环境规制相对力度变化对FDI的影响分析

本文利用1995-2007年间41个投资来源国和地区的数据,把41个投资来源国和地区分为25个发达国家与16个发展中国家(地区)两类,重点研究中国环境规制相对力度的变化对FDI的影响,并考察了借贷成本、双边贸易关系、经济发展水平的相似性等影响因素,运用面板数据进行中国环境规制相对力度的变化对FDI的影响的实证检验,为中国选择FDI的类型提供理论依据.本文的研究结论表明;中国——相对于投资来源国——环境规制相对力度越严格,来自发展中国家(地区)的FDI将减少;而来自发达国家的FDI并不受影响.产生这一结果的原因在于,不同外商直接投资来源国企业环保技术水平的差异导致其对环境规制的敏感程度不同.在上述结论的基础上,论文对中国选择FDI的类型从外资的来源结构、产业结构、环境技术三个方面提出了相应的政策建议.     

区域经济空间分异及其演变分析研究——以浙江省为例

区域经济空间分异是伴随区域经济增长而产生的,是区域经济空间结构研究中的重要内容之一。在理论研究的基础上分析了区域经济空间分异产生的原因是受到区域空间结构的影响,总结了区域经济空间分异的现象表征主要体现在绝对差异、相对差异和经济重心3个方面,并对这3个方面的测度方法进行了研究总结,构建了区域经济空间分异的测度体系。在此基础上,以浙江省作为实证研究对象,以各县域GDP为经济发展水平的衡量指标,综合运用数理统计方法和GIS方法,对1988~2008年浙江省区域经济空间分异的情况做了定量分析。实证研究结果表明浙江省区域经济差距呈现台阶式扩大,主要由富裕地区引起,并且经济重心在不断转移。结果与1988~2008年浙江省的实际发展情况较为吻合,表明该测度分析体系具有一定的科学合理,在未来类似研究中值得继续推广。     

Bed Stability and Sedimentation Associated With Human Disturbances in Pacific Northwest Streams1

Abstract: To evaluate anthropogenic sedimentation in United States (U.S.) Pacific Northwest coastal streams, we applied an index of relative bed stability (LRBS*) to summer low flow survey data collected using the U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program field methods in a probability sample of 101 wadeable stream reaches. LRBS* is the log of the ratio of bed surface geometric mean particle diameter (D_gm) to critical diameter (D*_cbf) at bankfull flow, based on a modified Shield’s criterion for incipient motion. We used a formulation of LRBS* that explicitly accounts for reductions in bed shear stress that result from channel form roughness due to pools and wood. LRBS* ranged from ?1.9 to +0.5 in streams within the lower quartile of human riparian and basin disturbance, and was substantially lower (?4.2 to ?1.1) in streams within the upper quartile of human disturbance. Modeling results suggest that the expected range of LRBS* in streams without human disturbances in this region might be generally between ?0.7 and +0.5 in either sedimentary or volcanic lithology. However, streams draining relatively soft, erodible sedimentary lithology showed greater reductions in LRBS* associated with disturbance than did those having harder, more resistant volcanic (basalt) lithology with similar levels of basin and riparian disturbance. At any given level of disturbance, smaller streams had lower LRBS* than those with larger drainages. In sedimentary lithology (sandstone and siltstone), high‐gradient streams had higher LRBS* than did low‐gradient streams of the same size and level of human disturbance. High gradient streams in volcanic lithology, in contrast, had lower LRBS* than low‐gradient streams of similar size and disturbance. Correlations between D_gm and land disturbance were stronger than those observed between D*_cbf and land disturbance. This pattern suggests that land use has augmented sediment supplies and increased streambed fine sediments in the most disturbed streams. However, we also show evidence that some of the apparent reductions in LRBS*, particularly in steep streams draining small volcanic drainages, may have resulted in part from anthropogenic increases in bed shear stress. The synoptic survey methods and designs we use appear adequate to evaluate regional patterns in bed stability and sedimentation and their general relationship to human disturbances. More precise field measurements of channel slope, cross‐section geometry, and bed surface particle size would be required to use LRBS* in applications requiring a higher degree of accuracy and precision, such as site‐specific assessments at individual streams.     

小型高精度恒温箱设计与应用

介绍了一种用于给倾角传感器提供恒温环境的小型高精度恒温箱的设计与实现。此恒温箱要求体积小、温度控制精度在±0．05℃以内。文中介绍了恒温箱的结构设计和温控算法并给出了详细的实验结构,证明了研制的这种高精度恒温箱不仅其控温精度高,且与同类产品比其体积小,安装调试方便。     

Nature of the field-to-field distribution of pesticide residues

The supervised trial datasets (1950), consisting of a minimum of five residue values and selected by the experts of FAO/WHO Joint Meeting on Pesticide Residues for recommending maximum residue levels between 1997 and 2011, were evaluated to obtain information on the typical spread of residue values in individual datasets. The typical relative standard deviation, CV, of field-to-field variation of pesticide residues was about 80%. The spread of residues in datasets is independent from the chemical structure of pesticides, residue level, pre-harvest interval and number of values in the datasets. The CV ranges within the Codex commodity groups and between groups overlapped and their difference were not statistically significant. The number of residues below the limit of quantification (LOQ) affects the CV at various extents depending on the ratio of LOQ/R _mean. The combined uncertainty of the highest residue in a dataset significantly affects the CV of the dataset. The lowest and intermediate ones have less influence. The residues in different fields receiving the same treatment vary within large range: 55%, 72%, 78%, 86% and 89% of the 25,766 residues values were, respectively, within 3, 4, 5, 6 and 7 times the median value of the corresponding dataset.     

不同氮素浓度与空间条件下青萍生长特征

以西部地区优势浮萍品种青萍为实验对象,研究了它在不同总氮(TN)初始浓度和空间条件下的生长特征。结果表明,在表面积为95 cm2,TN初始浓度为0、1、2、3 mg/L的条件下,青萍的生长能较好地服从经典生长模型,对数生长阶段的相对生长速率(RGR)随TN浓度的增长而线性增长,分别为0.10、0.11、0.13、0.13 d-1。在TN浓度为10 mg/L,表面积为95、130和230 cm2的条件下,青萍的生长能较好地服从Logistic生长模型,其环境最大承载量和对数生长阶段的RGR分别为1 899、2 101和1 962 g/m2以及0.21、0.21和0.20 d-1。     

Deposition in boreal forests in relation to type, size, number and placement of collectors

Open precipitation and throughfall was collected at a Norway spruce stand in Finland using funnel-type collectors and at a black spruce stand in Canada using trough-type collectors. The presence or absence of a rim on the funnel, funnel diameter (9, 14 and 20 cm) and length of sampling period (1, 2 and 4 weeks) on monthly values were evaluated at the Norway spruce stand, and the number of collectors required for defined levels of accuracy and precision of throughfall loads to be reached and the influence of the spatial arrangement of collectors on solute concentrations was studied at both stands. The presence of a rim had no significant effect on open precipitation and throughfall amounts, but did on throughfall DOC, Ca²⁺, Mg²⁺, K⁺, Na⁺ and Cl⁻ ion loads. Deposition loads increased with decreasing funnel diameter; for open precipitation, this was due to increased catch efficiency while for throughfall the increase was attributed to canopy interaction and leaching of litter trapped in the collectors. Calculated monthly H⁺ loads decreased and those for all other constituents increased with collection period length. Using 15 collectors at the Norway spruce stand would allow throughfall loads to be determined to within 20% of the true mean weekly value with a confidence level of 95% for most solute, but not for NH₄ ⁺–N, NO₃ ⁻–N, Mg²⁺ and SO₄ ²⁻-S. Using 15 trough collectors, the same confidence level at the more heterogeneous black spruce stand would only be achieved for H⁺, Cl⁻, DOC and SO₄ ²⁻-S loads. In both stands, using either random or systematic placements of throughfall collectors gave similar results.     

湿度对PZT铁电陶瓷压痕裂纹滞后扩展的影响

在不同湿度(2%、30%、98%)的空气中,研究了极化的锆钛酸铅(PZT-5)铁电陶瓷压痕裂纹在残余应力、电场作用下的滞后扩展.结果表明,当RH≤30%时残余应力不能引起PZT铁电陶瓷卸载压痕裂纹的滞后扩展,当RH=98%时,残余应力和介质的耦合作用能使压痕裂纹在经过1个孕育期后发生滞后扩展.在不同湿度(2%、30%、98%)的空气中沿试样极化方向加相同的外电场(E=1.5 kV/cm),压痕裂纹均发生滞后扩展,并且裂纹扩展量随空气湿度的增加而增大.     

Reaction mode between Si and Fe and evaluation of optimal species in poly-silicic-ferric coagulant

A kind of Fe-polysilicate polymer, poly-silicic-ferric （PSF） coagulant was prepared by co-polymerization （hydroxylation of mixture of Fe^3＋ and fresh polysilicic acid （PS））, in which PSF0.5, PSF1 or PSF3 denotes Si/Fe molar ratio of 0.5, 1 or 3, respectively. The effects of Si/Fe ratio and reaction time （co-polymerization time or aging time） on the reaction mode between Si and Fe were studies, and the optimal species of PSF was evaluated by pH change during the preparation of PSF and coagulation tests. The results showed that the characteristics of PSF are largely affected by both reaction time and Si/Fe ratio. PSF is found to be a essential complex of Si, Fe, and many other ions. The reaction mode between Si and Fe differs with various Si/Fe ratios. The pH of PSF0.5, PSF1 or PSF3 tended to be stable when reaction time is 10, 25 or 55 rain, respectively, which is almost consistent with the time reaching the relative stable morphology that is just the optimal species of higher coagulation efficiency. The optimal reaction time reaching optimal species can be evaluated by measuring the pH change during the polymerization process.     

Application of multiwalled carbon nanotubes treated by potassium permanganate for determination of trace cadmium prior to flame atomic absorption spectrometry

In this study we investigated the enrichment ability of oxidized multiwalled carbon nanotubes (MWCNTs) and established a new method for the determination of trace cadmium in environment with flame atomic absorption spectrometry.The MWCNTs were oxidized by potassium permanganate under appropriate conditions before use as preconcentration packing.Parameters influencing the recoveries of target analytes were optimized.Under optimal conditions,the target analyte exhibited a good linearity (R~2=0.9992) over the concentration range 0.5-50 ng/ml.The detection limit and precision of the proposed method were 0.15 ng/ml and 2.06%, respectively.The proposed method was applied to the determination of cadmium in real-world environmental samples and the recoveries were in the range of 91.3%-108.0%.All these experimental results indicated that this new procedure could be applied to the determination of trace cadmium in environmental waters.