Effects of salinity, temperature and light on germination of invasive Prosopis juliflora (Sw.) D.C.   总被引：1，自引：1，他引：1  

A. El-Keblawy  A. Al-Rawai 《Journal of Arid Environments》2005,61(4):555-565

Effects of salinity, temperature, light and their interactions on the rate and final percentage of germination were evaluated for the invasive shrub Prosopis juliflora, grown under arid environmental conditions of the United Arab Emirates (UAE). Seeds that were not treated with NaCl germinated well in a wide range of temperatures and in both full light and complete dark. Seed germination decreased significantly with the increase in both NaCl concentration and temperature. Optimal germination percentage occurred at 25 °C. The inhibitory effect of high salinity on final germination percentage was greater at 40 °C than at 15 and 25 °C. Germination was completely inhibited in 400 mM NaCl at 40 °C and in 600 mM NaCl at 25 °C. However, germination rate was significantly greater at 40 °C than at 15 and 25 °C in lower salinities and the reverse was true at higher salinities. Germination in light was significantly greater than in the dark at lower salinity levels and high temperature.  相似文献   

中国地震安全农居示范工程综述   总被引：10，自引：2，他引：10       下载免费PDF全文

王兰民  陶裕禄  袁一凡  张令心  韦开波  张勇  张守洁 《地震工程学报》2005,27(4):305-311

本文从建设社会主义新农村的高度,以提高农村民居抗御地震灾害的能力为目标,论述了在我国农村地区实施地震安全农居工程的必要性、可行性和目标;介绍了“十一五”国家防震减灾规划重点项目-地震安全农居示范工程的建设内容。涉及农村民居基础资料调查与抗震能力评价、农村民居抗震实用化技术研究与开发、地震安全农居示范工程建设、农村民居防震减灾知识宣传和技术培训、农村民居抗震技术服务网建设、地震安全农居工程投入机制、政策研究及国际合作等方面。  相似文献   

西北地区农村房屋抗震设防现状及对策   总被引：1，自引：1，他引：1  

魏英祖  郭金贵 《地震工程学报》2005,27(4):351-353,356

西北地区是中国地震活动多发区,由于经济落后农村多数房屋达不到抗震设防要求。本文分析了不同类型农村民房的抗震性能,总结了主要存在问题,提出了抗震设防的一些对策。  相似文献   

中国大陆及邻区地震序列类型的分区特征和震源环境讨论   总被引：4，自引：0，他引：4  

王华林  周翠英 《地震》1997,17(1):34-42

在对中国大陆及邻区的１７次ＭＳ≥８、５３次６≤ＭＳ≤７．９和４４次５≤ＭＳ〈６地震的序列类型分类的基础上，利用作者提出的考虑地震序列类型本身存在比例差异的地震序列类型概率百分比方法，划定了１５个地震序列类型活动区，并讨论了不同地震序列类型地震的震源环境。  相似文献   

距平植被指数在1992年特大干旱监测中的应用   总被引：6，自引：0，他引：6  

陈维英  肖乾广  盛永伟 《遥感学报》1994,(2)

本文重点阐述ＮＯＡＡ极轨气象卫星距平植被指数的处理技术及算法，以及在１９９２年干旱监测中的应用。距平植被指数是以归一化植被指数（ＮＤＶＩ）多年旬、月平均值作为背景，然后用当年旬、月的ＮＤＶＩ值减去背景值。植被指数的距平值不仅反映了植被年际间的变化，而且也指示了天气对植被的影响。用这个量监测农作物是否遭到旱灾威胁比只用ＮＤＶＩ的瞬时值优越。研究结果表明当月的距平植被指数与当月降水量距平百分率相一致。  相似文献   

地震对市政管道的破坏及管道的抗震处理     

吴少艳  吴德军  陈东 《地震工程与工程振动》2006,26(3):200-202

通过查阅大量的相关资料,总结了地震对市政管道产生的破坏,并提出了市政管道应采取的抗震措施。  相似文献   

Effects of poor quality irrigation waters on the nutrient leaching and groundwater quality from sandy soil     

M. Jalali  H. Merrikhpour 《Environmental Geology》2008,53(6):1289-1298

Sodium (Na⁺) in poor quality irrigation water participate in ion-exchange processes results in the displacement of base cations into solution and a raised concentration in groundwater. Knowledge of the rate of decrease of nutrients from soils resulting from poor water quality application is essential for long-term planning of crop production while minimizing the impact on groundwater quality. In this study, we examined the effect of sodium adsorption ratio (SAR) of irrigation water on nutrients leaching and groundwater quality in columns of sandy soil. Three types of irrigation waters at three NaCl–CaCl₂ solutions with the following levels of SAR (5, 15, and 30) were synthesized in laboratory. With the application of solutions, exchange occurred between solution Na⁺ and exchangeable cations (Ca²⁺, Mg²⁺, and K⁺), resulting in the displacement of these cations and anions into solution. Increasing the level of SAR from 5 to 15 and 30 resulted in increase in the average exchangeable sodium percentage (ESP) of the soil from 10.4 to 20.3, and 32.5, respectively. Adverse effect of high Na⁺ concentration in the solutions on raising ESP was less pronounced in solution having low SAR. Leaching of Ca²⁺, Mg²⁺, K⁺, and P from soil with the application of solutions represents a significant loss of valuable nutrients. This sandy soil showed the high risk for nutrients transfer into groundwater in concentrations exceeding the groundwater quality standard. Irrigation with poor quality water, which is generally more sodic and saline than regional groundwater, increases the rate of sodification and salinization of shallow groundwater.  相似文献   

Large Rock Avalanches: A Kinematic Model     

Oscar Marcos Zambrano 《Geotechnical and Geological Engineering》2008,26(3):283-287

Rock avalanches constitute geodynamic phenomena of great beauty and extraordinary power, but at the same time they usually mean destruction of life found in their way. Therefore, it is of prime importance to acquire information on the dynamics of such debris streams so that their kinematic behavior can be evaluated in regions where they present a potential risk to human life and life in general. The energy loss due to dissipative interaction is greater than previously estimated. Starting with the energy conservation equation, one formula for the overall frictional loss, and another for the movement velocity of the predicted trajectory of a potential rock avalanche body is estimated.  相似文献   

沙化土地遥感评价方法   总被引：5，自引：0，他引：5  

龙晶 《国土资源遥感》2005,16(1):17-19

 应用遥感数据,通过建立线性回归模型,进行沙化土地评价因子的反演,并以地面调查为基础进行遥感评价方法研究,探讨 遥感技术在沙化土地评价中应用的有效途径。  相似文献   

海底富钴结壳物理特性的试验研究          下载免费PDF全文

周知进  卜英勇 《地球物理学进展》2008,23(5):1456-1459

海底富钴结壳富含多种金属,是海底极为重要的矿产资源.在实验室里对用拖网采集的天然富钴结壳的湿密度、干密度、含水率、P波速度和抗压强度等物理特性进行了研究.研究表明:富钴结壳的湿密度或干密度的大小与孔隙率、含水量有关;富钴结壳的抗压强度与温密度、P波速度有较强的相关性,湿密度、P波速度越高,其抗压强度也相应越大.所以富钴结壳的物理特性与抗压强度之间的相互关系,为富钴结壳的资源评价、采选冶研究提供参考.  相似文献