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1.
Association colloids formed by surface active minor components play an important role in the oxidative stability of bulk oils. To imitate the formation of nanostructures in refined oils, multiple surface active minor components including phospholipids, free fatty acids, diacylglycerols and sterols were added to stripped corn oil. The critical micelle concentration (CMC) of the mixed components was determined. The impact of mixed minor components at below and above their CMC on oxidative stability of bulk oil and on antioxidant activity of α-tocopherol and Trolox was investigated. The CMC of the mixed surface active components in bulk oil was 20 µmol/kg oil in the presence of 383 ± 2 ppm of water. 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) played an important role on the formation of association colloids since it was the most important component in forming the association colloids as confirmed by CMC and fluorescence probe studies. The association colloids formed by the mixed components showed prooxidative activity in bulk oil as determined by monitoring the formation of lipid hydroperoxide and hexanal. The activity of α-tocopherol or Trolox was not changed by mixed components association colloids. These results suggest that association colloids both physically and chemically impacted the oxidative stability and activity of antioxidants in bulk oil.  相似文献   
2.
In this research, the steric effect of an exfoliation agent between n-ethylamine and triethylamine for the fabrication of Ca2Nb3O10 nanosheet was investigated. The experimental results revealed that the different structures of the exfoliation agent have affected to fabrication of Ca2Nb3O10 nanosheet. The use of n-ethylamine as an exfoliation agent gave a maximum exfoliation efficiency of 10 wt.% while the maximum exfoliation efficiency of triethylamine was 90 wt.%. The result showed that the difference in exfoliation efficiency was caused by the steric effect of exfoliation agents. The image of transmission electron microscopy exhibited Ca2Nb3O10 nanosheets which were formed by exfoliation of HCa2Nb3O10. Furthermore, the reaction time for liquid exfoliation was studied in this work. The reaction time at 4 h gave a maximum of exfoliation efficiency. The Ca2Nb3O10 suspension was tested capability to remove hazardous ions. After the experiment, we found the white precipitate which was the formation of CsCa2Nb3O10. The result showed that the Ca2Nb3O10 nanosheet was efficient for the removal of Cs+ ions in the wastewater.  相似文献   
3.
Sweet pickled mango named Ma-Muang Bao Chae-Im is a traditional preserved mango from Hat Yai, Thailand. This study investigated (I) volatile and non-volatile compound profiles of commercial Ma-Muang Bao Chae-Im and (II) their relationship to consumer preference. Untargeted metabolomics profiling was performed by gas chromatography-mass quadrupole-time of flight analysis. There were 117 volatile and 44 non-volatile compounds annotated in six commercial brands of Ma-Muang Bao Chae-Im. Furthermore, 46 volatile and 19 non-volatile compounds’ discriminant markers were found by Partial least square discriminant analysis. Among those markers, sorbic and benzoic acid were observed in several brands; moreover, the combination of both compounds altered the volatile profile, especially the ester group. Partial least square regression revealed that overall consumer liking is correlated to 1-heptanol; 1-octanol; acetoin; acetic acid, 2-phenylethyl ester; D-manitol; terpenes and terpenoids, while firmness to sucrose and L-(-)-sorbofuranose. On the other hand, most ester compounds were not related to consumer preference.  相似文献   
4.
The rheological behavior of ceramic glaze suspensions containing limestone, quartz, feldspar, and kaolin, has been improved by the addition of either a cationic (cetylpyridinium chloride, CPC) or an anionic (sodium dodecylbenzenesulfonate, SDBS) surfactant. Additional stability and lower viscosity can result from either electrical double layer repulsion or steric repulsion depending on the surfactant type, concentration, ionic strength, and pH. Underdosing may result in high viscosity due to charge neutrality and hydrophobic attraction between particles while overdosing may result in high viscosity possibly due to micelles in the solution. The situation is particularly complicated for glazes containing limestone and anionic surfactant at moderate to low pH where calcium carbonate is soluble. The anionic surfactant and calcium ions can form complexes that are poorly soluble and strongly adsorb to the surface of the particles. The resulting thick steric layer of complexes produces a significant repulsion and stable, low viscosity suspensions. ζ potential measurements and adsorption isotherms are used to interpret the rheological behavior.  相似文献   
5.
In this study, two kinds of melt-processed YBCO samples (Y1050-1 and Y1050-2) grown on a buffer layer of Y2O3 addition were fabricated. The compacted powders were located on a crucible with Y2O3 powder freely poured and a buffer layer of pressed Y2O3 to avoid liquid to spread on the furnace plate. The superconducting transition temperature was determined by a standard four-point method at temperatures between 40 and 100 K. The transition temperatures of Y1050-1 and Y1050-2 were found to be 91.6 and 92.9 K at zero magnetic fields, respectively. The magnetization measurements were performed using a vibrating sample magnetometer (VSM) on the same system at 5, 40, and 77 K. The critical current densities for Y1050-1 and Y1050-2 samples were determined to be 6.5×103 and 5.6×103 A/cm2 at 77 K in zero magnetic fields, respectively. The trapped magnetic field measurements of the samples were performed by using a Hall probe scanning device and a Fe–Nd–B permanent magnet at 77 K. It was found that the trapped magnetic field of the Y1050-1 sample is higher than that of the Y1050-2 sample.  相似文献   
6.
A facile route to synthesize silver-embedded-poly(methyl methacrylate)/polyethyleneimine (PMMA/PEI-Ag) core–shell particle composites was illustrated in this present work. PMMA/PEI core–shell particle templates were first prepared by a surfactant-free emulsion polymerization. PEI on the templates' surface was further used to complex and reduce Ag+ ions (from silver nitrate solution) to silver nanoparticles (AgNPs) at ambient temperature, resulting in the PMMA/PEI-Ag particle composites. The formation of AgNPs was affected by the pHs of the reaction medium. The pH of reaction medium at 6.5 was optimal for the formation of PMMA/PEI-Ag with good colloidal stability, which was confirmed by size and size distribution, FTIR spectroscopy, UV–vis spectroscopy and X-ray diffraction. Moreover, the amount of AgNO3 solution (4.17–12.50 g) was found to affect the formation of AgNPs. Transmission electron microscopy (TEM) indicated that the AgNPs were incorporated in the PMMA/PEI core–shell matrix, and had 6–10 nm in diameter. AgNPs immobilized on PMMA/PEI core–shell particles were also investigated by energy dispersive X-ray spectroscopy analysis mode extended from scanning electron microscopy (SEM/EDS). Furthermore, the presence of AgNPs was found to influence the thermal degradation behavior of PMMA/PEI particle composites as observed through thermogravimetric analysis (TGA).  相似文献   
7.
This paper introduces SArch, an environmental impact assessment tool developed in Thailand. SArch can be used to assess the environmental impact of construction materials throughout the lifecycle of buildings. The assessment starts with the raw materials and follows their preparation, transportation, utilization and maintenance to post-utilization or destruction. Five categories of impact are considered: global warming, acidification, eutrophication, ecological toxicity and smog. SArch can be used to assess the environmental impact of materials in the building design phase as well as the impact of existing buildings. An example of using SArch for the assessment of a residential house in Thailand is provided.  相似文献   
8.
In this work, single-crystal samples 20 mm in diameter were grown by a cold top-seeding method. In order to study the effect of an Y2O3 buffer layer, a compacted precursor was located in a crucible on a buffer layer of freely poured Y2O3 powder. The YBCO bulk samples were carefully prepared in the same chemical composition. In order to examine the homogeneity of the samples, rectangular specimens were cut from a sample. The structural orientation of the specimens was measured by a X-ray diffractrometer (XRD). The microstructure was observed with a Scanning Electron Microscope (SEM). The magnetic properties were measured using a Vibrating Sample Magnetometer (VSM) at 77 K with the applied magnetic field parallel to the c-axis. As a result only (00l) peaks were observed in X-ray diffraction data, indicating that all specimens are highly oriented with the c-axis perpendicular to the top surface. Also the cut samples exhibited very fine Y211 inclusion distributed in the bulk sample observed in SEM micrographs. The critical current density J c (A/cm2) has been estimated by the extended Bean model. The maximum value of the critical current density at 77 K is 5.2×104 A/cm2 in a self-field. The trapped magnetic field measurements of the samples were performed by using Hall probe scanning device with static field of 0.5 T at 77 K. The single-domain sample exhibits a trapped field of 1140 G at 77 K.  相似文献   
9.
Continuously cast ductile iron: Processing, structures, and properties   总被引:1,自引:0,他引:1  
Ductile iron billets were continuously cast using a horizontal casting machine. The billets were cast successfully, and the overall quality of the billets was acceptable. The as-cast microstructure consisted of eutectic carbide, chunky carbide and graphite nodules in a pearlite matrix. The amount of carbide was relatively large compared with that in traditional sand castings. Graphite nodularity decreased as the melt was held for longer periods of time before casting after inoculation and nodularisation treatments. The fading effect was significant when the melt was held for 6 min and longer. Graphite nodularity was found to affect the tensile strength and elongation, but not hardness, of the billets. The surface quality of the billets was fair, although light waves and drawal marks were clearly visible. The billets had good roundness. The tensile strength was found to be between 410 and 550 MPa; the elongation was 2.5-4.0%; and the hardness was 520-550 HB. Possible approaches to improving the as-cast structure and the implications of this research are discussed.  相似文献   
10.
The polar paradox states that polar antioxidants are more active in bulk lipids than their nonpolar counterparts, whereas nonpolar antioxidants are more effective in oil-in-water emulsion than their polar homologs. However, recent results, showing that not all antioxidants behave in a manner proposed by this hypothesis in oil and emulsion, lead us to revisit the polar paradox and to put forward new concepts, hypotheses, and theories. In bulk oil, new evidences have been brought to demonstrate that the crucial site of oxidation is not the air-oil interface, as postulated by the polar paradox, but association colloids formed with traces of water and surface active molecules such as phospholipids. The role of these association colloids on lipid oxidation and its inhibition by antioxidant is also addressed as well as the complex influence of the hydrophobicity on the ability of antioxidants to protect lipids from oxidation. In oil-in water emulsion, we have covered the recently discovered non linear (or cut-off) influence of the hydrophobicity on antioxidant capacity. For the first time, different mechanisms of action are formulated in details to try to account for this nonlinear effect. As suggested by the great amount of biological studies showing a cut-off effect, this phenomenon could be widespread in dispersed lipid systems including emulsions and liposomes as well as in living systems such as cultured cells. Works on the cut-off effect paves the way for the determination of the critical chain length which corresponds to the threshold beyond which antioxidant capacity suddenly collapses. The systematic search for this new physico-chemical parameter will allow designing novel phenolipids and other amphiphilic antioxidants in a rational fashion. Finally, in both bulk oils and emulsions, we feel that it is now time for a paradigm shift from the polar paradox to the next theories.  相似文献   
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