全文获取类型
收费全文 | 1388篇 |
免费 | 83篇 |
专业分类
电工技术 | 6篇 |
综合类 | 3篇 |
化学工业 | 406篇 |
金属工艺 | 12篇 |
机械仪表 | 18篇 |
建筑科学 | 28篇 |
矿业工程 | 2篇 |
能源动力 | 24篇 |
轻工业 | 563篇 |
水利工程 | 7篇 |
石油天然气 | 6篇 |
无线电 | 53篇 |
一般工业技术 | 139篇 |
冶金工业 | 85篇 |
原子能技术 | 6篇 |
自动化技术 | 113篇 |
出版年
2024年 | 4篇 |
2023年 | 10篇 |
2022年 | 50篇 |
2021年 | 53篇 |
2020年 | 32篇 |
2019年 | 28篇 |
2018年 | 45篇 |
2017年 | 44篇 |
2016年 | 42篇 |
2015年 | 42篇 |
2014年 | 56篇 |
2013年 | 83篇 |
2012年 | 86篇 |
2011年 | 100篇 |
2010年 | 71篇 |
2009年 | 61篇 |
2008年 | 90篇 |
2007年 | 55篇 |
2006年 | 62篇 |
2005年 | 66篇 |
2004年 | 46篇 |
2003年 | 41篇 |
2002年 | 37篇 |
2001年 | 30篇 |
2000年 | 12篇 |
1999年 | 18篇 |
1998年 | 35篇 |
1997年 | 34篇 |
1996年 | 32篇 |
1995年 | 17篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 11篇 |
1989年 | 12篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1972年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有1471条查询结果,搜索用时 9 毫秒
91.
Arantxa Rodriguez-Casado Pedro Carmona Pilar Moreno Ignacio Sánchez-González Antonella Macagnano Corado Di Natale Mercedes Careche 《Food chemistry》2007,103(3):1024-1030
Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy has been used for the first time to evaluate the postmortem changes in structure of components from sardine muscle in relation to quality loss. Sardines (Sardina pilchardus) were stored in ice for up to thirteen days. The spectroscopic study was focussed on the structural changes produced on the lipids and proteins. 相似文献
92.
Pilar Manglano María Jesús Lagarda María Dolores Silvestre Carmen Vidal Gonzalo Clemente Rosaura Farr 《European Journal of Lipid Science and Technology》2005,107(11):815-823
A study is made of the effects of storage (time and temperature) on the lipid fraction of four milk‐based adapted infant formulas with basically the same composition, though differing in the iron salt added (lactate or sulfate) and/or the vitamin E source (α‐tocopherol or α‐tocopherol acetate). Peroxide value, hydroperoxide C18 percentage and thiobarbituric acid‐reactive substance (TBARS) content were used as indicators of lipid peroxidation. Fat contents remained stable throughout storage. Peroxide values increased from the first storage month and were affected by storage time, although they exhibited irregular behavior. Storage time and temperature affected hydroperoxide percentage, which was seen to be the earliest indicator of lipid oxidation, being measurable in newly manufactured formulas. TBARS values were only affected by storage time. No statistically significant differences were found among the four infant formulas for any of the lipid oxidation indicators. 相似文献
93.
This article presents a generic project risk management process that has been particularized for construction projects from the point of view of the owner and the consultant who may be assisting the owner. The process could also be adapted to the needs of other project participants, and many points referred to in the article can be directly applied to them. Any project risk management process must be tailored to the particular circumstances of the project and of the organization undertaking it. First, the article explains a complete or generic project risk management process to be undertaken by organizations with the highest level of risk management maturity in the largest and most complex construction projects. After that, factors influencing possible simplifications of the generic process are identified, and simplifications are proposed for some cases. Then the application to a real project is summarized. As a final validation, a Delphi analysis has been developed to assess the project risk management methodology explained here, and the results are presented. 相似文献
94.
Gloria Urbano María López‐Jurado Jesús M Porres Sławomir Frejnagel Elena Gómez‐Villalva Juana Frías Concepción Vidal‐Valverde Pilar Aranda 《Journal of the science of food and agriculture》2007,87(7):1356-1363
The effect of treatment with α‐galactosidase, tannase or a cell‐wall‐degrading enzyme complex under optimal conditions of pH, temperature and length of incubation time on the chemical composition and nutritive utilisation of protein and carbohydrates from pea (Pisum sativum L.) flour was studied. Soaking of pea flours in combination with enzyme treatment led to reductions of 77–90% in the levels of α‐galactosides, and of 60–80% in the levels of trypsin inhibitor activity, increasing the content of total available sugars, which was highest in the pea flour treated with the cell‐wall‐degrading enzyme complex. All the treatments assayed caused a significant improvement in daily food intake, whereas the nutritive utilisation of protein was not increased in any of the pea products tested when compared to the raw pea flour. However, all the soaking and enzymatic treatments led to a significant improvement in daily weight gain associated with a higher dietary intake of food and total available sugars. Copyright © 2007 Society of Chemical Industry 相似文献
95.
Fernandez J. Hidalgo S. Paredes J. Berta F. Rebollo J. Millan J. Serra-Mestres F. 《Electron Device Letters, IEEE》1989,10(5):212-215
An analytical ON-resistance expression for different designs of VDMOS (vertically diffused metal-oxide-semiconductor) devices which takes into consideration the two-dimensional (2-D) nature of the current flow is obtained. This expression differs from other models that overestimate this resistance for large cell spacings. This formulation is in close agreement with experimental points obtained from the interdigitated fabricated structures and with 2-D simulations. Moreover, the effect of a two-level oxide thickness on the ON resistance has been investigated for the interdigitated case 相似文献
96.
97.
Marianne Wittrup Larsen Dr. Dorota F. Zielinska Mats Martinelle Dr. Aurelio Hidalgo Dr. Lars Juhl Jensen Prof. Uwe T. Bornscheuer Prof. Karl Hult Prof. 《Chembiochem : a European journal of chemical biology》2010,11(6):796-801
A water tunnel in Candida antarctica lipase B that provides the active site with substrate water is hypothesized. A small, focused library created in order to prevent water from entering the active site through the tunnel was screened for increased transacylation over hydrolysis activity. A single mutant, S47L, in which the inner part of the tunnel was blocked, catalysed the transacylation of vinyl butyrate to 20 mM butanol 14 times faster than hydrolysis. The single mutant Q46A, which has a more open outer end of the tunnel, showed an increased hydrolysis rate and a decreased hydrolysis to transacylation ratio compared to the wild‐type lipase. Mutants with a blocked tunnel could be very useful in applications in which hydrolysis is unwanted, such as the acylation of highly hydrophilic compounds in the presence of water. 相似文献
98.
The great urban and industrial development of the towns surrounding Madrid has caused an irreversible and rapid soil loss. In this paper, soil sealed evolution in Guadalajara province during the past 15 years, mainly in the capital, industrial district and small municipalities near Madrid, has been studied. This province has experimented a sharp reduction of the most fertile soils, located on the Henares valley, due to the action of new models of local and regional development. The main goal of this paper is the mapping of the covered soils in a pilot area of Spain. Supervised classification of Landsat images from 1989 to 2002 has been carried out. Geo-referred image analysis allows us to detect precisely the amount of covered soils and where this phenomenon has taken place. 相似文献
99.
Asanka P. Basnayake Juan P. Hidalgo Byron Villacorta Kameron G. Dunn Michael T. Heitzmann 《火与材料》2023,47(1):28-50
The interactions of Calcium carbonate (e.g., eggshell powder) and Lignin with ammonium polyphosphate (APP) when used as fire retardants were investigated. Three mixing ratios - 1:3, 1:1, and 3:1, were used with natural fibre reinforced composites containing a hemp mat and an epoxy matrix manufactured using a light resin transfer moulding (L-RTM) process. The thermal decomposition of the retardant mixtures and composites was investigated using thermogravimetric analysis (TGA). The findings showed that even though the decomposition reactions of APP with eggshell powder and lignin mixtures interacted and overlapped, the same interactions could not be seen in the composites. In the composite form while the residue was affected by the retardant, the decomposition reactions were driven primarily by the hemp and epoxy. Flammability of the composites was studied by testing to 20, 35, 50, and 75 kW/m2 with a cone calorimeter, and determining the critical heat flux. While the samples with eggshell powder had higher ignition times, the critical heat flux for ignition was 13 kW/m2 for all sample groups except for a ratio of 1:3 APP to eggshell powder, which was 14 kW/m2. The lowest burning rates (mass loss and heat release) occurred in composites containing only APP, however, the addition of eggshell powder or lignin at even a ratio of 3:1 APP to either provided a notable reduction. 相似文献
100.
Antimicrobial activity of reuterin in combination with nisin against food-borne pathogens 总被引:1,自引:0,他引:1
Arqués JL Fernández J Gaya P Nuñez M Rodríguez E Medina M 《International journal of food microbiology》2004,95(2):225-229
Antimicrobial activity of reuterin individually or in combination with nisin against different food-borne Gram-positive and Gram-negative pathogens in milk was investigated. Reuterin (8 AU/ml) exhibited bacteriostatic activity against Listeria monocytogenes, whereas its activity was slightly bactericidal against Staphylococcus aureus at 37 degrees C. Higher bactericidal activity was detected against Escherichia coli O157:H7, Salmonella choleraesuis subsp. choleraesuis, Yersinia enterocolitica, Aeromonas hydrophila subsp. hydrophila and Campylobacter jejuni. A significant synergistic effect on L. monocytogenes and a slight additive effect on S. aureus after 24 h at 37 degrees C were observed when reuterin was combined with nisin (100 IU/ml). The combination of reuterin with nisin did not enhance the antimicrobial effect of reuterin against Gram-negative pathogens. 相似文献