关于公路路基施工技术的研究

公路路基施工是公路施工质量保障的基础,也是公路的主体,因此路基施工的重要性在整个施工过程中应受到施工单位的高度重视。其中保证施工质量,认真监管路基施工是施工环节中应重点考虑的问题。本文主要从施工放样、路基施工和施工程序三个方面,结合多年来的经验对其进行了较详细的阐述。     

TBM在水工洞室开挖中的应用

TBM法施工作为近几年在超长隧洞施工中的先进技术得以飞速发展,文章简述了TBM施工技术的进展以及其在施工中的优势,并在施工中有效地印证了该施工方法的优越性。     

道路桥梁工程中绿色施工技术的应用探讨

在道路桥梁工程中应用绿色施工技术,能够显著提高施工效率与施工质量水平。从绿色施工技术角度进行阐述,并重点分析在道路桥梁工程施工阶段的扬尘控制、噪音与震动控制、资源能源控制、土壤控制、危险物控制等内容,在此基础上探究了在道路桥梁工程中绿色施工技术具体应用效果。     

喷锚支护技术在水工不良地质洞段的应用研究

水工隧洞施工中由于地质不良引起的塌方现象比较常见,对于在不良地质段施工要做到提前预防,做好合理的论证及施工措施,尽量避免施工中带来的不便。喷锚支护作为一种成熟有效的施工方法,解决了在不良地质洞段施工的相关问题,值得推广。     

水电站导流洞回填灌浆的施工技术

指出了在水工建筑物的施工过程当中,其重要部位和节点之一为水电站倒流洞回填灌溉,与水电站安全稳定的运行息息相关。就水电站导流洞灌浆施工技术作出了阐述,因为该技术其施工过程较为复杂,所以对其施工过程进行了合理化布置,分析了其施工所处环境,该隧道工程施工中所利用的是填灌浆及固灌浆的施工技术,在既定工期内,施工任务高质量完成,以此为例提供参考。     

桥梁工程中简支拱的施工技术

指出了桥梁项目中简支拱的施工环节相对较为繁琐,并且施工起来难度较大。在简支施工的过程中要求选用高效且适当的手段。以实际工程为例,对系梁支架施工、系梁施工和拱肋施工进行了分析,提出了拱肋施工的控制措施,可保障箱梁作业的安全性与稳定性,有效地缩短施工的工期,提升作业的效益。     

浅谈施工企业的成本管理

在经过激烈的投标竞争承揽到工程项目的施工任务后,如何优质、高效的完成施工任务,获取较好的盈利,已成为施工企业能否发展和壮大的关键所在。笔者就施工企业在经营投标、施工过程及完工考核等各个环节存在的影响成本费用的因素进行了简要分析。     

浅谈广西雨季铁路工程施工的控制措施

为了保证工程项目的正常施工,提出了雨季铁路工程施工的技术与质量保证措施以及安全管理、防洪抗汛措施,做到雨季施工有备无患,在赶工期的同时保证施工的安全和工程的质量。     

高桩码头工程施工期间的监理方法

指出了在软土地基施工中,高桩码头是一种常用的建筑结构形式,在施工过程中,为保证码头工程的施工质量需要做好施工监理工作。以实际工程为例,对高桩码头的施工难点进行了分析,结合工程特点对高桩码头施工期间的监理工作方法进行了总结,以供同行参考。     

大跨度预应力空心楼盖的施工抗浮

对大跨度预应力空心楼盖的施工抗浮问题,从施工过程的发生、发展以及抗浮的受力分析、抗浮的处理方法等作了深人的研究,对该类问题的施工解决提出了新的可行的办法.减少了施工的盲目性,减少了大跨度通情达理应力空心楼盖抗浮施工时各种质量问题的发生,填补了"空心管+预应力"技术在施工应用方面的一项空白.     

浅议野生动物所有权

野生动物所有权是所有权的一种,它与其他所有权的区别在于客体的不同。文章阐述了野生动物的内涵,分析了野生动物的分类和野生动物与野生动物资源的区别。在明确野生动物含义的基础上,提出了野生动物所有权的概念,深入论述了野生动物所有权与野生动物资源所有权的差异和联系,并对野生动物所有权的主体、客体、内容进行了分析。     

天牛体内纤维素酶研究进展

文章综述近年来国内外有关天牛体内纤维素酶的研究进展,主要包括:天牛体内纤维素酶的来源、不同天牛种类纤维素酶的性质、纤维素酶抑制剂、纤维素酶同工酶、纤维素酶基因以及天牛体内纤维素酶活性变化与寄主的关系,并展望了未来的研究方向。     

银杏不同品种生长及耐旱性的比较

对6个银杏品种7 a生幼树的树高、干径、1 a生枝长及离体叶片的相对含水量(RWC)和叶绿素稳定指数(CSI)进行研究,结果表明,不同品种的干径和1 a生枝长度的差异达到了极显著水平,干径以大佛手最粗,为2.0824 cm,马铃最细,仅为1.5378 cm;1 a生枝长度最长的是大圆铃达22.9773 cm,最短的是郯城9号,仅为12.0889 cm;马铃的耐旱性最强,CSI为20.67,RWC损失率为65.07%。     

森林资源调查监测综合体系现状分析

对我国现有森林资源调查监测体系现状特点进行了分析,指出现有森林资源调查体系中存在着监测指标综合性不强、技术标准不统一,监测数据管理混乱,监测管理体制不顺,调查队伍素质不高,装备设备落后等问题。提出抓好林业基础数表修编,理顺管理体制、整合监测职能,统一技术标准、加强成果共享,更新技术装备、提高监测水平,明确资金渠道、保证资金投入等对策。     

大兴安岭森林资源变化分析

阐述了人为破坏、过度采伐和自然森林火灾是引起大兴安岭森林资源变化的重要因子;通过对建国初到2002年大兴安岭森林资源在数量上和质量上的变化分析,得出了森林资源变化趋势。森林资源数量减少,且森林质量下降,大兴安岭的森林在经历着破碎化和年轻化的过程。     

枣树叶片营养元素含量的季节变化动态的研究

本文研究了枣树叶片中N、P、K、Ca、Mg、Mn、Cu、Fe、Zn9种营养元素含量的季节变化动态规律。结果表明:全N的含量在初花期以前随着叶龄的增大而迅速降低。在初花期至幼果发育前期较稳定且较低,在幼果发育中期迅速增高,采收后逐渐下降;全P和全K的含量随着叶龄的增加而减小,至叶片成熟后则较稳定;Ca和Mn的含量随着叶龄的增加而迅速增高;Fe的含量在初花期出现低谷,从盛花期到果实发育中期处于稳定的高水平状态,果实进入白熟后逐渐下降,采果后则变动不显著;Mn、Cu和Zn3元素含量的变化趋势与N素水平密切相关;施尿素显著地提高了大多数物候期中叶片全N和Mn的含量,也显著地降低了大多数物侯期中叶片全P、全K和Zn的含量:在年生长周期内,各营养元素的叶分析诊断大多数有2个适宜的采叶时期。     

Native woody species regeneration in exotic tree plantations at Munessa-Shashemene Forest,southern Ethiopia

Regeneration of native woody species was studied in the plantations and the adjacent natural forest at Munessa-Shashemene Forest Project Area, Ethiopia. The aim of the study was to test the hypothesis that tree plantations foster regeneration of native woody species. A total of 60 plots, having 10 × 10 m area each, were studied in monoculture plantations of 4 exotic species (Cupressus lusitanica, Eucalyptus globulus, E. saligna, Pinus patula) and an adjacent natural forest. Ages of the plantations ranged between 9 and 28 years. Soil seed bank analysis was also undertaken from soil samples collected in each of the 60 plots to examine the similarity between the soil seed flora and aboveground vegetation. A total of 56 naturally regenerated woody species were recorded beneath all plantation stands with densities ranging between 2300 and 18650 individuals / ha in different stands. There was a significant difference among plantation stands with regard to understorey density (standard deviation: 4836 ± 1341). Vegetation diversity was assessed through analyses of floristic composition, species richness and abundance. Generally, seedling populations were the most abundant components of the regeneration in most of the plantation stands, forming 68 % of the total regeneration count in all stands. A total of 77 plant species represented by 44 herbs, 13 woody species, 8 grasses and 12 unidentified species were recorded in the soil seed bank from all stands. Similarity between the soil seed bank and aboveground flora was very low implying that the role of soil seed banks is negligible rather dispersal plays an important role in the process of regeneration. These results support the concept that forest plantations can foster the regeneration of native woody species, thereby increasing biological diversity, provided that there are seed sources in the vicinity of the plantations.     

木材光降解机理及研究进展

木材受紫外可见光照射后易发生降解, 表面的材色和力学性能都会下降, 大大影响木材的使用价值和美学特点。文中针对木材光降解机理进行了讨论, 在提出木质素是木材光降解中关键组分的同时, 强调了抽提物对木材光变色的具体影响; 通过详细叙述光降解过程中木材发生的化学变化, 进一步表明该过程中自由基中间体的生成和新的发色团的产生; 系统总结了影响木材光降解的主要因素, 并提出防治木材表面光降解的技术手段。     

大通县退耕还林还草工程实施两年来的问卷调查分析

通过对青海省大通县退耕还林还草工程实施两年来干部、群众对退耕还林还草政策的态度、前景等进行问卷调查 ,发现有 98 5 %的干部、82 2 %的农民赞成退耕还林还草政策 ;绝大多数的干部、近半数的农民认为退耕 8年后的目标还是能够实现的。问卷调查也表明 ,虽然绝大多数干部群众支持退耕还林还草工程 ,但对退耕 8年后的经济效益等也心存疑虑。退耕还林还草工程必须坚持“全面规划、突出重点、宜林则林、宜草则草、林草复合”的方针 ,努力做到四个“确保” ,才能真正实现“退得下、稳得住、不反弹、能致富”的退耕还林还草总体目标     

An evaluation of the Acacia albida-based agroforestry practices in the Hararghe highlands of Eastern Ethiopia

Growing Acacia albida as a permanent tree crop, on farmlands with cereals, vegetables and coffee underneath or in between, is an indigenous agroforestry system in the Hararghe highlands of Eastern Ethiopia. However, there is practically no systematic record or data on the merits and benefits of this practice.The paper presents the results of an investigation into the effects of the presence of A. albida on farmlands on the yield of maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench). Twenty seven plot pairs each consisting of one plot underneath the A. albida foliage cover and the other in the open, away from the tree-on farmers' fields, in a 40 km radius around the Alemaya College of Agriculture, were sampled and the yield components analyzed. A statistically significant increase in crops yields by 56% on average was found for the crops under the tree canopies compared to those away from the trees. This increase was caused by the improvement in 1000 grain weight and number of grains of plants under the tree, indicating that the trees enhanced the fertility status of the soil and improved its physical conditions in terms of crop growth.Additional benefits from the A. albida trees include supply of fuelwood and fodder. Quantitative estimates of these outputs as well as their monetary values are presented in the paper. However, in order to realize these benefits to a discernible extent, higher stand densities of the tree than at present are required.Based on an enquiry about the farmers attitude towards A. albida, the prospects for an extension of this promising agroforestry technique are discussed against the background of the state and trends of development of agriculture in the area. It is surmised that despite some shortcomings like the relatively slow and highly variable growth of A. albida and a conflict with the spreading cultivation of Ch'at (Catha edulis Forsk.), the prospects of extension of this technique are good. It is recommended that its propagation should be incorporated into the programmes of the extension agencies of the various governmental agencies concerned with land use.