Allelopathic effects of giant foxtail on germination and radicle elongation of loblolly pine seed

Water extracts of giant foxtail grass inhibited germination and radicle elongation of loblolly pine seed in a laboratory test. Most of the toxic effects came from extracts of dried foxtail tops, with lesser amounts from fresh tops and roots. Soil texture affected the phytotoxicity of the extracts. Eight chemical compounds known to be phytotoxins inSetaria were identified in extracts of foxtail leaves but could not be found in soil samples under the leaves.     

软土中的基坑支护工程实例分析

武汉某地下车库基坑处于深厚淤泥中 ,采用排桩 +土层锚杆支护与放坡 +网喷分段支护方式 ,本文根据现场地质、地形条件 ,对本工程支护过程中支护桩与土体变形作了具体分析。     

高架桥中异形板裂缝的分析与加固

从分析某高架桥中异形板板底裂缝的特点及成因着手 ,对设计与施工工艺诸方面提出防止裂缝的对策和对裂缝进行加固的全过程。     

深层搅拌桩复合地基的现场试验研究

结合雍六高速公路长江二桥江北接线工程 ,对填土荷载下复合地基的应力、变形特性进行了长期现场观测研究 .结果表明 :路基经深搅桩加固后 ,沉降变形得到有效控制 .加固区沉降量较小 ,下卧层沉降量较大 ,总沉降量满足设计及规范的要求 ;柔性路堤下桩与桩间土的沉降规律有差别 ,桩身上部桩周土沉降较大 ,随着深度增加 ,桩周土沉降逐渐小于桩的沉降 ,在这个过程中 ,桩与桩周土存在等沉面 ;在填土加荷过程中 ,桩与土各自分担的应力处在动态的变化之中 :加荷时 ,桩上应力相对集中 ;间歇期 ,桩土应力比减小 ;体现了荷载传递过程中桩与土是相互协调作用的     

沪芦高速公路软土地基设计与研究

软土地基的处理是影响高等级公路工程质量和使用性能的重要因素 ,针对沪芦高速公路的工程特点 ,通过对不同土层力学性能分析 ,地基稳定验算以及沉降计算提出地基处理方案 ,并介绍通过地基处理后获得的显著效果     

黑土土壤质量演变初探I：不同开垦年限黑土主要质量指标演变规律

根据土壤质量的定义和研究方法 ,对黑土的主要质量指标演变规律进行初步研究。结果表明 :黑土的颗粒组成受开垦历史影响的程度较小 ,其质地没有发生显著变化 ;黑土的有机质、全氮、全硫和全磷随着黑土开垦时间的增加而不断降低 ;速效磷随黑土开垦时间的增加有增高的趋势。经过统计分析 ,黑土中粉砂(0.05～0.002mm)含量与细砂(0.25～0.05mm)和粘粒(<0.002mm)含量具有相关性,黑土有机质含量与全氮、全硫、全磷和速效钾具有明显的正相关。因此 ,初步认为黑土中粉粒和有机质含量可以作为土壤物理和养分方面的质量指标     

Electricity generation from rice husk in Indian rice mills: Potential and financial viability

Rice husk generated as a by-product of rice processing is an important energy resource. The availability of this resource in India has been assessed and the technologies for exploitation of its energy potential in rice processing industry discussed. Nomographs have been developed for estimation of the husk required to meet the energy demand of parboiling, drying and milling operations. The unit cost of electricity using rice husk gasifier-based power generation systems has been calculated and its financial feasibility assessed in comparison with utility-supplied and diesel-generated electricity. With the cost and efficiency data assumed here, the unit cost of electricity produced by rice husk gasifier-dual fuel engine-generator system varies between Rs 2/kWh and Rs 7/kWh. (Note: 35 Rs approximates to $US 1.)     

松嫩平原洪涝旱碱综合治理及水土资源可持续利用问题

文章依据松嫩平原洪、涝、旱、碱综合治理和在水土资源中存在的问题，提出必须加大科研力度，提高技术含量，从保护生态环境可持续开发利用自然资源的战略角度出发，综合治理洪、涝、旱、碱灾害，并提出了一些具体作法。     

Predicting plant yields using soil testing for phosphorus: Effects of error in the estimation of the maximum yield on interseasonal comparisons of yield prediction

Results from long-term field experiments in south-western Australia are presented in the form of relationships between yield, expressed as a percentage of the maximum yield, and soil test for phosphorus (P) values. Maximum yields were not always indicated by well defined yield plateaux. Different methods have been used to estimate the maximum yield value which is used to calculate yield as a percentage of the maximum yield so as to remove interseasonal variation. For all of these methods and for the same site, the same P fertilizer (superphosphate), and the same plant species, the relationship between yield and soil test P differed for different years. Consequently fertilizer recommendations based on the assumption that this relationship is constant are likely to be incorrect. We therefore question the validity of the common practice in soil testing programmes of using percentage yield values to remove interseasonal variation.     

渭河流域水利水保措施减水减沙效益初步分析

截止1989年底,渭河流域共有水库361座,塘坝2666座,引水有效灌溉面积40.4万公顷,治理总面积8136km~2,治理度17.1％。以1970年为效益计算起始年,并将全流域划分为18个片,分别采用水文法和水保法计算1970～1989年间各项水利水保措施减水减沙量及综合减水减沙效益。水文法算得的综合减水效益为24.1％,减沙效益为30.6％;水保法算得的结果相应为29.9％和30.8％,两者相近。