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1.
以苯氧乙醇为起始剂合成了两种新型氮支套索冠醚:N-苯氧乙基单氮杂-18-冠-6(18CE)与N-苯氧乙基单氮杂-15-冠-5(15CE),通过红外光谱、核磁共振氢谱、紫外光谱和元素分析表征了新冠醚及其中间体的结构,测试了18CE与15CE络合阳离子对溶液电导率的影响。  相似文献   
2.
Magnaporthe oryzae is a model for plant pathogenic filamentous fungi. We have assembled a simple sequence repeat (SSR)-based physical map of the species, using in silico sequence data. A set of 120 SSR markers was developed from the genomic sequence of the reference isolate 70-15. These markers were readily amplified from the genomic DNA of other isolates, and high levels of allelic variation characterised the parental isolates of the two crosses tested. All the markers were locatable to one of the seven M. oryzae chromosomes. An SSR-based physical in silico map was constructed, and pre-existing SSR and RFLP loci were integrated into the map, along with 23 Avr (avirulence) genes and two other genes of importance to the plant/pathogen interaction. This map provides a platform for population genetics and functional genomics studies in the model pathogen, and even in other evolu- tionally related pathogens.  相似文献   
3.
对固体材料热扩散系数测算方法进行了研究。以流动的高温水作为对流换热介质,与平板状固体试样构成第三类边界条件下的非稳态传热模型,进而利用共轭梯度法研究了固体材料热扩散系数估计的反问题。参数灵敏度分析表明对热扩散系数参数估计具有可行性,然后通过数值模拟计算,讨论了待估计参数初始猜测值、对流换热系数条件、测量误差等因素对估计结果的影响。结果表明,本文提出的方法准确性和抗不适定性较好,在初始值设定与真实值差别较大、测量温度存在明显误差时,仍能保证足够的参数反演精度(相对误差<10%),而对流换热系数条件对热扩散系数反演估计结果影响也不明显。  相似文献   
4.
激光雷达在森林生态系统监测模拟中的应用现状与展望   总被引:9,自引:0,他引:9  
激光雷达是一种新兴的主动遥感技术,能够在多重时空尺度上获取森林生态系统高分辨率的三维地形、植被结构参数.其对森林生态系统变化的精确、高效监测和模拟在认识这些变化如何影响陆地生态系统碳循环、全球气候变化,并促进生物多样性保护方面将发挥重要作用.本文拟对激光雷达技术的概念和发展应用简史作一介绍,通过分析其在数字地形产品生成、森林生态参数提取反演应用中的主流算法和优势,继而阐明其推广应用所面临的挑战,最后指出未来激光雷达技术在生态学应用中可能的研究热点.本文认为,构建集太空、天空、地面多源传感器于一体的数字生态系统是未来生态系统观测网络发展的必然趋势,而激光雷达技术能够在数字生态系统建设过程中搭建可靠的数据支撑体系,最终有助于决策部门调控、优化人与环境关系,实现二者和谐共存.  相似文献   
5.
A TiO2 slurry was prepared by hydrothermal treating mixture of commercial TiO2 (P25),ethanol and distilled water in an autoclave.A flexible photoanode and dye-sensitized solar cell (DSSC) was fabricated on an ITO-coated poly (ethylene naphthalate) sheet (ITO/PEN) substrate by a doctor-blade technique.The sample was characterized with SEM,UV-vis,FTIR,and the photoelectric properties of the DSSC were measured.The influence of preparation conditions on the properties of the flexible DSSC was investigated.It is...  相似文献   
6.
Short chain chlorinated paraffins (SCCPs) are possibly persistent organic pollutants (POPs), and are candidate POPs of the Stockholm Convention. In this study, three quantitative methods for analyzing CPs were compared using a gas chromato-graph-electron capture detector (GC-ECD), gas chromatograph-electron capture negative ion low resolution mass spectrometry (GC-ECNI-LRMS) and gas chromatograph-electron ionization tandem mass spectrometry (GC-EI-MS2). A quantitative method for the analysis of total CPs in soil samples was established. The environmental levels of CPs in an e-waste dismantling area in China were evaluated.  相似文献   
7.
The geometry of a heat generating volume cooled by forced convection is optimized by applying the entransy dissipation extremum principle and constructal theory, while the optimal spacing between the adjacent tubes and the optimal diameter of each tube are obtained based on entransy dissipation rate minimization. The results of this work show that the optimal constructs based on entransy dissipation rate minimization and maximum temperature difference minimization, respectively, are clearly different. For the former, the porosity of the volume of channels allocated to the heat generating volume is 1/2; while for the latter, the larger the porosity is, the better the performance will be. The optimal construct of the former greatly decreases the mean thermal resistance and improves the global heat transfer performance of the system compared with the optimal construct of the latter. This is identical to the essential requirement of the entransy dissipation extremum principle that the required heat transfer temperature difference is minimal with the same heat transfer rate (the given amount of heat generated in the heat generating volume) based on the entransy dissipation extremum principle.  相似文献   
8.
随着计算机技术和多媒体技术在教学中的应用,传统的教学模型已不适应现代化教学。本文阐述教学模型在工程图学教学中的重要作用,讨论了应用三维和二维绘图软件开发计算机虚拟图形库特点及制作要点,以及三维模型库在教学中的作用和它对教学改革的影响。  相似文献   
9.
Concentrations of polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs) and heavy metals in two sediment cores, taken from the Dagu Drainage River, were determined. The contamination trends of these three kinds of compounds were obtained. The results showed that concentrations of PBDEs increased in recent years; there were new contamination sources for OCPs in this area; contamination levels of heavy metals had no significant change in the last several years. Comparing the results of these two cores, erosion and dilution of seawater had different effects on the transportation of these compounds.  相似文献   
10.
Based on constructal theory,the structure of a tapered element and high-conductivity link is optimized by taking the minimization of the entransy dissipation rate as the optimization objective.The results show that the mean temperature difference of the heat transfer cannot always decrease when the internal complexity of the control-volume increases.There exists an optimal constructal order leading to the minimum mean temperature difference for heat transfer.The thermal current density in high-conductivity links with variable shapes does not linearly depend on the length.Therefore,the optimized constructs based on the minimization of the entransy dissipation rate are different from those based on the minimization of the maximum temperature difference.Compared with the construct based on the minimization of the maximum temperature difference,the construct based on the minimization of the entransy dissipation rate can reduce the mean temperature difference,and improve the heat transfer performance significantly.Because entransy describes the heat transfer ability more suitably,various constructal problems in heat conduction may be addressed more effectively using this basis.  相似文献   
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