全文获取类型
收费全文 | 1035篇 |
免费 | 84篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 1篇 |
综合类 | 18篇 |
化学工业 | 215篇 |
金属工艺 | 9篇 |
机械仪表 | 5篇 |
建筑科学 | 2篇 |
矿业工程 | 5篇 |
能源动力 | 2篇 |
轻工业 | 831篇 |
水利工程 | 3篇 |
石油天然气 | 19篇 |
无线电 | 2篇 |
一般工业技术 | 8篇 |
冶金工业 | 1篇 |
原子能技术 | 6篇 |
自动化技术 | 2篇 |
出版年
2024年 | 12篇 |
2023年 | 14篇 |
2022年 | 34篇 |
2021年 | 49篇 |
2020年 | 51篇 |
2019年 | 54篇 |
2018年 | 39篇 |
2017年 | 43篇 |
2016年 | 52篇 |
2015年 | 38篇 |
2014年 | 54篇 |
2013年 | 87篇 |
2012年 | 67篇 |
2011年 | 91篇 |
2010年 | 43篇 |
2009年 | 38篇 |
2008年 | 45篇 |
2007年 | 72篇 |
2006年 | 59篇 |
2005年 | 20篇 |
2004年 | 17篇 |
2003年 | 31篇 |
2002年 | 20篇 |
2001年 | 16篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有1129条查询结果,搜索用时 15 毫秒
81.
五种香辛料精油抑菌及抗氧化性能研究 总被引:3,自引:0,他引:3
选取牛至、丁香、连翘、山苍子及肉桂为原料,利用超临界CO2萃取法提取精油,研究测定了五种精油对供试菌种的抑菌圈直径、加热处理及pH值对精油抑菌效果的影响,同时研究了五种精油的抗氧化效果.结果表明:五种精油对细菌、霉菌和酵母均有较强的抑制作用,其综合抑菌能力是肉桂>丁香>牛至、连翘和山苍子,五种精油均表现出对霉菌抑制最强的特点;五种精油的抑菌效果均随pH值的降低而增强;121℃15min加热处理对五种精油的抑菌效果均无明显影响;五种精油均具有一定的抗氧化能力. 相似文献
82.
The Antimicrobial Effect of Spice‐Based Marinades against Campylobacter jejuni on Contaminated Fresh Broiler Wings
下载免费PDF全文
![点击此处可从《Journal of food science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Gintarė Zakarienė Anita Rokaitytė Sigita Ramonaitė Aleksandr Novoslavskij Kristina Mulkytė Gintarė Zaborskienė Mindaugas Malakauskas 《Journal of food science》2015,80(3):M627-M634
The antimicrobial effect of spice‐based marinades against Campylobacter jejuni on inoculated fresh broiler wings was investigated. Experiments were carried out with 1 strain of C. jejuni and 6 marinades. Four experimental marinades were composed for the study and contained spices (thyme, rosemary, basil, marjoram, and so on) and different combination of bioactive compounds. Two marinades were commercial and contained spices (black pepper, sweet red pepper, and so on) and chemical additives (monosodium glutamate, sodium diacetate, calcium lactate), 1 commercial marinade was also enriched with bioactive compounds (linalool, cinnamaldehyde, lactic acid). Total aerobic bacterial count was examined to estimate the possible effect of tested marinades on the shelf‐life of marinated broiler wings. Study revealed that thyme‐based marinade was the most effective against C. jejuni on broiler wings and reduced the numbers of campylobacters by 1.04 log colony forming unit (CFU)/g (P ≤ 0.05) during storage for 168 h at 4 °C temperature. Moreover, it was more effective against C. jejuni than commercial marinade with 0.47 log CFU/g (P ≤ 0.05) reduction effect. Both experimental and commercial marinades had very similar effect on the total aerobic bacterial count. Although experimental and commercial marinades had different effect on pH of broiler wings, this parameter did not show a major impact on the antimicrobial effect of tested marinades (P ≥ 0.05). Our study shows that experimental natural thyme‐based marinade can reduce numbers of C. jejuni more effectively than tested commercial marinades. 相似文献
83.
84.
Soo Peng Koh Norlelawati Arifin Oi Ming Lai Mohd Suria Affandi Yusoff Kamariah Long Chin Ping Tan 《Journal of the science of food and agriculture》2009,89(3):455-462
BACKGROUND: Medium‐ and long‐chain triacylglyerols (MLCT) enzymatically esterified using Lipozyme RM IM lipase has very low oxidative stability as it does not contain any antioxidants. The aim of this work was to study the ability of various antioxidants to increase the oxidative stability of palm‐ and soybean‐based MLCT blends which assist to bring up the oxidative stability of both MLCT blends. In this study, the effectiveness of rosemary extracts, sage extracts, tert‐butylhydroquinone (TBHQ) and mixtures of tert‐butyl‐4‐hydroxyanisole (BHA) and tert‐butyl‐p‐hydroxytoluene (BHT) in protecting against oxidation of various MLCT blends was investigated. RESULTS: Blending of MLCT oil with either palm olein or soybean oil improved its smoke point values and oxidative stability. TBHQ addition to both palm‐ and soybean‐based MLCT blends increased oxidative stability. Combination of BHA and BHT showed no significant improvement (P > 0.05) in ability to protect blends from oxidation compared to natural antioxidants such as sage or rosemary extracts. CONCLUSION: Blended oils with 500 g kg?1 MLCT and 500 g kg?1 palm olein (MP5) were the most suitable for use at high temperature based on the fatty acid composition of the MLCT blends, which subsequently had an effect on thermal oxidative stability. In general, addition of either natural or synthetic antioxidant assisted in improving the antioxidative strength of both MLCT blends. MLCT blends with added TBHQ showed the highest thermal oxidative stability among the antioxidants used. Copyright © 2008 Society of Chemical Industry 相似文献
85.
86.
87.
目的 建立超高效液相色谱法测定山楂原料、提取物和相关食品中金丝桃苷和异槲皮苷的分析方法。方法 采用ACQUITY UPLC BEH C18柱, 以甲酸乙腈-甲酸水为流动相进行梯度洗脱分离金丝桃苷和异槲皮苷, 在紫外检测波长360 nm下进行检测, 外标法定量。结果 金丝桃苷和异槲皮苷的检出限(limit of detections, LODs, S/N=3)均为2 mg/kg, 定量限(limit of quantifications, LOQs, S/N=10)均为5 mg/kg; 在0.5~10.0 mg/L的浓度范围内线性关系良好, 相关系数均为0.999; 在原料、提取物和相关食品中, 金丝桃苷和异槲皮苷的平均回收率分别为83.0%~108.0%和86.2%~105.0%, 相对标准偏差(relative standard deviations, RSDs)分别为1.6%~5.7%和1.1%~3.9%。结论 本方法操作简便、快速、分离度和准确度高, 可用于山楂原料、提取物和相关食品的质量控制。 相似文献
88.
89.
L
P Fonseca J
M
S Cabral 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(10):1176-1185
An integrated process strategy for the recovery of penicillin acylase was developed, based on precipitation of non‐enzymatic proteins directly from Escherichia coli homogenates or crude extracts using Rolquat (quaternary ammonium salt) and adsorption of the enzyme on Amp‐Seph (3.8 µmole ampicillin cm?3) under pseudo‐affinity conditions. The effect of pH, concentrations of ammonium sulfate and Rolquat, and also concentrations of protein and cell debris on the precipitation of non‐enzymatic proteins from homogenates and crude extracts of penicillin acylase were analysed. The method of addition of Rolquat to homogenates and crude extracts significantly influenced the size of the precipitated particles. Improved results on the specific activity of penicillin acylase were obtained for 22% and 1% (w/v) of ammonium sulfate and Rolquat, respectively, added sequentially to enzyme solutions and at room temperature. Under these experimental conditions, the specific activity of penicillin acylase in homogenates and crude extracts was enhanced 2.5–3.0‐fold. Finally, the integrated process strategy was implemented first by precipitation of non‐enzymatic proteins and recovery of penicillin acylase directly from the enzyme solution treated with Rolquat using an adsorption/filtration system with an overall yield of 86%. This system allows simultaneously the filtration of cell debris and fine precipitated particles, in situ recovery of penicillin acylase by its adsorption on Amp‐Seph, and selective desorption of the enzyme with a specific activity of 11 IU (mg prot)?1 and a desorption yield of 95%. © 2002 Society of Chemical Industry 相似文献
90.
Jasna M Canadanovic‐Brunet Sonja M Djilas Gordana S Cetkovic Vesna T Tumbas 《Journal of the science of food and agriculture》2005,85(2):265-272
In an effort to discover new antioxidant natural compounds, wormwood (Artemisia absinthium L) an aromatic‐bitter herb, was screened. The sequential extraction was realized with five solvents of different polarities (70% methanol, petroleum ether, chloroform, ethyl acetate, n‐butanol). The antioxidative activity was tested by measuring their ability to scavenge stable 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical and reactive hydroxyl radical during the Fenton reaction trapped by 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO), using electron spin resonance (ESR) spectroscopy. Results demonstrated that the antiradical and antioxidative activity depend on the type and concentration of applied extracts and increased in the order ethyl acetate > methanol > n‐butanol > chloroform > petroleum ether > remaining water extracts. The investigation showed that the antiradical activity increased with increasing concentration of all extracts. The high contents of total phenolic compounds (25.6 mg g?1) and total flavonoids (13.06 mg g?1) indicated that these compounds contribute to the antiradical and antioxidative activity. In a model system, the formation of o‐semiquinone radicals from quercetin and chlorogenic acid was obtained to prove the mechanism (hydrogen donating and/or one‐electron reduction) of free‐radical scavenging activity. Copyright © 2004 Society of Chemical Industry 相似文献