共查询到20条相似文献,搜索用时 62 毫秒
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采用自动顶空气相色谱法分析饮用水中苯,并对气相色谱条件和顶空条件进行了优化,与国标GB/T5750.8-2006中规定的溶剂萃取方法进行了比较.方法在0.00~105.00μg/L范围内具有良好线性关系,相关系数大于0.999,最低检出限为0.004 2 mg/L,回收率在96.2%~98.7%之间,相对标准偏差为0.70%.实验结果表明,自动顶空气相色谱法更为简便、准确、灵敏、基体干扰少. 相似文献
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食品包装纸中有机污染物在纸和空气间的分配系数Kpaper/air是研究食品包装纸中有机污染物向食品迁移的一个重要的理化参数.本研究推导了顶空气相色谱法(HS-GC)测定包装纸中有机污染物的Kpaper/air的理论关系式.本方法不需要测定纸张中有机污染物的具体浓度,只需测定两份纸样的不同体积及峰面积即可计算出Kpaper/air值.进行了顶空气相色谱法精确度和准确度的计算分析和实验验证,证实了本方法的精确性和准确性.研究还表明,本测定方法中两份纸样的体积比x是一个重要参数.本方法可以快速、便捷、准确的测定包装纸中有机污染物在纸和空气间分配系数Kpaper/air. 相似文献
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顶空气相色谱法在生物医学上的应用 总被引:1,自引:0,他引:1
顶空气相色谱法(Headspace Gas Chroma-tography以下简称HSGC)早在一九七八年就由Hachenberg作过系统的总结。近年来,国内外又有一些文献介绍了这一技术。有关静态顶空和动态顶空技术的发展与应用、固体样品的动态顶空分析技术以及痕量有机物顶空分析的 相似文献
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顶空气相色谱标准加入法测定自来水中的一溴二氯甲烷和二溴一氯甲烷 总被引:3,自引:0,他引:3
用于测定水中三卤甲烷的方法主要有吹扫捕集热解吸法和液液萃取法,固相微萃取技术与顶空法相结合也被应用于测定水中的挥发性卤代烃。我国水和废水标准方法规定用静态顶空外标方法测定三卤甲烷。作者曾报道了改变相比/顶空色谱法测定水中氯仿及其分配常数的方法。本文主要研究顶空气相色谱标准加入法测定城市自来水中的一溴二氯甲烷和二溴一氯甲烷。与顶空气相色谱外标法比较,该法避免了水样基体及色谱条件对测定结果的影响。与顶空气相色谱内标法比较,该法不用另外选择内标物,操作方便。 相似文献
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We review our research on the synthesis and study of the physical and biological properties of furyl- and thienylgermatranes and -silatranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 725–732, June, 1992. 相似文献
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David W. Murhammer 《Applied biochemistry and biotechnology》1991,31(3):283-292
The use of the insect cell/baculovirus expression system for producing recombinant proteins of bacterial, plant, insect, and mammalian origin has become widespread. The popularity of this eukaryotic expression system is due to many factors, including (1) potentially high protein expression levels, (2) ease and speed of genetic engineering, (3) ability to accommodate large DNA inserts, (4) protein processing similar to higher eukaryotic cells (e.g., mammalian cells), and (5) ease of insect cell growth (e.g., suspension growth). The following review of the literature discusses two engineering aspects of recombinant protein synthesis by insect cell cultures: bioreactor scale-up and insect cell line selection. Following this review patent abstracts and additional literature pertaining to expression of recombinant proteins in insect cell culture are listed. 相似文献
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多环芳二酐型聚酯亚胺膜的透气性能李悦生,丁孟贤,徐纪平(浙江大学高分子科学与工程研究所,杭州,310027)(中国科学院长春应用化学研究所)关键词聚醚酰亚胺,聚酯酰亚胺,膜,透气性通常的聚酰亚胺加工性能较差,在芳环二酐的苯环间引入醚键等柔性基团后,其... 相似文献
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Karadakov PB 《The journal of physical chemistry. A》2008,112(31):7303-7309
The aromaticity and antiaromaticity of the ground state (S 0), lowest triplet state (T 1), and first singlet excited state (S 1) of benzene, and the ground states (S 0), lowest triplet states (T 1), and the first and second singlet excited states (S 1 and S 2) of square and rectangular cyclobutadiene are assessed using various magnetic criteria including nucleus-independent chemical shifts (NICS), proton shieldings, and magnetic susceptibilities calculated using complete-active-space self-consistent field (CASSCF) wave functions constructed from gauge-including atomic orbitals (GIAOs). These magnetic criteria strongly suggest that, in contrast to the well-known aromaticity of the S 0 state of benzene, the T 1 and S 1 states of this molecule are antiaromatic. In square cyclobutadiene, which is shown to be considerably more antiaromatic than rectangular cyclobutadiene, the magnetic properties of the T 1 and S 1 states allow these to be classified as aromatic. According to the computed magnetic criteria, the T 1 state of rectangular cyclobutadiene is still aromatic, but the S 1 state is antiaromatic, just as the S 2 state of square cyclobutadiene; the S 2 state of rectangular cyclobutadiene is nonaromatic. The results demonstrate that the well-known "triplet aromaticity" of cyclic conjugated hydrocarbons represents a particular case of a broader concept of excited-state aromaticity and antiaromaticity. It is shown that while electronic excitation may lead to increased nuclear shieldings in certain low-lying electronic states, in general its main effect can be expected to be nuclear deshielding, which can be substantial for heavier nuclei. 相似文献
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微量元素与疾病诊断治疗的研究现状及展望 总被引:8,自引:0,他引:8
对国内外微量元素与疾病的关系及其诊断治疗的研究现状及研究动向进行了综述,包括:微量元素与地方病、癌肿、心血管病、糖尿病、眼病、神经系统病等。参考文献72篇。 相似文献