震区中小跨径桥梁墩柱配筋率取值范围

为研究配筋率对钢筋混凝土桥梁延性抗震性能的影响,并在不同设防烈度对主筋配筋率的合理取值进行细分。以钢筋混凝土桥梁为研究对象,通过拟静力模型试验与有限元数值分析的方法,研究竖向钢筋(主筋)配筋率对桥墩延性的影响,提出典型桥墩的多级性能水平量化指标;并探究在氯离子侵蚀的恶劣环境下,不同配筋率对桥梁抗震性能所带来的影响,从而对氯离子侵蚀环境下的震区中小跨径桥梁墩柱配筋率取值范围提供参考建议。结果表明：考虑氯离子侵蚀作用下的恢复力模型能够较好地反映刚度的退化特性,墩柱的最佳配筋率取值范围为1.11%～2.72%;当加速度为0.3g(g为重力加速度)时,仅从配筋率的角度已无法满足墩柱的损伤指标,建议采用减隔震体系进行抗震设计,如采用延性体系时配筋率不得小于2.64%。研究结果可为中小跨径连续桥梁抗震设计提供参考。     

回流充气法处理中,高量含铁地下水的研究

本文介绍一种深井回流充气工艺,它兼具充氧和除铁综合性能的新型工艺形式,能改善含铁地下水的过滤性能.在此基础上提出了深井回流充气稳定期的概念,建立了深井回流充气系统中氧量的平衡关系.通过正交试验,提出了处理中、高量含铁地下水的推荐工艺流程和工艺参数.采用χ—射线衍射方法测试了井内铁泥和成熟滤料表面滤膜的成分和形态,分析了"充气"和"过滤》两过程中的除铁机理.     

Osmium isotope determination on mantle-derived peridotite xenoliths from Panshishan with N-TIMS

The¹⁸⁷Os/¹⁸⁸Os ratios of spinel lherzolite xenoliths from Panshishan determined with N-TIMS are lower than that of the primitive mantle, which shows depleted mantle characteristics. Their positive correlation with Al₂O₃/MgO suggests that the geochemical behavior of trace elements Re and Os is similar to that of Al₂O₃ and MgO respectively during the magmatic evolution and Re-Os isotopic system is largely immune to mantle metasomatism. A model age of 2.8–3.4 Ga obtained by¹⁸⁷Os/¹⁸⁸Os-Al₂O₃/ MgO correlation might represent the homogeneous age of the mantle lithosphere beneath the area.     

Effect of lanthanum ions on tRNAphe structure: Imino proton NMR spectroscopy

The effect of lanthanum ions on the structural and conformational change of yeast tRNA Phe was studied by 1H NMR. The results suggest that the tertiary base pair (G-15)(C-48), which was located in the terminal in the augmented dihydrouridine helix (D-helix), was markedly affected by adding La 3+ and shifted 0.33 downfield. Based pair (U-8)(A-14), which is associated with a tertiary interaction, links the base of the acceptor stem to the D-stem and anchors the elbow of the L structure, shifted 0.20 upfield. Another imino proton that may be affected by La 3+ in tRNA Phe is the tertiary base pair (G-19)(C-56). The assignment of this resonance is tentative since it is located in the region of highly overlapping resonances between 12.6 and 12.2. This base pair helps to anchor the D-loop to the TΨC loop.     

多媒体网络中的时延控制方法

时延和时延的抖动是多媒体网络中两个重要的参数,它们与网络的服务质量相关．提出了一种新的网络时延和时延抖动的控制方法——按时服务原则．该方法以虚拟时钟算法为基础,吸收了Ｊｉｔｅｒ－ＥＤＤ算法的优点,能够同时对时延和时延抖动进行控制．同以往的时延和时延抖动控制算法相比,其优点在于：无需为会话建立通信模型,只要是受漏桶（ＲＳ,Ｄ０）限制的会话,那么,该会话在按时服务器组成的网络中就存在一个最大时延Ｔ１,ＭＳ,ｍａｘ．     

微量钠离子浓度测量方法

从能斯特方程出发,考虑到国产ＣＮａ电极的离散性,给出实用的数学模型,并用ＭＣＳ－５１单片机构成高性能价格比的微量钠离子检测仪。     

受控源作用分析

受控源作用分析程道林１房建州２（１徐州师范大学物理系,徐州,２２１００９;２徐州教育学院物理系,徐州,２２１００６）独立源作为电路的输入,代表着外界对电路的作用,在电路中起激励的作用．而受控源则不同于独立源,其电压或电流不是定值,也不是给定的时间函数...     

碳源对芽胞杆菌碱性纤维素酶合成的影响

芽胞杆菌ＥＶ２３基本为组成性地合成碱性纤维素酶,以不同碳源生长时酶合成水平差别不显著。葡萄糖（Ｇｌｕ）、果糖等易代谢碳源在ρ＝１０ｇ·Ｌ－１时,不但不抑制酶的合成,还相对地促进酶的合成。以Ｇｌｕ为碳源培养,ρ＝４０ｇ·Ｌ－１时酶合成水平最高,ρ≥５０ｇ·Ｌ－１时酶合成才有部分被阻遏。ＡＴＰ、三羧酸循环中间物对酶合成有一定的阻遏作用,表明ＥＶ２３碱性纤维素酶的抗阻遏合成是有一定限度的。     

电动势负反馈直流调速系统研究

在分析了电压负反馈直流调速系统的优缺点基础上,本文提出了电动势负反馈调速方法,并给出了该方法的系统图、框图和静特性。对电动势负反馈双直流电动机调速系统也进行了探讨。文中还对电动势负反馈直流调速系统的优缺点和应用范围加以了分析。     

Pathways of proton transfer in the light-driven pump bacteriorhodopsin

The mechanism of proton transport in the light-driven pump bacteriorhodopsin is beginning to be understood. Light causes the all-trans to 13-cis isomerization of the retinal chromophore. This sets off a sequential and directed series of transient decreases in the pK_a's of a) the retinal Schiff base, b) an extracellular proton release complex which includes asp-85, and c) a cytoplasmic proton uptake complex which includes asp-96. The timing of these pK changes during the photoreaction cycle causes sequential proton transfers which result in the net movement of a proton across the protein, from the cytoplasmic to the extracellular surface.