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排序方式: 共有305条查询结果,搜索用时 15 毫秒
1.
湘南地区杂柑天草高接换冠关键技术   总被引:3,自引:0,他引:3  
天草杂柑的高接换冠的关键技术主要是:注意选择母树并适当修剪;合理采穗和保湿;科学嫁接;嫁接后精心管理.  相似文献   
2.
<正>To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsidence, bed separation grouting technology of overburden is put forward. To provide theoretical support for the technology, the characteristics and the mechanics mechanism of mining overburden from layer-split to formation of bed separation are studied. On the basis of elastic sheet board theory, calculation formula of rock sheet deflection is presented, and the mechanics criteria of the separation formation and the calculation formula of bed separation volume are set up. Finally, the applications and technics of bed separation grout technology of mining overburden to control land subsidence in china are introduced.  相似文献   
3.
沉积物间隙水的几种制备方法   总被引:10,自引:0,他引:10  
刘素美  张经 《海洋环境科学》1999,18(2):66-71,78
间隙水的制备对研究沉积和中物质的动力学非常重要。间隙水的制备方法有离心法、压榨法、渗析法、吸气引液法等,这些方法各有利弊。本文对这些方法分别进行了了综合比较。  相似文献   
4.
For more than 30 years, multiple research groups have worked on the automation of hazard and operability (HAZOP) studies, or more specifically on the hazard identification process. So far, very few of these approaches have been used in the chemical process industry. Automatic hazard identification is a knowledge-intensive process that demands high standards with regard to the way in which knowledge is stored and made available. There are various suitable approaches to the qualitative modeling of processes and plants, which are the foundation for reasoning systems that are used for the identification of hazards. Additionally, there are quantitative methods that are based on process simulations and can be used to identify potential hazards. The investigation of the state of research demonstrates that there are sophisticated technologies for automated systems that include powerful reasoning techniques. The benefits and shortcomings of existing technologies are discussed with regard to their industrial applicability. Often, the quality of the necessary specific and generic knowledge is not sufficient to detect potential hazardous events and operational malfunctions. Computer-aided HAZOP systems should be integrated with computer-aided design- or process simulation software using common data models based on the digital representation of the process plant. In order to be used by HAZOP practitioners automated systems need to be comprehensive, serve as specialized decision support systems, and be tested and evaluated using round robin tests.  相似文献   
5.
根据渭河流域关中段的污染状况及《(渭河流域水污染防治三年行动方案(2012-2014年)》对科技攻关的实际需求,采用资料搜集、实地调查、问卷发放、数理统计等方式对渭河流域关中段55座城镇污水处理厂的污泥处理情况进行了调查与分析。根据调查分析结果,提出了渭河流域关中段城镇污水处理厂污泥处理技术在应用过程中存在的一些问题,并结合该流域实际情况提出了相应建议,期望能够对该流域污泥处理技术的良性发展提供"第一手"的参考资料。  相似文献   
6.
This work represents an attempt to define a simple method to classify the relative degree of disturbance of sites in lotic systems on the basis of comparison of their faunistic composition with reference sites. Two ecotypes were selected in northern Portugal where benthic invertebrates were sampled in reaches with different levels of contamination. As a first stage, previous Geographic Information System information was used to define reference sites in each ecotype. Afterwards, multivariate techniques and non linear estimation models were combined to assess biological quality. This method allowed us to quantify sites according to increasing levels of contamination, after the probabilities of occurrence of taxa along a gradient of contamination taking into account the reference condition. The results suggest that this method is sensitive to organic pollution, easy to interpret, namely the species tolerance, and could be a good framework to establish regional rankings depending on the ecological impact of river sites.  相似文献   
7.
A soil sampling intercomparison exercise for the ALMERA network   总被引:1,自引:0,他引:1  
Soil sampling and analysis for radionuclides after an accidental or routine release is a key factor for the dose calculation to members of the public, and for the establishment of possible countermeasures. The IAEA organized for selected laboratories of the ALMERA (Analytical Laboratories for the Measurement of Environmental Radioactivity) network a Soil Sampling Intercomparison Exercise (IAEA/SIE/01) with the objective of comparing soil sampling procedures used by different laboratories. The ALMERA network is a world-wide network of analytical laboratories located in IAEA member states capable of providing reliable and timely analysis of environmental samples in the event of an accidental or intentional release of radioactivity. Ten ALMERA laboratories were selected to participate in the sampling exercise. The soil sampling intercomparison exercise took place in November 2005 in an agricultural area qualified as a “reference site”, aimed at assessing the uncertainties associated with soil sampling in agricultural, semi-natural, urban and contaminated environments and suitable for performing sampling intercomparison. In this paper, the laboratories sampling performance were evaluated.  相似文献   
8.
If the goal for managing rangelands is to achieve a balance between production and conservation, then monitoring is essential to detect change and apply corrective action. In some range-land areas of northern Australia, monitoring has detected a tilt in the production-conservation balance towards excessive production. How big is this imbalance? Can it shift back? Robust monitoring is needed to answer these questions. The aim is to know what to monitor, and where. For example, to detect changes caused by livestock on rangeland forage production and soil erosion, indicators linking grazing disturbances to landscape function are needed, that is, indicators that signal how well landscapes are capturing, concentrating, and utilizing scarce water, nutrient, and organic resources. Studies in Australia and the USA document that simple vegetation and soil patch attributes can be measured as indicators of the 'state of health' of landscape function. For example, field and remote sensing-based grazing studies in Australia document that landscapes with a high cover of perennial plant patches function effectively to capture runoff water and nutrients in sediments, whereas landscapes with a low cover of these patches do not — they are dysfunctional — as indicated by large patches of bare soil. Aerial videography is proving to be a robust technique for measuring indicators of landscape function such as small patches of vegetation and the extent of bare soil. These indicators typically have a sigmoidal response to grazing impacts. We illustrate that if these indicators are measured on monitoring sites established near the sigmoidal 'point of inflection’ then small changes in these indicators can be detected.  相似文献   
9.
针对清河流域三级水生态功能分区功能定位和水质保护目标,按照"分类、分区、分级、分期"理念,应用流域水质目标管理技术方法,研究清河流域控制单元污染负荷核定、水环境容量计算与分配、污染负荷削减、污染物总量控制等关键技术应用示范,完善流域水质目标管理技术,为清河流域水环境管理提供科技支撑。  相似文献   
10.
我国水环境有机物分析前处理技术   总被引:1,自引:0,他引:1  
介绍了我国水环境有机物分析中常用的前处理技术,包括液液萃取、树脂吸附、固相萃取、固相微萃取、液膜萃取、半透膜被动采样、顶空、吹扫-捕集等,归纳了各种方法的原理、应用及优缺点,并对环境中有机污染物前处理技术的发展方向进行了展望。  相似文献   
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