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1.
应堂法 《网友世界》2014,(11):243-243
提出了用红外吸收光谱仪扫描样品中6中限用邻苯二甲酸酯的初步含量,后用气相色谱-质谱联用精确测定塑料玩具和儿童用品中6种限用增塑剂的方法,以四氢呋喃THF/正己烷(1:1)为萃取剂,以BB为内标进行定量。该方法平均回收率为91.15%~98.72%,RSD为1.98%~4.47%,检测限(S/N=5)分别为0.5mg/L(DBP、BBP、DEHP、DNOP)和10mg/L(DINP、DIDP)。  相似文献   

2.
采用室内模拟试验的方法,探讨了脲酶抑制剂N-丁基硫代磷酰三胺(NBPT)和硝化抑制剂3,4-二甲基吡唑磷酸盐(DMPP)的不同浓度组合对尿素氮转化的影响.结果表明,NBPT与DMPP不同浓度组合均不同程度的延缓了尿素的水解,使尿素N水解产物更加以NH4 -N形态保持在土壤中;延缓了硝化作用进程并减少了硝酸盐在土壤累积,在此基础上增加了土壤有效态N含量.综合不同浓度组合对尿素水解的抑制、土壤NH4 -N和NO3--N含量变化、硝化作用抑制效果、土壤有效态N水平等指标并结合成本考虑,NBPT和DMPP分别为0.1%和0.5%施氮量时为最适宜的组合.  相似文献   

3.
利用固相萃取技术富集了水中5种邻苯二甲酸酯类(邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸丁基苄基酯(BBP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)、邻苯二甲酸二辛酯(DOP))。借助均匀设计法及计算机回归建模优化技术对5种PAEs的固相萃取条件进行了设计与优化,得到最佳固相萃取条件为:洗脱剂配比(正己烷与丙酮的体积比) 30:1,洗脱体积2 ml,洗脱速率为4 ml·min-1,上样速率8 ml·min-1。富集后的样品用带电子捕获器的毛细管气相色谱检测,方法的线性范围为1~1 000lμg·l-1(DMP,DOP),0.2~100μg·l-1(DBP,DEHP),0.1~100μg·l-1(BBP);线性回归方程的相关系数为0.9970~1.000,检测限为0.01~0.4μg·l-1,方法回收率为69%~116.9%,相对标准偏差为2.5%~9.5%。  相似文献   

4.
研究了特殊形貌NiO对基于该类敏感电极的混合电位C3 H6传感器的影响,实验数据显示:线型结构NiO敏感电极传感器在600℃下具有最好的响应值,达到了60 mV,其90%的响应和恢复分别为15,25 s。此传感器在600℃对0%~0.05% C3 H6具有较好敏感性能,且响应信号与气体体积分数对数之间有良好的线性关系,其灵敏度达-50.26 mV/decade。经气相催化分析,在400~600℃和0.01% C3 H6下,线型形貌NiO电极的平均气相催化效率最低,为31.4%(其余两种分别为42.7%,52.4%),进而表现最优的传感器性能。  相似文献   

5.
对Triad im efon在土壤中的降解和吸附行为进行了研究。两年的大田试验结果表明Triad im efon在红壤中半衰期分别为3.68d和8.77d,水稻土中分别为3.69d和7.63d,其降解受温度影响较大。批量法研究的Triad im efon在四种土壤中的吸附行为的试验结果表明Triad im efon在土壤中的吸附符合Freund lich经验公式;Kd随土壤有机质含量的增加而增大,吸附性与土壤有机质含量呈正相关;土壤有机质吸附常数Koc为259,表明Triad im efon在土壤中的移动性为中等:在土壤中的吸附量随温度的升高而降低,在土壤中的吸附主要为物理吸附。  相似文献   

6.
压缩感知中迂回式匹配追踪算法   总被引:1,自引:0,他引:1  
迂回式匹配追踪(detouring matching pursuit,DMP)是一种计算复杂度低、准确率高、对传感矩阵列相关性要求低的贪婪重构稀疏信号算法.DMP中子内积逆和系数矩阵递增递减核心式被提出并证明,DMP利用子内积逆和系数矩阵减少残差误差变化量的计算量,达到降低计算复杂度的目的.另外,DMP采用先逐个最优缩减、后逐个最优扩增假定支撑集元素的方法提高重构准确率和扩大重构稀疏信号的稀疏度范围.DMP算法复杂度分析表明,DMP算法中获取、缩减和扩增假定支撑集的复杂度分别为O(K2 N),O(b(K-b)N)和O(b(K-b)N).加权间接重构0-1稀疏信号实验结果表明,对于稀疏度为M/2的0-1稀疏信号,DMP、逐步贪婪追踪(greedy pursuit algorithm,GPA)、子空间追踪(subspace pursuit,SP)、压缩采样追踪(compressive sampling matching pursuit,CoSaMP)、正交匹配追踪(orthogonal matching pursuit,OMP)的重构准确率分别为99%,65%,0%,0%和13%.非零值服从正态分布的稀疏信号实验结果也表明DMP的重构准确率优势显著.  相似文献   

7.
测定常压下35℃、45℃的N,N二甲基甲酰胺-三氯甲烷-水三元体系液液平衡数据.继而用矩阵表达DMF废水多级错流和多级逆流萃取的操作线方程与平衡线方程,最后应用MATLAT求解,获得多级错流和多级逆流萃取各级浓度,探讨萃取剂用量、初始浓度、级数、相比等参数对萃取过程的影响.结果表明:DMF废水浓度低于25%时的液液平衡可视为线性关系;对质量比为0.15的DMF废水,用三氯甲烷为萃取剂多级萃取,适当操作方式为逆流,在操作温度为35℃时,适当的萃取级数为3~4级、适当的相比为3~4;当萃取级数为3、相比为3时萃取率可达到96.9%.  相似文献   

8.
通过盆栽模拟试验,用静态箱法采样,气相色谱测定样品CO2浓度,研究大豆出苗到开花期长期定量施肥土壤CO2排放速率的变化规律。结果表明,长期定量施肥大豆生长对土壤呼吸影响有明显的规律性,NPK OM>NPK>NP>NK>CK;长期定量施肥对裸土呼吸速率影响较小,NPK OM呼吸速率较大为53.8mgCm-2h-1,NP次之为50.7mgCm-2h-1,其它施肥影响不大,气温对裸土呼吸影响较大,而对种植大豆的土壤呼吸前期(出苗后9天)影响较大,生长后期(出苗9天以后)影响较小。裸土呼吸速率变化与气温变化趋势相似,种植大豆促进土壤呼吸增大。如果忽略大豆生长对土壤有机质分解的激发效应,大豆根际呼吸占总土壤呼吸的23%~56%。  相似文献   

9.
通过对来自六种不同茶园土壤的三种农药残留量的监测,对茶同环境质量现状进行了较系统的调查,并进行了茶园的污染评价.本研究以丙酮为提取剂,样品经提取和浓缩后,采用毛细管柱气相色谱分离,电子捕获检测器(ECD)检测农药残留,外标法定量.不同种类茶园土壤的农药残留量是不同的.用气相色谱法分析茶园土壤中农药残留,全面了解茶园中拟除虫菊酯类农药残留量现状,有利于更好地采取行之有效的措施降低农药残留量,对促进茶叶的出口贸易也起到重要的作用.  相似文献   

10.
通过14C示踪技术模拟实验(25℃下)研究砂壤土、壤黏土、粉黏土3种质地的水稻土有机碳矿化对水分变化的响应.砂壤土和壤黏土中水稻秸秆(14C标记)的矿化率在75%田间持水量(WHC)达到最大值,160 d分别约为53%和58%,粉黏土在45%~105% WHC范围内的矿化率处于缓慢升高趋势(41.8%~49.0%);3种土壤原有有机碳的矿化率都在75% WHC最高,砂壤土为5.8%,壤黏土为8.0%,粉黏土为4.8%,但超过此含水量后,其矿化率显著下降.3种质地水稻土的添加和原有有机碳的矿化率与土壤含水量均呈二次曲线关系(p<0.01).本研究进一步澄清了淹水对水稻土有机碳矿化的抑制作用.  相似文献   

11.
Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.  相似文献   

12.
European Community policy and the market   总被引:1,自引:0,他引:1  
Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.  相似文献   

13.
融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。  相似文献   

14.
Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.  相似文献   

15.
This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.  相似文献   

16.
Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008  相似文献   

17.
Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.  相似文献   

18.
This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)SM and Team Software Process (TSP){SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.  相似文献   

19.
基于复小波噪声方差显著修正的SAR图像去噪   总被引:4,自引:1,他引:3  
提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。  相似文献   

20.
蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。  相似文献   

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