全文获取类型
收费全文 | 3285篇 |
免费 | 281篇 |
国内免费 | 113篇 |
专业分类
电工技术 | 127篇 |
综合类 | 166篇 |
化学工业 | 1165篇 |
金属工艺 | 276篇 |
机械仪表 | 37篇 |
建筑科学 | 60篇 |
矿业工程 | 191篇 |
能源动力 | 112篇 |
轻工业 | 16篇 |
水利工程 | 4篇 |
石油天然气 | 49篇 |
武器工业 | 6篇 |
无线电 | 79篇 |
一般工业技术 | 307篇 |
冶金工业 | 1049篇 |
原子能技术 | 24篇 |
自动化技术 | 11篇 |
出版年
2024年 | 9篇 |
2023年 | 88篇 |
2022年 | 106篇 |
2021年 | 114篇 |
2020年 | 90篇 |
2019年 | 85篇 |
2018年 | 76篇 |
2017年 | 109篇 |
2016年 | 94篇 |
2015年 | 89篇 |
2014年 | 174篇 |
2013年 | 146篇 |
2012年 | 163篇 |
2011年 | 209篇 |
2010年 | 156篇 |
2009年 | 196篇 |
2008年 | 130篇 |
2007年 | 190篇 |
2006年 | 185篇 |
2005年 | 168篇 |
2004年 | 151篇 |
2003年 | 165篇 |
2002年 | 135篇 |
2001年 | 121篇 |
2000年 | 103篇 |
1999年 | 75篇 |
1998年 | 85篇 |
1997年 | 60篇 |
1996年 | 41篇 |
1995年 | 27篇 |
1994年 | 38篇 |
1993年 | 23篇 |
1992年 | 21篇 |
1991年 | 15篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1975年 | 3篇 |
1967年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有3679条查询结果,搜索用时 78 毫秒
1.
《Ceramics International》2022,48(14):20158-20167
Vacuum induction melting is a potential process for the preparation of TiAl alloys with good homogeneity and low cost. But the crucial problem is a selection of high stability refractory. In this study, a BaZrO3/Y2O3 dual-phase refractory was prepared and its performance for melting TiAl alloys was studied and compared with that of a Y2O3 refractory. The results showed the dual-phase refractory consisted of BaZr1-xYxO3-δ and Y2O3(ZrO2), exhibited a thinner interaction layer (30 μm) than the Y2O3 refractory (90 μm) after melting the TiAl alloy. Although the TiAl alloys melted in the dual-phase and Y2O3 refractory exhibited similar oxygen contamination (<0.1 wt%), the alloy melted in the dual-phase refractory had smaller Y2O3 inclusion content and size than that in the Y2O3 refractory, indicating that the dual-phase refractory exhibited a better melting performance than the Y2O3 refractory. This study provides insights into the process of designing highly stable refractory for melting TiAl alloys. 相似文献
2.
Katerina Zaharieva Maya Shopska Ilyana Yordanova Sonia Damyanova 《Ceramics International》2018,44(1):326-332
Magnesium aluminate-based materials were prepared by applying different methods: (i) mechanochemical milling of the initial mixture of magnesium and aluminium nitrate powders (in appropriate stoichiometric amounts) followed by heat treatment at temperatures of 650 °C and 850 °C and (ii) melting of the mixture of nitrate precursors at 240 °C followed by thermal treatment at 650 °C, 750 °C and 850 °C. The effect of synthesis method on the structure and morphology of the obtained solids was studied by using various techniques such as: nitrogen adsorption-desorption isotherms, powder XRD, IR spectroscopy and SEM. It was shown that the mechanochemical milling performed before calcination procedure leads to obtaining of nanocrystalline magnesium aluminate spinel phase at lower temperature of 650 °C in comparison with the method using thermal treatment only (at 750 °C). The obtained nanomaterials exhibit mesoporous structure. 相似文献
3.
4.
In order to improve the physical properties and slag corrosion resistance of refractory materials for hot metal pretreatment, different contents of composite metal powders (CMP) were introduced into Al2O3-SiC-C refractory castables. The effect of CMP on the microstructure, physical properties and slag corrosion resistance of Al2O3-SiC-C refractory castables were studied. The results show that the multi scale reinforcing phases including flake crystals, rod shaped fibers, filamentous fibers and whiskers are in situ formed in the samples with addition of CMP, which result to the improvement of the cold modulus of rupture and cold crushing strength. When the addition of CMP is 6 wt.%, the high temperature modulus of rupture increases by 231%, the thermal shock resistance increases by 77% after thermal shock by water cooling 5 times and the percentage of the slag resistant area reduces by 37.2%. 相似文献
5.
6.
Six synthesized magnesium aluminate spinel-based refractory compositions used in steel and cement applications, were prepared using a two stage sintering process at 1760 °C, starting with approximately 1:1 wt% ratio of pure magnesia and alumina with additions of zirconium silicate (0.5, 1.0 and 2.0 wt%) and chromite (2.0, 3.0 and 5.0 wt%). These compositions were investigated for effects on densification, chemical and mineralogical phases formed. 相似文献
7.
8.
添加剂对尖晶石型锰酸锂性质表征的影响 总被引:1,自引:0,他引:1
以LiOH·H_20和MnO_2为原料,分别掺入H_2BO_3、Al_2O_3、SiO_2和P_2O_5等添加剂,用固相分段法制备尖晶石型锰酸锂。结果表明,SiO_2和P_2O_5可以有效地改善LiMn_2O_4的电化学性能,H_3BO_3对锰酸锂的电化学性能影响不大,而Al_2O_3破坏了LiMn_2O_4的电化学性能。面扫描结果显示,Si或P元素各自都均匀地分散于LiMn_2O_4的物相中。从元素电负性和原子半径的角度分析了B、Si、P和Al元素对尖晶石型LiMn_2O_4结构和性能的影响。 相似文献
9.
介绍了夹杂物的来源,包括内生夹杂和外来夹杂,着重于二次氧化产物、卷渣、内衬侵蚀.同时介绍了鄂钢电炉厂在冶炼和连铸过程中控制夹杂物的操作实践. 相似文献
10.
In target detection tasks, responses are faster when displays have 2 targets (redundant-targets effect; RTE) and slower when they have no targets (nontargets effect; NTE) relative to displays with a single target. The psychological refractory period paradigm was used to localize these effects. In Experiment 1, participants classified tones as high or low and then classified letters as targets or nontargets after a short or long stimulus onset asynchrony (SOA). The magnitudes of the RTE and NTE did not depend on SOA. In Experiment 2, the order of the tasks was reversed, and at short SOAs the RTE and NTE had similar magnitudes for both tone discrimination and target detection responses. These findings suggest that the RTE and NTE arise during response selection. Interactive effects of tone pitch with the number and type of target features were also observed, and these were tentatively interpreted as synesthetic effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献