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该文采用吡啶—巴比妥酸分光光度法对水样中的总氰化物进行测定,探讨了氰化物测定的各预处理体系,选用了9种预处理体系分别对八种金属氰络合物进行了实验研究,并使金属氰络合物与游离氰含量比为1:1的条件下考察其游离情况.实验表明,除3种预处理体系外,其它预处理体系均获得了满意的结果. 相似文献
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基于MIME邮件结构的邮件内容提取技术的研究 总被引：2，自引：0，他引：2
为准确提取电子邮件的内容,对邮件的组成结构进行详尽的分析,归纳出邮件正文特征,并设计出一个基于MIME邮件结构的邮件预处理系统。该系统采用分块处理和特征识别的方法,克服电子邮件不规范的缺点,并对邮件正文中的回复行和广告行进行过滤,从而实现对邮件内容快速准确提取。 相似文献
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INTRODUCTION ZSM-5 zeolite is a typical high silica zeolitewith MFI-type structure which makes ZSM-5 zeo-lite widely useful as catalysts in petroleum andpetrochemical industry. In recent years, the appli-cation of ZSM-5 is expanding into the synthesisfields of specialty and fine chemicals (Davis, 1998),such as the preparation of ethylene amines. The ex-cellent catalytic performance of ZSM-5 was noted(Hua and Hu, 2001). In most cases, the synthesis of ZSM-5 is ach-ieved… 相似文献
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CALIS联合目录西文数据预处理及机读目录问题探讨 总被引：5，自引：0，他引：5
通过列举实例,分析了在CALIS联合目录数据库建设中各成员馆提交的数据在MARC格式、书目著录以及系统数据转换中存在的一些问题,提出了解决办法,指出机读目录数据的规范化和标准化是联合目录质量的基本保证。 相似文献
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ZSM-5 zeolite was rapidly synthesized in system containing ethylenediamine from the initial gel: (5(8) Na2O: 44 EDA:Al2O3:100 SiO2:4000 H2O. The crystals were lath-shaped. The effect of pretreatment and alkalinity on crystallinity was investigated. The pretreatment of silicate source can cut down the crystallization time. Tuning the system alkalinity and controlling crystallization time can ensure forming of pure crystal. 相似文献
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目的:阐明油茶皂苷(SQS)所产生心肌保护作用与AE3蛋白的基因表达关系,方法:采用RNA i技术,在心肌细胞水平上建立AE3蛋白低表达、同时建立缺氧/复氧损伤(A/R)模型及SQS预适应模型;通过测定,心肌细胞的博动频律、细胞生存率以及细胞培养液中LDH的变化;同时检测心肌细胞中AE3 mRNA、AE3蛋白的表达变化,结果:SQS预处理能明显提高A/R损伤后细胞存活率,减少LDH的漏出,AE3 mRNA、AE3蛋白表达明显上调,与A/R组相比均有显著性差异(均p<0.01);结论:在心肌细胞中转导入三段有AE3基因序列特异性的dsRNA后,可引起AE3 mRNA及蛋白低表达,同时取消SQS预处理的心肌保护作用.为其进一步的新药开发提供理论与实验依据. 相似文献
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建立了HPLC检测土壤中辛硫磷的前处理方法,考察了提取溶剂种类,提取时间和溶剂用量.最佳实验条件为：用60mL乙酸乙酯作萃取溶剂,振荡提取50 min,经旋转蒸发仪浓缩,甲醇定容至5mL,过滤.滤液于高效液相色谱仪-二极管阵列检测器检测,用C18色谱柱,进样量10uL,流动相为V（乙腈）：V（水）=7：3,检测波长为283nm.辛硫磷在0.6～30.00μg/mL之间有良好的线性关系,相关系数为0.9999,加标回收率达88.27％,精密度（n=6）为3.35％.该方法具有较高的灵敏度和准确性. 相似文献
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Response to temperature stress of reactive oxygen species scavenging enzymes in the cross-tolerance of barley seed germination 总被引：1，自引：0，他引：1
A number of studies have shown the existence of cross-tolerance in plants, but the physiological mechanism is poorly understood.
In this study, we used the germination of barley seeds as a system to investigate the cross-tolerance of low-temperature pretreatment
to high-temperature stress and the possible involvement of reactive oxygen species (ROS) scavenging enzymes in the cross-tolerance.
After pretreatment at 0 °C for different periods of time, barley seeds were germinated at 35 °C, and the content of malondialdehyde
(MDA) and the activities of ROS scavenging enzymes were measured by a spectrophotometer analysis. The results showed that
barley seed germinated very poorly at 35 °C, and this inhibitive effect could be overcome by pretreatment at 0 °C. The MDA
content varied, depending on the temperature at which seeds germinated, while barley seeds pretreated at 0 °C did not change
the MDA content. Compared with seeds germinated directly at 35 °C, the seeds pretreated first at 0 °C and then germinated
at 35 °C had markedly increased activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), and
glutathione reductase (GR). The SOD and APX activities of seeds germinated at 35 °C after 0 °C-pretreatment were even substantially
higher than those at 25 °C, and GR activity was similar to that at 25 °C, at which the highest germination performance of
barley seeds was achieved. These results indicate that low-temperature pretreatment can markedly increase the tolerance of
barley seed to high temperature during germination, this being related to the increase in ROS scavenging enzyme activity.
This may provide a new method for increasing seed germination under stress environments, and may be an excellent model system
for the study of cross-tolerance. 相似文献
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难浸金矿氧化预处理方法评述 总被引：2，自引：0，他引：2
介绍了难浸金矿用焙烧法,加压氧化法和细菌氧化法预处理的原理,工业实践及几种方法的技术经济比较。 相似文献
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研究了超声波悬浮液制样横向加热石墨炉原子吸收光谱法直接测定铅、镉的条件．该方法快速、简便、准确．铅线性范围为0～100ng·ml^-1,r=0．9997,检测限为2．8ng·g^-1;镉线性范围为0～10ng·ml^-1,r=0．9992,检测限为0．8ng·g^-1．该方法用于河泥样品分析,效果良好,Pb的回收率为91．5％～105．5％,Cd的回收率为91．2％～101．2％． 相似文献
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