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国内外粮食中真菌毒素限量标准制定的现状与分析 被引量:76
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作者 苏福荣 王松雪 +1 位作者 孙辉 刘焓 《粮油食品科技》 2007年第6期57-59,共3页
粮食在田间和储藏中极易受到霉菌侵染而产生真菌毒素。这些真菌毒素的存在对消费者产生了潜在的健康危害,因此建立粮食中完善的真菌毒素限量标准体系很有必要。主要讨论了目前国际上存在的真菌毒素限量标准及其不足。
关键词 粮食 真菌毒素 限量 标准
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国际香辛料真菌毒素限量标准研究现状 被引量:15
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作者 李新颖 石英 《中国调味品》 CAS 北大核心 2006年第12期9-16,共8页
香辛料是一种很容易受到霉菌及其产生的真菌毒素污染的植物性农产品。这些真菌毒素的存在对消费者产生了潜在的健康危害。从香辛料真菌毒素污染情况着手,讨论了在我国建立香辛料真菌毒素限量标准的必要性。
关键词 香辛料 黄曲霉毒素 赭曲霉毒素 限量标准
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基于最大熵分布的控制图改进与评价研究 被引量:9
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作者 宋明顺 杨铭 方兴华 《中国管理科学》 CSSCI CSCD 北大核心 2019年第12期208-216,共9页
传统的控制图多是假定质量特性参数服从正态分布,但在很多情况下正态分布的假设并不成立。本文基于最大熵分布从控制图的构建和评价两个方面分别提出对Shewhart控制图和CUSUM控制图的改进方法。首先根据"经济性"原则构建最大... 传统的控制图多是假定质量特性参数服从正态分布,但在很多情况下正态分布的假设并不成立。本文基于最大熵分布从控制图的构建和评价两个方面分别提出对Shewhart控制图和CUSUM控制图的改进方法。首先根据"经济性"原则构建最大熵Shewhart控制图,实现对Shewhart控制图的改进;然后,提出结合最大熵分布和马尔科夫链方法的CUSUM控制图评价方法。仿真结果表明,基于最大熵分布改进后的Shewhart控制图控制性能优于改进之前的情况;而基于最大熵分布的CUSUM控制图的性能评价方法得到的结果能更符合真实的情况。在对不同偏移的监测中,最大熵Shewhart控制图更适用于分布未知的大偏移情况,而自适应CUSUM控制图对小偏移有更好地监控效果。 展开更多
关键词 最大熵 控制图 平均运行长度 控制界限
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The Effect of Mineral Composition and Quantity of Fines on the Atterberg Limits and Compaction Characteristics of Soils
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作者 Abdalhamid Musbah Muad Mohammed Adem Alfghia 《Open Journal of Civil Engineering》 2024年第2期258-276,共19页
Because of the various elements that come into play in natural soil formation, the impact of varied proportions of mineral composition and fines amount on Atterberg limits and compaction characteristics of soils is no... Because of the various elements that come into play in natural soil formation, the impact of varied proportions of mineral composition and fines amount on Atterberg limits and compaction characteristics of soils is not well known. Three distinct soil samples were used in this investigation. The findings indicated the effect of varied mineral composition proportions and fines amount on the liquid limit, plastic limit, and plasticity index as assessed by the Casagrande test and hand-rolling method. The fluctuation of maximum dry density and optimal moisture content with these three soils has also been studied. Furthermore, correlations were established to indicate the compaction parameters and the amount of minerals and particles in the soil. The data show that the mineral content of the soil has a direct impact on the Atterberg limits and compaction characteristics. Soils containing larger percentages of expansive minerals, such as montmorillonite, have more flexibility and volume change capability. Mineral composition influences compaction parameters such as maximum dry density, ideal water content, axial strain, and axial stress. Soils with a larger proportion of fines, such as Soil 2 and Soil 3, have stronger flexibility and lower compaction qualities, with higher ideal water content and lower maximum dry density. Soil 1 has moderate flexibility and intermediate compaction qualities due to its low fines percentage. The effect of different mineral compositions and fines on the Atterberg limits and compaction characteristics of soils can be used to predict the behavior of compacted soils encountered in engineering practices, reducing the time and effort required to assess soil suitability for engineering use. 展开更多
关键词 Atterberg limit Mineral Composition Quantity of Fines maximum Dry Unit Weight Optimum Water Content
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Residue behaviors and dietary risk of cyazofamid in turnip,onion and romaine lettuce assessed by a QuEChERS-LC-MS/MS methods 被引量:1
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作者 Ruijuan Li Xue Men +5 位作者 Rumei Li Tongjin Liu Hui Liang Feng Fang Dongxiao Sun-Waterhouse Yongli Wang 《Food Science and Human Wellness》 SCIE CSCD 2023年第5期1538-1544,共7页
In this study, the dissipation, terminal residues and dietary risk of the cyazofamid residue in three globally consumed minor crops, turnip(Brassica rapa L.), onion(Allium cepa L.)and romaine lettuce(Lactuca sativa L.... In this study, the dissipation, terminal residues and dietary risk of the cyazofamid residue in three globally consumed minor crops, turnip(Brassica rapa L.), onion(Allium cepa L.)and romaine lettuce(Lactuca sativa L.)were assessed by supervised field trials at 6 locations of China in 2020. A reliable QuEChERS-LC-MS/MS method was developed for simultaneous analysis of cyazofamid and its primary metabolite, 4-chloro-5-p-tolylimidazole-2-carbonitrile(CCIM). The average recoveries of cyazofamid and CCIM in turnip, onion and romaine lettuce were 79%–97% and 77%–99%, respectively. The half-lives of cyazofamid in these crops were 5.7–6.5, 5.3–8.7 and 5.8–6.5 days in turnip, onion and romaine lettuce, respectively, with the final cyazofamid residues at harvest all lower than limit of quantitation(LOQ, 0.01 mg/kg). The turnip roots, onion bulbs and romaine lettuce leaves grown in China under Good Agricultural Practices conditions and harvested 10, 14 and 5 days, respectively, after the cyazofamid SC(100 g/L)application, would be reasonably safe for consumption by the general population. The maximum residue limit(MRL)values of cyazofamid could be tentatively set as 10 mg/kg for turnip leaves, 0.3 mg/kg for turnip roots, 0.05 mg/kg for onion bulbs, and 10 mg/kg for romaine lettuce leaves. 展开更多
关键词 Cyazofamid residue Minor crops maximum residue limit DISSIPATION Dietary risk assessment
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变换器级联运行有功电流传输极限分析及优化 被引量:1
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作者 王凯 原熙博 +2 位作者 王晖 张永磊 伍小杰 《中国电机工程学报》 EI CSCD 北大核心 2023年第9期3515-3526,共12页
级联运行的电压控制型变换器和电流控制型变换器在离网型微网中广泛应用。针对电压控制型变换器和电流控制型变换器级联运行的电流极限问题,证明输出电流达到极限值会致使系统失稳,严重限制系统输出功率。因系统呈高阶特性,该电流极限... 级联运行的电压控制型变换器和电流控制型变换器在离网型微网中广泛应用。针对电压控制型变换器和电流控制型变换器级联运行的电流极限问题,证明输出电流达到极限值会致使系统失稳,严重限制系统输出功率。因系统呈高阶特性,该电流极限的理论值难以直接从阻抗稳定判据推导得到。由此,该文分析并验证阻抗稳定判据和复转矩系数法的一致性,并采用复转矩系数法推导系统有功电流传输极限值,其中包括电压控制型变换器和电流控制型逆变器的级联有功电流极限值以及电压控制型变换器和电流控制型整流器的级联有功电流极限值。然后,分析控制器参数对电流极限值的影响,指出调整控制器参数无法使系统电流极限得到有效突破。由此,为提升系统可传输有功电流,从而提升输出功率,针对电压控制型变换器,考虑其过载限流能力,提出一种改进电压控制方法。最后,通过仿真和实验结果验证研究结果的正确性和所提电压控制方法的有效性。 展开更多
关键词 级联系统 极限值 电压控制 逆变器 整流器
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有关食品中农药、污染物及致病菌限量的国家标准整合情况 被引量:3
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作者 旺久 魏玉翔 刘义满 《中国园艺文摘》 2014年第7期205-207,共3页
中华人民共和国农业部发布《农业部关于废止132项无公害食品农业行业标准的公告》(第1963号公告),从2014年1月1日起,132部涉及无公害食品农业行业标准停止施行。涉及农药残留、重金属等污染物及致病菌限量指标的国家标准最新版本为GB 27... 中华人民共和国农业部发布《农业部关于废止132项无公害食品农业行业标准的公告》(第1963号公告),从2014年1月1日起,132部涉及无公害食品农业行业标准停止施行。涉及农药残留、重金属等污染物及致病菌限量指标的国家标准最新版本为GB 2763-2014《食品安全国家标准食品中农药最大残留限量》、GB 2762-2012《食品安全国家标准食品中污染物限量》及GB 29921-2013《食品安全国家标准食品中致病菌限量》。这3部标准的最新版本对之前施行的食用农产品质量安全标准、食品卫生标准、食品质量标准和有关食品的行业标准中强制执行的标准进行整合。对于已经发布实施中的食品标准文本及已经引用先前版本的合同、协议或有关文件,要及时进行清理,消除与GB 2763-2012和GB 2762-2012相违背的内容。 展开更多
关键词 食品安全国家标准 代替 废止 整合 最大残留限量 农药 污染物 致病菌
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对混凝土中活性掺合料几个问题的讨论 被引量:3
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作者 张士刚 胡晓波 +1 位作者 梁卿达 张艳锋 《商品混凝土》 2011年第3期27-29,共3页
伴随混凝土活性掺合料的广泛应用,出现了一系列的问题值得注意与研究,如硅灰混凝土的塑性开裂与早期收缩;高掺粉煤灰的早期活性激发;活性掺合料的最大掺量问题等。笔者对此进行了粗陋分析,以期起到抛砖引玉之效。
关键词 活性掺合料 早期活性激发 最大掺量
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Almost sure limit theorem for the maximum of a class of quasi-stationary sequences
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作者 ZHUANG Guang-ming PENG Zuo-xiang 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2014年第1期44-52,共9页
This paper investigates the problem of almost sure limit theorem for the maximum of quasi-stationary sequence based on the result of Turkman and Walker. We prove an almost sure limit theorem for the maximum of a class... This paper investigates the problem of almost sure limit theorem for the maximum of quasi-stationary sequence based on the result of Turkman and Walker. We prove an almost sure limit theorem for the maximum of a class of quasi-stationary sequence under weak dependence conditions of D (uk, un) and αtm,ln = 0 ((log log n)-(1+ε)). 展开更多
关键词 quasi-stationary sequence maximum limit distribution almost sure central limit theorem
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The Limit Theorems for Maxima of Stationary Gaussian Processes with Random Index 被引量:1
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作者 Zhong Quan TAN 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2014年第6期1021-1032,共12页
Let {X(t), t ≥ 0} be a standard(zero-mean, unit-variance) stationary Gaussian process with correlation function r(·) and continuous sample paths. In this paper, we consider the maxima M(T) = max{X(t), ... Let {X(t), t ≥ 0} be a standard(zero-mean, unit-variance) stationary Gaussian process with correlation function r(·) and continuous sample paths. In this paper, we consider the maxima M(T) = max{X(t), t∈ [0, T ]} with random index TT, where TT /T converges to a non-degenerate distribution or to a positive random variable in probability, and show that the limit distribution of M(TT) exists under some additional conditions related to the correlation function r(·). 展开更多
关键词 limit theorem weak convergence maximum random index stationary Gaussian process
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Importance of Generalized Logistic Distribution in Extreme Value Modeling 被引量:1
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作者 K. Nidhin C. Chandran 《Applied Mathematics》 2013年第3期560-573,共14页
We consider a problem from stock market modeling, precisely, choice of adequate distribution of modeling extremal behavior of stock market data. Generalized extreme value (GEV) distribution and generalized Pareto (GP)... We consider a problem from stock market modeling, precisely, choice of adequate distribution of modeling extremal behavior of stock market data. Generalized extreme value (GEV) distribution and generalized Pareto (GP) distribution are the classical distributions for this problem. However, from 2004, [1] and many other researchers have been empirically showing that generalized logistic (GL) distribution is a better model than GEV and GP distributions in modeling extreme movement of stock market data. In this paper, we show that these results are not accidental. We prove the theoretical importance of GL distribution in extreme value modeling. For proving this, we introduce a general multivariate limit theorem and deduce some important multivariate theorems in probability as special cases. By using the theorem, we derive a limit theorem in extreme value theory, where GL distribution plays central role instead of GEV distribution. The proof of this result is parallel to the proof of classical extremal types theorem, in the sense that, it possess important characteristic in classical extreme value theory, for e.g. distributional property, stability, convergence and multivariate extension etc. 展开更多
关键词 Financial Risk MODELING STOCK Market Analysis GENERALIZED Logistic DISTRIBUTION GENERALIZED Extreme Value DISTRIBUTION TAIL EQUIVALENCE maximum Stability Random Sample size limit DISTRIBUTION
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论导数在函数中的应用 被引量:2
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作者 范梅 《牡丹江教育学院学报》 2014年第12期66-67,共2页
导数是微分学中最基本的概念,文章通过利用导数在求函数单调性、求函数的极值、求函数的最大值和最小值和求函数的极限等方面的应用分析,阐述了导数在研究函数中的重要性。
关键词 导数 函数的单调性 极值 最值 极限
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具有随机足标的弱相依高斯序列最大值的极限分布 被引量:2
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作者 庄光明 彭作祥 夏建伟 《应用数学学报》 CSCD 北大核心 2008年第6期1068-1079,共12页
设ξ_1,ξ_2,…为标准化的平稳高斯序列,M_n=max(1≦i≦n)ξ_i,协方差r_n=Cov(ξ_1,ξ_(n+1))= E(ξ_1ξ_(n+1)).{N(n)}为一列取正整数的随机变量,满足(N(n))/n■η>0,n→∞.在条件r_n logn→0,n→∞之下,给出了M_(N(n))的极限分布.
关键词 弱相依高斯序列 平稳序列 随机足标 最大值 极限分布
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Confidence Interval Estimation of the Correlation in the Presence of Non-Detects
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作者 Courtney E. McCracken Stephen W. Looney 《Open Journal of Statistics》 2021年第3期463-475,共13页
This article deals with correlating two variables that have values that fall below the known limit of detection (LOD) of the measuring device;these values are known as non-detects (NDs). We use simulation to compare s... This article deals with correlating two variables that have values that fall below the known limit of detection (LOD) of the measuring device;these values are known as non-detects (NDs). We use simulation to compare several methods for estimating the association between two such variables. The most commonly used method, simple substitution, consists of replacing each ND with some representative value such as LOD/2. Spearman’s correlation, in which all NDs are assumed to be tied at some value just smaller than the LOD, is also used. We evaluate each method under several scenarios, including small to moderate sample size, moderate to large censoring proportions, extr</span><span style="font-family:Verdana;">eme imbalance in censoring proportions, and non-bivariate nor</span><span style="font-family:Verdana;">mal (BVN) data. In this article, we focus on the coverage probability of 95% confidence intervals obtained using each method. Confidence intervals using a maximum likelihood approach based on the assumption of BVN data have acceptable performance under most scenarios, even with non-BVN data. Intervals based on Spearman’s coefficient also perform well under many conditions. The methods are illustrated using real data taken from the biomarker literature. 展开更多
关键词 Confidence Interval Coverage Probability Left Censoring limit of Detection maximum Likelihood Spearman Correlation
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有限混合偏t分布极值分布的点点收敛速度 被引量:1
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作者 侯景耀 彭作祥 《西南大学学报(自然科学版)》 CAS CSCD 北大核心 2016年第5期94-99,共6页
研究了独立同有限混合偏t分布随机变量序列{Tn,n≥1}的规范化最大值的极限分布及其点点收敛速度.
关键词 有限混合偏t分布 最大值 极限分布 点点收敛速度
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Prediction of forming limit curve for pure titanium sheet 被引量:1
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作者 Young-Suk KIM Bong-Hyun LEE Seung-Han YANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第2期319-327,共9页
Commercially pure titanium(CP Ti) has been actively used in the plate heat exchanger due to its light weight, high specific strength, and excellent corrosion resistance. However, researches for the plastic deformati... Commercially pure titanium(CP Ti) has been actively used in the plate heat exchanger due to its light weight, high specific strength, and excellent corrosion resistance. However, researches for the plastic deformation characteristics and press formability of the CP Ti sheet are not much in comparison with automotive steels and aluminum alloys. The mechanical properties and hardening behavior evaluated in stress-strain relation of the CP Ti sheet are clarified in relation with press formability. The flow curve denoting true stress-true strain relation for CP Ti sheet is fitted well by the Kim-Tuan hardening equation rather than Voce and Swift models. The forming limit curve(FLC) of CP Ti sheet as a criterion for press formability was experimentally evaluated by punch stretching test and analytically predicted via Hora's modified maximum force criterion. The predicted FLC by adopting Kim-Tuan hardening model and appropriate yield function shows good correlation with the experimental results of punch stretching test. 展开更多
关键词 Kim-Tuan hardening equation Hora modified maximum force criterion pure titanium sheet forming limit curve
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闭区间上连续函数有最大值最小值的多种证明方法 被引量:1
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作者 杜素勤 《三明学院学报》 2003年第4期64-66,共3页
利用数学分析中的有界性定理、Weierstrass定理、有限覆盖定理、闭区间套定理、"单调有界数列有极限"定理、上下确界定义来证明闭区间上的连续函数能取到最大、最小值。
关键词 最大值 区间序列 连续 上确界 极限
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略论限度观
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作者 龚耀南 具惠兰 《广州大学学报(社会科学版)》 2011年第10期27-32,共6页
限度对于人们生存和发展具有重要的指导意义。为更好地适应时代发展要求,人们应该确立科学合理的限度观:必须恪守"最低限度",应该追求"最大限度",务必防止"无意过度",可以倡导"超越限度"。确... 限度对于人们生存和发展具有重要的指导意义。为更好地适应时代发展要求,人们应该确立科学合理的限度观:必须恪守"最低限度",应该追求"最大限度",务必防止"无意过度",可以倡导"超越限度"。确立科学合理限度观体现了科学发展的精神,有利于和谐社会的构建,有益于社会主客体的发展。人们要在实践和感悟中去寻求、把握和发展限度。科学合理限度观的确立,必须坚持求真务实、持续发展和公正发展等实践原则。 展开更多
关键词 有限度 最低限度 最高限度 无意过度 超越限度 限度原则
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Statistical Properties and Confidence Limits about the Mean Time between the Failures (MTBF) in Failure-free Period Life Test (FFPLT)
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作者 王庆成 《Chinese Quarterly Journal of Mathematics》 CSCD 2001年第1期9-19,共11页
On the basis of strict mathematical description about Failure_Free Period Life Test (FFPLT), the statistical properties of the tests and optimal confidence limit of the parameter are discussed in detail and correspond... On the basis of strict mathematical description about Failure_Free Period Life Test (FFPLT), the statistical properties of the tests and optimal confidence limit of the parameter are discussed in detail and corresponding calculating formulae are found out. 展开更多
关键词 FFPLT MTBF operating characteristic (OC) function expected test time (ETT) maximum likelihood estimation lower confidence limit
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网络流的完整极限:临界流曲线
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作者 肖峻 宋晨辉 +3 位作者 屈玉清 陈飞龙 孙哲 吕良福 《数学的实践与认识》 2021年第20期107-127,共21页
提出了临界流和临界流曲线的概念,完整地描述了网络流的极限.首先,利用最大流刻画网络的极限流量并不完整,还存在非最大流的极限状态,即堵塞流现有研究仅将堵塞流视为最大流优化时的“次优解”.提出一种新视角来认识最大流和堵塞流:它... 提出了临界流和临界流曲线的概念,完整地描述了网络流的极限.首先,利用最大流刻画网络的极限流量并不完整,还存在非最大流的极限状态,即堵塞流现有研究仅将堵塞流视为最大流优化时的“次优解”.提出一种新视角来认识最大流和堵塞流:它们均为网络流的极限状态,将其定义为临界流.其次,现有研究尚未找到所有的临界流,找到了所有的临界流,并将临界流的流量排序后绘制成临界流曲线,曲线的最高点即为最大流的流量.给出了临界流和临界流曲线的数学定义及求解方法,首次完整描述了网络流的极限,采用典型算例进行验证并给出了典型的应用案例. 展开更多
关键词 最大流 网络流 极限 临界流 临界流曲线
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