铀的中和还原成矿模拟试验     

史维浚  袁晓庆 《华东地质学院学报》1992,15(2):177-186,200

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金属锂提取工艺比较分析   总被引：8，自引：0，他引：8       下载免费PDF全文

狄晓亮  庞全世  李权 《盐湖研究》2005,13(2):45-52

简述了金属锂的应用以及熔盐电解法和真空热还原法提取金属锂的技术特点,评述了两种方法的优缺点并提出了改进方法,对金属锂冶炼的未来发展进行了展望。  相似文献   

Groundwater inflow and associated transport of phosphorus to a hypereutrophic lake   总被引：2，自引：0，他引：2  

W.-J. Kang  K. V. Kolasa  M. W. Rials 《Environmental Geology》2005,47(4):565-575

Hydrogeochemical data from lake, sediment pore, and well waters were used to quantify groundwater seepage and the associated transport of phosphorus to Lake Persimmon, Florida, USA. The data show that lake chloride concentrations vary as a function of lake elevations that are controlled by groundwater inflow. A whole-lake average seepage rate, estimated using a simple one dimensional advection-diffusion model fitted to the lake chloride profile, currently averages 2.3 ± 0.3 cm yr^-1 and is in reasonable agreement with the rate of advective flow obtained from the pore water chloride profile. The ratios of nutrient regeneration versus sulfate consumption indicate that the phosphorus enrichment in deeper portions of sediment pore water is most likely a result of groundwater phosphorus transport through sediment. Thus, the net inputs of groundwater phosphorus to the lake, calculated using the deep pore water phosphorus concentration, are about 7.4 ± 4.3 mg P m^-2 yr^-1 and comparable with recent in situ estimates from seepage meters. This study provides a simple hydrogeochemical method for estimating hydrologic and phosphorus inputs via groundwater to the lake, thereby supporting current efforts for lake management.  相似文献   

防灾减灾问题刍议     

哈辉 《高原地震》2003,15(1):29-35

对防灾减灾涉及的自然灾害的特征、科学研究与技术、减灾化、综合防御措施、灾后应急救援等问题进行了简要总结概括和初步讨论分析。  相似文献   

Reduction of nutrient loading, planktivore removal and piscivore stocking as tools in water quality management: The feldberger haussee biomanipulation project     

Peter Kasprzak  Rainer KoschelLothar Krienitz  Thomas GonsiorczykKarl Anwand  Uwe LaudeKlaus Wysujack  Henry BrachThomas Mehner 《Limnologica》2003,33(3):190-204

The Feldberger Haussee, a highly eutrophic stratified hard-water lake located in the eastern part of Germany's Baltic lake district, was selected for a restoration programme combining external nutrient loading reduction and long-term biomanipulation. In 1980 the external phosphorus loading (1.8 g TP m⁻² a⁻¹) decreased by 90%, but water quality did not improve significantly within the following 6 years. In 1985 biomanipulation was initiated, with manual removal of cyprinid fish coupled with piscivore introductions as the principal measures. The expected changes in the pelagic community and improvements of water quality occurred after a delay of several years. Despite intensive manual removal of cyprinids and stocking of piscivores, standing stocks of cyprinid fish remained relatively high (130-260 kg ww ha⁻¹) after some years of decline. Compared to the pre-biomanipulation period, mean seasonal (May-September) Daphnia spp. biomass roughly doubled (0.037 g C m⁻³vs. 0.084 g C m⁻³). However, the predominance of small (<1 mm) D. cucullata throughout the whole investigation period indicated that planktivory was still substantial. Paired observations between edible phytoplankton biomass and Daphnia spp. indicated that a significant decline in algal stocks would only occur if herbivorous biomass was above a certain threshold (0.2 g C m⁻³). Reduced external and internal loading in concert with pelagic calcite precipitation were most likely responsible for the decline in lake phosphorus concentrations, thereby substantially improving the water quality of Feldberger Haussee. Although this is not supported by quantitative evidence, we hypothesize that resource-related water quality improvements were caused by changes in the structure of the pelagic community leading to increased calcite precipitation. In agreement with the results of other investigations, we conclude that because stabilising mechanisms such as macrophyte growth were lacking in Feldberger Haussee, biomanipulation in stratified lakes may not be as successful as has been observed in shallow lakes. However, in hard-water lakes, calcite precipitation may act as another stabilising resource-related mechanism. Phosphorus associated with sedimenting calcite particles is insensitive to redox-conditions and may therefore not be re-mobilised from lake sediments even if hypolimnetic oxygen is depleted.  相似文献   

Studies on seismic reduction of story‐incresed buildings with friction layer and energy‐dissipated devices     

Hong‐Nan Li  Yong‐Wei Yin  Su‐Yan Wang 《地震工程与结构动力学》2003,32(14):2143-2160

A new type of energy‐dissipated structural system for existing buildings with story‐increased frames is presented and investigated in this paper. In this system the sliding‐friction layer between the lowest increased floor of the outer frame structure and the roof of the original building is applied, and energy‐dissipated dampers are used for the connections between the columns of the outer frame and each floor of the original building. A shaking table test is performed on the model of the system and the simplified structural model of this system is given. The theory of the non‐classical damping approach is introduced to the calculation analyses and compared with test results. The results show that friction and energy‐dissipated devices are very effective in reducing the seismic response and dissipating the input energy of the model structure. Finally, the design scheme and dynamic time‐history analyses of an existing engineering project are investigated to illustrate the application and advantages of the given method. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

区域可持续发展指标的相关性分析及降维模型研究——以中国省级区域为例   总被引：12，自引：0，他引：12  

王黎明  冯仁国  杨燕风 《地球科学进展》2001,16(6):802-812

增大指标的覆盖面与减少指标的信息重复是可持续发展指标选取中面临的一对矛盾。在通常情况下指标数量越多，指标的覆盖面就越大，但指标的信息重复就越多。分析了近年来有关文献通常采用的指标，并结合中国省级区域可持续发展指标的可获取性，选取46个指标对其相关性进行分析。分析结果表明这些指标之间绝大多数呈现不同程度的相关关系，即指标间含有大量的重复信息。应用统计分析技术建立基于主成分分析的指标降维模型，得到 8个彼此独立的综合指标。根据综合指标得分，对中国31个省级区域（不包括港澳台）的可持续发展状况进行了排序。  相似文献   

工程力学研究所地震工程宽带网的建设     

贾相玉  苏哲明  戴志勇  王秀珍 《地震工程与工程振动》2001,21(3):154-158

计算机技术和网络技术的发展及应用对加快地震工程领域的研究重要意义，我们建立内部网站，发布内部信息。通过网络服务器以宽带接入方式访问Internet，快速查询国际上有关地震工程、工程振动、防震减灾等方面的科研信息，及时公布和交流最新科研成果，为促进地震工程事业的发展提高了工作效率，简化了工作环节。  相似文献   

上海市煤气系统和供水系统抗震防灾对策研究     

翟永梅  沈祖炎  李文艺  沈成康 《地震研究》2001,24(3):267-271

煤气系统和供水系统在一定的地震作用下能否发挥正常功能，对于整个城市的抗震救灾工作至关重要，根据上海市煤气和供水系统中的主要建（构）筑物，管网及管渠，过江管井进行震害预估的结果提出了相应的抗震对策建议。  相似文献   

结构抗震设计中的强度折减系数研究   总被引：27，自引：12，他引：27  

卓卫东  范立础 《地震工程与工程振动》2001,21(1):84-88

借助于单自由度弹塑性动力时程分析程序，对延性结构的强度折减系数进行了研究，在统计平均和回归分析的基础上，建立了平均强度折系数的函数形式，本文所建立的平强度折减系数函数，从理论上明确了结构具有延性对弹性地震力的折减关系，研究成果可供结构抗震设计规范采纳应用。  相似文献