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31.
为了检测环境中潜在的LXRα效应物质.本研究以LXRα蛋白为例,利用核受体蛋白与小分子亲和结合的原理,构建了pCold-TF-LXRα重组蛋白并优化了重组蛋白的表达条件,建立了特异性捕获活性物质的方法.结果表明:诱导温度为20℃、诱导剂IPTG浓度为0.4mmol/L为重组蛋白的最佳表达条件;同时,利用LXRα激动剂T0901317 4个梯度浓度(0.25,2.5,25,250μg/L)的加标回收率实验测得线性回归曲线为y =0.83604x+0.40763,R2=0.9948,证明方法具有有效性;对比pCold-TF空载体蛋白(6.42%)和重组蛋白(79.83%)对T0901317(250 μg/L)的回收率,说明方法具有特异性.为了验证方法的实用性,将重组蛋白与15种典型的有机磷酸酯类化合物(OPEs)的混合标样进行“捕获”实验,证明了TPHP、BPADP、TCrP、EHDPP、TNBP、RDP、TEHP、TDCIPP具有LXRα的活性效应.最后,用酵母双杂交实验验证了这8种OPEs均为LXRα的拮抗剂. 相似文献
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目的针对矢量毫米波系统中因传输链路和光电转换带来的非线性问题,提出一个基于维特拉级数的非线性均衡方案。方法首先给出该方案的基本原理,然后搭建一个射频载波频率为40 GHz、传输信号为5Gbaud 16QAM的矢量毫米波仿真系统,分析基于维特拉级数的非线性模型各阶非线性项的贡献,并比较在不同传输距离情况下,该方案相对于仅采用线性均衡方案对系统性能的提升。结果在传输距离为10 km时,该方案能够将平台误码率降低到10~(-3)以下。结论该方案明显提升了系统的性能。 相似文献
36.
根据奎屯市区城市废水的排放量大、排污口多、污染物浓度高以及排污下水管道污水处理设施的建成现状等特点,提出了以污水处理厂为治理中心,市区排污管道网络化的改造设想、存在问题及对策。 相似文献
37.
Rodríguez-Maroto JM García-Delgado RA Gómez-Lahoz C Vereda-Alonso C García-Herruzo F Muñoz MP 《Environmental monitoring and assessment》2003,89(2):165-177
Lead and cadmium contamination of an agricultural soil has been studied using batch and column experiments. Thermodynamics of theretention phenomena may be represented by a Langmuir isotherm foran aqueous metal concentration up to 100 mg L-1. First order kinetics with respect to the solid phase yield good predictabilityfor both batch and column experiments. Kinetics and thermodynamics of lead retention predominate over those ofcadmium. As a consequence, lead is preferentially retainedand can even displace sorbed cadmium. In the event of anspill involving both metals, cadmium would move further inthe soil and its aqueous concentration downstream could beeven higher than that of the influent solution, increasingpotential risks. A two-region model has been used to fit all the experimental results. Satisfactory predictions for column experiments are obtained with parameters which are consistent with those obtained for the batch experiments, for which sorption is described by a Langmuir isotherm including competitive retention. 相似文献
38.
Ulla Haverinen Mikko Vahteristo Juha Pekkanen Tuula Husman Aino Nevalainen Demetrios Moschandreas 《Environmental Modeling and Assessment》2003,8(4):303-309
An empirical moisture damage index was developed in order to reduce the subjectivity of the estimation of moisture damage in domestic residences, in relation to occupant health. The database was generated using information gathered from a sample of 164 houses that were examined by civil engineers, and questionnaire data collected from the occupants. The index was formulated to associate with the occupant reported respiratory symptoms by calculating weighted estimates of selected moisture damage attributes using 80% of the sample. The remaining 20% of the sample was used to verify the final index. The index associated strongly with the health symptoms of interest. This index is a tool that may be used as an indicator of moisture damage induced exposure in domestic residences. 相似文献
39.
The increasing use of the landscape by humans has led to important diminutions of natural surfaces. The remaining patches
of wild habitat are small and isolated from each other among a matrix of inhospitable land-uses. This habitat fragmentation,
by disabling population movements and stopping their spread to new habitats, is a major threat to the survival of numerous
plant and animal species. We developed a general model, adaptable for specific species, capable of identifying suitable habitat
patches within fragmented landscapes and investigating the capacity of populations to move between these patches. This approach
combines GIS analysis of a landscape, with spatial dynamic modeling. Suitable habitat is identified using a threshold area
to perimeter ratio. Potential movement pathways of species between habitat patches are modeled using a cellular automaton.
Habitat connectivity is estimated by overlaying habitat patches with movement pathways. The maximum potential population is
calculated within and between connected habitat patches and potential risk of inbreeding within meta-populations is considered.
The model was tested on a sample map and applied to scenario maps of predicted land-use change in the Peoria Tri-county region
(IL). It (1) showed area of natural area alone was insufficient to estimate the consequences on animal populations; (2) underscored
the necessity to use approaches investigating the effect of land-use change spatially through the landscape and the importance
of considering species-specific life history characteristics; and (3) highlighted the model's potential utility as an indicator
of species likelihood to be affected negatively by land-use scenarios and therefore requiring detailed investigation. 相似文献
40.
土壤重金属污染的灰色模糊评价 总被引:14,自引:1,他引:14
以灰色聚类为基础,提出了灰色模糊聚类分析法,并将其应用于土壤环境质量评价中,经实例分析表明,这是一种较为简便,合理、有效的评价方法。 相似文献