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41.
Mariela N. Acosta Daniel R. Ercoli Graciela S. Goizueta Jorge E. Lozano Numa J. Capiati 《Packaging Technology and Science》2011,24(4):223-235
The aim of this work was to obtain films of polypropylene (PP)/polyethylene co‐octene (POE) blends and study the influence of their composition and mixing conditions on final morphology and ultimate properties (thermal, mechanical, oxygen and water vapour transmission rates). Scanning electron microscopy showed segregation of POE domains in the PP matrix. Thermal analysis indicated that the addition of POE modified neither the melting temperature nor the crystallinity of PP in the pressed films. It was found that permeabilities of films were mainly related to POE content rather than morphological features. For the maximum POE concentration used (40%), the oxygen permeability increased up to ∼100% from that of neat PP. A similar trend was found for water vapour permeability. Rigidity of blends dropped significantly with the addition of POE although their ductility slightly increased when compared to pure PP. No significant effect of blend preparation conditions on these properties was found. Mechanical and permeability characteristics of films make them very attractive to be used for MAP of fresh produce such as apple, blueberry and mushroom. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
42.
Laurent Abouchar Mariela D. Petkova Cynthia R. Steinhardt Thomas Gregor 《Journal of the Royal Society Interface》2014,11(97)
Developmental processes in multicellular organisms occur in fluctuating environments and are prone to noise, yet they produce complex patterns with astonishing reproducibility. We measure the left–right and inter-individual precision of bilaterally symmetric fly wings across the natural range of genetic and environmental conditions and find that wing vein patterns are specified with identical spatial precision and are reproducible to within a single-cell width. The early fly embryo operates at a similar degree of reproducibility, suggesting that the overall spatial precision of morphogenesis in Drosophila performs at the single-cell level. Could development be operating at the physical limit of what a biological system can achieve? 相似文献
43.
Damin M Maestri Rene H Fortunato Carlos A Guzmn Mariela M Torres Alicia L Lamarque 《Journal of the science of food and agriculture》2002,82(3):248-251
Seeds of 17 wild leguminous species belonging to the Papilionoideae subfamily were analysed for their proximate, fatty acid and sterol compositions. Centrosema virginianum, Tipuana tipu, Adesmia volckmanni and some species of Desmodium contained high amounts (>300 g kg?1) of protein. Geoffroea decorticans and Clitoria cordobensis were noteworthy for their high oil content (>350 g kg?1). The seed lipids had a high proportion of unsaturated (oleic and linoleic mainly) fatty acids. Linolenic acid had the highest value in Adesmia volckmanni (25.4% of total fatty acids). β‐Sitosterol was the major component of the sterol fraction. Chemical analyses indicated that all species studied are suitable sources of animal feed. © 2002 Society of Chemical Industry 相似文献
44.
Md. Nurul Kabir Bhuiyan Mariela MenghiniJin Won Seo Jean-Pierre Locquet 《Microelectronic Engineering》2011,88(4):411-414
Ultra-thin films of Dy are grown on Ge(0 0 1) substrates by molecular beam deposition near room temperature and immediately annealed for solid phase epitaxy at higher temperatures, leading to the formation of DyGex films. Thin films of Dy2O3 are grown on the DyGex film on Ge(0 0 1) substrates by molecular beam epitaxy. Streaky reflection high energy electron diffraction (RHEED) patterns reveal that epitaxial DyGex films grow on Ge(0 0 1) substrates with flat surfaces. X-ray diffraction (XRD) spectrum suggests the growth of an orthorhombic phase of DyGex films with (0 0 1) orientations. After the growth of Dy2O3 films, there is a change in RHEED patterns to spotty features, revealing the growth of 3D crystalline islands. XRD spectrum shows the presence of a cubic phase with (1 0 0) and (1 1 1) orientations. Atomic force microscopy image shows that the surface morphology of Dy2O3 films is smooth with a root mean square roughness of 10 Å. 相似文献
45.
Copello GJ Mebert AM Raineri M Pesenti MP Diaz LE 《Journal of hazardous materials》2011,186(1):932-939
This work describes the synthesis of chitosan hydrogel/SiO(2) and chitin hydrogel/SiO(2) hybrid mesoporous materials obtained by the sol-gel method for their use as biosorbents. Their adsorption capabilities against four dyes (Remazol Black B, Erythrosine B, Neutral Red and Gentian Violet) were compared in order to evaluate chitin as a plausible replacement for chitosan considering its efficiency and lower cost. Both chitin and chitosan were used in the form of hydrogels. This allowed full compatibility with the ethanol release from tetraethoxysilane. The hybrid materials were characterized by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Nitrogen Adsorption Isotherms and (13)C solid-state Nuclear Magnetic Resonance. Adsorption experimental data were analyzed using Langmuir, Freundlich and Dubinin-Radushkevich isotherm models along with the evaluation of adsorption energy and standard free energy (ΔG(0)). The adsorption was observed to be pH dependent. The main mechanism of dye adsorption was found to be a spontaneous charge associated interaction, except for EB adsorption on chitin/SiO(2) matrix, which showed to involve a lower energy physical adsorption interaction. Aside from highly charged dyes the chitin containing matrix has similar or higher adsorption capacity than the chitosan one. 相似文献
46.
RAPD-based screening for spore-forming bacterial populations in Uruguayan commercial powdered milk 总被引:1,自引:0,他引:1
Reginensi SM González MJ Olivera JA Sosa M Juliano P Bermúdez J 《International journal of food microbiology》2011,148(1):36-41
The occurrence of spore-forming bacteria in powdered milk is of concern to the dairy industry due to potential deleterious effects including those resulting from proteolytic and lipolytic activities. Twenty-two powdered milk samples representative of spring and summer production obtained from Uruguayan retail stores were analyzed for type and number of thermophilic and spore-forming bacterial species. Bacillus licheniformis isolates were found to be the most prominent milk powder contaminant followed by Anoxybacillus flavithermus representing 71.5 to 84% of the total microflora. Geobacillus stearothermophilus, however, was not found. B. licheniformis strains F and G were both found in this study but strain F was the prevalent isolate representing 98.9% of the total isolates of this species. A. flavithermus isolates corresponded to strain C in accordance with 16S rRNA gene sequence analysis, however, in contrast with other reports, the RAPD profiles showed three characteristic bands at approximately 650, 1000 and 1650 bp, but lacking a band at 1250 bp. A third group of isolates was identified corresponding to members of a Bacillus subtilis group and Bacillus megaterium. Isolates designated B. licheniformis, A. flavithermus, B. megaterium and the B. subtilis group represented 89.1 to 93.6% of those analyzed, and depended on previous heat treatment and incubation temperatures of the plates. The remaining isolates were Bacillus pumilus and unidentified spore-formers. 相似文献
47.
Mariela M Torres Damin M Maestri 《Journal of the science of food and agriculture》2006,86(14):2311-2317
The chemical composition of virgin olive oils from Arbequina olives cultivated in Córdoba (Argentina) was studied in relation to the oil extraction system and production year. Significant variations were found between oils obtained by pressure (PEOs) and centrifugation (CEOs) systems. PEOs were characterised by higher values of acidity, pigments and oleic acid, while CEOs showed greater phenol content. Moreover, a significant effect of crop year was observed. Arbequina oils produced in Córdoba contained lower amounts of oleic acid but higher amounts of phenolic compounds than Arbequina oils produced in Spain. A storage stability test was carried out in order to study the combined effects of oil extraction system and storage conditions (packaging material and illumination) on quality indices related to oxidative stability. Multivariate analysis applied to the chemical data emphasised the differences between PEOs and CEOs, indicating that variations due to extraction system were greater than those due to illumination condition and package type. Cluster analysis of oils from each extraction system stressed the influence of illumination condition on the oxidative stability of olive oils, showing increased amounts of secondary oxidation products in oils exposed to light. Glass and tin packages appear to be the most appropriate containers for maintaining the quality of olive oils, but this supposition is strongly dependent on the type of oil (PEO or CEO) and its initial chemical properties. Copyright © 2006 Society of Chemical Industry 相似文献
48.
Mariela M. Salazar-gutierrez Joe L. White Stanley L. Hem 《Drug development and industrial pharmacy》1989,15(1):17-24
Eighty-eight percent hydrolyzed polyvinyl alcohol was effective in dispersing an amorphous carbonate-containing aluminum hydroxide suspension. It is believed that the polyvinyl acetate units are adsorbed, providing an anchor for the highly hydrated polyvinyl alcohol units. Hydroxypropyl cellulose did not exhibit steric stablization, probably because it is too soluble to be significantly adsorbed. 相似文献
49.
The fundamental solution of the two-dimensional convection–diffusion equation with variable coefficients and its adjoint equation
are obtained in complex form in terms of the unknown density of two equivalent uniquely solvable Volterra integral equations
of the second kind whose analytical solutions are given explicitly as convergent Neumann series. The Volterra integral equations
are obtained by integrating the complex form of the original differential equations, without additional change of variables
as proposed by previously authors. In the numerical examples, cases corresponding to non-self-adjoint operators are considered.
As a validation, the proposed approach is used to derive the fundamental solution of the adjoint to the convection–diffusion
equation with constant velocity. In this case, the series solution can be evaluated analytically. For more general velocity
fields, the recursive terms of the series can be evaluated by symbolic computation or numerical integration. 相似文献
50.
Thermochromic Materials: Versatile Thermochromic Supramolecular Materials Based on Competing Charge Transfer Interactions (Adv. Funct. Mater. 47/2016)
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