全文获取类型
收费全文 | 138篇 |
免费 | 9篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 1篇 |
综合类 | 4篇 |
化学工业 | 34篇 |
金属工艺 | 6篇 |
机械仪表 | 15篇 |
建筑科学 | 16篇 |
矿业工程 | 6篇 |
能源动力 | 17篇 |
轻工业 | 19篇 |
石油天然气 | 6篇 |
无线电 | 5篇 |
一般工业技术 | 7篇 |
冶金工业 | 2篇 |
原子能技术 | 1篇 |
自动化技术 | 13篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 2篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 6篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2007年 | 12篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有152条查询结果,搜索用时 15 毫秒
1.
The reduction of NO by propene in the presence of excess oxygen over mechanical mixtures of Au/Al2O3 with a bulk oxide has been investigated. The oxides studied were: Co3O4, Mn2O3, Cr2O3, CuO, Fe2O3, NiO, CeO2, SnO2, ZnO and V2O5. Under lean C3H6-SCR conditions, these oxides (with the exception of SnO2) convert selectively NO to NO2. When mechanically mixed with Au/Al2O3, the Mn2O3 and Co3O4 oxides and, to a much greater extent, CeO2 act synergistically with this catalyst greatly enhancing its SCR performance. It was found that their synergistic action is not straightforwardly related to their activity for NO oxidation to NO2. The exhibited catalytic synergy may be due to the operation of either remote control or a bifunctional mechanism. In the later case, the key intermediate must be a short-lived compound and not the NO2 molecule in gas-phase. 相似文献
2.
Many good evolutionary algorithms have been proposed in the past. However, frequently, the question arises that given a problem, one is at a loss of which algorithm to choose. In this paper, we propose a novel algorithm portfolio approach to address the above problem for single objective optimization. A portfolio of evolutionary algorithms is first formed. Covariance Matrix Adaptation Evolution Strategy (CMA-ES), History driven Evolutionary Algorithm (HdEA), Particle Swarm Optimization (PSO2011) and Self adaptive Differential Evolution (SaDE) are chosen as component algorithms. Each algorithm runs independently with no information exchange. At any point in time, the algorithm with the best predicted performance is run for one generation, after which the performance is predicted again. The best algorithm runs for the next generation, and the process goes on. In this way, algorithms switch automatically as a function of the computational budget. This novel algorithm is named Multiple Evolutionary Algorithm (MultiEA). The predictor we introduced has the nice property of being parameter-less, and algorithms switch automatically as a function of budget. The following contributions are made: (1) experimental results on 24 benchmark functions show that MultiEA outperforms (i) Multialgorithm Genetically Adaptive Method for Single Objective Optimization (AMALGAM-SO); (ii) Population-based Algorithm Portfolio (PAP); (iii) a multiple algorithm approach which chooses an algorithm randomly (RandEA); and (iv) a multiple algorithm approach which divides the computational budget evenly and execute all algorithms in parallel (ExhEA). This shows that it outperforms existing portfolio approaches and the predictor is functioning well. (2) Moreover, a neck to neck comparison of MultiEA with CMA-ES, HdEA, PSO2011, and SaDE is also made. Experimental results show that the performance of MultiEA is very competitive. In particular, MultiEA, being a portfolio algorithm, is sometimes even better than all its individual algorithms, and has more robust performance. (3) Furthermore, a positive synergic effect is discovered, namely, MultiEA can sometimes perform better than the sum of its individual EAs. This gives interesting insights into why an algorithm portfolio is a good approach. (4) It is found that MultiEA scales as well as the best algorithm in the portfolio. This suggests that MultiEA scales up nicely, which is a desirable algorithmic feature. (5) Finally, the performance of MultiEA is investigated on a real world problem. It is found that MultiEA can select the most suitable algorithm for the problem and is much better than choosing algorithms randomly. 相似文献
3.
应用分形、智能Agent和神经网络自适应控制技术,研究分形供应链适应环境变化的结构模式和策略模式.探讨了分形供应链Agent关联结构,提出了分形供应链双层自适应协同计算模式,论述了资源Agent,信息协调Agent,人机交互Agent和领域计算Agent之间的相互作用关系.以一个分形模块的策略协同为分析对象,研究了领域单元的自适应协同计算模式,分析了分形模块的成本模型,并对基于Agent交互的神经网络模型部分进行了算例仿真. 相似文献
4.
A rubber wheel type test apparatus has been constructed which allows abrasion testing to be conducted in slurry or dry environments in otherwise identical conditions. Abrasion tests of a steel, a sintered tungsten carbide–cobalt hardmetal and an HVOF sprayed nickel chrome–chromium carbide cermet coating have been performed in dry and aqueous slurry conditions, the latter with both neutral and acidic carriers. It has been shown that the aqueous carrier acts as an effective lubricant and thus significantly reduces the abrasion rate over that observed in dry conditions. However, enhancement of corrosion by use of an acid slurry lead to an increase in the rate of material removal over that of the neutral aqueous conditions in all cases. Increases were small for the corrosion resistant cermet coating and moderate for the steel. Significant enhancement of wear was observed for the sintered WC–Co hardmetal where rapid removal of the cobalt binder by the acid resulted in a change in dominant mechanism of carbide removal from attritive wear to pullout. 相似文献
5.
Qi-Ning Song Nan Xu Yao Tong Chen-Ming Huang Shou-Yu Sun Chen-Bo Xu Ye-Feng Bao Yong-Feng Jiang Yan-Xin Qiao Zhi-Yuan Zhu Zheng-Bin Wang 《金属学报(英文版)》2019,32(12):1470
The effect of sulphide(Na_2S) concentration(SC) on the corrosion and cavitation erosion behaviours of a cast nickel aluminium bronze(NAB) in 3.5% NaCl solution is investigated in this study.The results show that when the SC exceeds 50 ppm,the hydrogen evolution reaction dominates the cathodic process,and a limiting current region appears in the anodic branch of the polarisation curve due to the formation of a copper sulphide film,which is a diffusion-controlled process.After longterm immersion,the increased mass loss rate of NAB with the sulphide additions of 20 and 50 ppm is attributed to the less protective films,which contains a mixture of copper oxides and sulphides.Moreover,NAB undergoes severe localised corrosion(selective phase corrosion,SPC) at the β' phases and eutectoid microstructure α+κ_Ⅲ.By comparison,NAB undergoes general corrosion and a copper sulphide film is formed in 100 and 200 ppm sulphide solutions.Cavitation erosion greatly increases the corrosion rate of NAB in all solutions and causes a negative potential shift in 3.5% NaCl solution due to the film destruction.However,a positive potential shift occurs in the solutions with SC higher than 50 ppm due to the accelerated mass transfer of the cathodic process.The cavitation erosion mass loss rate of NAB increases with the increase of SC.The occurrence of severe SPC decreases the phase boundary cohesion and causes brittle fracture under the cavitation impact.The corrosion-enhanced erosion is the most predominant factor for the cavitation erosion damage when the SC exceeds 50 ppm. 相似文献
6.
Perfectly Wetting Mixtures of Surfactants from Renewable Resources: The Interaction and Synergistic Effects on Adsorption and Micellization
下载免费PDF全文
![点击此处可从《Journal of surfactants and detergents》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper presents a study of the surface properties of mixtures of surfactants originating from renewable sources, i.e., alkylpolyglucoside (APG), ethoxylated fatty alcohol (AE), and sodium soap (Na soap). The main objective was to optimize the surfactant ratio which produces the highest wetting properties during the analysis of the solution of the individual surfactants, two- and three-component mixtures, and at different pH values. The results showed the existence of a synergistic effect in lowering the interfacial tension, critical micelle concentration and the formation of mixed micelles in selected solutions. We found that best wetting properties were measured for the binary AE:APG mixtures. It has been demonstrated that slightly lower contact angles values were observed on Teflon and glass surfaces for the AE:APG:soap mixtures but the results were obtained for higher concentration of the components. In addition, all studied solutions have very good surface properties in acidic, basic and neural media. However, the AE:soap (molar ratio of 1:2), AE:APG (2:1) and AE:APG:soap (1:1:1) compositions improved their wetting power at pH 7 on the aluminium and glass surfaces, as compared to solutions at other pH values tested (selected Θ values close to zero—perfectly wetting liquids). All described effects detected would allow less surfactant to be used to achieve the maximum capacity of washing, wetting or solubilizing while minimizing costs and demonstrating environmental care. 相似文献
7.
8.
Total volatile basic nitrogen (TVB-N) content is one of important index of pork’s freshness, and Warner–Bratzler shear force (WBSF) is seen as the important index of pork’s tenderness. This paper attempted the feasibility to determine TVB-N content and WBSF in pork by Fourier transform near infrared (FT-NIR) spectroscopy. Synergy interval partial least square (SI-PLS) algorithm was performed to calibrate regression model. The number of PLS factors and the number of intervals were optimised simultaneously by cross-validation. The performance of the model was evaluated according to two correlation coefficients (R) in calibration and prediction sets. Experimental results showed that the correlations coefficients in the calibration set (Rc) and prediction set (Rp) were achieved as follows: Rc = 0.8398 and Rp = 0.8084 for TVB-N content model; Rc = 0.7533 and Rp = 0.7041 for WBSF model. The overall results demonstrated that NIR spectroscopy combined with SI-PLS could be utilised to determinate TVB-N content and WBSF in pork. 相似文献
9.
Core business concentration vs. corporate diversification in the US electric utility industry: Synergy and deregulation effects 总被引:1,自引:1,他引:0
Many economists such as Wilson (2002) [Wilson, R., 2002. Architecture of power market, Econometrica, 70, 1299–1340] have considered that there are similarities between electricity and gas services in the US electric utility industry. Hence, they expect a synergy effect between them. However, the two businesses do not have technology similarities at the level that the gas service produces a synergy effect with electricity. To examine whether there is a synergy effect of corporate diversification in the industry, we compare electricity-specialized firms with diversified utility firms in terms of their financial performance and corporate value. The comparison indicates that core business concentration is more effective for electric utility firms than corporate diversification under the current US deregulation policy. 相似文献
10.
Yongqiang Sun Kai H. Lim Chunping Jiang Jerry Zeyu Peng Xiaojian Chen 《Computers in human behavior》2010
Informativeness and entertainment are regarded as two types of advertising value that can influence consumers’ attitudes toward Web advertising. Despite of many studies on these two factors, there are two research gaps in extant literature. First, the effects of informativeness and entertainment on attitude are considered separately, yet their interaction effect is neglected. Second, the role of individual characteristics (e.g., gender) in the advertising evaluation process is far from clear. To address these two issues, a laboratory experiment was conducted to investigate the interaction effect between informativeness and entertainment, and also the moderating role of gender. The results indicate that informativeness can help form a more positive attitude for males than for females, and entertainment can lead to a more positive attitude for females than for males. It is also found that there is a three-way interaction among informativeness, entertainment, and gender. More specifically, the interaction effect between informativeness and entertainment is significant for females, but insignificant for males. Results, research contributions, and limitations are discussed, and implications for future studies are suggested. 相似文献