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摘要:The duck circovirus (DuCV) infection in sick ducks from Fujian Province was investigated. The liver samples of 43 sick Muscovy ducks with infectious serositis were collected from 12 duck farms in Fujian Province Based on the published sequences of DuCV, two primers were designed for the detection of DuCV and four pairs of primers were designed to amplify four overlapping fragments that cover the complete genome of DuCV. The specific PCR products were amplified from positive samples. The fragments were then cloned into pMD18-T vector and sequenced, and the full length genomic sequence of the FJ0601 isolate of DuCV was obtained. PCR analysis showed that the proportion of ducks which were positive for circovirus was 79% and 10 out of the 12 farms were positive. Sequence analysis showed that the complete genome of DuCV-FJ0601 was 1988 bp and possessed features common to the family Circoviridae which included a stem-loop structure and the Rep protein motifs. Homology analysis showed that FJ0601 isolate of DuCV had 97.3%-97.5% nucleotide sequence identity to all the four Taiwan isolates (TC1/2002, TC2/2002, TC3/2002, TC4/2002), 82.9% identity to the America (33753-52) isolate and 82.3% identity to the Germany isolate. Phylogenetic analysis with Clustal W, however, showed that FJ0601 isolate of DuCV was on a common branch with Taiwan isolates, and Germany and America isolates belonged to the other branch.
摘要:为研究某长大缓倾顺层边坡的支护效果,通过对边坡开挖失稳阶段和双排桩支护阶段的离心模型实验,研究开挖失稳模型和双排桩支护模型的变形破坏规律。着重探讨了长大缓倾顺层边坡失稳原因和支护效果,实验结果表明:利用离心模型实验方法研究长大缓倾顺层边坡的支护研究是可行的;长大缓倾顺层边坡在降雨、开挖等诱发因素作用下是可能发生活动的;双排桩支护方法治理长大缓倾顺层边坡是有效的。
摘要:研究了美国、欧洲、日本等发达国家大型航空航天企业集团供应链管理情况,提出了对我国航空航天物流与供应链在理论研究、顶层设计、流程再造、管理方法、先进技术、标准体系和人才队伍等方面进行管理提升的启示。
摘要:为了解决波导传输线中硬连接问题,部分波导组件将使用软波导,但软波导的使用会带来传输线损耗的增大。为了探究其在真实工作条件下的损耗和电热情况,搭建了基于谐振环的测试平台,谐振环行波功率增益为13.4 dB,通过两个2 kW功率放大器,成功在波腹位置实现了140 kW的等效功率。根据仿真和实验结果,对矩形软波导进行了优化设计,改进其结构和材料,以更好地应对高功率输入下的热形变和应力问题。优化后的软波导电热性能表现优于国外同类型产品。
摘要:【目的】某市采用潜流人工湿地-表流人工湿地处理污水厂尾水,虽然污水处理效果得到了进一步的提高,但总氮(TN)、悬浮物和透明度等指标仍有待改善。【方法】为探索改善污水厂尾水表流人工湿地水质的有效途径,构建了以矮生苦草为主,辅以少量金鱼藻和轮叶黑藻等沉水植物组成的生态系统,在表流人工湿地中围隔出面积约为300m^(2)的区域进行了为期60d的应用试验。【结果】结果显示:试验区水质得到明显的改善,试验结束时,水体的平均浑浊度为4.32NTU,比非试验区降低了95.4%,水体由浑浊转变为清澈,透明度达到1m以上;化学需氧量(COD_(Cr))、总氮(TN)、氨氮、硝酸盐氮(NO_(3)^(-)-N)、亚硝酸盐氮(NO_(2)^(-)-N)、总磷(TP)和叶绿素a的平均质量浓度分别为18.09、1.59、0.06、1.07、0.01、0.06mg/L和15μg/L,分别比非试验区降低了59.1%、85.6%、59.9%、89.6%、87.5%、85.5%和87.0%;水生植被覆盖率大幅度提高,逐渐形成草型生态系统。【结论】沉水植物的恢复与重建是改善尾水表流人工湿地水质的关键,恢复并建立相对完善的水生态系统,是解决尾水表流人工湿地水体富营养化的根本途径。
摘要:Background:Traditional tissue engineering methods to fabricate urinary tract patch have some drawbacks such as compromised cell viability and uneven cell distribution within *** this study,we combined three-dimensional(3D)bioprinting and tissue engineering method to form a tissue-engineered urinary tract patch,which could be employed for the application on Beagles urinary tract defect mode to verify its effectiveness on urinary tract ***:Human adipose-derived stem cells(hADSCs)were dropped into smooth muscle differentiation medium to generate induced microtissues(ID-MTs),flow cytometry was utilized to detect the positive percentage for CD44,CD105,CD45,and CD34 of *** of vascular endothelial growth factor A(VEGFA)and tumor necrosis factor-stimulated gene-6(TSG-6)in hADSCs and MTs were identified by Western *** the ID-MTs were employed for 3D *** bioprinted structure was encapsulated by transplantation into the subcutaneous tissue of nude mice for 1 *** retrieval of the encapsulated structure,hematoxylin and eosin and Masson’s trichrome staining were performed to demonstrate the morphology and reveal collagen and smooth muscle fibers,integral optical density(IOD)and area of interest were calculated for further semiquantitative *** double staining of CD31 andα-smooth muscle actin(α-SMA)were used to reveal vascularization of the encapsulated *** was performed to evaluate the expression of interleukin-2(IL-2),α-SMA,and smoothelin of the MTs in the implanted ***,the encapsulated structure was seeded with human urothelial *** staining of cytokeratins AE1/AE3 was applied to inspect the morphology of seeded encapsulated ***:The semi-quantitative assay showed that the relative protein expression of VEGFA was 0.355±0.038 in the hADSCs vs.0.649±0.150 in the MTs(t=3.291,P=0.030),while TSG-6 expression was 0.492±
摘要:针对模块化设计理论难以工程实现的问题,提出了基于物元模型及可拓方法的产品可拓模块化设计方法。该方法首先在物元模型的基础上,结合模块自身特点,建立了模块物元与模块族物元,以有序三元组的形式规范化地保存了历史模块和模块族数据,并研究了模块物元的可拓性及其变换。然后运用可拓方法对模块物元进行变换与操作,既实现了对模块划分、模块检索与匹配,以及模块综合等模块化设计过程的形式化描述,又为模块化设计提供了新的思维方法。最后,给出了可拓模块化设计方法在导弹产品开发中的应用实例。
摘要:重载铁路长大下坡道小曲线地段病害多发,是危及行车安全的风险源。以双机牵引30 t轴重万吨列车为研究对象,在考虑列车纵向冲动和曲线车辆动力学行为基础上,建立了长大列车动力学模型,分析了大轴重重载列车在常用全制动工况下长大坡道曲线参数设置对行车性能的影响。研究表明:重载列车在13‰下坡道500 m半径曲线地段制动时,整列车产生最大压钩力的车辆与曲线上出现最大车钩力的车辆并不一致,当曲线距头车初始制动位置距离700 m时,曲线段上第48节车车钩力达到最大值;制动产生的纵向冲动作用可使轮重减载率增大72%、倾覆系数增大47%、轮轨横向力增大41%、脱轨系数增大27%,这一作用会对行车安全性和轨道服役性能造成不利影响;从提高运营期行车安全、减缓曲线病害角度考虑,建议长大坡度最小曲线半径选取800 m。该研究可为重载铁路设计提供参考。
摘要:针对目前合金元素对铝水解制氢的活化机制尚不明晰,无法用来指导材料的配方设计与性能调控的问题,基于已有的实验经验结论和理论相图,进行了材料样本点的设计、合成、表征及产氢性能测试,并以合金速率峰值作为优化目标,分别探究了合金的物相组成和元素组成对产氢速率的耦合关系。结果显示:合金的元素组成与产氢峰值的耦合关系比物相组成的耦合关系具有更高的可信度,运用此耦合关系可以在一定程度上指导材料的定向设计,为未来此类材料的定向设计合成提供了一种新的思路。
摘要:Institute of Modern Physics,Chinese Academy of Sciences is the rst domestic institute that widely applied solid-state power source to linear accelerator project since 2011 in *** to now,the same design has already been considered for the large-scale scientific facilities in Guangdong Province of southeast China,China initiative Accelerator Driven System(CiADS).
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