全文获取类型
收费全文 | 594篇 |
免费 | 31篇 |
国内免费 | 25篇 |
专业分类
电工技术 | 170篇 |
综合类 | 19篇 |
化学工业 | 69篇 |
金属工艺 | 50篇 |
机械仪表 | 29篇 |
建筑科学 | 28篇 |
矿业工程 | 11篇 |
能源动力 | 17篇 |
轻工业 | 7篇 |
水利工程 | 12篇 |
石油天然气 | 24篇 |
武器工业 | 3篇 |
无线电 | 52篇 |
一般工业技术 | 43篇 |
冶金工业 | 35篇 |
原子能技术 | 21篇 |
自动化技术 | 60篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 13篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 14篇 |
2016年 | 18篇 |
2015年 | 19篇 |
2014年 | 48篇 |
2013年 | 27篇 |
2012年 | 59篇 |
2011年 | 64篇 |
2010年 | 47篇 |
2009年 | 58篇 |
2008年 | 24篇 |
2007年 | 37篇 |
2006年 | 28篇 |
2005年 | 32篇 |
2004年 | 24篇 |
2003年 | 22篇 |
2002年 | 17篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1988年 | 7篇 |
排序方式: 共有650条查询结果,搜索用时 31 毫秒
51.
通过仿真某110 kV线路接地故障,利用希尔伯特-黄变换(Hilert-Huang Transform,HHT)分析了甲站、乙站单相跳闸以及甲站三相跳闸三种可能引起的保护跳闸方式下甲站1号变压器末屏A相电压与电流的波形特征,并分解计算了信号分解重构下低频与高频部分的能量函数值。计算结果表明:HHT所得到的能量函数能较好地识别线路故障引起站内保护跳闸的方式。 相似文献
52.
以大洋多金属结核为原料, 采用低温氢还原-湿法冶金联用工艺回收有价金属, 湿法冶金过程包括硫酸浸出、M5640萃取铜、针铁矿法除铁、P204萃取除锌、HBL110萃取回收镍。在HBL110萃取回收镍过程中, 考察了平衡pH值、相比O/A等因素对萃取镍的影响, 并绘制了镍萃取与反萃平衡等温线。结果表明, 采用50%HBL110+50%磺化煤油组成的有机相, 经过6级逆流萃取-4级逆流洗涤, 镍萃取率达99.85%, 除钴外, 杂质金属Mn、Ca、Mg、Al基本不被萃取。负载有机相经5级逆流反萃, 镍反萃率达98.53%。 相似文献
53.
The abrasion resistances of CO2 corrosion scales formed on API P110 grade carbon steel at different temperatures and CO2 corrosion behaviour of P110 carbon steel have been investigated utilising weight loss method, scanning electron microscope (SEM) and X-ray diffraction (XRD). The results showed that as the film forming temperature increased, the abrasion rate of CO2 corrosion scales increased firstly and then decreased, the variation trend was similar to that of the corrosion rate, and the maximal abrasion rate was present at 70°C rather than 100°C, at which the maximal corrosion rate was obtained and CO2 corrosion scales were loose and porous and were composed of FeCO3, Fe3C and CaCO3. The abrasion resistances of CO2 corrosion scales formed at 100°C was reinforced by the sand particles embedded easily in the loose and porous layer, together with a very hard residual skeleton, Fe3C. In addition, CaCO3 was worn out easily and substituted by SiO2 during abrasive wear. 相似文献
54.
Allan Abraham B. Padama Bhume Chantaramolee Hiroshi Nakanishi Hideaki Kasai 《International Journal of Hydrogen Energy》2014
The absorption of H atom in H-covered Pd(110) (1 × 2) missing-row surface is investigated using density functional theory based calculations. For 1.5 monolayer H coverage, interaction among the adsorbed H atoms is found to be negligible and was verified by analyzing the electronic structure of the system and by comparing the calculated binding energies with low H coverage case. Neither the monoatomic absorption of H nor the assistance from the initially adsorbed H atom explains the experimentally observed presence of subsurface H in Pd(110) at high H coverage. Instead, H absorption is realized through the assistance of incoming H atoms from vacuum. The absorption of H in the H-covered surface is non-activated while the dissociation of H2 is the rate-limiting process. Dissociation on ridge site is energetically more preferred than on trough site and the difference in the activation barrier is elucidated by investigating the electronic structures of the system. 相似文献
55.
Martin Beerbom Oliver Henrion Andreas Klein Thomas Mayer Wolfram Jaegermann 《Electrochimica acta》2000,45(28):4663
We have applied photoelectron spectroscopy to investigate the surface composition after different surface treatments involving Br2–H2O mixtures in order to study wet chemical etching. Emersion experiments from Br2–H2O solution are compared with model experiments, in which Br2–H2O adsorbate and coadsorbate mixtures react with clean GaAs(110) surfaces. Our results indicate that Ga- and As-bromides formed initially are hydrolyzed to form the respective oxides. Without addition of Br2, only slight oxidation of the surface takes place. There is an enrichment of Ga due to loss of As both in adsorption as well as in emersion experiments. Since in emersion experiments only a final situation is analyzed, the relative influence of surface reactivity and subsequent solvation effects cannot be distinguished easily, while model experiments give clear information on reaction products formed intermediately. However, model experiments differ in environment and temperature from the real solid–liquid interface. The presented results demonstrate that a combination of emersion and model experiments provide valuable insight into the mechanism of wet chemical etching on a microscopic level. 相似文献
56.
The adsorption and desorption behaviors of Yb(Ⅲ) on gel-type weak acid resin (110) were investigated. The influence of operational conditions such as contact time,initial concentration of Yb(Ⅲ),initial pH of solution and temperature on the adsorption of Yb(Ⅲ) were also examined. The results showed that the optimal adsorption condition of 110 resin for Yb(Ⅲ) was achieved at pH=5.5 in HAc-NaAc medium. The maximum uptake capacity of Yb(Ⅲ) was 265.8 mg/g at 298 K. Yb(Ⅲ) could be eluted by using 3.0 mol/L HCl solution and the 110 resin could be regenerated and reused. The adsorption of Yb(Ⅲ) followed the Langmuir isotherm,and the correlation coefficients were evaluated. Various thermodynamic parameters such as standard enthalpy change (△H),standard entropy change (△S) and standard free energy change (△G) were evaluated. The adsorption of Yb(III) on the 110 resin was found to be endothermic in nature. Thomas model was successfully applied to experimental data to predict the breakthrough curves and to determine the characteristics parameters of the column useful for process design. And the resin sample both before and after adsorption was described by IR spectroscopy. 相似文献
57.
阐述了CARTA轧管工艺控制技术的组成及应用,并对这种控制技术作出了评价,将它和轧管工艺自动控制软件包进行了对比。强调在建设新的钢管厂时或对连轧管厂进行技术改造时,有必要对两种限动芯棒连轧管工艺和两种轧管工艺自动控制技术联系起来考虑以取得最佳的经济效果。 相似文献
58.
ZnSe heteroepitaxial layers have been grown on GaAs (100), (110) on axis, and (110) 6° miscut substrates by molecular beam
epitaxy. ZnSe on GaAs (110) shows smooth and featureless spectra from Rutherford backscattering channeling measurements taken
along major crystalline directions, whereas ZnSe on GaAs (100) without pre-growth treatments exhibit large interface disorder
in channeling spectra. ZnSe films grown on GaAs (110) on axis show facet formation over a wide range of growth conditions.
The use of (110) 6° miscut substrates is shown to suppress facet formation; and under the correct growth conditions, facet-free
surfaces are achieved. Etch pit density measurements give dislocation densities for ZnSe epitaxial layers grown on GaAs (100),
(110) on axis, and (110) 6° miscut substrates of 107/cm2, 3 × 105/cm2 and 5 × 104/cm2, respectively. These results suggest that with further improvements to ZnSe growth on GaAs (110)-off substrates it may be
possible to fabricate defect free ZnSe based laser devices. 相似文献
59.
Haijun Tang Xuexu Gao Maocai Zhang Jie Zhu Shouzeng Zhou 《Journal of Alloys and Compounds》2008,450(1-2):58-61
Giant magnetostriction TbDyFe alloys, with 1 1 0 orientation and designated TDT-110, were prepared by a zone melting directional solidification technique with a high temperature gradient. Samples in the as-grown and heat-treated states, having various magnetostrictive properties, have been studied by transmission and scanning electron microscopy. The results of microscopy studies indicate that the density and distribution of microstructural defects substantially influence the magnetostrictive strains for these alloys. 相似文献
60.