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Mesostasis material present in the interstices of volcanic rocks is the main cause of the alkali-aggregate reaction (AAR) in concretes made with these rock aggregates. Mesostasis often is referred to as volcanic glass, because it has amorphous features when analyzed by optical microscopy. However, this study demonstrates that mesostasis in the interstitials of volcanic rocks most often consists of micro to cryptocrystalline mineral phases of quartz, feldspars, and clays. Mesostasis has been identified as having different characteristics, and, thus, this new characterization calls for a re-evaluation of their influence on the reactivity of the volcanic rocks. The main purpose of this study is to correlate the characteristics of mesostasis with the AAR in mortar bars containing basalts and rhyolites.  相似文献   
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Sourdough is a type of dough fermented by yeast and lactic acid bacteria (LAB) used as sponge dough in bread making. Sourdough may have four classifications according to the fermentation type and the technological process used. On sourdough type I, the fermentation of yeasts and LAB present in the flour occurs spontaneously whereas in type II, fermentation occurs after the inoculation of a starter culture. Type III is simply type II sourdough dehydrated and type IV is a mixture of type I and type II sourdough, produced on laboratory scale. With LAB’s growth during fermentation, pH decreases with subsequent hydrolysis of starch and protein, favoring the growth of yeasts. The yeast in turn, releases amino acids during autolysis, contributing to the growth of LAB. Due to this synergistic growth of LAB and yeasts, the products obtained from sourdough show more concentration of flavor, more elastic dough, and a longer shelf life than bread fermented only by yeast. Although, the benefits of this technology, using sourdough, is present just in a few countries, where it is also possible to obtain the dehydrated sourdough starters, for domestic use, in local supermarkets. Due to its fermentative process complexity, this paper presents updated information about the fabrication process of sourdough, main factors affecting this process, benefits of sourdough use for bakery products, and the varieties of dehydrated sourdough commercially available throughout the world.  相似文献   
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Lactobacillus plantarum growth in a vacuum‐packaged cooked meat product under different storage temperatures (4, 10 and 16 °C) and the relation between the microorganism growth and sensory quality were investigated. The Gompertz model was fitted to experimental counts of L. plantarum showing a good fitting to growth curves at different temperatures. A root‐square secondary model and linear model were satisfactorily fitted to estimated growth rates () and lag times (), respectively. The sensory attributes (colour, flavour, taste, appearance) were also evaluated due to their importance to the global quality (Q). The sensory deterioration was detected several days after L. plantarum reached the stationary phase, that is, 59, 45 and 25 days for 4, 10 and 16 °C, respectively. According to results, sensory deterioration was related to time when microorganism reached late stationary phase, phenomenon known as ‘delayed change’.  相似文献   
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Thermal fatigue can cause irreversible damage in aluminum alloys restricting their use in the automotive industry, despite their excellent mechanical and technological properties. The application of ceramic coating is an alternative to obtain a protective barrier to improve the wear resistance at high temperatures. However, the low melting point and high coefficient of thermal expansion (CTE) of aluminum alloys limit the coating options. Thus, a suitable coupling feature can be obtained between aluminum alloys and a glazed coating. A glazed coating based on the aluminum borophosphate system was developed and applied onto an aluminum-silicon-copper commercial alloy. The coating was characterized by X-ray diffractometry, scanning electron microscopy, hardness tests, and thermal analysis. The coupling between the glazed coating and the aluminum alloy surface was studied employing optical dilatometry and optical fleximetry. A dense, good adhesion coating and presenting adequate dilatometric coupling (effective coupling temperature of 345 °C) related to the investigated aluminum alloy was obtained at 500 °C. The good compatibility of CTE between the layers (24.54 × 10?6 °C-1 for the substrate and 14.56 × 10?6 °C-1 for the coating) led to a crack-free material. For this reason, microhardness increased from 136 (aluminum alloy) to 325 HV (glazed aluminum alloy). The glazed coating can expand the use of this alloy, improving its performance and thermal efficiency. This result suggests an enormous potential of applications in the automotive industry, for instance.  相似文献   
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In this paper we explore the accumulation of different phosphorus (P) fractions in soil submitted to successive applications of pig slurry (PS) and deep pig litter (DL). After 88?months of no-till crop cycles, soil samples were collected in the following treatments: control (C), PS applications equivalent to 90 and 180?kg?N?ha?1 (PS90 and PS180), and DL applications equivalent to 90 and 180?kg?N?ha?1 (DL90 and DL180). The cumulative application of P of the C, PS90, PS180, DL90 and DL180 treatment was 0, 303, 606, 825 and 1650?kg P ha?1, respectively. The soil samples were then submitted to P chemical fractionation. Successive applications of 303 and 606?kg P ha?1 in PS form and 825 and 1.650?kg P ha?1 in DL form increased P levels down to 20?cm depth, especially in the labile inorganic fraction extracted by anion exchange resin and 0.5?M NaHCO3 and to a lesser extent extracted by 0.1?M NaOH. Successive additions of PS180 and DL180 increased the levels of organic P extracted by 0.5?M NaHCO3, 0.1?M NaOH and 0.5?M NaOH, and successive applications of PS and DL caused P accumulation in the soil profile, especially in labile fractions. This increased the availability to plants, but also increases the potential for environmental contamination.  相似文献   
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