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861.
862.
综述了第五方物流及其相关技术发展,研究基于第五方物流的GIMIS中间件,提出基于第五方物流的GIMIS对讲调度运营平台.  相似文献   
863.
Tumor ablation by nanosecond pulsed electric fields (nsPEF) is an emerging therapeutic modality. We compared nsPEF cytotoxicity for human cell lines of cancerous (IMR-32, Hep G2, HT-1080, and HPAF-II) and non-cancerous origin (BJ and MRC-5) under strictly controlled and identical conditions. Adherent cells were uniformly treated by 300-ns PEF (0–2000 pulses, 1.8 kV/cm, 50 Hz) on indium tin oxide-covered glass coverslips, using the same media and serum. Cell survival plotted against the number of pulses displayed three distinct regions (initial resistivity, logarithmic survival decline, and residual resistivity) for all tested cell types, but with differences in LD50 spanning as much as nearly 80-fold. The non-cancerous cells were less sensitive than IMR-32 neuroblastoma cells but more vulnerable than the other cancers tested. The cytotoxic efficiency showed no apparent correlation with cell or nuclear size, cell morphology, metabolism level, or the extent of membrane disruption by nsPEF. Increasing pulse duration to 9 µs (0.75 kV/cm, 5 Hz) produced a different selectivity pattern, suggesting that manipulation of PEF parameters can, at least for certain cancers, overcome their resistance to nsPEF ablation. Identifying mechanisms and cell markers of differential nsPEF susceptibility will critically contribute to the proper choice and outcome of nsPEF ablation therapies.  相似文献   
864.
Aquaporins are implicated in a wide variety of plant physiological processes, although the mechanisms involved in their regulation are not fully understood. To gain further insight into the regulatory factors involved in this process, we used a yeast two-hybrid system to screen for potential binding partners to the Arabidopsis tonoplast intrinsic protein (TIP) AtTIP1;1. This was the first protein identified to be associated with high water permeability in vacuolar membranes from Arabidopsis thaliana. Using ...  相似文献   
865.
本文通过计算模拟和实验研究,用三维APV(AdaptivePhase/DopplerVelocimeter)系统对雾场中大粒子的特性参数进行了测量,对三维APV的光路系统进行了选择设定。  相似文献   
866.
α类蛋白的构建模式及拓扑结构预测   总被引:1,自引:1,他引:0  
给出了α类蛋白的构建规则,指出了螺旋片段的长短是决定相邻两个片段取向的重要原因.讨论了4螺旋束的构建及理论模式,对α类蛋白的分类进行了补充,给出了区分平行和垂直拓扑结构的简明预测规则  相似文献   
867.
Two letters from William Burnside have recently been found in the Nachlass of Robert Fricke that contain instances of the Burnside Problem prior to its first publication. We present these letters as a whole to the public for the first time. We draw a picture of these two mathematicians and describe their activities leading to their correspondence. We thus gain an insight into their respective motivations, reactions, and attitudes, which may sharpen the current understanding of professional and social interactions of the mathematical community at the turn of the twentieth century. Dedicated to Heiko Harborth on the occasion of his seventieth birthday.  相似文献   
868.
利用数学问题的通用软件包Mathematica,设计出一组新颖的数值模拟实验,可以有效地帮助学生通过自己探索来了解和掌握振动过程的规律,促进学生创新精神和实际能力的培养。  相似文献   
869.
Human ζ-crystallin is a Zn2+-lacking medium-chain dehydrogenase/reductase (MDR) included in the quinone oxidoreductase (QOR) family because of its activity with quinones. In the present work a novel enzymatic activity was characterized: the double bond α,β-hydrogenation of medium-chain 2-alkenals and 3-alkenones. The enzyme is especially active with lipid peroxidation products such as 4-hydroxyhexenal, and a role in their detoxification is discussed. This specificity is novel in the QOR family, and it is similar to that described in the distantly related alkenal/one reductase family. Moreover, we report the X-ray structure of ζ-crystallin, which represents the first structure solved for a tetrameric Zn2+-lacking MDR, and which allowed the identification of the active-site lining residues. Docking simulations suggest a role for Tyr53 and Tyr59 in catalysis. The kinetics of Tyr53Phe and Tyr59Phe mutants support the implication of Tyr53 in binding/catalysis of alkenal/one substrates, while Tyr59 is involved in the recognition of 4-OH-alkenals.  相似文献   
870.
The effects of Cl-concentration,temperature,pH,flow velocity,soluble oxygen content of seawater and anodic current on the potential of high purity zinc and Zn-Al-Cd reference electrodes were investigated. The results show that the investigated metal materials are liable to establish stable potential and act as reference electrodes in seawater,diluted seawater and urban tap water. Cl-concentration,temperature,seawater flow velocity and anodic current have an obvious effect on zinc potentials. However,seawate...  相似文献   
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