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A rapid micro‐analytical multiresidue method was developed for analysis of pyrethroids (kadethrin K, cypermethrin C and permethrin P) in soil micro‐sample (200 mg). It uses on‐line flow‐through extraction of soil micro‐samples (packed into a short glass column) with a methanol‐aqueous citric acid buffer mixture, successive on‐line SPE preconcentration of analytes from the extract and on‐line RP‐HPLC analysis with UV photometric detection. The separation of pyrethroids is performed on a Purospher RP‐18e column with methanol/water as mobile phase. Effects of sorbent placed at the bottom of a short column holding the soil sample and different kinds of on‐line SPE columns were tested. Besides, the influence of volume of the effluent on the pyrethroids recovery was also studied. Calibration curves were linear over the range assayed from 0.01 to 0.2 μg/mL with correlation coefficients of linear regression (least‐squares method) in the range 0.998–0.999. Recovery studies were carried out at 0.25–1.00 μg/g dry soil fortification level and obtained recoveries were for K 81–84%, C 56–59% and for P 58–63%. Achieved LOD (confidence band) of studied pyrethroids were for large‐volume injection (1 mL) 4.5 ng K, 3.7 ng C, 3.6 ng P or 27 ng/g K, 32 ng/g C and 29 ng/g P in dry soil “solid sampling HPLC”. 相似文献
104.
为提高结构的鲁棒性,针对传统矩形钢管柱隔板贯通式栓焊连接构造,提出了一种加固型栓焊盖板连接构造及其设计方法,并进行了数值模拟分析,该分析考虑了断裂模拟及裂后路径跟踪.结果表明,加固型栓焊盖板连接构造能够提高下翼缘连接区域传力失效前梁柱子结构的竖向变形能力,并充分发挥梁内轴向拉力产生的悬链线效应,进而使梁柱子结构提供更大的竖向承载力,可用于提高结构抗连续倒塌能力的加固改造. 相似文献
105.
采用定向钻机进行管道穿越大型河流的工程地质问题 总被引:1,自引:0,他引:1
霍计明 《科技情报开发与经济》2005,15(1):149-150,154
分析了影响定向钻穿越大型河流施工的因素,指出工程地质条件在穿越设计和制定施工方案时具有决定性作用,系统地进行工程地质勘察是非常必要的。并针对这类特殊工程,提出了勘察工作的具体内容和方法。 相似文献
106.
Tatsuro Matsumoto Tamio Nishida 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2004,80(5):225
Based on the stratigraphically well sorted material from Japan and southern Sakhalin, the ammonoid species belonging to the genus Desmoceras are classified as follows in ascending order: D. latidorsatum (Michelin) (Middle to mid-Upper Albian), D. dawsoni shikokuense (Yabe and Shimizu) (Upper Albian), D. kossmati Matsumoto (uppermost Albian–Lower Cenomanian), D. japonicum Yabe (uppermost Albian–Cenomanian), and D. ezoanum Matsumoto (mid-Upper Cenomanian–mid-Lower Turonian). D. japonicum can be subdivided into the earlier and later subspecies. D. poronaicum Yabe is a junior synonym of D. japonicum. Despite the scarcely ornamented shell, each taxon can be defined by its own characters. 相似文献
107.
Palynological studies on the Vitab?ck Clay help resolve the position of the Jurassic-Cretaceous boundary in southern Sweden. Well-preserved assemblages of terrestrial pollen and spores, together with abundant algae (Botryococcus), and for the first time, dinoflagellates have been identified in the Vitab?ck Clay. A Berriasian age is corroborated for the Vitab?ck Clay based on the palynological data; the Jurassic-Cretaceous boundary being placed around the contact of this unit with the underlying “Nytorp Sand”. The terrestrial vegetation was dominated by coniferous forest with an understorey of ferns in a warm, temperate climate. The palynoflora shows compositional similarities to the Northern Chinese Floral Province and especially the Jehol Group. The majority of the Vitab?ck Clay represents a moderate-to low-energy paralic succession. However, the basal part of the unit incorporates anomalously coarse material of mixed terrestrial and marine origin. This sedimentary package is herein interpreted to represent tsunami deposits and is similar to coeval tsunami-related deposits in France. 相似文献
108.
许令誉 《温州大学学报(自然科学版)》2005,26(5):19-25
用比较法并采用“温故知新”的形式对向量代数和空间解析几何进行教学,使学生学得更加轻松. 相似文献
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110.
本文通过宽板拉伸试验,根据全面屈服准则和COD参量直接研完和评定了焊接构件中的表面裂纹。指出依据COD概念不能合理地评定和保证具有表面裂纹构件的安全性,而全面屈服准则是评定构件表面缺陷的有力工具。因为他不但保证构件具有不低于屈服限的强度,而且还具有良好的塑性。本文同时还详细地讨论了低温对表面裂纹极限尺寸的影响, 相似文献