosion resistance is inferior to the weld metal. The base metal consists of ferrite and bainite, the bainite is island-like distribution and the corrosion resistance is the worst. Microstructure of the inside welding is more refined, owing to the influence of outside welding thermal cycle, and the volume fraction of M-A constituent in inside welding is higher than that of the outside welding, so the corrosion resistance is better than that of the outside welding. 相似文献
122.
123.
钴(Co)因拥有较低的电阻率、良好的热稳定性、与Cu黏附性好等优点,可以替代钽(Ta)成为铜(Cu)互连结构的阻挡层;当特征尺寸减小到10 nm后,由于Co良好的抗电迁移能力,可以在很薄的阻挡层上实现无空隙填充,作为理想的互连金属候选材料,表现出了巨大的应用潜力。但由于Co的反应活性较强,以及不同金属材料之间的腐蚀电位差异,在化学机械抛光(CMP)过程中容易形成点蚀和电偶腐蚀缺陷,严重影响器件的性能,而成为研究的热点。综合分析近年来关于钴CMP过程中表面缺陷的产生及控制的相关研究,重点分析抛光液中的络合剂、缓蚀剂等成分对于钴表面缺陷的产生以及控制的作用机制;指出在碱性环境下,选择合适的缓蚀剂和络合剂以及利用不同缓蚀剂的协同作用,可以有效控制点蚀缺陷的发生,并指出量子化学可从分子层面上定性定量地分析抛光液中各试剂的相互协同机制,为抛光液的设计提供理论支撑。 相似文献
124.
125.
126.
X80和X52钢在模拟海水环境中的腐蚀行为与规律 总被引:3,自引:0,他引:3
采用模拟浸泡实验、腐蚀形貌分析以及动电位极化和电化学阻抗技术研究了X52和X80钢在模拟海水环境中的腐蚀行为。结果表明:饱和氧时即模拟浅海条件下,X80和X52钢试样表面全面腐蚀和点蚀都会发生,腐蚀速率较大;低氧时即模拟深海条件下,二者主要发生点蚀,腐蚀速率较小。通过对X52和X80钢在模拟海水环境中针对含氧量这一影响因素的腐蚀行为与规律的对比分析得出,X80钢更适用于深海。 相似文献
127.
128.
Aluminium is the second most often used metal after steel. In this paper, the most current uses of aluminium alloys are first summarised. Then, their different corrosion modes, i.e. pitting, crevice, filiform, galvanic and structural corrosion (including inter‐granular, exfoliation and stress corrosion cracking) are reviewed, with particular attention paid to metallurgical factors controlling the corrosion process. For each mode, some instances of possible in‐service failure are given, followed by the discussion of the involved mechanisms and the presentation of appropriate solutions to prevent corrosion. Last, passivity and polarisation behaviour are discussed with reference to stainless steels. 相似文献
129.
Methods for service life prediction of reinforced concrete structures exposed to chloride‐bearing environments require, amongst other parameters, the knowledge of the chloride threshold for pitting corrosion initiation (Clth). Nowadays, although the main factors influencing the chloride threshold are well known, it is often difficult to quantify a value of the chloride threshold, partly because of its intrinsic high variability, and partly because of the different test methods that have been used to measure it. All the experimental tests rely on the detection of steel depassivation and simultaneous measurement of chloride content or steel potential. This paper deals with the methods that can be used to detect steel depassivation in relation with the determination of the chloride threshold. Tests in concrete‐pore‐simulating solutions as well as tests in concrete will be considered, and advantages and limitations will be discussed. 相似文献
130.
对某石化公司642号废汽油储罐0Cr18Ni9不锈钢浮盘盖板和浮筒腐蚀情况进行了物理测试,分析了腐蚀的原因。结果表明,不锈钢浮盘盖板和浮筒是由于废汽油中有硫化物而导致局部腐蚀穿孔。腐蚀穿孔是由浮盘盖板下表面萌生,并向接触其相部位的上表面发展。同时,由于海水冲洗和稀释引起氯化物对不锈钢浮盘盖板和浮筒的局部腐蚀。在分析的基础上提出了切实可行的防护措施。 相似文献