全文获取类型
收费全文 | 2773篇 |
免费 | 230篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 33篇 |
综合类 | 1篇 |
化学工业 | 695篇 |
金属工艺 | 58篇 |
机械仪表 | 60篇 |
建筑科学 | 90篇 |
矿业工程 | 7篇 |
能源动力 | 93篇 |
轻工业 | 573篇 |
水利工程 | 27篇 |
石油天然气 | 22篇 |
无线电 | 212篇 |
一般工业技术 | 406篇 |
冶金工业 | 401篇 |
原子能技术 | 4篇 |
自动化技术 | 323篇 |
出版年
2024年 | 11篇 |
2023年 | 18篇 |
2022年 | 64篇 |
2021年 | 113篇 |
2020年 | 65篇 |
2019年 | 119篇 |
2018年 | 109篇 |
2017年 | 118篇 |
2016年 | 112篇 |
2015年 | 77篇 |
2014年 | 112篇 |
2013年 | 203篇 |
2012年 | 198篇 |
2011年 | 196篇 |
2010年 | 143篇 |
2009年 | 146篇 |
2008年 | 137篇 |
2007年 | 120篇 |
2006年 | 102篇 |
2005年 | 63篇 |
2004年 | 65篇 |
2003年 | 55篇 |
2002年 | 56篇 |
2001年 | 48篇 |
2000年 | 45篇 |
1999年 | 41篇 |
1998年 | 137篇 |
1997年 | 92篇 |
1996年 | 49篇 |
1995年 | 38篇 |
1994年 | 32篇 |
1993年 | 27篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 14篇 |
1973年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有3005条查询结果,搜索用时 15 毫秒
101.
102.
C. Taltavull Z. Shi B. Torres J. Rams A. Atrens 《Journal of materials science. Materials in medicine》2014,25(2):329-345
This research studied the influence of the chloride ion concentration on the corrosion behaviour of high-purity magnesium (Mg) and two Mg alloys in Hank’s solution, using hydrogen evolution and weight loss. A buffer based on CO2 and NaHCO3 was used to maintain the pH constant. The corrosion behaviour was governed by a partially protective surface film, and film breakdown by the chloride ions. The carbonated calcium phosphate layer that formed in Hank’s solution was important in determining the protective properties of the surface film. 相似文献
103.
María J. Aguirre Mauricio Isaacs Betty Matsuhiro Leonora Mendoza Leonardo S. Santos Simonet Torres 《Food chemistry》2011
Anthocyanins in aged Cabernet Sauvignon red wines were studied by HPLC–MS. The major anthocyanin in 6, 7, and 8 year old red wine extracts was the dimer vitisin A produced by condensation of malvidin-3-O-glucoside mediated by pyruvic acid. In aged wine, the content of malvidin-3-O-glucoside decreased with age with a concomitant increase of vitisin A. The latter is accompanied by several condensation products with molecular weight up to 1500 m/z. Differential pulse voltammetry indicated that aged wines have lower antioxidant capacity than young wine (400 mV), but higher than malvidin-3-O-glucoside (483 mV). Tafel’s plots showed that the electrochemical process occurring in aged wines is different from young wines. Six, seven and eight year old wines show similar behaviour with plots of 234, 177 and 188 mV/dec, respectively. These values are higher than the expected 120 mV/dec corresponding to a first electronic transfer but smaller compared to the 523 mV/dec corresponding to young wine. 相似文献
104.
Betina Piqueras-Fiszman Vanessa Harrar Jorge Alcaide Charles Spence 《Food quality and preference》2011,22(8):753-756
In many categories, weight has been found to influence how users perceive and appraise products. However, to date, the influence of the weight of the dish in which food is served on people’s perception has not been studied empirically. This exploratory study was therefore designed to investigate whether the weight of the container would exert a significant influence on people’s sensory and hedonic responses to the food consumed from it. Three bowls, identical except for the fact that they were different weights, were filled with exactly the same yoghurt. Consumers evaluated the yoghurt samples from the three bowls holding them with one hand, one at a time. Participants rated flavor intensity, density, price expectation, and liking using 9-point likert scales. Significant effects were found for all attributes except for flavor intensity. The effects on both density and price expectation ratings were highly significant.These findings are potentially relevant for designers and those working in restaurants, the hospitality sector, and food production, since the design and choice of dishes (or packages) of various weights could potentially be used to help enhance and/or modify the way in which consumers perceive and experience the food consumed from them. 相似文献
105.
Paula C. Rodrigues Bruno D. Fontes Bruno B. M. Torres Washington S. Sousa Gregório C. Faria Debora T. Balogh Roberto M. Faria Leni Akcelrud 《应用聚合物科学杂志》2015,132(38)
Synthesis of a polyfluorene/poly(p‐phenylene vinylene) derivative, the Poly [(9,9′‐di‐hexylfluorenediylvinylene‐alt‐1,4‐phenylenevinylene)‐co‐((9,9′‐(3‐t‐butylpropanoate) fluorene‐1,4‐phenylene)] (LaPPS 42) was performed following Wittig and Suzuki routes. Polyfluorenes and derivatives have been used in electroluminescent devices, and the synthesis described here has the advantage in pave the way to get distinct structures having different emission spectra. An extensive study of its electrochemical, thermomechanical, optical, and structural properties was carried out, as well as its application in electroluminescent devices. Polymer light‐emitting diodes (PLEDs) and polymer light‐emitting electrochemical cells (PLECs) were built using LaPPS 42 as active layer, and their electric and optical characterizations confirm they have a potential as active element in electroluminescent devices. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42579. 相似文献
106.
Oxidative Stability and Changes in Chemical Composition of Extra Virgin Olive Oils After Short‐Term Deep‐Frying of French Fries
下载免费PDF全文
![点击此处可从《Journal of the American Oil Chemists](/ch/ext_images/free.gif)
Emília Akil Vanessa Naciuk Castelo‐Branco André Mesquita Magalhães Costa Ana Lúcia do Amaral Vendramini Verônica Calado Alexandre Guedes Torres 《Journal of the American Oil Chemists' Society》2015,92(3):409-421
We aimed at investigating oxidative stability and changes in fatty acid and tocopherol composition of extra virgin olive oil (EVOO) in comparison with refined seed oils during short‐term deep‐frying of French fries, and changes in the composition of the French fries deep‐fried in EVOO. EVOO samples from Spain, Brazil, and Portugal, and refined seed oils of soybean and sunflower were studied. Oil samples were used for deep‐frying of French fries at 180 °C, for up to 75 min of successive frying. Tocopherol and fatty acid composition were determined in fresh and spent vegetable oils. Tocopherol, fatty acid, and volatile composition (by SPME–GC–MS) were also determined in French fries deep‐fried in EVOO. Oil oxidation was monitored by peroxide, acid, and p‐anisidine values, and by Rancimat after deep‐frying. Differential scanning calorimetry (DSC) analysis was used as a proxy of the quality of the spent oils. EVOOs presented the lowest degree of oleic and linoleic acids losses, low formation of free fatty acids and carbonyl compounds, and were highly stable after deep‐frying. In addition, oleic acid, tocopherols, and flavor compounds were transferred from EVOO into the French fries. In conclusion, EVOOs were more stable than refined seed oils during short‐term deep‐frying of French fries and also contributed to enhance the nutritional value, and possibly improve the flavor, of the fries prepared in EVOO. 相似文献
107.
Incorporation of Alpha‐Linolenic Acid and Enhancement of n‐3 Fatty Acids in Nile Tilapia: a Factorial Design
下载免费PDF全文
![点击此处可从《Journal of the American Oil Chemists](/ch/ext_images/free.gif)
Vanessa Vivian Almeida Schneider Fabiana Carbonera Paula Fernandes Montanher Ana Paula Lopes Makoto Matsushita Jesuí Vergílio Visentainer 《Journal of the American Oil Chemists' Society》2015,92(5):693-700
A 22 factorial design (two factors at two levels, in triplicate) was performed to investigate the influence of factors A (time of treatment, 15 and 30 days) and B (chia oil content in a supplemented diet, at 2.1 and 4.2 %) in three responses of interest referring to: (a) the incorporation of alpha‐linolenic acid (LNA) in lipids of Nile tilapia fillet; (b) the enhancement of n‐3 fatty acids; and (c) the decrease in the omega‐6/omega3 (n‐6/n‐3) ratio in fish. Factors A and B were significant in the three regression models obtained and the interaction AB was a significant contributor to the LNA and n‐6/n‐3 ratio. Analysis of variance suggested three significant and predictive mathematical models. Response surfaces analyses from designs indicated higher LNA and n‐3 contents and a lower n‐6/n‐3 ratio using both factors A and B in the higher levels (30 days of treatment and 4.2 % of chia oil in the diet for fish) chosen for this study. 相似文献
108.
109.
110.
Rayssa Ferreira Zanatta Tatiane Josefa da Silva Maria Filomena Rocha Lima Huhtala Alessandra Bühler Borges Carlos Rocha Gomes Torres 《Journal of Adhesion Science and Technology》2016,30(23):2557-2564
Purpose: The aim of this study was to evaluate the influence of previous application of an adhesive system on bond strength of resinous liner materials to dentin. Methods: Ninety bovine incisors crowns had a 6 × 6 mm area of dentin exposed, with minimum of 2 mm thickness. They were embedded in acrylic resin, and the dentin was polished with P600 SiC sandpaper for 30 s to standardize the smear layer. The specimens were divided into 6 groups (n = 15) according to the application or not of a self-etching system (Futurabond U – Voco) and the type of resinous liner used: A+Ionoseal (adhesive and Ionoseal – Voco); Ionoseal (Ionoseal only); A+Vitrebond (adhesive and Vitrebond – 3M/ESPE); Vitrebond (Vitrebond only); A+Ionosit (adhesive and Ionosit – DMG) and Ionosit (Ionosit only). Adhesives were used following manufacturer’s instructions, and the liner materials were applied inside a 2-mm-depth matrix and light-cured for 20 s. The bond strength was measured by microtensile test, using a universal testing machine with a cross-speed of 1 mm/min. Data were analyzed using one-way ANOVA and Tukey’s test (p < 0.05). Results: The adhesive system application increased bond strength of all liners tested. Ionoseal presented the highest bond strength when the adhesive system was used and exhibited similar performance to Vitrebond without adhesive. Ionosit without adhesive showed the smallest bond strength compared with the other liners tested. Conclusion: The application of an adhesive system prior to the use of the resinous liners improved the bond strength to dentin and should be preconized. 相似文献