全文获取类型
收费全文 | 2121篇 |
免费 | 214篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 17篇 |
综合类 | 2篇 |
化学工业 | 671篇 |
金属工艺 | 23篇 |
机械仪表 | 70篇 |
建筑科学 | 79篇 |
矿业工程 | 4篇 |
能源动力 | 77篇 |
轻工业 | 531篇 |
水利工程 | 26篇 |
石油天然气 | 14篇 |
无线电 | 129篇 |
一般工业技术 | 301篇 |
冶金工业 | 203篇 |
原子能技术 | 8篇 |
自动化技术 | 181篇 |
出版年
2024年 | 7篇 |
2023年 | 33篇 |
2022年 | 33篇 |
2021年 | 147篇 |
2020年 | 83篇 |
2019年 | 93篇 |
2018年 | 102篇 |
2017年 | 100篇 |
2016年 | 97篇 |
2015年 | 64篇 |
2014年 | 120篇 |
2013年 | 128篇 |
2012年 | 139篇 |
2011年 | 182篇 |
2010年 | 132篇 |
2009年 | 116篇 |
2008年 | 83篇 |
2007年 | 78篇 |
2006年 | 65篇 |
2005年 | 50篇 |
2004年 | 43篇 |
2003年 | 50篇 |
2002年 | 35篇 |
2001年 | 29篇 |
2000年 | 19篇 |
1999年 | 22篇 |
1998年 | 66篇 |
1997年 | 44篇 |
1996年 | 44篇 |
1995年 | 23篇 |
1994年 | 22篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1976年 | 7篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有2336条查询结果,搜索用时 15 毫秒
81.
de Matos Pedro André Pinto Jorge Sousa Pereira David Pinho Luís Miguel 《International Journal on Software Tools for Technology Transfer (STTT)》2018,20(4):379-395
International Journal on Software Tools for Technology Transfer - Current real-time embedded systems development frameworks lack support for the verification of properties using explicit time where... 相似文献
82.
Nathália Maria P. Rocha e Silva Fabíola Carolina G. Almeida Fernanda Cristina P. Rocha e Silva Juliana M. Luna Leonie A. Sarubbo 《Journal of surfactants and detergents》2020,23(6):1111-1123
The use of toxic petroleum-based heavy oils is common in industrial processes. The cleaning of machines, equipment, and other surface covered in these oils is achieved with expensive products that are often also toxic and harmful to both the health of workers and the environment. The present paper proposes the development of a sustainable biodetergent made from plant-based materials. Tests were performed to determine the properties of the biodetergent in terms of its surfactant and emulsifying capacities, stability, toxicity, and the removal of heavy oil from glass plates and metallic surfaces. The formulation was composed of a natural solvent (cottonseed oil), a plant-based surfactant agent (saponin), and two natural stabilizers (carboxymethylcellulose and glycerine). The formulation was stable, nontoxic, and highly efficient, removing 100% of the heavy oil from glass and metallic surfaces. This solution developed in this study could be used in diverse industries with the need to clean machines and parts encrusted with oil and grease as well as the cleaning of floors covered with petroleum-based residues. A preliminary analysis of the economic feasibility of using the detergent was carried out at a Brazilian power plant. Besides the reduction in environmental impact due to the use of a nontoxic, biodegradable product as well as the reduction in health risks to workers associated with toxic cleaning products, this new product can have a considerable impact on the market as an environmentally friendly solution. 相似文献
83.
Knowledge transfer offices (KTOs) are required to adopt a comprehensive approach to managing a broad set of channels of university–industry collaboration, including collaborative research, business services, exchange of human resources and informal relations within a regional innovation system. The perspectives of firms and academic researchers, the main stakeholders of KTOs, are useful complements to assess KTO activity. The goal of this article is to study the effectiveness that these stakeholders attribute to KTOs. Based on survey data collected in the Spanish region of Andalusia, the article explores stakeholders’ perceptions and determinants. The results show that the level of engagement in a diversified range of activities and the importance attributed to knowledge transfer in the strategy of both research groups and firms are the best predictors of the perceived effectiveness of KTOs. The article also underlines specific differences between the two types of stakeholders. 相似文献
84.
85.
86.
Valéria T. Crexi Micheli L. Monte Maurício L. Monte Luiz A. A. Pinto 《Journal of the American Oil Chemists' Society》2012,89(2):329-334
The aims of this study were to compare three treatments in the chemical hydrolysis reaction of bleached oil from carp (Cyprinus carpio) heads and to obtain polyunsaturated fatty acid concentrates by urea complexation. The three treatments were carried out
with different oil:ethanol molar ratios. In the treatment with a 1:39 molar ratio, a higher yield of free fatty acids was
found. These fatty acids were submitted to urea complexation (−10 °C for 20 h, and urea–fatty acid ratio of 4.5–1). There
was a 31.4% increase in monounsaturated and polyunsaturated fatty acids (MUFA and PUFA) content and a 75% decrease in saturated
fatty acids (SAF) content. An increase of 85.4% in the EPA + DHA content was found. The non-urea complexing fraction can be
considered a rich source of MUFA and PUFA with a total amount of 88.9%. 相似文献
87.
L. S. Ribeiro T. Pinto A. Monteiro O. S. G. P. Soares C. Pereira C. Freire M. F. R. Pereira 《Journal of Materials Science》2013,48(14):5085-5092
The aim of this work was the fabrication of mesoporous silica nanoparticles functionalized with thermochromic dye for further incorporation onto textiles. The nanosilicas were prepared under alkaline conditions in the presence of the surfactant hexadecyltrimethylammonium chloride and functionalized with the organosilane dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (C18-NTMS). The dye was incorporated onto the mesoporous silica nanoparticles by two different methods: co-condensation and post-grafting, i.e. by adding the dye during or after the synthesis of the nanosilica, respectively. The morphology, particle and pore size, chemical composition, and textural properties of the silica nanoparticles were characterized by scanning electron microscopy (SEM), dynamic light scattering, N2 adsorption isotherms at ?196 °C, Fourier transform infrared spectroscopy and thermogravimetry. The silica nanoparticles prepared with and without dye presented spherical shape (by SEM) and particle size ranging from 15 to 40 nm. The infrared spectra revealed the characteristic bands of silica and organosilane (in the cases where it was used). The prepared materials presented colour change when submitted to different conditions. The thermochromic dye-functionalized nanosilicas were efficiently immobilized into cotton fabric and tests were performed to verify the washing fastness. After washing, a slight decrease on the amount of silica was noticed, but much of it remained on the textile. The functionalized textiles presented a colour change within different conditions. 相似文献
88.
Stability of the antimicrobial activity of acetogenins from avocado seed,under common food processing conditions,against Clostridium sporogenes vegetative cell growth and endospore germination 下载免费PDF全文
Adriana Pacheco Dariana Graciela Rodríguez‐Sánchez Raúl Villarreal‐Lara Jesús Manuel Navarro‐Silva Carolina Senés‐Guerrero Carmen Hernández‐Brenes 《International Journal of Food Science & Technology》2017,52(11):2311-2323
Anticlostridial activity of acetogenins from avocado seed was further characterised, and their stability and effectiveness under food processing conditions, and in a model food system, studied for the first time. Isolated AcO‐avocadenyne (1) and AcO‐avocadene (2) showed anticlostridial potential, particularly the latter molecule. Enriched acetogenins extracts, obtained at laboratory scale (EAE) and semi‐commercially (Avosafe®), presented similar MIC values (3.9–9.8 ppm) and a bacteriostatic effect. Extracts bioactivity showed resistance to heat (≤120 °C), high hydrostatic pressure (HHP; 300–600 MPa, 3–6 min, 25 °C) and salt (≤3% w/v). In addition, the extract was most stable at pH ≥ 7.0 and potency against endospores increased after HHP treatment and exposure to pH 9.5, suggesting a positive effect on solubility or structure of particular acetogenins. In a model food system processed by HHP, acetogenins were retained; however, initial quantities gradually declined by 63% and 32% at 25 and 4 °C, respectively, at the end of the storage period (42 days). Most stable molecules (persediene (4) > persenones > AcO‐avocadene (2)) possess a keto or trans‐enone group at C‐4 in the aliphatic chain, which could support hydrogen donation to surrounding carbon atoms and confer antioxidant activity. Active endospores were completely inhibited by 5000 ppm Avosafe® in the model food system (37 °C, 72 h) and lower concentrations (500–1000 ppm) resulted in 1–2 log reduction of a 3 log inoculum target. Efficacy information generated in the present work is considered crucial to improve scientific knowledge on spore inhibition properties of avocado acetogenins. 相似文献
89.
The goal of this contribution was to determine the impact of HIUS on the thermal aggregation, gelation, foaming and emulsifying properties of egg white (EW) proteins. 相似文献
90.
L. S. Araujo D. S. dos Santos S. Godet J. Dille A. L. Pinto L. H. de Almeida 《Journal of Materials Engineering and Performance》2014,23(11):4130-4135
In the current work, sheets of superalloy 718 were processed via thermomechanical route by hot and cold rolling, followed by annealing below the δ phase solvus temperature and precipitation hardening to optimum strength. Grain boundary character distribution throughout the processing was mapped via EBSD and its evolution discussed. The results show that it is possible to process the alloy to a fine grain size obtaining concomitantly a considerably high proportion of special boundaries Σ3, Σ9, and Σ27. The precipitation of δ phase presented a strong grain refining role, without significantly impairing the twinning mechanism and, consequently, the Σ3, Σ9, and Σ27 boundary formations. 相似文献