全文获取类型
收费全文 | 8719篇 |
免费 | 749篇 |
国内免费 | 399篇 |
专业分类
电工技术 | 87篇 |
综合类 | 777篇 |
化学工业 | 750篇 |
金属工艺 | 1457篇 |
机械仪表 | 289篇 |
建筑科学 | 1913篇 |
矿业工程 | 660篇 |
能源动力 | 128篇 |
轻工业 | 73篇 |
水利工程 | 892篇 |
石油天然气 | 1793篇 |
武器工业 | 19篇 |
无线电 | 39篇 |
一般工业技术 | 293篇 |
冶金工业 | 622篇 |
原子能技术 | 22篇 |
自动化技术 | 53篇 |
出版年
2024年 | 42篇 |
2023年 | 101篇 |
2022年 | 236篇 |
2021年 | 312篇 |
2020年 | 284篇 |
2019年 | 200篇 |
2018年 | 226篇 |
2017年 | 244篇 |
2016年 | 306篇 |
2015年 | 315篇 |
2014年 | 477篇 |
2013年 | 410篇 |
2012年 | 641篇 |
2011年 | 630篇 |
2010年 | 441篇 |
2009年 | 447篇 |
2008年 | 418篇 |
2007年 | 533篇 |
2006年 | 587篇 |
2005年 | 486篇 |
2004年 | 398篇 |
2003年 | 369篇 |
2002年 | 311篇 |
2001年 | 277篇 |
2000年 | 225篇 |
1999年 | 198篇 |
1998年 | 155篇 |
1997年 | 128篇 |
1996年 | 81篇 |
1995年 | 98篇 |
1994年 | 82篇 |
1993年 | 49篇 |
1992年 | 43篇 |
1991年 | 22篇 |
1990年 | 28篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 10篇 |
排序方式: 共有9867条查询结果,搜索用时 0 毫秒
91.
Andrew J. Wright Chuying Huang Michael J. Walock Anindya Ghoshal Muthuvel Murugan Jian Luo 《Journal of the American Ceramic Society》2021,104(1):448-462
Sand corrosion, thermal expansion, and ablation properties of a new class of medium- and high-entropy compositionally complex fluorite oxides (CCFOs) are examined as potential protective coating materials. Five binary oxides were mixed and sintered into dense, single-phase CCFOs of the general formula: [Hf(1-2x)/3Zr(1-2x)/3Ce(1-2x)/3YxYbx]O2-δ (x = 0.2, 0.074, and 0.029). These CCFOs exhibit decreased molten sand infiltration and interaction at intermediate temperatures (1200-1300°C) in comparison with a cubic yttria-stabilized zirconia (YSZ) reference; however, at higher temperatures, the trend is reversed due to the increased chemical reactivity. The equimolar high-entropy (Hf0.2Zr0.2Ce0.2Y0.2Yb0.2)O2-δ exhibits no grain boundary penetration by molten sand at all examined temperatures (1200°C-1500°C), although reaction and precipitation are significant. Moreover, these CCFOs exhibit higher intrinsic thermal expansion coefficients (CTE) than the YSZ reference, thereby being more compatible with Ni-based superalloys. The 8YSZ-like (Hf0.284Zr0.284Ce0.284Y0.074Yb0.074)O2-δ exhibits the highest CTE in this series of CCFOs due to oxygen clustering effects. Finally, these CCFOs also exhibit lower emissivities and form unique faceted microstructures in ablative environments. 相似文献
92.
93.
Diamond films were deposited on the WC-Co cemented carbide and Si3N4 ceramic cutting tool substrates by hot-filament-assisted chemical vapour deposition. The adherence property of diamond films was estimated using the critical load (Pcr) in the indentation test. The adhesive strength of diamond films is related to the intermediate layer between the film and the substrate. Poor adhesion of diamond films to polished cemented carbide substrate is owing to the formation of graphite phase in the interface. The adhesion of diamond films deposited on acid etched cemented carbide substrate is improved, and the peeling-off of the films often happens in the loosen layer of WC particles where the cobalt element is nearly removed. The diamond films' adhesion to cemented carbide substrate whose surface layer is decarbonizated is strengthened dramatically because WC phase forms by reaction between the deposited carbon and tungsten in the surface layer of substrates during the deposition of diamond, which results in chemical combination in the film-substrate interface. The adhesion of diamond films to silicon nitride substrate is the firmest due to the formation of chemical combination of the SiC intermediate layer in the interfaces. In the piston-turning application, the diamond-coated Si3N4 ceramic and the cemented carbide cutting tools usually fail in the form of collapsing of edge and cracking or flaking respectively. They have no built-up edge(BUE) as long as coating is intact.As it wears through, BUE develops and the cutting force on it increases 1 - 3 times than that prior to failure. This can predict the failure of diamond-coated cutting tools. 相似文献
94.
96.
97.
硬质合金与钢的热等静压扩散连接 总被引:2,自引:1,他引:2
研究了硬质合金YG15C与45~#碳钢的热等静压扩散连接工艺,探讨厂连接温度、压力、保温保压时间、中间夹层及其厚度和连接残余热应力等对接合强度的影响.结果表明:热等静压扩散连接强度强烈依赖于连接温度,受控于连接后因YG15C与45~#钢热膨胀失配而产生的残余热应力。采用镍箔作中间夹层可有效地减小残余热应力对连接的影响,显著提高接合强度. 相似文献
98.
99.
粘土砂湿型铸造,铸件表面容易产生粘砂。某厂采用粘土砂湿型生产拖拉机铸件,也遇到了铸件表面粘砂的问题。通过不断选择醇基涂料悬浮剂,调整涂料的配比,最后采用SN-1悬浮剂,经试验和应用取得较好的效果。 相似文献
100.
用自制的型砂多项性能测试仪,获得了型砂抗压、松弛、抗剪和抗拉测试过程中的应力-应变本质特征曲线,并对它们进行了深入研究,在特征曲线上确定了反映型砂本质性能的8项性能参数,考察了膨润土含量和紧实率对型砂本质特征曲线和型砂性能参数的影响。型砂力学本质特征曲线决定于型砂的内部微观组织结构,反映出型砂的粘弹性和粘塑性等本质性能,体现出型砂在受力变形过程中的微变形本质特征。 相似文献