检索结果-南通市图书馆

Determination of Rotenone Residues in Foodstuffs by Solid-Phase Extraction (SPE) and Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS)

引用

Agricultural Sciences in China 2010年第9期9卷 1299-1308页

作者： XU Dun-ming ZHOU Yu LIN Li-yi ZHANG Zhi-gang ZHANG Jin LU Sheng-yu YANG Fang HUANG Peng-ying Xiamen entry-exit inspection and quarantine bureau Xiamen 361026 P.R. China Fujian entry-exit inspection and quarantine bureau Fuzhou 350001 P.R.China

We developed a novel approach to determine rotenone residues in foodstuffs, by integrating solid-phase extraction （SPE） and liquid chromatography/tandem mass spectrometry （LC-MS/MS） technologies, to achieve high sensitivity and selectivity. In our method, the solvent extraction with n-hexane-dichloromethane （50：50, v/v） and cleanup with florisil SPE cartridges using ethyl acetate-ethyl ether （25：75, v/v） as eluents provided adequate recovery of rotenone. The detection of rotenone was then carried out by LC-MS/MS using acetonitrile-water with the 0.1% formic acid （w/v） as the mobile phase. The multiple reaction monitoring （MRM） scheme employed in the approach involved the transitions of the precursor ion to three selected product ions, in which one pair for quantification was m/z 395.3 〉 213.2 and the other two pairs for identification were m/z 395.3 〉 192.2 and 395.3 〉 367.0. The limits of quantification （LOQs） of the method ranged from 0.001 to 0.005 mg kg-1 depending on the matrix. Intra- and inter-day precisions （relative standard deviations, RSDs） for rotenone were less than 7.1 and 14.8%, respectively. Results from repetitive analysis suggested good reproducibility of the method for rotenone residue detection. The recoveries at three concentrations （LOQ, 10LOQ and 100LOQ） ranged from 79.3-118.3% in cabbage, potato, onion, carrot, apple, orange, banana, lichee, tea, and Shiitake mushroom. The proposed procedure was then applied to the analysis of 129 real samples collected from Xiamen, Fujian Province, China. The existence of rotenone was found in two tea products with concentrations of 0.012 and 0.016 mg kg-1, respectively. The method has great potential for routine analysis of monitoring rotenone residue in foodstuffs.

关键词： rotenone LC-MS/MS foodstuff residue SPE

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Anomaly Detection Algorithm of Power System Based on Graph Structure and Anomaly Attention

引用

Computers, Materials & Continua 2024年第4期79卷 493-507页

作者： Yifan Gao Jieming Zhang Zhanchen Chen Xianchao Chen Zhaoqing Power Supply bureau of guangdong Power Grid Co. Ltd.Zhaoqing526060China

In this paper, we propose a novel anomaly detection method for data centers based on a combination of graphstructure and abnormal attention mechanism. The method leverages the sensor monitoring data from targetpower substations to construct multidimensional time series. These time series are subsequently transformed intograph structures, and corresponding adjacency matrices are obtained. By incorporating the adjacency matricesand additional weights associated with the graph structure, an aggregation matrix is derived. The aggregationmatrix is then fed into a pre-trained graph convolutional neural network (GCN) to extract graph structure ***, both themultidimensional time series segments and the graph structure features are inputted into a pretrainedanomaly detectionmodel, resulting in corresponding anomaly detection results that help identify abnormaldata. The anomaly detection model consists of a multi-level encoder-decoder module, wherein each level includesa transformer encoder and decoder based on correlation differences. The attention module in the encoding layeradopts an abnormal attention module with a dual-branch structure. Experimental results demonstrate that ourproposed method significantly improves the accuracy and stability of anomaly detection.

关键词： Anomaly detection transformer graph structure

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Preparation of hydrophilic molecularly imprinted polymers for tetracycline antibiotics recognition

引用

Chinese Chemical Letters 2011年第5期22卷 611-614页

作者： Peng Wang Xiao Fang Fu Jing Li, Jing Luo Xiao Ya Zhao Ming Jun Sun Yin Zhu Shang Cheng Ye Hubei entry-exit inspection and quarantine bureau of PRC Wuhan 430022 China

Hydrophilic molecularly imprinted polymers（MIPs） were prepared using tetracycline as template,methacrylic acid as monomer and glycidilmethacrylate as pro-hydrophilic *** with common MIPs,the imprinting effect and adsorption amounts of hydrophilic MIPs for tetracycline（TC） were greatly improved in water ***,the electrochemical sensor fabricated by modifying hydrophilic MIPs on glassy carbon electrode was developed for the determination of TC in foodstuff samples.

关键词： Hydrophilic molecularly imprinted polymers Electrochemical sensor Tetracycline antibiotics Foodstuff samples

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Synthesis, Characterization and Crystal Structure of (+)-N-[(3S)-3-(4- fluorophenyl)heptanoyl]bornane-10,2-sultam

引用

Chinese Journal of Structural Chemistry 2012年第9期31卷 1247-1250页

作者：韩勰汪淼李菲徐媛原曹秀芳 College of Science Huazhong Agricultural University inspection and quarantine Technology Center Hainan Entry-exit Inspection and Quarantine Bureau

The chiral molecule （＋）-N-[（3S）-3-（4-fluorophenyl）heptanoyl]bornane-10,2-sultam （C23H32FNO3S, Mr = 421.56）, a fluorine-containing derivative of camphorsultam, was conveniently obtained and crystallized in the orthorhombic space group P212121 with a = 7.9044（11）, b = 11.6680（16）, c = 24.899（3） , V = 2296.4（5） 3, Z = 4, Dc = 1.219 Mg/m3, λ = 0.71073 , μ（MoKα） = 0.172 mm-1 and F（000） = 904. X-ray diffraction analysis reveals that the six-membered ring of sultam shows a boat conformation （Fig. 1）. The planes constructed by （（C6）, （C7）, （C8）, （C9）） and （（C4）, （C5）, （C6）, （C9）） form a dihedral angle of 70.3（3）°. The plane of （C1）-（C2）-（C3） forms dihedral angles to the aforementioned planes of 85.9（4） and 89.5（4）°, respectively. The molecules are linked via C-H···O/F interactions.

关键词： (+)-N- [(3S)-3-(4-fluorophenyl)heptanoyl] bornane-10,2-sultam,synthesis crystal structure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Determination of Tetracyclines in Honey Using Liquid Chromatography with Ultraviolet Absorbance Detection and Residue Confirmation by Mass Spectrometry

引用

Chinese Journal of Chemistry 2007年第9期25卷 1294-1299页

作者：刘艳徐锦忠丁涛李公海 Food Laboratory Jiangsu Entry-Exit Inspection and Quarantine Bureau Nanjing Jiangsu 210001 China

A determination method has been optimized and validated for the simultaneous analysis of tetracycline （TC）, oxytetracycline （OTC）, chlortetracycline （CTC） and doxycycline （DC） in honey. Tetracyclines （TCs） were removed from honey samples by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns and eluted with Na2EDTA-Mcllvaine pH 4.0 buffers. Extracts were further cleaned up by Oasis HLB solid-phase extraction （SPE）, while other solid-phase extraction cartridges were compared. Chromatographic separation was achieved using a polar end-capped C 18 column with an isocratic mobile phase consisting of oxalic acid, acetonitrile and methanol. LC with ultraviolet absorbance at 355 nm resulted in the quantitation of all four tetracycline residues from honey samples fortified at 15, 50, and 100 ng/g, with liner ranges for tetracyclines of 0.05 to 2 μg/mL. Mean recoveries for tetracyclines were greater than 50% with R.S.D. values less than 10% （n= 18）. Detection limits of 5, 5, 10, 10 ng/g for oxytetracycline, tetracycline, chlortetracycline and doxycycline, respectively and quantitation limits of 15 ng/g for all the four tetracyclines were determined. Direct confirmation of the four residues in honey （2-50 ng/g） was realized by liquid chromatography-tandem mass spectrometry （LC/MS/MS）. The linear ranges of tetracyclines determined by LC/MS/MS were between 5 to 300 ng/mL, with the linear correlation coefficient r〉 0.995. The limits of detection of 1 to 2 ng/g were obtained for the analysis of the TCs in honey.

关键词： tetracyclines honey metal chelate affinity chromatography LC/MS/MS

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Distributed Harmonic Power Sharing with Voltage Distortion Suppression in Islanded Microgrids Considering Non-linear Loads

引用

CSEE Journal of Power and Energy Systems 2024年第1期10卷 117-128页

作者： Guannan Lou Shanlin Li Wei Gu Quan Yang School of Electrical Engineering Southeast UniversityNanjingJiangsu 210096China the Jiangsu Provincial Key Laboratory of Smart Grid Technology and Equipment Southeast University Dongguan Power Supply bureau of guangdong Power Grid Company Guangdong 523000China

In contemporary power grids or microgrids,harmonic distortion has emerged as one of the critical power quality issues for utility power grids,which has escalated especially due to the high penetration of power-electronic-converter-interfaced distributed generation(DG).This paper first illustrates the prevalent dispute revolving around the harmonic power sharing and distortion restraint,and subsequently proposes a consensusbased framework that facilitates an accurate sharing of harmonics among multi-DGs connected in parallel,with an effective suppression of the output voltage *** with the majority of existing studies addressing the issue of voltage harmonics at the point of common coupling(PCC),our method primarily emphasizes on the output voltage distortion since the power quality requirement for certain local critical loads is often known to be *** the help of adaptive regulation,the overall distortion produced at the output terminals of DGs can be retained within an acceptable *** working principle of the proposed control method,which is not only easy to implement but also independent of model parameters,is further described in *** the small-signal dynamic model,the system stability and robustness are *** hardware-in-the-loop(HIL)simulations aid in determining the outcome of the proposed strategy in microgrid control.

关键词： Distributed generation droop control harmonic power sharing microgrid voltage distortion mitigation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

In vitro Selection of DNA Aptamers and Fluorescence-Based Recognition for Rapid Detection Listeria monocytogenes

引用

Journal of Integrative Agriculture 2014年第5期13卷 1121-1129页

作者： LIU Guo-qing LIAN Ying-qi GAO Chao YU Xiao-feng ZHU Ming ZONG Kai CHEN Xue-jiao YAN Yi School of Biotechnology and Food Engineering Hefei University of Technology Anhui entry-exit inspection and quarantine bureau

Aptamers are specific nucleic acid sequences that can bind to a wide range of nucleic acid and non-nucleic acid targets with high affinity and specificity. Nucleic acid aptamers are selected in vitro from single stranded DNA or RNA ligands containing random sequences of up to a few hundred nucleotides. Systematic evolution of ligands by exponential enrichment （SELEX） was used to select and PCR amplify DNA sequences （aptamers） capable of binding to and detecting Listeria monocytogenes, one of the major food-borne pathogens. A simplified affinity separation approach was employed, in which L. monocytogenes in exponential （log） phase of growth was used as the separation target. A fluorescently-labeled aptamer assay scheme was devised for detecting L. monoeytogenes. This report described a novel approach to the detection of L. monocytogenes using DNA aptamers. Aptamers were developed by nine rounds of SELEX. A high affinity aptamer was successfully selected from the initial random DNA pool, and its secondary structure was also investigated. One of aptamers named e01 with the highest affinity was further tested in aptamer-peroxidase and aptamer-fluorescence staining protocols. This study has proved the principle that the whole-cell SELEX could be a promising technique to design aptamer-based molecular probes for dectection of pathogenic microorganisms without tedious isolation and purification of complex markers or targets.

关键词： aptamers systematic evolution of ligands by exponential enrichment (SELEX) Listeria monocytogenes,rapid detection

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Prediction of the Shearing Property of Worsted Fabrics Using BP Neural Network

引用

Journal of Donghua University(English Edition) 2006年第6期23卷 47-49页

作者：徐广标张向华王府梅 College of Textiles Donghua University Panyu entry-exit inspection and quarantine bureau

In this paper, three layers of BP neural network were used to model the shearing properties of worsted fabrics. We train the neural network models with 27 kinds of fabrics, and then use 6 kinds of fabrics to validate ... 详细信息

关键词： worsted fabric shearing properties neural network models predictive accuracy.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The Technology Parameters Optimization of Extracting Natural Cellulose Fibers from Eulaliopsis Binata

引用

Journal of Donghua University(English Edition) 2010年第4期27卷 516-521页

作者：曲丽君郭肖青由瑞华孙亚宁迟德玲 College of Textile and Clothing Qingdao University Shandong entry-exit inspection and quarantine bureau

The extracting process and parameters optimization of Eulaliopsis binata fibers were *** components of Eulaliopsis binata were tested,the cellulose contents was about 45%,and the lignin content was as high as 18.5%.And the components of Eulaliopsis binata fibers were compared with some bast *** analysis of physical and chemical properties related to acid,alkali,and auxiliary agent about cellulose and pectin,and lignin components in Eulaliopsis binata fibers were *** chemical processing was employed to extract Eulaliopsis binata fibers in which NaOH as cooking agent and Na5P3O10 as auxiliary *** universal rotatable composite experiment design was used to get the highly precise regression equations,in which the NaOH concentration,the auxiliary agent Na5P3O10 concentration and the processing time were the main technological *** residual gum content,fiber fineness,fiber strength,and fiber length of Eulaliopsis binata were the evaluation *** on the relation among parameters of extracting process,degumming effect and quality indexs of Eulaliopsis binata fibers,the optimum parameters of extracting process on Eulaliopsis binata fibers can be *** fibers extracted from Eulaliopsis binata can be developed as one kind of natural cellulose fibers suitable for producing various textile products.

关键词： Eulaliopsis binata fibers extracting parameters optimization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Identification of Plant-Pathogenic Fungi Using Fourier Transform Infrared Spectroscopy Combined with Chemometric Analyses

引用

光谱学与光谱分析 2016年第11期36卷 3764-3771页

作者： CHAI A-li WANG Yi-kai ZHU Fa-di SHI Yan-xia XIE Xue-wen LI Bao-ju Institute of Vegetables and Flowers Chinese Academy of Agricultural Sciences Beijing 100081 China Beijing entry-exit inspection and quarantine bureau Beijing 100026 China

Identification of plant-pathogenic fungi is time-consuming due to cultivation and microscopic examination and can be influenced by the interpretation of the micro-morphological characters *** present investigation aimed to create a simple but sophisticated method for the identification of plant-pathogenic fungi by Fourier transform infrared(FTIR)*** this study,FTIR-attenuated total reflectance(ATR)spectroscopy was used in combination with chemometric analysis for identification of important pathogenic fungi of horticultural *** of mycelia and spores from 27fungal strains belonging to nine different families were collected from liquid PD or solid PDA media cultures and subjected to FTIR-ATR spectroscopy *** FTIR-ATR spectra ranging from 4 000to 400cm-1 were *** classify the FTIRATR spectra,cluster analysis was compared with canonical vitiate analysis(CVA)in the spectral regions of3 050~2 800and 1 800~*** showed that the identification accuracies achieved 97.53%and99.18%for the cluster analysis and CVA analysis,respectively,demonstrating the high potential of this technique for fungal strain identification.

关键词： Fourier transform infrared spectroscopy(FTIR) Plant-pathogenic fungi Identification Cluster analysis Canonical vitiate analysis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：