全文获取类型
收费全文 | 373篇 |
免费 | 27篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 127篇 |
金属工艺 | 4篇 |
机械仪表 | 6篇 |
建筑科学 | 15篇 |
能源动力 | 32篇 |
轻工业 | 32篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 17篇 |
一般工业技术 | 83篇 |
冶金工业 | 18篇 |
原子能技术 | 14篇 |
自动化技术 | 49篇 |
出版年
2023年 | 17篇 |
2022年 | 45篇 |
2021年 | 44篇 |
2020年 | 33篇 |
2019年 | 23篇 |
2018年 | 27篇 |
2017年 | 20篇 |
2016年 | 24篇 |
2015年 | 9篇 |
2014年 | 18篇 |
2013年 | 15篇 |
2012年 | 12篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 5篇 |
2008年 | 12篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有403条查询结果,搜索用时 15 毫秒
31.
Marwa A. El Wardani John I. Messner Michael J. Horman 《Canadian Metallurgical Quarterly》2006,132(3):230-238
The design-build delivery method is increasingly used in the United States due to numerous advantages it can offer a project. An important issue associated with design-build delivery is the procurement method used to select the design-build team. It is a critical decision that involves several key project team members, including the owner, designer, and contractor organizations, and requires the owner to carefully choose the design-build procurement method that will be used to select the team that will deliver the project. This research quantitatively analyzed the correlation between the design-build procurement method and the performance of the design-build project with regard to cost, time, and quality metrics. The procurement methods studied were sole source, qualifications-based, best value, and low bid selection. Data were collected through surveys from 76 design-build projects in the United States. Based on the patterns and relationships identified from these data, a better understanding of the procurement process and how it influences project performance is achieved. The impact of project-specific factors and guidelines are presented to assist owners in selecting the design-build team procurement method that responds to their project goals. 相似文献
32.
Umer Shafique Jamil Anwar Waheed uz-Zaman Rabia Rehman Muhammad Salman Amara Dar Nadia Jamil 《Journal of Hydro》2012,6(3):221-226
Migration of soluble and suspended materials by directional freezing of aqueous systems has been studied qualitatively. Slow freezing was employed vertically as well as horizontally through solutions and suspensions. In all cases, the impurities (soluble salts as well as suspended materials) were appreciably forced out by dynamic freezing front. The phenomenon worked for concentrating/separating inorganic ions, soluble organic compounds and dyes in synthetic solutions as well as in natural streams. Various analytical techniques were employed to monitor the migrating species through the freezing media. It was found that separation efficiency depends on different factors like rate of cooling, pH and concentration. Model experiments were designed and exercised successfully to employ the technique for treatment of dye-polluted water. 相似文献
33.
Loni D. Gattinger Zdravko Duvnjak Waheed A. Khan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1990,49(2):155-164
For the enzymatic saccharification of canola meal by enzyme preparations from Trichoderma reesei as well as by commercially available hemicellulase and multienzyme preparations, a pretreatment consisting of autoclaving is necessary. These enzyme preparations hydrolysed over 20% (w/w) of pretreated canola meal, which constitutes over 70% saccharification of the total polysaccharides present in canola meal. The results show that saccharification of canola meal is mainly brought about by hemicellulases capable of degrading arabinogalactan, arabinoglucan, galactan and galactomannan, while cellulases and xylanases play a minor role. These hemicellulases were found to be more stable at 50°C than cellulases or xylanases. This pretreatment also released water-soluble polysaccharides consisting mainly of arabinose and glucose. Trichoderma reesei was unable to produce enzymes capable of hydrolysing this polysaccharide when cultivated on canola meal as substrate. 相似文献
34.
Marwa T.A. Abdel-Wareth Rafat T. Abdel-Wahed 《The International journal of environmental studies》2018,75(4):605-622
The presence of fungi in water systems represents a threat to human health. Hydrogen peroxide is known for its disinfecting properties and easy decomposition to water and oxygen. Its activity can be enhanced by the addition of iron as a catalyst, a reagent known as Fenton?s reagent. In the present study, different Fenton concentrations were investigated on the spores of Aspergillus flavus, Aspergillus niger and Penicillium citrinum at different time intervals. The results indicate that complete inactivation of spores was noticed after 60 min of exposure to both 2 and 3% H2O2 catalyzed by 0.025 g Fe2+/100 ml for A. niger, and 3% H2O2 catalysed by 0.075 g Fe2+/100 ml for P. citrinum. The activity of two antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), was determined in mycelial mat harvested after 7 days. Their activities were either highly increased or reached their minimum values prior to inactivation of spores. 相似文献
35.
Marwa A. A. Mohamed Azza El‐Maghraby Mona Abd El‐Latif Hassan Farag Kyriaki Kalaitzidou 《Polymer Composites》2014,35(12):2343-2352
The focus of this study is to improve the dispersion state of nanocrystalline (nc) Fe‐Ni particles in polyamide 6 (PA6) matrix and the filler‐matrix interfacial interactions to provide Fe‐Ni alloy/PA6 nanocomposites of remarkable mechanical performance for engineering applications. nc Fe40Ni60 particles were chemically synthesized. Then Fe40Ni60/PA6 nanocomposites of various nanofiller loading were prepared by compounding via a newly modified master batch technique called ultrasound assisted master batch (UMB), followed by injection molding (IM). Their mechanical properties, morphology and structural parameters were characterized and compared with the corresponding properties of Fe40Ni60/PA6 nanocomposites made by solution mixing (SM) and IM. The study reveals that the UMB process is more cost effective and time efficient, simpler and easier to scale up compared with the SM process. In addition, UMB nanocomposites exhibit superior mechanical properties and distinctive morphology compared with the corresponding SM ones. Moreover, structural analyses indicate that physical structural changes occurred in PA6 due to presence of alloy particles are affected differently by the different compounding methods, profound understanding of such phenomenon is focused throughout the article. These distinctive advantages recommend that UMB technique can be of great potential in commercial production of polymer nanocomposites (PNCs). It is concluded that the sonication of nc Fe40Ni60 particles in dilute polymer solution during UMB compounding, a new step that is incorporated for the first time in the master batch process, is mainly responsible for the good wetting between nanoparticles and polymer chains, strong filler‐matrix interactions and consequently the remarkable mechanical performance of UMB PNCs. POLYM. COMPOS., 35:2343–2352, 2014. © 2014 Society of Plastics Engineers 相似文献
36.
37.
38.
Mahmoud R. Noor El-Din Sabrnal H. El-Hamouly Hamed M. Mohamed Marwa R. Mishrif Ahmad M. Ragab 《Journal of surfactants and detergents》2014,17(4):819-831
In this work, water-in-diesel fuel nanoemulsions were prepared with mixed nonionic surfactants. Several mixtures of sorbitan monooleate and polyoxyethylene (20) sorbitan monooleate, with different Hydrophilic–Lipophilic Balance (HLB) values (9.6, 9.8, 10, 10.2 and 10.4) were prepared to achieve the optimal HLB value. Three mixed surfactant concentrations were prepared at 6, 8 and 10 wt% to identify the optimum concentration. Five emulsions with different water contents: 5, 6, 7, 8 and 9 % (wt/wt) were prepared using a high energy method under the optimum conditions (HLB = 10 and mixed surfactant concentration = 10 %). The effect of the HLB value, mixed surfactant concentration and water content on the droplet size has been studied. The interfacial tension and thermodynamic properties of the individual and the blended emulsifiers were investigated. Droplet size of the prepared nanoemulsions was determined by dynamic light scattering and the nanoemulsion stability was assessed by measuring the variation of the droplet size as a function of time. From the results obtained, it was found that the mean droplet size was formed between 49.5 and 190 nm depending on the HLB value, surfactant concentration and water content of the blended emulsifiers. 相似文献
39.
Xuefei Guan Jingjing He El Mahjoub Rasselkorde Jingdan Zhang Waheed A. Abbasi S. Kevin Zhou 《Journal of Nondestructive Evaluation》2014,33(1):51-61
The paper presents a general method and procedure for fatigue reliability assessment integrating automated ultrasonic non-destructive inspections. The basic structure of an automated ultrasonic inspection system is presented. Fatigue reliability assessment methodology is developed using uncertainty quantification models for detection, sizing, and fatigue model parameters. The probability of detection model is based on a classical log-linear model coupling the actual flaw size with the ultrasonic inspection reported size. Using probabilistic modeling, the distribution of the actual flaw size is derived. Reliability assessment procedure using ultrasonic inspection data is suggested. A steam turbine rotor example with realistic ultrasonic inspection data is presented to demonstrate the overall method. Calculations and interpretations of assessment results based on risk recommendations for industrial applications are given. 相似文献
40.
Waheed S. KhanChuanbao Cao Dong Yu PingGhulam Nabi Sajad HussainFaheem K. Butt Tai Cao 《Materials Letters》2011,65(9):1264-1267
Zinc nitride nanoneedles (ZNNs) with diameters at stem and tip parts as 200-300 nm and 30-70 nm respectively have been prepared by the nitridation of ball-milled zinc powders at 600 °C for 120 min under NH3 gas environment. The structural, compositional and morphological characterizations of the product were conducted by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and transmission electron microscopy. From transmission spectrum data, an indirect band gap of 2.72 eV has been calculated for ZNNs whereas photoluminescence studies exhibited a strong UV excitonic mission band at 395 nm as well as two weak defect related blue emissions at 453 and 465 nm. A vapor-solid (VS) process based growth mechanism for the formation of ZNNs has also been discussed briefly. 相似文献