全文获取类型
收费全文 | 474篇 |
免费 | 17篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 49篇 |
金属工艺 | 13篇 |
机械仪表 | 3篇 |
建筑科学 | 30篇 |
能源动力 | 11篇 |
轻工业 | 34篇 |
水利工程 | 3篇 |
无线电 | 81篇 |
一般工业技术 | 65篇 |
冶金工业 | 137篇 |
原子能技术 | 4篇 |
自动化技术 | 56篇 |
出版年
2023年 | 3篇 |
2021年 | 5篇 |
2019年 | 6篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 12篇 |
2013年 | 34篇 |
2012年 | 12篇 |
2011年 | 18篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 12篇 |
2007年 | 13篇 |
2006年 | 15篇 |
2005年 | 14篇 |
2004年 | 6篇 |
2003年 | 14篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 42篇 |
1997年 | 26篇 |
1996年 | 19篇 |
1995年 | 15篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 8篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 6篇 |
1970年 | 3篇 |
1969年 | 4篇 |
排序方式: 共有491条查询结果,搜索用时 890 毫秒
21.
22.
23.
Multi-allergen screening immunoassay for the detection of protein markers of peanut and four tree nuts in chocolate 总被引:1,自引:0,他引:1
S. Ben Rejeb M. Abbott D. Davies C. Cl roux P. Delahaut 《Food Additives & Contaminants》2005,22(8):709-715
A multiresidue enzyme immunoassay was developed to check for the presence of markers of peanut, hazelnut, almond, cashew and Brazil nuts in a single run. The assay was designed under the competitive indirect format and adapted for screening purposes applied to chocolate samples. The limit of detection for this assay was below 1 µg g-1 protein for each allergenic food. In most cases, the high specificity of the antibodies used allowed the identification of each particular allergenic food with no possible confusion. This assay was proven to be useful as part of an analytical procedure involving the identification of the unknown allergenic food among peanut and other tree nuts in recalled samples before the application of a quantitative technique to determine the level of cross-contamination. 相似文献
24.
Quality Measurement of Intact and Fresh-cut Slices of Fuji, Granny Smith, Pink Lady, and GoldRush Apples 总被引:1,自引:0,他引:1
Robert A. Saftner Juditha Abbott Arvind A. Bhagwat Bryan Vinyard 《Journal of food science》2005,70(5):S317-S324
ABSTRACT: Development of fresh-cut apple products requires consideration of cultivars that store well as both intact and fresh-cut fruit. We compared the instrumental and sensory quality of 2 apple cultivars, Granny Smith and Fuji, that are used for fresh cutting with 2 new cultivars, Pink Lady and GoldRush, which were considered to have quality characteristics suitable for fresh cutting. Firmness, titratable acidity (TA), soluble solids content (SSC), and aromatic volatile concentration were measured in intact fruit of the 4 cultivars during 12 mo storage in air at 0 °C and during 3 wk storage at 5 °C as fresh-cut slices. After 1 wk storage as fresh-cut slices, sensory evaluations for acceptability of flesh and peel appearance, flavor, texture, and overall eating quality were performed. During storage, GoldRush apples maintained > 80 N firmness, approximately 17% SSC, > 0.5% TA, and had high aromatic volatile production, that is, maintained quality better than the other cultivars. The quality and shelf stability of GoldRush slices were also as good as or better than slices from the other cultivars, whereas Granny Smith slices generally rated lower than the other cultivars. The acceptability of flavor, texture, and overall eating quality of GoldRush slices was as good as that for Pink Lady and Fuji. The quality of GoldRush apples can be maintained throughout the year in refrigerated air storage and still remain suitable for fresh-cut processing. The results indicate that GoldRush and Pink Lady are 2 promising new, high-quality apple cultivars for fresh cutting. Keywords: fresh-cut fruit, Malus × domestica , postharvest quality, respiration rate, shelf life 相似文献
25.
26.
Alison Wenham Lihui Song Malcolm Abbott Iskra Zafirovska Sisi Wang Brett Hallam Catherine Chan Allen Barnett Stuart Wenham 《Frontiers in Energy》2017,11(1):60-66
Cast-mono crystalline silicon wafers contain crystallographic defects, which can severely impact the electrical performance of solar cells. This paper demonstrates that applying hydrogenation processes at moderate temperatures to finished screen print cells can passivate dislocation clusters within the cast-mono crystalline silicon wafers far better than the hydrogenation received during standard commercial firing conditions. Efficiency enhancements of up to 2% absolute are demonstrated on wafers with high dislocation densities. The impact of illumination to manipulate the charge state of hydrogen during annealing is investigated and found to not be significant on the wafers used in this study. This finding is contrary to a previous study on similar wafers that concluded increased H– or H0 from laser illumination was responsible for the further passivation of positively charged dangling bonds within the dislocation clusters. 相似文献
27.
Jean-Michel Lamarre Pierre Marcoux Michel Perrault Richard C. Abbott Jean-Gabriel Legoux 《Journal of Thermal Spray Technology》2013,22(6):947-953
Many processes and systems require hot surfaces. These are usually heated using electrical elements located in their vicinity. However, this solution is subject to intrinsic limitations associated with heating element geometry and physical location. Thermally spraying electrical elements directly on surfaces can overcome these limitations by tailoring the geometry of the heating element to the application. Moreover, the element heat transfer is maximized by minimizing the distance between the heater and the surface to be heated. This article is aimed at modeling and characterizing resistive heaters sprayed on metallic substrates. Heaters were fabricated by using a plasma-sprayed alumina dielectric insulator and a wire flame-sprayed iron-based alloy resistive element. Samples were energized and kept at a constant temperature of 425 °C for up to 4 months. SEM cross-sectional observations revealed the formation of cracks at very specific locations in the alumina layer after thermal use. Finite-element modeling shows that these cracks originate from high local thermal stresses and can be predicted according to the considered geometry. The simulation model was refined using experimental parameters obtained by several techniques such as emissivity and time-dependent temperature profile (infra-red camera), resistivity (four-probe technique), thermal diffusivity (laser flash method), and mechanical properties (micro and nanoindentation). The influence of the alumina thickness and the substrate material on crack formation was evaluated. 相似文献
28.
Abbott AP Barker GW Davies DL Griffiths GA Walter AJ Kocovský P 《Analytical chemistry》2002,74(16):4002-4006
The use of ephedrine-substituted quaternary ammonium binaphthyl salts as molecular receptors is demonstrated. The electrochemical oxidation of the receptor is affected by the binding of an analyte in solution. The binding site on the binaphthyl salt has been determined using computer modeling and confirmed using 1D and 2D NMR studies. It is shown that the sensitivity of the receptor is related to the size of the analyte. Axially chiral binaphthyl salts are shown to bind chiral analytes in a different manner and this is demonstrated using lactic and mandelic acid. The presence of a polar functional group on the analyte is also shown to have an effect on the guest-host interaction. 相似文献
29.
We report the uniform planar anchoring of thermotropic liquid crystals on films of bovine serum albumin (BSA) covalently immobilized on the surface of glass microscope slides and mechanically rubbed using a cloth. The azimuthal orientations of the liquid crystals were measured to be parallel to the direction of rubbing. Following immersion and removal of these rubbed films of BSA from aqueous solutions containing either BSA, fibrinogen, lysozyme, anti-FITC immunoglobulin G (IgG), or antistreptavidin IgG, we measured liquid crystals placed onto these surfaces to largely retain their uniform alignment. In contrast, following immersion of a rubbed film of BSA into an aqueous solution of anti-BSA IgG, we observed liquid crystals on these surfaces to assume nonuniform orientations. We conclude that specific binding of anti-BSA IgG to the film of rubbed BSA erased anisotropy induced within the film of BSA by rubbing. This result suggests that the spatial scale of anisotropy within the rubbed film of BSA is comparable to or smaller than the size of the IgG molecule. Because the anisotropy within a rubbed film of a protein can be erased by specific binding of a second protein, we believe these types of substrates (rubbed films of proteins) have the potential to be useful in a variety of label-free biomolecular assays where specific binding of a target species to its ligand can be imaged through observation of the optical appearance of liquid crystal placed onto the surface. 相似文献
30.
Do simple cells in primary visual cortex form a tight frame? 总被引:1,自引:0,他引:1
Sets of neuronal tuning curves, which describe the responses of neurons as functions of a stimulus, can serve as a basis for approximating other functions of stimulus parameters. In a function-approximating network, synaptic weights determined by a correlation-based Hebbian rule are closely related to the coefficients that result when a function is expanded in an orthogonal basis. Although neuronal tuning curves typically are not orthogonal functions, the relationship between function approximation and correlation-based synaptic weights can be retained if the tuning curves satisfy the conditions of a tight frame. We examine whether the spatial receptive fields of simple cells in cat and monkey primary visual cortex (V1) form a tight frame, allowing them to serve as a basis for constructing more complicated extrastriate receptive fields using correlation-based synaptic weights. Our calculations show that the set of V1 simple cell receptive fields is not tight enough to account for the acuity observed psychophysically. 相似文献