排序方式: 共有29条查询结果,搜索用时 31 毫秒
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Synthetic erythropoietic proteins: tuning biological performance by site-specific polymer attachment
Chen SY Cressman S Mao F Shao H Low DW Beilan HS Cagle EN Carnevali M Gueriguian V Keogh PJ Porter H Stratton SM Wiedeke MC Savatski L Adamson JW Bozzini CE Kung A Kent SB Bradburne JA Kochendoerfer GG 《Chemistry & biology》2005,12(3):371-383
Chemical synthesis in combination with precision polymer modification allows the systematic exploration of the effect of protein properties, such as charge and hydrodynamic radius, on potency using defined, homogeneous conjugates. A series of polymer-modified synthetic erythropoiesis proteins were constructed that had a polypeptide chain similar to the amino acid sequence of human erythropoietin but differed significantly in the number and type of attached polymers. The analogs differed in charge from +5 to -26 at neutral pH and varied in molecular weight from 30 to 54 kDa. All were active in an in vitro cell proliferation assay. However, in vivo potency was found to be strongly dependent on overall charge and size. The trends observed in this study may serve as starting points for the construction of more potent synthetic EPO analogs in the future. 相似文献
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A comparison of undecafluorocyclohexane and dodecafluorocyclohexane shows that both exist at 23 degrees in face-centred cubic cells with edges a(0) = 10.00 +/- 0.02 A for C(6)HF(11) and a(0) = 10.11 +/- 0.02 A for C(6)F(12). The X-ray data are consistent with internal rotation of the molecules or statistical randomness of the molecules in the compounds. 相似文献
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怀菊花中微量铁的测定 总被引:5,自引:3,他引:2
为探讨邻二氮菲分光光度法测定怀菊花中微量元素铁含量的可行性,怀菊花的药理功效、食用营养价值与微量元素含量可能存在的关系,根据铁离子与特定显色剂显色产生可见吸收,采用混合酸y(HNO3):V(HClO4)=4+1对怀菊花样品湿法消化处理,在pH2~9的溶液中试剂与铁生成稳定的橙色络合物,并用分光光度法测定了怀菊花中微量元素铁含量。结果表明,所选的怀菊花中铁含量303.9~337.9μg/g,加标回收率为90.2%~100.6%。分光光度法操作简便、干扰离子少,测量快速、结果准确度和灵敏度高,易推广和 普及使用。 相似文献
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提出了强拟Armendariz环的概念,给出了强Armendariz环和强拟Armendariz环上的一些结果. 相似文献
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J. E. Bigelow E. B. Cagle J. B. Knauer 《Journal of Radioanalytical and Nuclear Chemistry》1988,123(2):471-489
The Transuranium Processing Plant (TPP) at the Oak Ridge National Laboratory (ORNL) has been requested by the Food and Drug Administration (FDA) to furnish 200 mg of252Cf for use in their new activation analysis facility. This paper discusses the procedure to be employed in fabricating the californium into four neutron sources, each containing a nominal 50-mg of252Cf. The completed neutron sources will be assayed using a precision fast-neutron counter, decontaminated and loaded into a concreete-shielded shipping container weighing 10.7 Mg for shipment to the FDA facility located at Howard University in Washington, D. C.Research sponsored by the Office of Basic Energy Sciences, U. S. Department of Energy, under contract DE-AC05-840R21400 with Martin Marietta Energy Systems, Inc. 相似文献
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丝瓜中维生素C含量的测定 总被引:1,自引:0,他引:1
为建立丝瓜中维生素C含量直接测定的新方法,以10%盐酸溶液为溶剂,采用紫外分光光度法测定其含量。结果表明,维生素C在0~10 mg/L质量浓度范围内与吸光度呈良好的线性关系,回归方程为:y=0.047 46ρ+0.001 09,r=0.999 7。检出限为0.023μg/mL,加标回收率在90.6%~99.0%之间。该法操作简单,结果准确,应用于维生素C含量的测定,结果准确,令人满意,可作为控制维生素C质量的方法。 相似文献