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1.
采用制备型升温淋洗分级方法,对流化床聚合反应器在持液操作模式和冷凝态操作模式下生产的A、B两种乙烯/1-丁烯/1-己烯三元共聚物进行了分级,并结合多种分析手段对样品及其各级份进行了结构表征,同时测试对比了A、B两种聚乙烯样品的力学性能.结果表明,与冷凝态操作模式生产的聚乙烯样品B相比,持液操作模式下生产的聚乙烯样品A的拉伸屈服强度、拉伸断裂强度、断裂伸长率、冲击强度和雾度都比样品B优异.样品A的低温淋洗级份相对含量低于样品B,而其高温淋洗级份相对含量高于样品B;样品A低温淋洗级份的分子量略低于样品B,而其高温淋洗级份的分子量高于样品B;样品A的薄片晶含量和厚片晶含量都比样品B多,同时样品A的片晶厚度分布比样品B宽;样品A的总支化度以及每个级份的支化度都比样品B高,且样品A的支链在分子链间的分布比样品B宽,即样品A的支链比样品B的支链更倾向于生长在高分子量部分.通过以上表征分析,发现持液操作模式下生产的样品A比冷凝态操作模式下生产的样品B的物理使用性能更加优异,适合制备高性能的拉伸缠绕膜.  相似文献   

2.
复杂样品近红外光谱定量分析模型的构建方法   总被引:3,自引:0,他引:3  
针对复杂样品近红外光谱分析中校正集的设计问题, 探讨了标准样品参与复杂样品建模的可行性. 通过标准样品和复杂基质样品共同构建的偏最小二乘(PLS)模型, 考察了波段筛选和建模参数对预测结果的影响. 结果表明, 采用PLS方法建立定量模型时, 校正集样品性质应该尽量与预测集样品相似, 当样品的性质相差较大时, 适当增加校正集样品的差异性可使模型具有更强的预测能力. 同时, 波段优选对提高预测结果的准确性具有重要的意义.  相似文献   

3.
从煤质材料、生产制备工艺方面介绍了影响煤、焦炭标准样品物理化学特性稳定性的因素,以实际煤、焦炭国家标准样品为例,考察了煤、焦炭标准样品物理化学特性值的稳定性,介绍了煤、焦炭标准样品稳定性评价的方法.根据稳定性考察结果,提出了保证煤、焦炭标准样品物理化学特性稳定性的措施.  相似文献   

4.
传统的离子色谱主要应用于水溶液中的阴、阳离子和极性化合物。随着离子色谱应用范围的扩大,通过合适的样品制备,将非水溶液的样品转化为水溶液,包括有机溶剂、固体样品和气态样品,特别是随着我们对大气环境、气体纯度以及呼出气体中气态样品的组成等方面的重视,越来越多的气体和气态样品,特别是离子态和极性化合物,可通过合适的样品制备、采集转化为水溶液,通过离子色谱技术进行分析。综述了气体组分的离子色谱检测技术,总结了气体样品、气溶胶以及液态样品中气体物质的制备和采集方法,运用离子色谱技术对上述样品进行测定,并对该技术运用过程中存在的问题及发展前景进行了展望。  相似文献   

5.
正确使用标准物质/标准样品   总被引:2,自引:0,他引:2  
介绍了标准物质与标准样品、有证与非有证标准物质/标准样品的区别与联系,国內外有证标准物质/标准样品的判断依据,标准物质/标准样品及其证书的科学使用。对正确理解和使用标准物质/标准样品提出了一些建议。  相似文献   

6.
研制了钛矿石与钛精矿X射线荧光光谱分析与化学分析用标准样品。从国内外有代表性的矿区取点,采用了多级破碎、三维机械混筛工艺,确保了标准样品化学成分的均匀性,多家权威实验室用准确可靠的分析方法确定了16种化学成分的标准值和不确定度,实验表明,标准样品的线性与稳定性良好。该项目标准样品填补了国内外同类X射线荧光光谱分析标准样品的空白,已被国家检验检疫总局和国家标准化管理委员会批准为国家级标准样品。  相似文献   

7.
掺锰氢氧化镍的结构与电化学性能   总被引:5,自引:0,他引:5  
采用化学共沉淀法制备了锰取代的氢氧化镍样品,应用XRD技术对不同锰含量样品的相结构进行了表征,并用恒电流充放电、电流脉冲弛豫法和电化学阻抗技术研究了样品的电化学行为. XRD结果显示:锰含量少于20%时,样品主要由β相组成;而当锰含量达到28.3%时,可以得到具有纯α相结构的样品. 电化学研究结果表明:掺锰的氢氧化镍样品具有优良的电化学循环稳定性;锰的掺杂提高了氢氧化镍电极的析氧电位,增大了样品的质子扩散系数; 具有较低锰含量的氢氧化镍样品显示了较大的放电容量和较高的放电电位.  相似文献   

8.
为了进一步了解不锈钢钝化膜与过钝化膜的性质,本文对比研究了在不同电位下极化处理后304不锈钢样品的点蚀及表面膜性质,发现空白对照组样品的点蚀电位和1.1 V过钝化处理后样品的点蚀电位相近,而0.5 V钝化处理后样品的点蚀电位较高. 扫描Kelvin探针(SKP)实验结果也验证了这一现象. 扫描电子显微镜(SEM)结果显示,空白对照组样品表面只呈现一般样品抛光后形貌;0.5 V钝化处理后的样品表面被颗粒状钝化膜所覆盖,该膜层决定了样品具有较好的耐蚀性;而1.1 V过钝化处理后的样品表面出现裂缝,导致不锈钢基体继续发生严重的局部腐蚀,可能成为过钝化膜保护性变差的主要原因.  相似文献   

9.
涡流色谱技术在生物样品分析中的应用   总被引:1,自引:0,他引:1  
刘朋  周建良  安婧婧  李萍 《色谱》2010,28(2):168-174
生物样品的复杂性使其在进行分析测定前必须经过处理。传统的样品前处理方法(如液-液萃取、固相萃取等)耗时长且操作繁琐。涡流色谱作为在线萃取技术,可以实现生物样品直接进样,减少了样品处理步骤,有效富集纯化了分析物,是一种高通量、高选择性的生物样品前处理方法。为此,本文介绍了涡流色谱技术的原理及优势,并总结了不同涡流柱的特点及其在生物样品分析领域中的应用情况。  相似文献   

10.
采用六面顶压机制备了尼龙1010(PA1010)/单壁碳纳米管(SWNT)复合材料在350℃、不同压力下处理30min后的高压结晶样品,通过DSC、TGA、SEM、TEM等手段研究了高压结晶样品的结晶行为、热稳定性以及形貌特征。研究结果表明,在实验研究范围内2.0GPa下获得的高压结晶样品的熔点和结晶度最高,分别达到208.5℃和64.6%。SEM结果表明,与常压结晶样品相比高压结晶样品内部显示出更加致密的质地结构。此外,在样品断面还观察到了规则块状晶体的生成。TGA结果显示高压结晶样品的热稳定性显著高于纯PA1010。密度测试结果显示,高压结晶样品的密度几乎均高于纯PA1010,而且高压熔体结晶样品的密度随着压力的升高而增大。  相似文献   

11.
综述了壳聚糖、甲壳素在污水处理、电化学、原子吸收光谱、高效液相色谱、吸光光度法中的应用。引用文献28篇。  相似文献   

12.
用原子吸收光谱法测定延边地区317名65~108岁老人头发中锌、铜、铁、锰、镁含量,观察不同民族、性别、年龄老人这些元素的差异。结果表明:1.朝鲜旗发锌低于汉族,满族发铜低于汉族、朝鲜族,汉族发镁高于朝鲜族、满族,发铁、发锰在汉、朝、满民族之间无区别。2.汉族、朝鲜族男发锌高于女性,汉族女性发铜高于男性,发铁、发锰、发镁在性别之间无区别。3、90岁组朝鲜族发锰、发镁低于65岁、76岁组,朝鲜族发锌、发铜、发铁在65~108岁之间无统计学意义。  相似文献   

13.
为研究Graves病(GD)患者经^131I治疗后血浆和红细胞锌(Zn)含量的变化及其临床意义,采用原子吸收分光光谱法(AAS)和放射免疫分析法(Rn)分别检测了40例GD患者、20例经^131I治疗后甲状腺功能恢复至正常水平GD患者与30名健康人血浆和红细胞Zn的含量以及血浆甲状腺激素水平。结果表明,GD组红细胞Zn含量明显低于对照组(P<0.01);血浆Zn含量虽略低于对照组,但无统计学意义(P<0.05);且Zn与FT4呈明显负相关(P<0.01)、与TSH呈正相关(P<0.05)。GD治疗缓解组红细胞Zn明显高于治疗前(P<0.01),血浆Zn明显低于治疗前(P<0.05);红细胞Zn检测GD的敏感性与特异性分别为95.0%与96.7%。提示GD患者存在红细胞Zn含量改变,甲状腺激素可能干扰红细胞Zn的代谢,同时测定红细胞Zn可作为GD的临床诊断、治疗以及疾病转归的参考指标。  相似文献   

14.
Calibration methods for microdialysis sampling were studied in the muscle and adipose tissue of rats. Both the delivery method and the no-net-flux method were used to determine the extraction efficiency (EE) of acetaminophen and caffeine in both tissues. There was no concentration dependence of the EE either in vitro or in vivo for either acetaminophen or caffeine. The EEs determined by the delivery and no-net-flux methods were not different. However, the EEs of both caffeine and acetaminophen determined in vitro were significantly higher than those determined in the muscle and adipose. This indicates that mass transfer in the tissue is the rate-determining factor for the EE in vivo. The relative difference between the EE in vitro and the EE in the muscle was smaller than the difference between the EE in vitro and the EE in the adipose. In addition, the EE in the muscle decreased more than the EE in the adipose after the animal was euthanized. This indicated that exchange between the extracellular fluid and plasma is the rate-determining step in mass transport relative to microdialysis sampling. This has a more significant effect on the EE in the muscle than the EE in the adipose. Both the delivery and no-net-flux methods can be used to calibrate microdialysis probes in the muscle and adipose.  相似文献   

15.
The accelerated growth of aquaculture has resulted in a series of harmful effects to human health. The widespread and unrestricted use of antibiotics in this industry, to prevent bacterial infections, leads to remaining amounts in the aquatic environment. This has resulted in the emergence of antibiotic-resistant bacteria in aquaculture environments, in the increase in antibiotic resistance in fish pathogens as well as in the transfer of these resistance determinants to human pathogens. Moreover, the use of large amounts of antibiotics may lead to the presence of residual antibiotics in fish tissue and fish products. Fluoroquinolones, tetracyclines, penicillins, sulphonamides and other antibiotics, exhibiting activity against both Gram-positive and Gram-negative bacteria, are widely used for the treatment and prevention of diseases in fish. An extended and comprehensive review on the recent analytical methodologies concerning antibiotic residues in fish reported in the literature is provided in the present article. Emphasis is given on sample preparation regarding isolation and purification, chromatographic conditions and method validation according to legislation. Results of published assays are comparatively presented and criticised.  相似文献   

16.
采集了贵族个煤烘玉米为主要介质和河北2个饮水为介质氟病区内骨畸形病人的全血、尿、检测了其中8种元素含量,结果表明,贵州各氟病区少儿骨软化与成年骨硬化畸形病人的全血铝、钙、磷、铁和尿氟、铝均显著高于同龄对照组,尿磷均低于同龄对照组。少儿骨软化病人全血锌均下降,尿锌多下降。某水型氟病区骨软化经产妇尿氟、全血铜升高;骨软化少年全血铝显著升高,锌、铁下降,尿氟升高,尿锌,磷下降。海边的典型氟骨症病人全血、  相似文献   

17.
Abstract

The accumulation, persistence and fate of systemic pesticide aldicarb was melencholy evaluated in orange crops. The concentration of this pesticide and its two toxic metabolites, aldicarb sulfoxide and aldicarb sulfone was determined in leaves, rind and pulp of three orange varieties (Satsuma, Navelina and Clemetina de Nules) and in the top soil of the orange groves. The groves were located in two different places in the Valencia Community (Spain). The analysis showed that the aldicarb concentration was lower than those of aldicarb sulfoxide and aldicarb sulfone. In all cases, the residues persisted at least 160 days in vegetable samples and between 157 and 227 days in soil samples. Residue concentrations measured in the soil samples were highly variable but a relation with the organic matter content can be observed. The residue levels found in vegetal products were higher in leaves than in rind, and in rind than in pulp. The maximum residue values were obtained between 47 and 70 days after the application. One hundred days after treatment (Security period) the residue levels of total fruit were lower than the maximum residue level of 0.2 mg/kg established by law.  相似文献   

18.
Worldwide, yellows diseases impact plants important in human nutrition, the natural environment, and the culture and commerce of humans. Since the presumed pathogens, mycoplasma-like organisms (MLOs), have not been isolated in pure culture in vitro, their study must proceed by other experimental approaches. In a study of disease affecting grapevines in Europe and North America, polymerase chain reactions (PCR) and restriction analyses of PCR-amplified DNA were used to detect and differentiate strains of MLOs associated with grapevine yellows. MLOs were detected both in naturally diseased grapevines and in experimentally inoculated host plants. The data indicated an unexpected genomic diversity among grapevine-infecting MLOs, and supported their classification with MLOs in the aster yellows, X-disease, and elm yellows groups. The presence of diverse MLOs in grapevines provokes consideration that these MLOs may be present in overlapping geographic ranges and that multiple MLO infections may occur in individual plants, increasing the complexity of grapevine yellows epidemiology and control and the significance of sensitive MLO detection in planting stock and phytosanitary-regulated germplasm.  相似文献   

19.
Methods of stripping voltammetry, quartz microgravimetry, and x-ray-fluorescence analysis are employed to explore the copper displacement process on thin electrodeposited layers of pure cobalt and nickel and on deposits of these metals with inclusions of copper. The displacement reaction proceeds at a considerable rate on cobalt in the sulfate and sulfosalicylate solutions and virtually does not proceed on nickel in both the sulfate or sulfate-chloride solutions. An estimate of the rate of the copper displacement reaction following a change in the concentration of copper ions in the solution and in the pH of the sulfosalicylate solution is given. A decrease in the contact exchange rate is facilitated by a decrease in the concentration of copper ions in solution and their participation in the formation of complexes.  相似文献   

20.
The conductance of aqueous solutions of sodium glycodeoxycholate and sodium taurodeoxycholate displays a complex concentration dependence (0–0.5 C) with a maximum and minimum occurring in dilute solutions. This behavior can be related to physiologic concentrations observed in hepatic and gallbladder bile and interpreted in terms of anion dimerization and ultimately micellization. The addition of lecithin in 1:2 or 1:5 molar ratios results in micellization at lower concentration, disappearance of the maximum and minimum in the conductance curve, and a decrease in the total conductance.  相似文献   

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