全文获取类型
收费全文 | 204篇 |
免费 | 17篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 81篇 |
金属工艺 | 3篇 |
建筑科学 | 9篇 |
能源动力 | 2篇 |
轻工业 | 51篇 |
水利工程 | 1篇 |
无线电 | 7篇 |
一般工业技术 | 36篇 |
冶金工业 | 8篇 |
原子能技术 | 2篇 |
自动化技术 | 19篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 2篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 13篇 |
2013年 | 10篇 |
2012年 | 14篇 |
2011年 | 22篇 |
2010年 | 11篇 |
2009年 | 12篇 |
2008年 | 17篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1997年 | 5篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有221条查询结果,搜索用时 15 毫秒
211.
Remoundaki E Kousi P Joulian C Battaglia-Brunet F Hatzikioseyian A Tsezos M 《Journal of hazardous materials》2008,153(1-2):514-524
The characteristics of the biofilm and the solids formed during the operation of a sulphate-reducing fixed-bed reactor, fed with a moderately acidic synthetic effluent containing zinc and iron, are presented. A diverse population of delta-Proteobacteria SRB, affiliated to four distinct genera, colonized the system. The morphology, mineralogy and surface chemistry of the precipitates were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The XRD patterns observed are characteristic of amorphous solid phases. Peaks corresponding to crystalline iron sulphide, marcasite, sphalerite and wurtzite were also identified. SEM-EDX results confirm the predominance of amorphous phases appearing as a cloudy haze. EDX spectra of spots on the surface of these amorphous phases reveal the predominance of iron, zinc and sulphur indicating the formation of iron and zinc sulphides. The predominance of these amorphous phases and the formation of very fine particles, during the operation of the SRB column, are in agreement and can be explained by the formation pathways of metal sulphides at ambient temperature, alkaline pH and reducing conditions. Solids are precipitated either as (i) amorphous phases deposited on the bed material, as well as on surface of crystals, e.g. Mg(3)(PO(4))(2) and (ii) as rod-shaped solids characterized by a rough hazy surface, indicating the encapsulation of bacterial cells by amorphous metal sulphides. 相似文献
212.
Bruno Fayolle Emmanuel Richaud Jacques Verdu Fabienne Farcas 《Journal of Materials Science》2008,43(3):1026-1032
Polypropylene (PP) fibres for geotextile applications were oxidized under two exposure conditions: 110 °C in air under atmospheric
pressure and 80 °C under pure oxygen at 5 MPa pressure corresponding to two distinct ISO standards. Fibre ageing has been
monitored by rheometric molar mass, WAXS and tensile measurements. The results put in evidence the existence of predominant
chain scission, chemicryrallization and embrittlement, the latter occurring at a structural state (M
W = 130 kg mol−1, crystallinity ratio 80%) almost independent of exposure conditions. The relationships between all processes are discussed. 相似文献
213.
Courtois F Olguin LF Whyte G Bratton D Huck WT Abell C Hollfelder F 《Chembiochem : a European journal of chemical biology》2008,9(3):439-446
Microdroplets have great potential for high-throughput biochemical screening. We report the design of an integrated microfluidic device for droplet formation, incubation and screening. Picolitre water-in-oil droplets can be stored in a reservoir that contains approximately 10(6) droplets. In this reservoir droplets are stable for at least 6 h, which gives an extended timescale for biochemical experiments. We demonstrate the utility of the system by following the in vitro expression of green fluorescent protein. The high efficiency allows protein expression from a single molecule of DNA template, creating "monoclonal droplets" in which genotype and phenotype are combined in one emulsion compartment. 相似文献
214.
Schwab F Bucheli TD Lukhele LP Magrez A Nowack B Sigg L Knauer K 《Environmental science & technology》2011,45(14):6136-6144
Due to growing production, carbon nanotubes (CNT) may soon be found in a broad range of products and thus in the environment. In this work, an algal growth test was developed to determine effects of pristine and oxidized CNT on the green algae Chlorella vulgaris and Pseudokirchneriella subcapitata. CNT suspensions were prepared in algal test medium and characterized taking into account the suspension age, the reduced light transmittance of nanoparticle suspensions defined as shading of CNT and quantified by UV/vis spectroscopy, and the agglomeration of the CNT and of the algal cells. Growth inhibition and photosynthetic activity were investigated as end points. Growth of C. vulgaris was inhibited with effect concentrations of 50% (EC(50)) values of 1.8 mg CNT/L and of 24 mg CNT/L in well dispersed and in agglomerated suspensions, respectively, and 20 mg CNT/L and 36 mg CNT/L for P. subcapitata, respectively. However, the photosynthetic activity was not affected. Growth inhibition was highly correlated with the shading of CNT and the agglomeration of algal cells. This suggests that the reduced algal growth might be caused mainly by indirect effects, i.e. by reduced availability of light and different growth conditions caused by the locally elevated algal concentration inside of CNT agglomerates. 相似文献
215.
Chema Borchani Fabienne Fonteyn Guilhem Jamin Jacqueline Destain Luc Willems Michel Paquot 《Critical reviews in food science and nutrition》2016,56(10):1746-1752
β-D-glucans are a (1→3)-linked glucose polymer with (1→6)-linked side chains and a major component of fungal cell walls. They exhibit structural integrity to the fungal cell wall. In addition, β-glucans are widely used as food adjuvant in food and pharmaceutical industries because of their physico-chemical properties. Several studies have focused on different isolation processes of (1→3) (1→6)-β-glucan that could affect the physico-chemical and functional properties of β-glucan such as chemical composition, solubility, viscosity, hydration properties, and oil binding capacity. Immunological activity is one of the most important properties of β-glucans. Thus, they are effective in inhibiting growth of cancer cells and metastasis and preventing bacterial infection. In humans, β-glucans reduce blood cholesterol, improve glucose absorption by body cells, and so help wound healing. This review described the prebiotic potentiality of fungal β-D-glucans with the objective to detail the methodologies applied for their extraction, their structure and techno-functional properties, and finally their biological effects. 相似文献
216.
217.
Battaglia-Brunet F Crouzet C Burnol A Coulon S Morin D Joulian C 《Water research》2012,46(12):3923-3933
Arsenic (As) is a toxic element frequently present in acid mine waters and effluents. Precipitation of trivalent arsenic sulphide in sulphate-reducing conditions at low pH has been studied with the aim of removing this hazardous element in a waste product with high As content. To achieve this, a 400 mL fixed-film column bioreactor was fed continuously with a synthetic solution containing 100 mg L−1 As(V), glycerol and/or hydrogen, at pH values between 2.7 and 5. The highest global As removal rate obtained during these experiments was close to 2.5 mg L−1 h−1. A switch from glycerol to hydrogen when the biofilm was mature induced an abrupt increase in the sulphate-reducing activity, resulting in a dramatic mobilisation of arsenic due to the formation of soluble thioarsenic complexes. A new analytical method, based on ionic chromatography, was used to evaluate the proportion of As present as thioarsenic complexes in the bioreactor. Profiles of pH, total As and sulphate concentrations suggest that As removal efficiency was linked to solubility of orpiment (As2S3) depending on pH conditions. Molecular fingerprints revealed fairly homogeneous bacterial colonisation throughout the reactor. The bacterial community was diverse and included fermenting bacteria and Desulfosporosinus-like sulphate-reducing bacteria. arrA genes, involved in dissimilatory reduction of As(V), were found and the retrieved sequences suggested that As(V) was reduced by a Desulfosporosinus-like organism. This study was the first to show that As can be removed by bioprecipitation of orpiment from acidic solution containing up to 100 mg L−1 As(V) in a bioreactor. 相似文献
218.
219.
Sumio Michnick Jean-Louis Roustan Fabienne Remize Pierre Barre Sylvie Dequin 《Yeast (Chichester, England)》1997,13(9):783-793
The possibility of the diversion of carbon flux from ethanol towards glycerol in Saccharomyces cerevisiae during alcoholic fermentation was investigated. Variations in the glycerol 3-phosphate dehydrogenase (GPDH) level and similar trends for alcohol dehydrogenase (ADH), pyruvate decarboxylase and glycerol-3-phosphatase were found when low and high glycerol-forming wine yeast strains were compared. GPDH is thus a limiting enzyme for glycerol production. Wine yeast strains with modulated GPD1 (encoding one of the two GPDH isoenzymes) expression were constructed and characterized during fermentation on glucose-rich medium. Engineered strains fermented glucose with a strongly modified [glycerol] : [ethanol] ratio. gpd1Δ mutants exhibited a 50% decrease in glycerol production and increased ethanol yield. Overexpression of GPD1 on synthetic must (200 g/l glucose) resulted in a substantial increase in glycerol production (×4) at the expense of ethanol. Acetaldehyde accumulated through the competitive regeneration of NADH via GPDH. Accumulation of by-products such as pyruvate, acetate, acetoin, 2,3 butane-diol and succinate was observed, with a marked increase in acetoin production. © 1997 John Wiley & Sons, Ltd. 相似文献