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Effects of various roasting conditions on antioxidant properties of five Theobroma cacao L. varieties were investigated. The cocoa beans were roasted at four different temperatures (110–150°C) and three different air humidities (0.3–5.0%). The raw cocoa beans were characterized by high antioxidant activities. The antioxidant properties of the roasted cocoa beans varied markedly among the analyzed cultivars and geographical regions and were affected by roasting conditions. Generally, cocoa beans of the cv. Forastero from Brazil exhibited higher total phenolic content, free radical scavenging activity, and metal chelating ability than samples of the other analyzed cocoa varieties. Roasting at 110°C caused negligible changes in total phenolics content and antioxidant activity of cocoa beans, while almost all samples tended to have lower antioxidant potential when roasting temperature increased. The air humidity used in roasting did not affect the total phenolics content and antioxidant activity for lowest roasting temperature (110°C). Moreover, the obtained results revealed that thermal processing at the higher temperatures and elevated air humidity resulted in the higher antioxidant capacities. It was also found that the ferrous ion chelating activity of cocoa beans increased with the roasting temperature (in the range from 110 to 150°C), with the exception of cv. Trinitario from Papua New Guinea. The data showed that roasting at lower temperatures with humid air are more favorable in terms of preserving the bioactivity of roasted cocoa beans. 相似文献
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As the sulfide ore deposits become less economically viable as a source of nickel, increasing attention is being paid to the nickeliferous laterite ores. However, in contrast to the sulfide ores, these oxide ores cannot be as easily concentrated by current technologies. Consequently, considerable research effort is being directed at developing new techniques for beneficiating the nickeliferous laterites. The pyrometallurgical production of a high-grade ferronickel alloy using a low cost carbonaceous reductant at relatively low temperatures is particularly attractive. In the current research, a thermodynamic model has been developed to aid in the understanding of the carbothermic reduction roasting process as a potential upgrading method for the nickeliferous limonitic laterite ores. The effects of process parameters such as temperature and reductant to ore ratio on the grade of the ferronickel alloy produced and the nickel recovery in the alloy have been studied. The thermodynamic predictions are shown to be in general agreement with the experimental results currently available in the literature. 相似文献
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Formation of Benzo(a)pyrene in Sesame Seeds During the Roasting Process for Production of Sesame Seed Oil 下载免费PDF全文
Weiwei Cheng Guoqin Liu Xuede Wang Xinqi Liu Bingge Liu 《Journal of the American Oil Chemists' Society》2015,92(11-12):1725-1733
The main aim of this research was to enhance the understanding of the formation mechanisms of benzo(a)pyrene (BaP) during roasting of sesame seeds (SS). BaP levels in hot‐ and cold‐pressed sesame seed oil (SSO) were evaluated to correlate oil technology and BaP formation. Extracted principal components from SS were roasted either singly or in mixtures at 230 °C for 30 min. BaP was measured by HPLC with fluorescence detection. The results showed that BaP levels in hot‐pressed SSO were significantly higher than those in cold‐pressed SSO (p < 0.05), BaP formation mostly occurred during SS roasting and increased with roasting temperature (between 80 and 280 °C) and time (from 10 to 50 min). Furthermore, the BaP level in the roasted hulled SS (3.64 μg/kg) was higher than it was in roasted whole SS (1.63 μg/kg). The maximum BaP level observed (5.03 μg/kg) was detected in a roasted mixture of SS protein and SSO. The addition of sesame protein to protein‐free SSO promoted the formation of BaP, which suggests that the pyrolysis products of protein and triacylglycerols are probably important precursors in BaP formation. 相似文献
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Enzymatic treatment of peanut kernels to reduce allergen levels 总被引:1,自引:0,他引:1
This study investigated the use of enzymatic treatment to reduce peanut allergens in peanut kernels as affected by processing conditions. Two major peanut allergens, Ara h 1 and Ara h 2, were used as indicators of process effectiveness. Enzymatic treatment effectively reduced Ara h 1 and Ara h 2 in roasted peanut kernels by up to 100% under optimal conditions. For instance, treatment of roasted peanut kernels with α-chymotrypsin and trypsin for 1–3 h significantly increased the solubility of peanut protein while reducing Ara h 1 and Ara h 2 in peanut kernel extracts by 100% and 98%, respectively, based on ELISA readings. Ara h 1 and Ara h 2 levels in peanut protein extracts were inversely correlated with protein solubility in roasted peanut. Blanching of kernels enhanced the effectiveness of enzyme treatment in roasted peanuts but not in raw peanuts. The optimal concentration of enzyme was determined by response surface to be in the range of 0.1–0.2%. No consistent results were obtained for raw peanut kernels since Ara h 1 and Ara h 2 increased in peanut protein extracts under some treatment conditions and decreased in others. 相似文献
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阐述了影响煤系硬质高岭土矿用于造纸涂料的主要因素和解决途径,并以四川普格高岭土矿加工利用研究为例,论述了该矿的矿石性质、加工工艺及其特点。通过研究最终获得了高档级涂布原料、中档级涂布原料和造纸填料三种产品,并进行了产品应用试验和技术经济分析。 相似文献
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Effects of oven-drying,roasting, and explosive puffing process on isoflavone distributions in soybeans 总被引:1,自引:0,他引:1
Distributions of isoflavones in soybeans treated with oven-drying, roasting, or explosive puffing were analysed using high-performance liquid chromatography (HPLC). As oven-drying time increased from 0 to 120 min at 100 °C, concentration (μmol/g) of malonyl derivatives of isoflavones decreased and β-glucosides increased significantly with over 0.99 coefficient of determination (R2) (P < 0.05). Roasting at 200 °C for 7, 14, and 21 min and explosive puffing at 490, 588, and 686 kPa decreased malonyl derivatives significantly and increased acetyl-β-glucosides and β-glucosides significantly (P < 0.05). Total isoflavones (TI) in 21 min roasted and 686 kPa puffed soybeans decreased by 25.46% and 10.42%, respectively, while TI in 120 min oven-dried soybeans was not significantly different (P > 0.05) compared to untreated samples. Regression analysis showed that malonyl-β-genistin had higher slopes of decreases (μmol/g/min) than malonyl-β-daidzin in oven-dried soybeans. This is the first report on the effects of explosive puffing and the changes of isoflavone profiles in soybeans. 相似文献