正确分析经济形势积极参与宏观调控为湖南省经济社会发展提供国土资源保障

中央对国土资源工作空前重视,赋予了十地政策参与宏观调控的新任务：中央高度重视国家宏观经济运行,对当前经济形势分析后认为国民经济保持良好的发展态势,但经济运行中一些矛盾进一步显现,最突出的是固定资产投资增长过快、规模过大,特别是一些行业投资增长过猛。任其发展下去,势必引起一系列问题,最终会造成经济大起大落。为此,中央决定进一步加强宏观调控,先后出台了一系列政策文件,以解决经济运行中出现的问题。4月1日,国务院办公厅下发了《关于开展资源节约活动的通知》：4月26日,国务院发出《关于调整部分行业固定资产投资项目资本金比例的通知》;4月27日,国务院办公厅发出《关于清理固定资产投资项目的通知》;4月29日,国务院办公厅下发了《关于深入开展土地市场治理整顿严格土地管理的紧急通知》(以下简称《紧急通知》)。     

树立科学的发展观合理开发利用土地资源

从我国土地资源开发利用中遇到新的挑战分析入手,深刻分析造成土地与人口矛盾的根源,说明我们的发展思路必须改变,指出新时期的土地资源管理工作必须坚持以人为本,树立全面、协调、可持续的发展观,按照新的发展观的思路来开展工作,作政策、战略、制度的调整。     

Statistical analysis on the influence of mechanical parameters in the vibration of pylons

We present a statistical investigation of the degree of influence that assumptions made in relation to the mechanical parameters of a pylon have on its ground-induced vibrations. The study is set up by using as a key kinematic variable the displacement at the top of a reference, a stand-alone pylon with a uniform cross-section and fixity at its base. Next, statistics are produced using a dimensionless displacement ratio defined between the ‘parental’ and the ‘subsidiary’ cases, the latter define...     

Is delta-aminolevulinic acid dehydratase activity in bivalves from south-west Iberian Peninsula a good biomarker of lead exposure?

The coast of Huelva is considered as a heavily contaminated area where the Tinto and Odiel rivers discharge after running through a metalliferous mining area in the Iberian Pyrite Belt and end in common estuary called Ría of Huelva. Lead is a highly toxic and widely distributed element in the aquatic environment; therefore there is a great interest in assessing the impact of this contaminant on aquatic organisms. To study the bioavailability and sources of lead, the bivalve species Chamelea gallina was collected from six sampling sites along the coast of Huelva. Besides the effect of this metal on the enzyme activity, delta-aminolevulinic acid dehydratase (ALA-D) was determined in the whole tissue. Results show the inverse relationship between the lead concentration and the activity of ALA-D measured in whole tissues (r2=0.7). Individuals collected from the Ría of Huelva estuary had the highest levels of total lead concentrations and the lowest activity of ALA-D. Lead isotope analyses demonstrated the different sources of lead contamination and also confirmed the influence of Ría of Huelva on the metal input to the marine environment.     

Critical tissue copper residues for marine bivalve (Mytilus galloprovincialis) and echinoderm (Strongylocentrotus purpuratus) embryonic development: conceptual, regulatory and environmental implications

Critical tissue copper (Cu) residues associated with adverse effects on embryo-larval development were determined for the Mediterranean mussel (Mytilus galloprovincialis) and purple sea urchin (Strongylocentrotus purpuratus) following laboratory exposure to Cu-spiked seawater collected from San Diego Bay, California, USA. Whole body no-observed-effect-residues (NOER) were similar, with means of 21 and 23mugg(-1)dw, for M. galloprovincialis and S. purpuratus, respectively. Mean whole body median effect residues (ER50) were 49 and 142mugg(-1)dw for M. galloprovincialis and S. purpuratus, respectively. The difference in ER50s between species was reduced to a factor of <2 when expressed as soft tissue residues. Coefficients of variation among whole body-ER50s were 3-fold lower than median waterborne effect concentrations (EC50) for both species exposed to samples varying in water quality characteristics. This suggests that tissue concentrations were a better predictor of toxicity than water concentrations. The CBRs described herein do not differentiate between the internal Cu concentrations that are metabolically available and those that are accumulated and then detoxified. They do appear, however, to be well enough related to the level of accumulation at the site of action of toxicity that they serve as useful surrogates for the copper concentration that affects embryonic development of the species tested. Results presented have potentially important implications for a variety of monitoring and assessment strategies. These include regulatory approaches for deriving saltwater ambient water quality criteria for Cu, contributions towards the development of a saltwater biotic ligand model, the conceptual approach of using CBRs, and ecological risk assessment.     

远红外纳米陶瓷对叉鞭金藻生长的影响

单细胞藻类是鱼、虾、贝类等苗种生产的重要基础性活饵料.探索单细胞藻的培育新技术对于解决饵料藻类生产中的诸多问题具有重要的现实意义.远红外纳米陶瓷具有改变水分子团簇结构诱发生物效应的功能.本试验在叉鞭金藻(Dicrateria sp.)培养瓶中放入远红外纳米陶瓷材料一枚,其他培养条件与对照组相同,在培养结束时,置入纳米陶瓷的试验组的最高藻密度为345.3×104～397.8×104cells/cm3,而所有对照组在平台期能达到的最高藻密度为293.8×104～323.0×104cells/cm3,平均增长约20%,试验组达到最大密度的时间比对照组达到最高密度的时间提前了2～4d,试验组与对照组存在显著性差异,表明远红外纳米陶瓷可促进叉鞭金藻的生长,具有生产应用的前景.     

多时相耕地覆盖提取和变化分析：一种结合遥感和空间统计的时空上下文方法

基于多时相影像的耕地提取和变化分析是有效管理和保护耕地资源的重要手段。然而就多时相耕地的分类提取而言,现有方法对于多时相影像中地物的时空特征表达和时空上下文关系建模存在着局限性,导致耕地的提取精度不佳;其次,对于耕地的变化分析,现有方法往往只关注基于行政单元的耕地面积统计变化,而对耕地变化在空间上的相关性分布特点考虑较少。因此,本文首先提出了一种时空上下文分类方法,综合表达和利用多时相影像中地物的光谱、纹理和空间等特征,建模时空维度上地物间在特征和语义上的上下文关系,来提高耕地覆盖分类的精度;其次,基于耕地覆盖的提取结果,在规则格网和行政区划单元上,采用GIS空间统计方法分析耕地变化的空间相关性特点;最后,以北京市顺义区为例,以2015—2019年的多时相Sentinel-2影像为数据源对本文方法进行验证。结果表明,与常见的2种多时相影像分类方法相比,本文方法在多时相耕地分类上精度最高,平均用户精度和制图精度分别达到91.21%和90.53%,所有类别的总体精度为90.79%。这表明本文方法能精确提取多时相耕地覆盖信息。通过对耕地变化的空间分布特点进行分析,发现2015—2019年顺义...     

精密GPS卫星钟差两种插值方法的比较

影响GPS高精度定位和低轨卫星高精度定轨等的一个重要因素就是卫星钟差,具体分析、比较了采用不同多项式内插来加密GPS精密卫星钟差的方法,并对德国GFZ（Geo Forschungs Zentrum）数据处理中心提供的精密卫星钟差进行处理,通过MATLAB编程计算后,比较了不同加密方法处理的精密卫星钟差的结果,得出了一些有益的结论。