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Irradiation caused DNA single-strand breaks in S180 cells in the presence oflaser-hematoporphyrin derivative(HPD).The number of single strand breaks was 3.69 ×10~(10)break dolton~(-1).The analysis of base composition of DNA showed that the effect of laser-HPDirradiation on guanine was the highest,being 5-12 times as high as those of the three others(adenine,cytosine and thymine).It was different from the nature of DNA damage caused by γ-ray irradiation. 相似文献
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本文介绍了聚砜类共聚物的合成方法和表征手段。报道了这类材料的结构和性能。指出了由硬的无定型热塑性链段和结晶链段共聚得到的新材料的优异功能,结晶链段的存在提高了材料的耐溶剂性能和耐应力开裂性。嵌段共聚物(AB或A-B-A)可作为下相容聚合物之间或溶剂之间的相容剂。 相似文献
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Xiang-wen Chen Hui-zhen Li Gui-qing Li Ling Qin Zhi-fang Zhang 《International Journal of Infrared and Millimeter Waves》1994,15(9):1555-1566
This paper presents a theoretical method for design quasi-optics power combiner of solid-state millimeter — wave sources, and gives theory analysis to some problem concerned. Here is the structure:
相似文献
1. | Epitome of microwave power combiner. |
2. | Gauss light beam and the field distribution in the resonator. |
3. | The design of the resonator |
(1) | Confocal resonator |
(2) | Objective function |
(3) | The global optimization method and the program flow chart. |
4. | Example |
5. | Reference |
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Precolumn back‐flushing is a matrix minimization technique in GC in which the carrier gas flow of the precolumn is reversed after the transfer of the highest boiling analyte to the analytical column. Practical details concerning this technology have rarely been published although it is widely used. This paper now focuses on the practical implementation of precolumn back‐flushing for pesticide residue analysis of complex food matrices. Fitting the analytical column into the precolumn was found to be essential for comparable analyte responses with and without back‐flushing. The effectiveness of the reverse column flow technique is mainly affected by the transfer time after which back‐flushing starts. The transfer time was found to depend on which kind of injected matrix is used and the state of the precolumn. For the regular adaptation of the transfer time in routine analysis, a simple test was introduced in which 13‐C‐labeled deltamethrin and indeno[1,2,3‐c,d]pyrene were added to the prepared extract. Chromatograms, LOQ and RSD of up to 99 pesticides in citrus oil and liver extracts proved a clearer identification and enhanced quantification using precolumn back‐flushing compared to measurements without this technology. Furthermore, reduced system maintenance could be achieved through back‐flushing. 相似文献
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利用多相位片实现光束整形 总被引:2,自引:0,他引:2
光束整形是许多应用所必须的,偿试利用二元光学的方法选择合适数的相位片对光束进行整形,并就高斯光束均匀化为例进行了数值计算。 相似文献
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