全文获取类型
收费全文 | 1853篇 |
免费 | 127篇 |
国内免费 | 24篇 |
专业分类
电工技术 | 29篇 |
综合类 | 145篇 |
化学工业 | 876篇 |
金属工艺 | 8篇 |
机械仪表 | 8篇 |
建筑科学 | 112篇 |
矿业工程 | 6篇 |
能源动力 | 6篇 |
轻工业 | 498篇 |
水利工程 | 17篇 |
石油天然气 | 17篇 |
无线电 | 4篇 |
一般工业技术 | 251篇 |
冶金工业 | 19篇 |
原子能技术 | 4篇 |
自动化技术 | 4篇 |
出版年
2024年 | 4篇 |
2023年 | 14篇 |
2022年 | 24篇 |
2021年 | 33篇 |
2020年 | 43篇 |
2019年 | 54篇 |
2018年 | 29篇 |
2017年 | 44篇 |
2016年 | 64篇 |
2015年 | 57篇 |
2014年 | 76篇 |
2013年 | 87篇 |
2012年 | 183篇 |
2011年 | 134篇 |
2010年 | 102篇 |
2009年 | 89篇 |
2008年 | 84篇 |
2007年 | 120篇 |
2006年 | 104篇 |
2005年 | 99篇 |
2004年 | 65篇 |
2003年 | 74篇 |
2002年 | 59篇 |
2001年 | 49篇 |
2000年 | 58篇 |
1999年 | 43篇 |
1998年 | 33篇 |
1997年 | 33篇 |
1996年 | 30篇 |
1995年 | 19篇 |
1994年 | 19篇 |
1993年 | 21篇 |
1992年 | 20篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 1篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有2004条查询结果,搜索用时 15 毫秒
41.
42.
Alain Doyen Linda Saucier Lucie Beaulieu Yves Pouliot Laurent Bazinet 《Food chemistry》2012,132(3):1177-1184
Recently, a snow crab by-products hydrolysate has demonstrated antibacterial properties due to a peptide with a molecular weight of about 800 Da, but only at high concentration. Consequently, peptide hydrolysate has been fractionated to obtain peptides in a more purified form. The aim of this work was to separate a snow crab by-products hydrolysate by electrodialysis with ultrafiltration membranes (EDUF). EDUF, which allows separation of molecules according to their charges and molecular weights, was used to recover and concentrate the active antibacterial fraction. Two different ultrafiltration membranes (20 and 50 kDa) and two electrical field strengths (2 and 14 V/cm) were used as separation parameters. After EDUF separation, the 300-600 Da peptide molecular weight range was the most recovered with an abundance of 94%. Moreover, fractionation at 14 V/cm with ultrafiltration membranes of 50 kDa allowed the recovery of an anionic fraction which showed antibacterial properties on Escherichia coli ATCC 25922 and Listeria innocua HPB 13. 相似文献
43.
《分离科学与技术》2012,47(5):1164-1180
Abstract In this study water soluble complexible polymers, poly(vinyl pyrrolidone) (PVP) and dextran, were used for the ultrafiltration (UF) of aqueous Fe+3 solutions by using poly(methyl methacrylate-co-methacrylic acid) (PMMA-co-MA) membranes. Effects of polymer concentration and pH on the volume collected in the filtration of Fe+3 solutions and percent retentions (R%) were examined. It was determined that increase in polymer concentration decreased the permeability of PMMA-co-MA membrane and pH increased the retention of Fe3+ solutions. R% for Fe3+ solutions were obtained as 62% and 48% with PVP and dextran respectively at pH 3.0, for a filtration period of 80 minutes and retention for Fe3+ solution without using any complex forming polymer was found as 14%. Membranes were characterized by AFM analysis and contact angle measurements. 相似文献
44.
《分离科学与技术》2012,47(7):1884-1895
Abstract Droplet size is a key factor in the treatment of oil‐in‐water (O/W) emulsions, because of its influence on emulsion properties. The addition of a coagulant salt generally causes emulsion destabilization, increasing the droplet size, and enhancing coalescence between oil droplets, which helps its further treatment. The influence of CaCl2 addition on droplet size distribution of a commercial O/W emulsion used in machining processes was studied in order to facilitate oil removal and to improve its further treatment by centrifugation, ultrafiltration (UF) and vacuum evaporation. The critical coagulation concentration (CCC) was observed at a CaCl2 concentration of 0.05 M. The quality of the final aqueous effluent, expressed as its chemical oxygen demand (COD) value, was compared for all treatments. The highest COD values were obtained for centrifugation, while the COD of the UF permeate was approximately constant for all UF trials. The best effluent quality was obtained by vacuum evaporation. A combination of these techniques should be appropriate for most industrial treatments of O/W emulsions, depending on the subsequent use of the resulting aqueous effluent. 相似文献
45.
K. Savaş Bahçeci 《International Journal of Food Science & Technology》2012,47(2):315-324
The central composite design with a quadratic model was used to investigate the effect of temperature (20–40 °C) and transmembrane pressure (TMP) (100–300 kPa) as well as pretreatment with gelatin and bentonite (0:0–300:1500 mg L?1) on permeate flux and fouling resistance during ultrafiltration of apple juice. The changes in some physicochemical properties were also investigated. Pretreatment of apple juice with gelatin and bentonite and an increase in the temperature and TMP significantly improved the permeate flux. In general, physicochemical properties of apple juice other than polyphenolics were not affected by the applied parameters. Using 150 mg L?1 of gelatin and 750 mg L?1 of bentonite for fining significantly reduced the total phenolic content and so did the fouling resistance. Fouling resistance also decreased with increasing temperature, and increasing pressure increased the fouling resistance. 相似文献
46.
超滤技术在无锡中桥水厂深度处理工程中的应用 总被引:1,自引:0,他引:1
近年来,膜处理技术在水处理领域的应用已趋成熟。随着对供水安全的日益关注,超滤技术在饮用水处理领域中得到越来越广泛的应用。无锡市自来水总公司中桥水厂于2009年采用西门子外压式超滤膜处理技术,率先建成15×104m3/d采用超滤膜饮用净水处理系统,出水水质全面达到且部分优于《生活饮用水卫生标准》(GB 5749—2006)。根据无锡中桥水厂升级改造工程的经验以及两年多的实际运行情况,分析了超滤系统运行操作的特点。超滤技术在无锡中桥水厂的应用可以为国内其他水厂的工艺升级改造,特别是大型水厂的膜法水处理工程项目的决策和建设提供参考。 相似文献
47.
48.
Gurpreet S. Dhillon Satinder K. Brar Mausam Verma 《International Journal of Food Science & Technology》2012,47(3):542-548
Submerged citric acid (CA) bioproduction was carried out by Aspergillus niger NRRL‐567 using various industrial wastes, such as brewery spent liquid (BSL), lactoserum and starch industry water sludge. CA bioproduction was carried out by varying the temperature (25–35 °C), pH (3–5), addition of inducers, incubation time and supplementation with different proportions of apple pomace ultrafiltration sludge (APS). The results indicated that under the best conditions with 3% (v/v) methanol, the optimal concentration of 11.34 g L?1 CA was recorded using BSL at pH 3.5 and temperature 30 °C after 120‐h incubation period. Supplementation of methanol resulted in an increase of 56% CA production. Meanwhile, under similar conditions, higher concentration of 18.34 g L?1 CA was reported with the supplementation of BSL with 40% (v/v) APS having suspended solids concentration of 30 g L?1. The present study demonstrated the potential of BSL supplemented with APS as an alternative cheap substrate for CA fermentation. 相似文献
49.
Ultrafiltration based purification strategies for surfactin produced by Bacillus subtilis LB5A using cassava wastewater as substrate
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
50.