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31.
Heat-shock proteins are normal constituents of cells whose synthesis is increased on exposure to various forms of stress. They are interesting because of their ubiquity and high conservation during evolution. Two families of heat-shock proteins, hsp60s and hsp70s, have been implicated in accelerating protein folding and oligomerization and also in maintaining proteins in an unfolded state, thus facilitating membrane transport. The Escherichia coli hsp70 analogue, DnaK, and two other heat-shock proteins, DnaJ and GrpE, are required for cell viability at high temperatures and are involved in DNA replication of phage lambda and plasmids P1 and F. These three proteins are involved in replication in vitro of P1 DNA along with many host replication proteins and the P1 RepA initiator protein. RepA exists in a stable protein complex with DnaJ containing a dimer each of RepA and DnaJ. We report here that DnaK and DnaJ mediate an alteration in the P1 initiator protein, rendering it much more active for oriP1 DNA binding. 相似文献
32.
J. S. Frankel 《Cellular and molecular life sciences : CMLS》1982,38(6):673-674
Summary The tissue specificity of lactate dehydrogenase (EC 1.1.1.27) in brain and eye of the teleostPhallichthys amates was examined by acrylamide gel electrophoresis. It is suggested that subunit association is a function of gene product accessibility superimposed upon genetic restriction of assembly. 相似文献
33.
Summary Host cell reactivation capacity for ozone T3 phage was determined for differentE. coli strains deficient in one or more of the DNA repair mechanisms. The results indicate that DNA polymerase I appears to play a key role in the repair of damage produced on the DNA by ozone while thelexA gene product seems to play a minor one.This research was sponsored by the National Sciences and Engineering Council of Canada. One of us (PLH) acknowledges a scholarship from the NSERCof Canada. 相似文献
34.
We discuss a generalization of the standard notion of probability space and show that the emerging framework, to be called operational probability theory, can be considered as underlying quantal theories. The proposed framework makes special reference to the convex structure of states and to a family of observables which is wider than the familiar set of random variables: it appears as an alternative to the known algebraic approach to quantum probability. 相似文献
35.
A. E. Yassen H. A. Hassan L. S. Kawashti 《Cellular and molecular life sciences : CMLS》1994,50(11-12):1111-1114
A detailed karyotypic analysis of two Egyptian species of bats,Taphozous perforatus andTaphozous nudiventris, was made on the basis of conventional data and G-band patterns. No detectable karyotypic difference was found between the two species (2n=42, F.N. 64). By comparison of G-band patterns, some differences between the two species were seen in the corresponding autosomal pairs. These results are reported for the first time in Egypt. 相似文献
36.
A latent class probit model for analyzing pick any/N data 总被引:3,自引:3,他引:0
A latent class probit model is developed in which it is assumed that the binary data of a particular subject follow a finite
mixture of multivariate Bermoulli distributions. An EM algorithm for fitting the model is described and a Monte Carlo procedure
for testing the number of latent classes that is required for adequately describing the data is discussed. In the final section,
an application of the latent class probit model to some intended purchase data for residential telecommunication devices is
reported.
Geert De Soete is supported as “Bevoegdverklaard Navorser” of the Belgian “Nationaal Fonds voor Wetenschappelijk Onderzoek.” 相似文献
37.
提出了一个关于氧化物半导瓷晶界势垒起源的新观点,认为晶界势垒起源于烧结过程中外界氧在晶界中的扩散,与材料的结构、化学缺陷、掺杂、外界气氛、烧结工艺、组成状态等有密切关系,并用此理论解释了许多实验现象。 相似文献
38.
论述了交织编码的工作原理,给出了一种交织扩展Golay码的改进型软件设计方案,用TMS320C25实现了其编译码器并给出了模拟实验结果。实验结果表明,它能准确地纠正不大于72比特位的差错;处理128×128×8比特位的一幅图像数据的运行时间为0.412s. 相似文献
39.
Aspirin-like drugs may block pain independently of prostaglandin synthesis inhibition 总被引:2,自引:0,他引:2
K. Brune W. S. Beck G. Geisslinger S. Menzel-Soglowek B. M. Peskar B. A. Peskar 《Cellular and molecular life sciences : CMLS》1991,47(3):257-261
Summary Using flurbiprofen, a chiral anti-inflammatory and analgesic 2-arylpropionic acid derivative, the enantiomers of which are not converted to each other (less than 5%) in rats or man, we obtained evidence that prostaglandin synthesis inhibition is primarily mediating the anti-inflammatory activity but prostaglandin synthesis independent mechanisms contribute to the analgesic effects. Thus, the S-form inhibited prostaglandin synthesis, inflammation and nociception in rats. The R-form had much less effect on prostaglandin synthesis and did not affect inflammation. It did, however, block nociception in rats almost as potently as the S-form. S-flurbiprofen, in contrast to the R-form, was clearly ulcerogenic in the gastrointestinal mucosa. These results indicate additional molecular mechanisms of analgesia and suggest the use of R-arylpropionic acids as analgesics. 相似文献
40.
史济群 《华中科技大学学报(自然科学版)》1994,(3)
报道一种新颖的激光开槽、埋槽电极硅太阳电池的结构、工艺流程及其研制结果。在AM1.5,25℃,100mW/cm2的条件下,以面积为45cm3的36片硅片研制的硅太阳电池的输出参数的平均值为JSC=36.1mA/cm2,V∞=633mV,F.F.=0.798,η=18.23%,最后分析了种高性能硅太阳电池的设计特点。 相似文献