斜拉桥锚固段环向预应力钢绞线伸长量误差分析

通过广州大桥索塔锚固段环向预应力钢绞线伸长量试验,发现后张法“U”形预应力钢绞线的实际伸长量大于理论限值,同时国内类似试验研究资料也表明对于后张法“U”形预应力钢绞线来说是一种普遍现象。文中分析了产生此类问题的原因,并提出了相应的建议,可供工程实践参考。     

动蛋白相关蛋白在烟草花粉管高尔基体上的存在与分布

有关研究表明, 中央马达动蛋白AtKinesin-13A在拟南芥不同细胞中与高尔基体结合. 用简并引物, 通过RT-PCR方法从烟草中克隆到一个2067 bp的基因片段, 其编码的多肽序列与拟南芥中AtKinesin-13A相应序列的相似性为77.33%, 其原核表达产物可与AtKinesin-13A抗体进行特异反应. 进一步研究发现, AtKinesin-13A抗体可以与烟草不同组织提取物中一个120 kD的多肽进行反应. 这些结果表明, 烟草中存在AtKinesin-13A的同源蛋白NtKinesin-13A, 其分子量约为120 kD. 经免疫荧光标记, 在共焦激光扫描显微镜下观察发现, NtKinesin-13A在烟草花粉管中呈颗粒状分布, 且与高尔基体标记蛋白58K共分布, 说明烟草花粉管中NtKinesin-13A也存在于高尔基体上. 经免疫金标, 在透射电子显微镜下观察, 发现烟草花粉管中的NtKinesin-13A定位在高尔基体附近的囊泡膜上. 以上结果表明, 烟草中NtKinesin-13A可能参与了花粉管中高尔基体运动的调控或与高尔基体囊泡的分泌有关.     

线索初伸长对接触网参数的影响

介绍了铁路电气化接触网施工中新线索初伸长对接触网参数的影响,分析了其原因,探讨了如何通过对线索进行超拉减小其对接触网参数影响的方法。     

弹性地基有限长梁的动力学建模

弹性地基梁模型的动力响应对于土木工程抗震和土-结构动力相互作用的研究均有非常重要的意义.本文考虑梁的不可伸长条件作用效应,分别运用Newton法和Hamilton变分原理建立了弹性地基有限长梁的精细化动力学模型.由于考虑了地基反力的二次弯矩效应,在动力学方程中包括了相互作用导致的平方非线性.最后研究了弹性地基梁的主共振响应,并分析了二次弯矩对非线性响应的影响.     

Characterization of an endo-1,4-β-glucanase from Lilium longiflorum that functioned in pollen germination and pollen tube growth

Endo-β-glucanases play vital roles in the regulation of pollen tube growth. Here, a previously identified endo-l,4-β-glucanase from Lilium Iongiflorum （lily）, named LlpCell, was expressed in Escherichia coli, purified, and further investigated for its physiological function. The recombinant LlpCell protein hydrolyzed carboxy-methylcellulose （CMC） and exhibited activity towards laminarin from Eisenia. arborea and 1,3：l,4-β-glucan of barley. The pH for the optimum activity was 6.0 and the value of Km calculated from CMC was 5.0 mg/mL. Adding EDTA resulted in the total loss of the enzymatic activity, and this effect could be restored by the addition of Ca^2＋. Western blotting analysis showed that LlpCell protein was present in pollen grains and rehydrated pollen grains, and the amount of the protein was increased during pollen germinating, but not in the pollen tube. Consistently, the immunofluorescence labeling study with the antibody against LIpCell also indicated the presence of LIpCell at the begin-ning of germination, but not in the elongating pollen tube. Furthermore, incubation of LlpCell with pollen at the beginning of pollen germination increased the germination percentage and the length of pollen tube. All of these results suggested that LlpCell could play an important role in the regulation of lily pollen germination and the initiation of pollen tube growth.     

多跨连续钢绞线预应力张拉伸长值计算分析

为得到多段曲线布置长钢铰线预应力张拉理论伸长值,需要进行复杂的计算分析。以某大桥175m整联现浇箱梁的预应力施工为例,采用Excel电子表格及其函数功能进行分段计算后汇总,可作为解决多段曲线长钢绞线理论伸长值复杂的计算问题的一种途径。通过对比计算值与实际量测数据,表明计算方法可靠,能为同类工程提供借鉴。     

多环芳烃对土壤中小麦发育的生态毒性效应

以高等植物小麦的种子发芽和根伸长的抑制率进行土壤苯并[a]芘生物毒．f生研究．将小麦种子播种于土壤中,置于培养箱中25℃黑暗培养47h,观测在不同土壤类型和苯并[a]芘不同浓度下的种子发芽和根伸长．结果表明,多环芳烃苯并[a]芘污染土壤对小麦的种子发芽和根伸长有抑制作用（与对照比较）,因土壤类型的不同,污染物浓度的不同,抑制作用不同．苯并[a]芘污染土壤中,小麦的根伸长抑制浓度大小顺序为：红壤〉水稻土〉潮土,IC50（50％的根伸长抑制浓度）分别为：1670、1515、1451mg／kg．小麦根伸长抑制率与土壤污染物浓度间的相关性高干种平右莽抑制率与苴的相姜性     

Overexpression of OsRAA1 promotes flowering and hypocotyls elongation in Arabidopsis

Previously, OsRAA1, an AtFPF1 homologue gene, was found to play an important role in modulating rice root development. In the current study, OsRAA1 was overexpressed in Arabidopsis, and the transgenic plants showed early flowering and elongated hypocotyl phenotypes as compared with the wild-type under white-light conditions. The hypocotyls of transgenic lines were twice as long as those of wild-type plants under red-light conditions but were indistinguishable from those of the wild-type under blue and far-red light and darkness. In addition, the phenotypes of AtFPF1 transgenic lines were similar to those of OsRAA1 transgenic lines. These results suggested that OsRAAI/AtFPF1 protein is involved in regulating flowering time and plays an important role in the inhibition of hypocotyl elongation under continuous red light. The functions were preserved during the evolution.     

后张法预应力施工控制要点

文章针对后张法预应力混凝土箱梁施工技术进行总结,并对施工过程中遇到问题进行浅析.     

预应力混凝土拼装箱梁应力孔道摩阻试验研究

介绍常兴渭河特大桥的预应力孔道测试方法,在测试进行中,针对常规方法进行了改进。利用最小二乘法得出预应力损失参数μ、k建议值,其结果为孔道预应力损失和理论伸长量提供了正确的依据,也为同类型预应力混凝土拼装箱梁施工提供了工艺指导。