全文获取类型
收费全文 | 8449篇 |
免费 | 858篇 |
国内免费 | 533篇 |
专业分类
电工技术 | 426篇 |
综合类 | 519篇 |
化学工业 | 1504篇 |
金属工艺 | 1821篇 |
机械仪表 | 336篇 |
建筑科学 | 592篇 |
矿业工程 | 689篇 |
能源动力 | 255篇 |
轻工业 | 275篇 |
水利工程 | 109篇 |
石油天然气 | 226篇 |
武器工业 | 699篇 |
无线电 | 113篇 |
一般工业技术 | 1398篇 |
冶金工业 | 536篇 |
原子能技术 | 115篇 |
自动化技术 | 227篇 |
出版年
2024年 | 45篇 |
2023年 | 134篇 |
2022年 | 304篇 |
2021年 | 253篇 |
2020年 | 249篇 |
2019年 | 201篇 |
2018年 | 177篇 |
2017年 | 301篇 |
2016年 | 280篇 |
2015年 | 254篇 |
2014年 | 485篇 |
2013年 | 465篇 |
2012年 | 620篇 |
2011年 | 671篇 |
2010年 | 589篇 |
2009年 | 536篇 |
2008年 | 462篇 |
2007年 | 592篇 |
2006年 | 597篇 |
2005年 | 470篇 |
2004年 | 414篇 |
2003年 | 344篇 |
2002年 | 286篇 |
2001年 | 243篇 |
2000年 | 193篇 |
1999年 | 165篇 |
1998年 | 108篇 |
1997年 | 81篇 |
1996年 | 79篇 |
1995年 | 62篇 |
1994年 | 55篇 |
1993年 | 30篇 |
1992年 | 26篇 |
1991年 | 21篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1979年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1959年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有9840条查询结果,搜索用时 15 毫秒
81.
82.
Electrotribological applications require materials with both high electrical conductivity and wear resisance. For this purpose,
a copper- base plasma sprayed coating containing titanium diboride particles was developed. The process for fabricating this
CU- TiB2 coating consists of plasma spraying reactive powders that contain a Cu- Ti alloy and boron. The reaction between the copper
alloy and boron proceeds in different steps going from solid- state diffusion of titanium and copper to the synthesis of TiB2 in a liquid below 1083 ‡C. Plasma sprayed copper coatings contain finer TiB2 crystals than Cu- TiB2 materials synthesized in a furnace at 1200 ‡C. Coatings with 25 vol% TiB2 have hardnesses that are comparable to Cu- Co-
Be and Cu- Ni- Be alloys and to Cu- W and Cu- Mo alloys used in spot welding. Their low electrical resistivity of 52 ΜΩ cm
could be increased by lowering the oxygen content with coatings and controlling the formation of TiB2 clusters, the titanium content in solution in copper remaining low after the synthesis reaction. 相似文献
83.
介绍了某露天山坡矿采用水耦合装药爆破技术,通过与常规爆破对比试验分析,提出利用水耦合爆破可以改善露天深孔爆破效果、提高原矿大块合格率和降低炸药单耗,达到安全增效、降耗的目的。 相似文献
84.
Ti—C—Al体系热爆合成过程 总被引:4,自引:0,他引:4
采用整体加热燃烧合成法(即热爆合成)制备了TiC-Al复合体系,利用差热分析(DTA)、X射线衍射分析(XRD)和扫描电镜(SEM)等手段研究了Ti-C-Al体系中升温速度及Al含量对TiC反应合成过程的影响,分析了Al基体对TiC粒子的形成机理.结果表明,在TiC反应合成过程中,首先是Ti与Al反应形成Ti与Al的化合物,放出热量,随后促使Ti与C的放热反应发生,合成TiC时放热产生的高温使Ti与Al的化合物分解,从而制得TiC-Al复合体系;升温速度及Al含量只有超过一定值时,该体系才能在较低温度发生热爆反应;当Al的质量分数从10%升至50%时,TiC的粒度从5.0μm阵至0.5μm. 相似文献
85.
Molybdenum and tungsten coatings for x- ray targets obtained through the low-pressure plasma spraying process 总被引:1,自引:0,他引:1
A. A. Khan J. C. Labbe A. Grimaud P. Fauchais 《Journal of Thermal Spray Technology》1997,6(2):228-234
Low-pressure plasma spraying under an argon atmosphere was employed to deposit molybdenum and tungsten coatings on different
metallic, ceramic, and composite substrates. Molybdenum coatings ob-tained through this technique presented a homogeneous
structure with an average porosity of about 17 %. These coatings exhibited adhesion greater than 40 MPa on molybdenum and
grey cast iron (FT25) substrates. No adhesion was observed on an A1N surface regardless of the preheating temperature and/or
surface preparation. Adhesion on AIN-Mo (AM25) composite substrate, containing 25 % dispersed metal-lic phase by volume, showed
intermediate results. Tungsten coatings exhibited porosity between 10 to 12% and a typical lamellar structure. The adhesion
of tungsten coatings on molybdenum and FT25 sub-strates was around 40 MPa. 相似文献
86.
A new technology of functionally graded materials(FGM) mould fabricated by plasma spraying and arc spraying was developed. According to applied characteristic of plastic mould, the reasonable coatings of FGM were designed and their microstructures were analyzed. At the same time, some key problems were solved including spray mould fabricating, FGM forming and demoulding, etc. The results show that the service performance of the FGM mould is much more excellent than the one composed of the traditional materials, and the life span can also be greatly increased. The technology will have a significant influence on materials development in mould industry. 相似文献
87.
The effect of Ti-OH groups on bioactivity of NaOH treated titanium coating was investigated in this paper. The NaOH-heat treatment was also applied to modify the titanium coating for comparison. The results show that the amount of Ti-OH groups was important to induce apatite formation on the treated titanium coating. When the NaOH treated titanium coating was exposed to SBF, it released Na+ ions from the sodium titanate layer on its surface into the SBF via exchanging with H3O+ ions in the fluid and Ti-OH groups were rapidly formed on the surface. So the NaOH treated titanium coating has good bioactivity in simulated body fluid (SBF). The amount of Ti-OH groups on the titanium coating was reduced after heat treatment, so the bioactivity of NaOH-heat treated titanium coating was obviously affected. 相似文献
88.
89.
A mathematical model is developed to predict particle velocity and temperature during high-velocity oxyfuel (HVOF) spraying.
This model accounts for internal heat conduction in powder particles; particle heating, fusion, cooling, and solidification;
the influence of particle morphology on thermal behavior; and the composite structure of the particles. Analytical results
are obtained that describe particle velocity and temperature variations. The dependence of fluid velocity on particle density
and volume fraction is shown. The results agree with empirically established HVOF spraying practice.
Physical Metal-lurgy—Materials Science 相似文献
90.
Robert B. Heimann 《Surface & coatings technology》2006,201(5):2012-2019
Osteoconductive hydroxyapatite coatings for metallic endoprostheses for hip and knee joint replacement provide a state-of-the-art template for enhanced in-growth of bone cells. However, the high temperature of the plasma jet leads to large scale dehydroxylation and decomposition of the starting powder. A model is being developed to explain the formation of chemically and mechanically inhomogeneous porous calcium phosphate coatings deposited by atmospheric plasma spraying onto titanium alloy substrates. In addition the biofunctionality is being discussed of titania bond coats and their influence on the in vivo performance of hydroxyapatite-titania duplex coating systems. 相似文献