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161.
Networks and Spatial Economics - In this paper, we investigate a multi-product, three-stage production/distribution system design problem (PDSD) with direct shipment and lateral transshipment... 相似文献
162.
Streptococcus thermophilus is a commonly used starter bacterium in dairy industry. It reduces the pH of milk rapidly and equilibrates the medium for the growth of Lactobacillus delbrueckii subsp. bulgaricus during yoghurt fermentation. Efforts to increase the diversity of artisanal yoghurt starters are not only important to bring new strains with novel and desirable characteristics, but also for the preservation of natural diversity which diminishes with the overuse and spread of industrial starters to natural resources. In the present study, 14 artisanal yoghurt samples were processed for the isolation of promising strains for yoghurt starter culture production and 66 strains were subsequently characterized. They were all identified as S. thermophilus using species-specific PCR and 16S rRNA gene sequencing. Genotypic diversity at the strain level was investigated by pulsed field gel electrophoresis (PFGE), and 22 homology groups were obtained. Further phenotypic characterization unearthed a significant phenotypic heterogeneity within homology groups, mostly with atypical novel character. Only 7 out of 66 strains showed S. thermophilus type-strain like phenotypic traits. Majority of the isolates were determined to be protease positive and fast milk acidifier to be used as yoghurt starter culture. 相似文献
163.
Aytaç Gülşen Burcu Turan Dimitris P. Makris Panagiotis Kefalas 《European Food Research and Technology》2007,225(3-4):435-441
Quercetin was oxidized with CuSO4 in aqueous acetonitrile, a reaction that has been previously shown to generate products that were detected in polyphenol
oxidase and peroxidase-catalysed oxidation of quercetin. The major oxidation product was isolated and characterized by means
of 1H-NMR and LC-MS, as 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxybenzofuran-3(2H)-one. This compound is a natural polyphenol reported
to occur in the outer dry layers of onion bulbs. Its in vitro antioxidant properties were evaluated in comparison with the
parent molecule and other natural polyphenols, employing three representative tests and the alterations in the activity observed
were discussed on the basis of structure–activity relationships. 相似文献
164.
Zümrüt Ceren Özduman Burcu Oglakci Miraç Doğan Ceren Deger Evrim Eliguzeloglu Dalkilic 《Microscopy research and technique》2022,85(3):1199-1208
This study compares the effect of different mouthwashes that have been recommended during the Coronavirus disease 2019 (COVID-19) pandemic on shear bond strength (SBS) of universal adhesive to enamel in regards to self-etch (SE) and etch-and-rinse (ER) modes. Flat enamel surfaces were obtained from 100 sound human maxillary central incisors. They were randomly allocated to five groups according to the different mouthwashes (no mouthwash/control [Ctrl], 0.2% chlorhexidine 1.5% hydrogen peroxide [H2O2], 0.2% povidone-iodine [PVP-I], Listerine [L]), and adhesive application modes (ER and SE) (n = 10). After the application of a universal adhesive (single bond universal), composite resin (Filtek Z250) was bonded by a cylinder-shaped mold (height: 2 mm, diameter: 2.4 mm). They were subjected to SBS test using a universal testing machine (AGS-X, Shimadzu Corp.) (crosshead speed: 1 mm/min). The resin–enamel interfaces were observed with a scanning electron microscope (SEM). The semiquantitative chemical microanalyses were performed with energy-dispersive spectroscopy (EDS). The data were statistically analyzed by two-way analysis of variance and Bonferroni test (p < .05). In SE mode, Group Ctrl revealed significantly higher SBS than all mouthwash groups (p < .05). In ER mode, Group Ctrl showed significantly higher SBS than H2O2 and PVP-I groups (p < .05). ER mode caused significantly higher SBS than SE mode in all mouthwash groups (p < .05). The SEM observations highlighted that Group Ctrl had a regular and intact hybrid layer with resin tag formation while the H2O2 and PVP-I groups exhibited a thin hybrid layer in both modes. EDS analysis indicated that in SE mode, all mouthwash groups presented increased O content compared to Group Ctrl. H2O2 and PVP-I that were suggested for preprocedural use during the COVID-19 pandemic, reduced the enamel bond strength of the universal adhesive in ER mode. 相似文献
165.
In this study, free radical copolymerization of acrylonitrile (AN)–vinyl acetate (VAc) was performed for five different feed ratio of VAc (wt %) by using ammonium persulfate (APS) in the aqueous medium. The effect of VAc content on the spectrophotometric and thermal properties of AN–VAc copolymers was investigated by Fourier Transform Infrared–Attenuated Total Reflectance spectrophotometer (FTIR–ATR), differential scanning calorimeter (DSC), and thermal gravimetric analyzer (TGA). Thermal stability of homopolymer of AN is improved after being copolymerized. The electrospun P(AN‐co‐VAc) nanofibers were fabricated and the effect of VAc content on the morphologic properties of nanofibers was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The viscosity of the solution had a significant effect on P(AN‐co‐VAc) electrospinning and the nanofiber morphology. The average diameters of P(AN‐co‐VAc) nanofibers decreased 3.4 times with increasing feed ratio of VAc wt %. The P(AN‐co‐VAc) electrospun nanofiber mats, with the feed ratio of 30 wt % VAc, can be used as a nanofiber membrane in filtration and as a carbon nanofiber precursor for energy storage applications due to high surface to volume ratio, high thermal stability, homogeneous, and thinner nanofiber distribution. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
166.
F. Dilek Sanin Aysun Vatansever Ipek Turtin Fadime Kara Burcu Durmaz Mohamed L. Sesay 《Drying Technology》2013,31(10):1297-1306
Selected operational conditions of activated sludge are investigated in relation to their effect on flocculation and dewatering. Semi-continuous reactors with 2 -L volume were operated at different mean cell residence times, C/N ratios, and three different influent cations. Results show that MCRT, C/N ratio, and the cation type affect the bioflocculation capacity of activated sludge measured by the quantity of extracellular polymeric substances. As the MCRT value operated in the reactors and the C/N ratio of the influent wastewater increase, total amount of polymers produced increases. High MCRT values and low C/N values cause good dewatering of the sludge. All cations are shown to stimulate the EPS production in a way that the highest total EPS concentrations are observed at the highest cation dosages. The dewaterability of the sludges improves only with increasing calcium and magnesium concentrations and deteriorates with increasing potassium concentration. 相似文献
167.
While estimating activity production rates, cost estimators rely on historical production rates. To have realistic and useful cost estimates based on historical production rates, such production rate data should be augmented with historical contextual information that depict conditions under which activity production rates were achieved in past projects. This information is needed in determining which production rate to use among alternates for a similar activity existing in a new bid. Estimators need contextual information especially when they are unfamiliar with the work being estimated. Hence, such information items need to be identified, collected, and stored for estimators’ use in new projects. This paper details a construction-method specific and an extensible approach that is developed for enabling cost estimators to define contextual information items that need to be collected on job sites and stored as part of project histories. Based on this approach, the writers implemented a prototype system, called as ContextGen, and performed user-tests with estimators with different experience levels. Results showed that the developed approach captures method-specific information needs of estimators and is extensible to incorporate new contextual information items that can have different data representations. The developed approach is also precise in retrieving contextual information items specific to a construction method from a set of predefined contextual information items available in a library. 相似文献
168.
Burcu Akata Trevor L. Goodrich Katherine S. Ziemer Albert Sacco 《Microgravity science and technology》2007,19(2):5-11
The Lewis activity of the Meerwein-Ponndorf-Verley (MPV) reactions is hypothesized to be due to partial framework aluminum
(PFAl) that is either octahedrally or tri-coordinated. Crystals grown in the free-fall environment of low earth orbit (LEO)
are more uniform; that is, have fewer lattice “defects” compared to those grown in a gravity field (i.e., on earth). Therefore,
crystals grown in orbit should be less catalytically active relative to their earth grown counterparts. The catalytic activity
towards the MPV reaction, and the associated IR and XPS spectrum for zeolite Beta that was synthesized on earth (1g) and aboard
the International Space Station (10−3–10−5g) were compared in their as-synthesized forms, and after applying heat treatment protocols designed to stress the crystal
structure to generate Lewis acid sites (i.e., tri and octahedrally coordinated PFAl). The activity of the MPV reaction and
cis-alcohol selectivity over the heat-treated flight samples was observed to be lower than the identically heat-treated terrestrial
zeolite Beta samples. Higher MPV activity as well as cis-alcohol selectivity is related to both a higher number of partial
framework Al atoms (PFAl), and a constrained pore volume. As PFAl are created by the destruction of the framework upon heat
treatment, flight samples were shown to be thermally more stable with fewer lattice defects and less associated stress in
zeolite Beta crystals. The changes observed in the IR spectra, as well as the XPS Al Auger and 2p peaks, of the terrestrial
samples support this conclusion. Additionally, the flight samples showed higher tr-alcohol selectivity, which implies more
pore volume and less channel blockage. This is consistent with the fact that crystals grown in space have less stress, fewer
lattice defects, and thus there are fewer channel obstructions. 相似文献
169.
170.