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931.
滦县ML5.0地震前重力异常探讨 总被引:6,自引:3,他引:6
分析研究了2004年1月20日河北省滦县ML5.0地震孕育过程中首都圈重力场的异常变化和动态演化特征。结果表明,震前出现的重力上升-下降-上升变化是较明显的中短期异常反映;重力场动态图像较清晰地反映了研究区重力场的准均匀态-非均匀态一发震的演化过程;滦县地区重力场的异常变化形态支持了孕震体震前膨胀的理论。 相似文献
932.
ENVIRONMENTAL CHANGE AND ITS IMPACTS ON HUMAN SETTLF, MENT IN THE CHANGJIANG RIVER DELTA IN NEOLITHIC AGE 总被引:1,自引:0,他引:1
ZHANGQiang LIUChun-ling ZHUCheng JIANGTong 《中国地理科学(英文版)》2004,14(3):239-244
Dating data, altitude of Neolithic sites, climatic changes from sedimentary records and previous research results were collected and analyzed to detect possible connections between climatic changes and human activities in the Changjiang River Delta in the Neolithic Age. The results indicated that hydrological changes greatly impacted the human activities in the study region. Low-lying geomorphology made the floods and sea level changes become the important factors affecting human activities, especially the altitude change of human settlements. People usually moved to higher places during the periods characterized by high sea level and frequent floods to escape the negative influences from water body expansion, which resulted in cultural hiatus in certain profiles. However, some higher-altitude settlements were not the results of climatic changes but the results of social factors, such as religious ceremony and social status. Therefore, further research will be necessary for the degree and types of impacts of climatic changes on human activities in the study area at that time. 相似文献
933.
随着经济的快速发展和城镇化进程的加快,土地的价值日益显现出来,如何发挥市场机制合理配置土地资源,经营和管理好城镇国有存量建设用地,促进经济社会环境可持续发展,就需要认真作好土地资产经营这篇文章。 相似文献
934.
LIUJuan JIANGWensheng SUNWenxin WANGYongzhi 《中国海洋大学学报(英文版)》2005,4(2):108-114
In order to forecast storm surge inundation, a two-dimensional model is established. In the model, an alternating computation sequence method is used to solve the governing equations, and the dry and wet method is introduced to treat the moving boundary. This model is easy to use. It has a friendly input interface and Arcview GIS is used as the output interface. The model is applied to the Shantou area to simulate the storm surge elevations and inundations caused by Typhoons 6903 ane 0104 using the same relevant parameters. The calculated results agree well with the observations. 相似文献
935.
Advances in the Study on Nutrient Requirements of Grouper(Epinephelus sp. ):a Review 总被引:1,自引:0,他引:1
LUOZhi LIUYongjian MAIKangsen TIANLixia 《中国海洋大学学报(英文版)》2005,4(2):93-98
The paper reviews the recent advances in studying grouper nutrition requirement for the development of cost-effective and environmentally friendly artificial diets. It consists of seven parts: protein and amino acid, lipid and essential fatty acid, carbohydrate, vitamin, mineral, alternative protein source, broodstock and larval nutrition. The review provides some basic information for further investigation of nutrient requirements of groupers. 相似文献
936.
An alkaline protease from Acetes chinensis was purified and characterized in this study. The steps of purification include ammonium sulfate precipitation, ion-exchange
chromatography with Q-sepharose Fast Flow, gel filtration chromatography with S300 and the second ion-exchange chromatography
with Q-sepharose Fast Flow. The protease was isolated and purified, which was present and active on protein substrates (azocasein
and casein). The specific protease activity was 17.15 folds and the recovery was 4.67. The molecular weight of the protease
was estimated at 23.2 kD by SDS-PAGE. With azocasein as the susbstrate, the optimal temperature was 55°C and the optimal pH
value was 5.5. Ion Ca2+ could enhance the proteolytic activity of the protease, while Cu2+, EDTA and PMSF could inhibit its activity. 相似文献
937.
938.
土地利用规划环境影响评价中不确定性分析 总被引:2,自引:0,他引:2
在分析土地利用规划环境影响评价中的不确定来源、特点及其对决策的影响基础上,提出了降低环境影响评价中不确定性的方法。通过研究认为:土地利用规划环境影响评价中的不确定主要由土地利用规划方案的不确定、环境信息的不确定和环境影响程度的不确定引起的,这些不确定性具有客观性、传递性、累积性,对决策会产生较大的干扰,但是可以通过使用基于情景分析的预测方法、多方协作的方式以及广泛开展公众参与等方法来降低。 相似文献
939.
940.
LIU Fushun LI Huajun YU Guangming ZHANG Yantao WANG Weiying SUN Wanqing 《中国海洋大学学报(英文版)》2007,6(2):199-204
A new damage-locating method for bridges subjected to a moving load is presented, and a new ‘moving load damage-locating indicator' (MLDI) is introduced. A vehicle is modeled as a moving load, the bridge is simplified as an Euler-Bernoulli beam, and the damage is simulated by a reduction of stiffness properties of the elements. The curvature and MLDI values at each node of the baseline model (undamaged) and the damage model are computed respectively. Then the damage or damages can be located from a sudden change of the MLDI value. The feasibility and effectiveness of the proposed method are validated by numerical simulation. The results indicate that the method is effective, being able to not only locate a single damage accurately, but also locate multiple damages in simply-supported bridges, including multiple damages in continuous bridges. The results also indicate that the MLDI can accurately locate damages under 5% measurement noise. 相似文献