全文获取类型
收费全文 | 241篇 |
免费 | 15篇 |
专业分类
化学工业 | 95篇 |
金属工艺 | 4篇 |
机械仪表 | 9篇 |
建筑科学 | 16篇 |
矿业工程 | 1篇 |
能源动力 | 12篇 |
轻工业 | 28篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 4篇 |
一般工业技术 | 30篇 |
冶金工业 | 28篇 |
原子能技术 | 1篇 |
自动化技术 | 22篇 |
出版年
2024年 | 3篇 |
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 17篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 25篇 |
2012年 | 20篇 |
2011年 | 21篇 |
2010年 | 14篇 |
2009年 | 25篇 |
2008年 | 12篇 |
2007年 | 11篇 |
2006年 | 9篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2002年 | 4篇 |
2000年 | 1篇 |
排序方式: 共有256条查询结果,搜索用时 0 毫秒
201.
202.
While estimating activity production rates, cost estimators rely on historical production rates. To have realistic and useful cost estimates based on historical production rates, such production rate data should be augmented with historical contextual information that depict conditions under which activity production rates were achieved in past projects. This information is needed in determining which production rate to use among alternates for a similar activity existing in a new bid. Estimators need contextual information especially when they are unfamiliar with the work being estimated. Hence, such information items need to be identified, collected, and stored for estimators’ use in new projects. This paper details a construction-method specific and an extensible approach that is developed for enabling cost estimators to define contextual information items that need to be collected on job sites and stored as part of project histories. Based on this approach, the writers implemented a prototype system, called as ContextGen, and performed user-tests with estimators with different experience levels. Results showed that the developed approach captures method-specific information needs of estimators and is extensible to incorporate new contextual information items that can have different data representations. The developed approach is also precise in retrieving contextual information items specific to a construction method from a set of predefined contextual information items available in a library. 相似文献
203.
We report on the fabrication and characterization of all nanowire (NW) network photodetectors. For this purpose, germanium (Ge) NW networks are used as active semiconducting elements, whereas single walled carbon nanotube (SWNT) and silver (Ag) NW networks are used as the contacts. Following their synthesis, all NW networks are deposited through simple solution based methods. Photoresponse characteristics and transparency of the photodetectors for different Ge NW densities are measured. The fabricated devices show a large response with short relaxation times (<10 ms), are flexible and transparent within the visible spectrum. 相似文献
204.
Gulsum Melike Urper-Bayram Burcu Sayinli Reyhan Sengur-Tasdemir Turker Turken Enise Pekgenc Oguz Gunes Esra Ates-Genceli Volodymyr V. Tarabara Ismail Koyuncu 《应用聚合物科学杂志》2019,136(45):48205
Thin-film nanocomposite (TFN) membranes were fabricated by interfacial polymerization of a polyamide (PA) layer on the shell side of hollow fiber membrane supports. TiO2 nanoparticle loadings in the thin-film layer were 0.01, 0.05, and 0.20 wt %. Nanoparticle-free PA thin-film composite (TFC) membranes served as the comparative basis. The TFN membranes were characterized in terms of the chemical composition, structure, and surface properties of the separation layer. Incorporating nanoTiO2 improved membrane permeability up to 12.6-fold. During preliminary laboratory-scale evaluation, TFN membranes showed lower salt rejection but higher TOC rejection in comparisons with the corresponding values for TFC controls. Based on the performance in lab-scale tests, TFN membranes with 0.01 wt % nanoTiO2 loading were selected for an evaluation at the pilot scale with synthetic surface water as the feed. While the permeate flux during long-term pilot-scale operation gradually decreased for TFC membranes, TFN membranes had a higher initial permeate flux that gradually increased with time. The TOC rejection by TFN and TFC membranes was comparable. We conclude that TFN membranes show promise for full-scale surface water treatment applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48205. 相似文献
205.
206.
Silicone-based amphiphilic surfactants were synthesized as anti-foaming agents through a polycondensation reaction between
chlorine-terminated polysiloxane and polyethers. Poly(ethylene glycol) (PEG) and poly(propylene glycol) of different molecular
weights were used. The structures of these tri-block co-polymers were characterized by FTIR, 1H NMR and ESI–MS analysis. Surface tension, foam height and foam destruction properties of these co-polymers were determined.
Spectroscopic analysis confirmed that bonding of polyether to polysiloxane was successful and two types of different tri-block
co-polymers were obtained. The anti-foaming efficiency of these co-polymers tended to increase with an increase in the hydrophilic
character of the co-polymer chains. The synthesized tri-block co-polymers, which can be used as anti-foaming agents in paper-coating
applications of poly(vinyl acetate-co-butyl acrylate) latexes, showed low surface tension values, fast liquid drainage and efficient foam destruction. PEG 200-b-PDMS-b-PEG 200 was determined to be the most efficient anti-foaming agent among all co-polymers synthesized. 相似文献
207.
We consider a fixed charge two-stage location problem in which a given number of intermediate transshipment points are to be located between the supply plants and the customer locations. Both plants and transshipment points are capacitated. Scatter search is a population-based heuristic that has been applied to several combinatorial optimization problems. We develop an efficient scatter search-based heuristic approach with hybrid improvements including local search and path-relinking routines. Computational results demonstrate the effectiveness of the heuristic even for realistic problems with larger instances and tighter capacities. 相似文献
208.
Feyza Gökaliler Burcu Selen ÇağlayanZ. İlsen Önsan A. Erhan Aksoylu 《International Journal of Hydrogen Energy》2008
Indirect partial oxidation, or oxidative steam reforming, tests of a bimetallic Pt–Ni catalyst supported on δ-alumina were conducted in propane–n -butane mixtures (LPG) used as feed. H2 production activity and H2/CO selectivity were investigated in response to different S/C, C/O2 and W/F ratios. It was confirmed that higher steam content in the reactant stream increases both the activity and the H2/CO selectivity of the process. Low residence times created a positive impact on catalyst activity not only for hydrogen but also for carbon monoxide production due to the increased amount of fresh hydrocarbon in the feed stream. Hence, the highest selectivity level was obtained at intermediate residence times. The response of the system to C/O2 ratio was found to depend on the available steam content due to the complex nature of IPOX. The Pt–Ni catalyst was very prone to catalyst deactivation at low S/C ratios accompanied by high C/O2 ratios, but this problem was not encountered at high S/C ratios. A comparison of catalyst performance for different propane-to-n-butane ratios in the LPG feed indicated that the Pt–Ni catalyst has slightly better activity and selectivity at higher n-butane contents at the expense of becoming more sensitive to coke deposition. 相似文献
209.
The catalytic activities of the iron catalysts over activated carbon supports prepared by different activation methods in the heterogeneous Fenton-like oxidation of Procion Red MX-5B were investigated. The activated carbons were prepared from walnut shells by applying physical and three chemical activation methods, including HNO3, ZnCl2, and KOH activations to obtain various catalyst supports. KOH-activated carbon catalyst was assessed to be the most efficient one. Under the optimum reaction conditions, 47.5% COD removal, 51.6% degradation, and 91.6% decolorization efficiencies were achieved in the presence of this catalyst. In the kinetic study, the activation energy was evaluated as 47.36 kJ/mol. 相似文献
210.
Ozturk Kemal Savaskan Burcu Abdioglu Murat Cansiz Ahmet Dilek Durukan Burak Karaahmet Zekeriya 《Journal of Superconductivity and Novel Magnetism》2021,34(12):3151-3161
Journal of Superconductivity and Novel Magnetism - In this study, a detailed static and dynamic experimental studies were carried out in different cooling heights (CH) by using two different... 相似文献