Upstream CRP-binding site is not essential for CRP-cAMP-mediated inhibition on the nifU promoter

When the NifA-mediated activation of Klebsiella pneumoniae nifU promoter is recreated in Escherichia coli, it has been observed that CRP-cAMP has an inhibitory effect on the nifU promoter. Sequence analysis indicates that there is a strong CRP-binding site located upstream of the nifU promoter, overlapping completely with a previously identified NifA-binding site. In vitro gel retardation analysis indicates that this putative CRP-binding site has similar affinity for CRP, when compared with that at the lac promoter, suggesting that CRP could effectively compete with NifA for such a binding site under physiological conditions. When this putative CRP-binding site on nifU was mutated, in vitro gel retardation analysis indicates that CRP can no longer bind to the mutant promoter. However, when constitutively expressed NifA is used as the activator, CRP-cAMP-mediated inhibitory effect on this mutant nifU promoter has no significant difference when compared with that obtained from its wild-type promoter. These results suggest that direct interaction between CRP and Eσ54, other than the DNA binding site(s) competition between CRP and NifA, plays the principal role in the CRP-cAMP-mediated inhibitory effect on nifU.     

韩国古建筑实例的基本尺度取值规律探析

通过对部分韩国古建筑实例测绘数据的分析，探索其营造尺复原值，并提出一种尺度规律的推定结果：存在一种基本模数，控制建筑的面阔、进深和高度各项基本尺度．     

电梯交流调速的类型及特点

介绍了电梯交流调速的3种类型(变极调速、变压调速和变频变压调速)及其特点。     

输入受限的隐式广义预测控制算法的仿真研究

本文基于CARIMA模型提出了一种简单的隐式广义预测自校正控制算法。它避免了在线求解Dioaphantine方程;利用并列预测器间的特点,直接辨识输出预测器中的参数,并针对广义预测控制问题,在整个预测时域和控制时域,对输入幅值施加了约束;在此基础上以二次规划作为滚动优化策略,进行计算机仿真,获得预测控制信息和输出信息;然后采用加权控制律,不仅使预测信息得以充分利用,而且使系统的性能得到明显改善。     

河南省持续发展系统动力学模拟与调控

区域发展的动力来源于区域人地相互作用，区域的持续发展有赖于区域人地系统的合理结构和优化模式以及人们对该系统的有效调控。本文以河南省为实例论述了区域人地系统的模拟和调控等有关问题.     

浅析大容量矿井提升机之电力拖动

分析了大容量矿井提升机采用直流拖动和同步电动机交－交变频调速的特点，指出了采用同步电动机拖动应该解决的问题     

Conservation,evolution, and specificity in cellular control by protein phosphorylation

The glycolytic control enzyme phosphofructokinase from the parasitic nematodeAscaris lumbricodies is regulated by reversible phosphorylation. The enzyme is phosphorylated by an atypical cyclic adenosine monophosphate (cAMP)-dependent protein kinase whose substrate specificity deviates from that of the mammalian protein kinase. This variation is explained by structural peculiarities on the surface part of the catalytic groove of the protein kinase. Also, the protein phosphatases responsible for the reversal of phosphorylation appear to act specifically in glycolysis and are different from those participating in regulation of glycogenolysis.     

浅论高校档案工作中的管理意识

论述了高校管理中加强档案意识的重要性，强调了档案管理意识的提高对高校的发展有积极的推动作用。从三方面阐述了档案管理的六大意识的时代意义和社会作用。     

关于我国服装质量标志的立法与推广

本文对我国服装质量标志、质量保证、立法程序和推广以及国内、国外服装的立法和标准等有关内容进行了研究探讨。目的在于通过服装质量标志的立法与实施,提高我国服装的附加价值和服装生活消费水平,更好地与国际市场接轨。     

中枢胆碱能神经系统对心血管活动的调节

本文阐述了晚近国内外研究中枢胆碱能系统具有调节心血管活动功能的进展概况。中枢M受体可分为升与降压两种功能的类型,激动中枢N受体可致升压,中枢毒蕈碱与去甲肾上腺素系统对心血管的调节有相互关系。