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341.
342.
志贺菌多重耐药性研究进展 总被引:1,自引:0,他引:1
一般认为志贺菌产生耐药性与抗菌药的结构和作用机制有关,并通过质粒携带的耐药基因扩散耐药性,同类结构药物或作用机制相似的药物具有部分或全部交叉耐药性。然而,近几年随着分子生物学手段的不断应用,人们开始从更多层面来认识志贺菌的耐药性。细菌对不同结构类别或不同作用机制的抗菌药物都能产生耐药性,即多重耐药(multi drug resistance)。本文就志贺菌耐药机制的研究进展进行了综述。 相似文献
343.
Fuel moisture content is an important variable for forest fires because it affects fuel ignition and fire behavior. In order to accurately predict fuel ignition potential, fuel moisture content must be assessed by evaluating fire spread, fireline intensity and fuel consumption.Our objective here is to model moisture content of surface fuels in normally stocked Calabrian pine(Pinus brutia Ten.) stands in relation to weather conditions, namely temperature, relative humidity, and wind speed in the Mugla province of Turkey. All surface fuels were categorized according to diameter classes and fuel types. Six fuel categories were defined: these were 0–0.3, 0.3–0.6, and0.6–1 cm diameter classes, and cone, surface litter, and duff. Plastic containers 15 9 20 cm in size with 1 9 1 mm mesh size were used. Samples were taken from 09:00 to19:00 h and weighed every 2 h with 0.01 g precision for10 days in August. At the end of the study, samples were taken to the laboratory, oven-dried at 105 °C for 24 h and weighed to obtain fuel-moisture contents. Weather measurements were taken from a fully automated weather station set up at the study site prior to the study. Correlation and regression analyses were carried out and models were developed to predict fuel moisture contents for desorption and adsorption phase for each fuel type categories. Practical fuel moisture prediction models were developed for dry period. Models were developed that performed well with reasonable accuracy, explaining up to 92 and 95.6%of the variability in fuel-moisture contents for desorption and adsorption phases, respectively. Validation of the models were conducted using an independent data set and known fuel moisture prediction models. The predictive power of the models was satisfactory with mean absolute error values being 1.48 and 1.02 for desorption and adsorption as compared to the 2.05 and 1.60 values for the Van Wagner's hourly litter moisture content prediction model. Results obtained in this study will be invaluable for fire management planning and modeling. 相似文献
344.
基于红外光谱三级鉴别技术的螺旋藻产品品质分析 总被引:3,自引:0,他引:3
【目的】利用红外光谱技术分析天然螺旋藻、螺旋藻粉和螺旋藻片的主要成分,为螺旋藻相关产品品质检测和真伪鉴别提供一种快速、准确和有效的方法。【方法】采集2种天然螺旋藻、4种螺旋藻粉和4种螺旋藻片的红外光谱(FTIR),解析样品的红外光谱、二阶导数光谱和二维相关光谱确定出主要吸收官能团,主体成分以及不同样品之间的差异。通过扫描电镜图像(SEM)、样品蛋白质含量和氨基酸组成的测定结果对红外光谱中的差异进行说明。【结果】天然螺旋藻的红外光谱在1 154/1 156 cm-1、1 079 cm-1和1 039/1 035 cm-1出现3个糖类特征吸收峰;二维相关红外光谱在1 161、1 138、1 083、1 054和1 026 cm-1出现5个强自动峰。螺旋藻粉和螺旋藻片的糖类特征吸收峰形状和位置与天然螺旋藻不同,并且二维相关红外光谱中自动峰减少。天然螺旋藻蛋白质的α-螺旋含量为24.6%,螺旋藻粉和螺旋藻片中α-螺旋含量在15.0%左右。在二维相关红外光谱中天然螺旋藻的酰胺带吸收峰光滑、少分叉,可完全分离的两个尖峰,而螺旋藻粉和螺旋藻片的酰胺带吸收峰宽,分离度不好,并且出现多个分叉峰。蛋白质含量和氨基酸组成测定结果表明螺旋藻产品中蛋白质含量过高,且氨基酸组成与纯螺旋藻的氨基酸组成存在很大差异。【结论】红外光谱技术可以对天然螺旋藻、螺旋藻粉和螺旋藻片的糖类和蛋白成分的差异进行鉴别,并为螺旋藻产品的品质评价和真伪鉴别提供一种有效方法。 相似文献
345.
[目的]研究新疆野生沙枣仁中脂肪和蛋白质组分。[方法]采用气质联用法测定新疆野生沙枣仁油脂中脂肪酸的含量及组分;采用分级提取法分离沙枣仁中的蛋白质,并用半微量定氮法对蛋白质中的氨基酸组分进行分析。[结果]新疆野生沙枣仁的含油率为8.2%.以不饱和脂肪酸为主要成分,其中以亚油酸含量最高,为46.52%,其次为油酸,亚麻酸和硬脂酸。沙枣仁中粗蛋白平均含量为11.31%。其中以球蛋白和清蛋白为主,占蛋白质总量的70%以上,而残渣蛋白、醇溶蛋白、谷蛋白含量比较低。沙枣仁蛋白质中含有18种氨基酸,其中天冬氨酸含量最高,为12.7%,其次为谷氨酸,占11.8%,酪氨酸为9.33%,亮氨酸为8.11%,赖氨酸为7.22%,精氨酸、丝氨酸、丙氨酸、缬氨酸含量次之,组氮酸、蛋氨酸和胱氨酸含量最少。其中人体必需氨基酸含量达28.76%。[结论]新疆野生沙枣仁营养丰富,具有广阔的应用前景。 相似文献
346.
The tensile properties of air-entangled textured polyester single and multiple yarn ends before and after weaving were analyzed.
The effects of weaving process considering fabric unit cell interlacement and number of yarn ends were evaluated by regression
model. For this purpose, plain, ribs and satin woven fabrics were produced. The yarns were raveled from fabrics, and the tensile
tests were applied to these yarns. The developed regression model showed that the number of interlacement and crimp ratio
on the warp and weft yarns influence their tensile strength. Tensile strength of raveled yarns decreased compared to that
of the bobbin yarn due to the effect of weaving process. This property degradation on the ravel yarns considered process degradation.
Generally, when the number of warp and weft yarn ends increases, the warp and weft yarn tensile strengths for each fabric
type decrease, whereas the warp and weft yarn tensile elongations slightly increase. The results from regression model were
compared with the measured values. This study confirmed that the method in the study can be a viable and reliable tool. The
research finding could be useful those who work on preform fabrication. 相似文献
347.
348.
349.
Osman Kadir Topuz Nalan Gökoğlu Pınar Yerlikaya İlknur Uçak 《Journal Of Aquatic Food Product Technology》2013,22(6):905-915
ABSTRACTThis study describes the potential use of olive oil-lemon juice emulsions containing different levels of lemon juice (0, 25, 35, and 50% v/v) as a flavoring, preservative, and antioxidant agent in marinated anchovy. The phenolic content and antioxidant activity of lemon juice, olive oil, and olive oil-lemon juice sauces as well as chemical, oxidative, and sensorial changes of marinade samples were analyzed. Increasing the level of lemon juice in sauces retarded the chemical and oxidative changes of marinated anchovy. However, increasing the level of lemon juice more than 35% in sauces led to a decrease in sensorial acceptability. Chemical and oxidative qualities of all the sauced samples were in the limit of deterioration during 100 days of storage. Although marinated anchovy samples treated with sauce containing 50% lemon juice had a significant inhibitor effect on chemical and oxidative deterioration, samples treated with sauce containing 35% lemon juice received the highest overall acceptability score. 相似文献
350.
过氧化氢改性苹果渣膳食纤维的研究 总被引:1,自引:1,他引:0
【目的】研究过氧化氢对苹果渣膳食纤维的改性作用,为提高苹果渣可溶性膳食纤维含量、改善苹果渣理化性质提供一种简单高效、成本低廉的方法。【方法】采用不同pH和浓度的过氧化氢溶液处理果汁厂苹果渣,经醇沉、干燥、粉碎后,制得过氧化氢改性苹果渣。研究pH及过氧化氢浓度对改性苹果渣得率、膳食纤维组成及含量、物理性质及结构特性的影响。其中,膳食纤维组成及含量包括总膳食纤维(Total dietary fibre, TDF)含量、不可溶性膳食纤维(Insoluble dietary fibre, IDF)含量、可溶性膳食纤维(Soluble dietary fibre, SDF)含量,物理性质包括改性苹果渣持水力、膨胀力、持油力、堆积密度、颜色,结构特性包括改性苹果渣热稳定性、超微结构,并检测改性苹果渣中过氧化氢残留量。【结果】(1)过氧化氢溶液的pH对苹果渣理化结构性质具有显著影响。过氧化氢溶液浓度相同时,经酸性(pH 3.8)、中性(pH 7)过氧化氢处理的苹果渣,TDF含量、持水力、膨胀力、持油力均有不同程度的提高,而SDF含量、堆积密度较原果渣无显著变化,颜色变暗。经碱性(pH 11.5)过氧化氢处理的苹果渣,SDF含量显著提高,持水力、膨胀力、颜色等理化性质均得到极大改善,堆积密度增加,TDF含量较未处理苹果渣有所提高。热重及超微分析结果表明,酸性、中性过氧化氢处理后苹果渣热稳定性及超微结构与原果渣相比无明显差异,碱性过氧化氢处理后苹果渣热稳定性下降,超微结构变得紧密平滑。(2)过氧化氢溶液浓度对苹果渣理化结构性质也具有显著性影响。在pH为11.5的碱性条件下,使用不含过氧化氢的溶液处理后,苹果渣理化结构性质与经酸性、中性过氧化氢处理的苹果渣相似。随着过氧化氢浓度逐渐升高,苹果渣SDF含量逐渐增加,SDF含量由3.30%增加到19.02%-28.32%,提高476%-758%,膨胀力、颜色逐渐改善,堆积密度增加,持水力先上升后下降,苹果渣得率、TDF、IDF含量逐渐下降,持油力未得到改善。此外,随着过氧化氢浓度升高,苹果渣结构性质也发生变化,苹果渣热稳定性逐渐降低,结构变得更加松碎。(3)过氧化氢残留量检测结果表明,过氧化氢在处理过程中可完全分解除去,改性苹果渣中无残留。【结论】碱性过氧化氢处理可作为一种清洁高效的提高苹果渣SDF含量并改善苹果渣理化性质的改性方法,改性效果与过氧化氢pH及浓度密切相关。 相似文献