谈地震科技期刊与读者需求的关系     

董莹 《山西地震》2003,(1):44-45

为使从事地震科技期刊的编辑能正确地把握读者的心理，并实施有效的办刊对策，对地震科技期刊与读者的要求进行了研究，指出，作为地震科技期刊工作者，只有懂得读者的各种的心理现象和各种心理趋向，才能保证地震刊物的质量、生命力并得到读者的认同。而只有真正了解、认识和掌握各种读者的心理现象各心理趋向，才能更准确、更完美地扣住读者的心弦，使得编者与读者产生强烈的共鸣。  相似文献   

生态环境需水研究现状和展望   总被引：24，自引：1，他引：24  

丰华丽  夏军  占车生 《地理科学进展》2003,22(6):591-598

生态环境需水是国内外生态水文学研究的热点问题。本文回顾了国内外生态环境需水研究的现状,并对今后生态环境需水研究进行了展望。研究认为:国外对生态需水的研究侧重于河流生态系统,主要是利用所关心的鱼类对河道物理形态、水流状况等变化的响应关系,来确定河流的最小或最佳流量,研究方法主要以水文学法、水力学法和生境模拟法为主。20世纪90年代后,提出了考虑河流生态系统可接受的流量变化,以维持河流生态系统整体功能为目标确定河流生态需水的研究思路。在国内,生态需水研究起步较晚,但发展较快。研究大致经历了二个阶段:1988年至1998年是对生态需水相关概念的认识阶段,1998年之后才真正进入起步性研究阶段。因此,许多理论和方法都有待加强研究。最后,本文提出了以同位素示踪、遥感等技术为支撑,加强生态需水机理和不同时空尺度生态需水转化等问题的研究。  相似文献   

Estimation of water requirement per unit carbon fixed by Eucalyptus camaldulensis in semi-arid land of Western Australia     

T.Kojima  Y.Tanaka  S.Katoh  K.Tahara  N.Takahashi  K Yamada 《中国科学D辑(英文版)》2002,45(Z1)

Afforestation in arid land is a promising method for carbon fixation, but the effective utili-zation of water is highly important and required. Thus, the evaluation of the amount of water perunit carbon fixed with the tree growth is required to minimize the amount of water supplied to theplants. In this research, a tree is regarded as a carbon fixation reactor with inflows of water andnutrients from roots, and CO2 as the carbon source from leaves with outflow of water vapor fromleaves and accumulation in the tree itself. In the process of photosynthesis and respiration nutri-tional elements are dissolved in water flow in trees. They do not flow out by these reactions, butare accumulated in trees. Thus, we have treated the behaviour of nutrients as a marker to evaluatethe water/carbon ratio. Assuming that nutrient concentration is constant in sap, and the differences in the ratios ofnutrient to carbon in living trees and dead (i.e. litter fall, etc.) are negiected, the ratio of the usedwater to fixed carbon is given as the ratio of nutrient to carbon in the tree body divided by the ratioof nutrient to water in sap. However, some nutrients are translocated and concentrated within thetree and some may be discarded through litter fall. Thus it is important to examine which nutrientelement is the most suitable as the tracer. In this paper, the results of the above method applied to Eucalyptus camaldulensis in semi-arid land of Western Australia are shown. The value of water requirement per unit carbon fixationdetermined from potassium balance is between 421 kg-H2O/kg-C for mature trees and 285kg-H2O/k9-C for young trees, while the values from calcium balance are much larger than these.The cause of the discrepancy between these values is discussed based on the measured elementconcentrations in sap and trees and the plant physiology. Finally, the actual average value throughthe life of a tree is suggested to fall between the two values.  相似文献   

新疆干旱区天然植被最低生态耗水量概念分析     

杨海梅  李明思  彭玉刚 《干旱区地理》2005,28(6):770-774

干旱区天然植被的最低生态耗水量问题关系到该地区生态建设的标准问题，也是评价水资源生态承载力所必须考虑的指标。同时，天然植被的最低生态耗水量是制定绿洲农业用水和节水规划的依据之一。据不同的生态目标分析并提出了天然植被不同的最低生态耗水量的概念，指出植物的最低生态耗水量是最低生态效应下的植物的耗水量，而且不同生态区要求的生态效应不同，因此，植物在不同生态目标下会表现出的最低生态耗水量不同。进行天然植被最低生态耗水量评价时，首先要明确生态目标。另外，通过试验发现，天然植被存在着生态耗水效率的概念，水分的生态效应存在最优值。  相似文献   

浅论岩土工程极限状态设计基本思想     

徐光黎  苏爱军 《地质科技情报》2005,24(Z1):145-150

论述了岩土工程极限状态设计的基本思想,包括极限状态的概念、土工参数设计值的确定过程和方法、构造物的重要度和场地地基复杂程度的划分、岩土工程类别、作用载荷组合、分项安全系数和极限状态设计等;给出了土工参数的实测值、导出值、标准值和设计值的确定原则或方法;指出在极限状态设计中,可通过增大设计作用效应或降低设计抗力的方法来进行岩土工程的可靠性设计.  相似文献   

工作流理论中系统需求模型及其形式化描述     

纪晓东  边馥苓 《武汉大学学报(信息科学版)》2005,30(3):230-233

描述了系统需求元模型的概念体系．提出了系统需求元模型的内容．描述了系统需求定义与分析的流程，最后采用了一种层次描述法与Petri网描述法相结合的形式化描述方法对系统需求的结果进行描述。  相似文献   

Environmental and ecological water requirement of river system: a case study of Haihe-Luanhe river system     

LI Li-juan  ZHENG Hong-xing 《地理学报》2001,11(2):224-230

In order to reduce the environmental and ecological problems induced by water resources development and utilization, this paper proposes a concept of environmental and ecological water requirement. It is defined as the minimum water amount to be consumed by the natural water bodies to conserve its environmental and ecological functions. Based on the definition, the methods on calculating the amount of environmental and ecological water requirement are determined. In the case study on Haihe-Luanhe river system, the water requirement is divided into three parts, i.e., the basic in-stream flow, water requirement for sediment transfer and water consumption by evaporation of the lakes or everglades. The results of the calculation show that the environmental and ecological water requirement in the river system is about 124×108 m3, including 57×108 m3 for basic in-stream flow, 63×108 m3 for sediment transfer and 4×108 m3 for net evaporation loss of lakes. The total amount of environmental and ecological water requirement accounts for 54% of the amount of runoff (228×108 m3). However, it should be realized that the amount of environmental and ecological water requirement must be more than that we have calculated. According to this result, we consider that the rational utilization rate of the runoff in the river systems must not be more than 40%. Since the current utilization rate of the river system, which is over 80%, has been far beyond the limitation, the problems of environment and ecology are quite serious. It is imperative to control and adjust water development and utilization to eliminate the existing problems and to avoid the potential ecological or environmental crisis.  相似文献   

Environmental and ecological water requirement of river system: a case study of Haihe-Luanhe river system   总被引：4，自引：0，他引：4  

LI Li-juan  ZHENG Hong-xing 《地理学报(英文版)》2001,11(2):224-230

1 IntroductionRiver system, to some extent, can be regarded as an independent eco-system, which includes river channels, lakes and the lands near the water bodies. In the engineering view, river system can be defined as the flooded area with a flood frequency of 1%[1,2]. The major aspects of the river system may be its water quantity, water quality and aquatic species. The three aspects of the system have a close relation with each other. The river system has a lot of functions, of which in g…  相似文献   

土壤水分对氮肥肥效影响的试验   总被引：1，自引：0，他引：1       下载免费PDF全文

李象山  张廷珠 《应用气象学报》1993,4(1):73-78

针对当前高产麦田中氮肥用量过大，浇水次数过多，严重影响小麦产量问题进行了试验。分析了不同肥、水条件对产量的影响，建立了数学模式。并根据投入、产出综合评判，得出不同产量水平下的经济最佳氮肥施用量和浇水次数。对提高小麦肥、水利用率有较高的实用价值。  相似文献   

现代化地震台网建设与观测技术人员教育培训     

续新民  郭若眉  段志英 《华南地震》1990,(4)

本文根据我国现代化地震台网建设的规划和发展战略,较系统地分析了观测技术队伍的素质与现代化台网建设不相适应的问题;论述了继续教育在现代化台网建设中的重要作用;进而提出了观测技术人员继续教育培训的内容和方法,为加强和推动观测技术人员的教育培训提供科学依据。  相似文献