检索结果-南通市图书馆

基于FTIR的两种模式识别方法在两面针产地鉴别中的应用

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

光谱学与光谱分析 2011年第10期31卷 2697-2701页

作者：毛晓丽郑娟梅李自达雷欣潮黄庶识刘华钢广西科学院生物物理实验室广西南宁530007 广西中医学院广西南宁530001 广西师范大学物理科学与技术学院广西桂林541004 广西医科大学广西南宁530021

为了探求建立快速鉴别两面针产地的方法，基于傅里叶变换红外光谱（FTIR）技术，选取1800400cm^-1红外指纹图谱带，采用Fisher比值法和SIMCA聚类分析法建立产地分类模型，分别对广西区内四个产地的两面针进行鉴别，并通过计算识别率与... 详细信息

为了探求建立快速鉴别两面针产地的方法，基于傅里叶变换红外光谱（FTIR）技术，选取1800400cm^-1红外指纹图谱带，采用Fisher比值法和SIMCA聚类分析法建立产地分类模型，分别对广西区内四个产地的两面针进行鉴别，并通过计算识别率与拒绝率来验证模型。结果表明，红外光谱技术不但能准确提取中药材的整体信息，并且基于红外光谱建立起的两种模式识别模型对未知样品进行预测，识别率和拒绝率均达到90％以上，说明所建模型具有较强的识别能力。通过自编计算程序以及现有统计软件，还可以将模式识别模型实现实时在线化检测与快速样品鉴别，大大提高了鉴别速度而更具应用价值。

关键词：红外光谱法 Fisher比值法 SIMCA 两面针

The Burial of Biogenic Silica, Organic Carbon and Organic Nitrogen in the Sediments of the East China Sea

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2015年第3期14卷 464-470页

作者： WANG Lisha ZHANG Chuansong shi Xiaoyong College of Chemistry and Chemical Engineering Ocean University of China Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education Ocean University of China National Marine Hazard Mitigation Service

We sampled the sediments of the East China Sea during 2005 and 2006, and analysed the contents of the biogenic matters: biogenic silica, organic carbon, and organic nitrogen. From the surface distribution we found the contents of these substances to be in the ranges of 0.72%-1.64%, 0.043%-0.82%, and 0.006%-0.11%, respectively. Their distributions were similar to each other, being high inside the Hangzhou Bay and low outside the bay. The vertical variations of the contents were also similar. In order to discuss the relation between them we analysed the variations of content with depth. They increased in the first 7 cm and then decreased with depth. The peaks were found at depths between 20 to 25 cm. The distribution of carbonate showed an opposite trend to that of biogenic matters. The content of total carbon was relatively stable with respect to depth, and the ratio of high organic carbon to carbonate showed a low burial efficiency of carbonate, which means that the main burial of carbon is organic carbon. In order to discuss the source of organic matters, the ratio of organic carbon to organic nitrogen was calculated, which was 8.01 to 9.65, indicating that the organic matter in the sediments was derived mainly from phytoplankton in the seawater.

关键词： burial sediment biogenic matters carbon and nitrogen ratio East China Sea

Aerosol exposure assessment during reclaimed water utilization in China and risk evaluation in case of Legionella

在线全文

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2022年第7期16卷 173-183页

作者： Menghao Chen Liangliang shi Gang Liu Xiaojin Wu Yun Lu State Key Joint Laboratory of Environmental Simulation and Pollution Control State Environment Protection Key Laboratory of Microorganism Application and Risk ControlSchool of EnvironmentTsinghua UniversityBeijing100084China

Reclaimed water utilization provides an effective way to alleviate water ***,the residual pathogens in the recycled water like Legionella,could be spread into the air as aerosols through water-to-air transmission *** the aerosols by the people nearby increases their susceptibility to *** estimating the health risks associated with the potential exposure of airborne Legionella emitted from the urban use of reclaimed water in China,nationwide questionnaire was designed to investigate the exposure habits of Chinese population in different *** microbial risk assessment(QMRA)served as the suitable explanatory tool to estimate the *** results indicated that annual infection probability of populations exposed to Legionella for three scenarios,0.0764(95%CI:0.0032−0.6880)for road cleaning,1.0000(95%CI:0.1883−1.0000)for greenfield irrigation,0.9981(95%CI:0.0784−1.0000)for landscape fountain,were markedly higher than the threshold recommended by WHO(10^(−4) per person per year(pppy))according to the concentration distribution of Legionella in the reclaimed *** age-,educational background-,region-and gender-specific data in annual infection probability also showed different tendencies for some *** study provides some detailed information on the health risks from the water reuse in China and will be useful to promote the safe application of reclaimed water in water-deficient areas.

关键词： Legionella QMRA Reclaimed water Aerosol Water reuse

Immobilization of urease in metal–organic frameworks via biomimetic mineralization and its application in urea degradation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2020年第8期28卷 2173-2180页

作者： Xiao Liang Qing Li Zhiyuan shi Shaowei Bai Quanshun Li Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education School of Life SciencesJilin UniversityChangchun 130012China

Enzyme immobilization has been accepted as an efficient technique for improving the stability and recyclability of ***,biomimetic mineralization strategy was employed to achieve the immobilization of urease in a type of metal–organic frameworks(zeolite imidazolate framework-8,ZIF-8),and the immobilized enzyme urease@ZIF-8 was systematically evaluated for its structure,activity,stability and recyclability,using the hydrolysis of urea as a *** entrapment of urease was found to be realized in a synchronous manner with the formation of ZIF-8 *** loading of urease in ZIF-8 was measured to be ca.10.6%through the bicinchoninic acid(BCA)protein *** encapsulated urease could efficiently maintain its native conformation,which endowed the immobilized urease with excellent activity and stability,even in harsh conditions(e.g.,in the presence of trypsin,acidic or alkali conditions,or at high temperature).Further,urease@ZIF-8 exhibited good recyclability during the degradation of urea,in which it could keep 58.86%of initial activity after being used for 5 ***,biomimetic mineralization could be potentially utilized as a promising method to prepare immobilized ureases with superior activity,stability and recyclability,thereby facilitating the construction of efficient catalysts for industrial biocatalysis and biosensing.

关键词： Urease Metal–organic frameworks Immobilization Biomimetic mineralization Stability Recyclability

Aeration performances and air—Water mass transfer on steep stepped weirs with horizontal and inclined steps

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2022年第5期34卷 904-916页

作者： Yvan Arosquipa Nina Rui shi Davide Wüthrich Hubert Chanson The University of Queensland School of Civil EngineeringBrisbaneAustralia Department of Hydraulic Engineering Delft University of TechnologyDelftThe Netherlands

At hydraulic structures,some strong interactions may develop between fast flowing waters and the air adjacent to the water in motion that enhance the air-water transfer of atmospheric and volatile gases in the *** turn,in-stream structures may contribute to the aeration and re-oxygenation during *** present study aims to characterize the aeration performance of a steep stepped weir,based upon a detailed physical investigation of air-water interfacial properties across a relatively wide range of *** data showed a strong fragmentation of the air-water flows,a very broad range of entrained bubbles and drops,and a large amount of particle *** results implied a monotonic increase in re-aeration with increasing rate of energy dissipation,while the largest aeration efficiency was observed on the horizontal step weir chute,with the smallest on the 1V:2.33H inclined downward ***,the study showed that a steep stepped chute can make a sizeable contribution to the re-oxygenation of the waters,although the downward inclined steps reduce the re-aeration performances.

关键词： Stepped weirs aeration re-oxygenation physical modeling flow fragmentation

Progress on the mechanisms of Ru-based electrocatalysts for the oxygen evolution reaction in acidic media

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

Journal of Energy Chemistry 2023年第10期85卷 220-238,I0008页

作者： Yuanyuan shi Han Wu Jiangwei Chang Zhiyong Tang Siyu Lu Green Catalysis Center and College of ChemistryZhengzhou UniversityZhengzhou 450001HenanChina CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China

Water electrolysis using proton-exchange membranes is one of the most promising technologies for carbon-neutral and sustainable energy ***,the overall efficiency of water splitting is limited by the oxygen evolution reaction(OER).Nevertheless,a trade-off between activity and stability exists for most electrocatalytic materials in strong acids and oxidizing media,and the development of efficient and stable catalytic materials has been an important focus of *** this view,gaining in-depth insights into the OER system,particularly the interactions between reaction intermediates and active sites,is significantly *** this end,this review introduces the fundamentals of the OER over Ru-based materials,including the conventional adsorbate evolution mechanism,lattice oxygen oxidation mechanism,and oxide path ***,the up-to-date progress of representative modifications for improving OER performance is further discussed with reference to specific mechanisms,such as tuning of geometric,electronic structures,incorporation of proton acceptors,and optimization of metal-oxygen ***,some valuable insights into the challenges and opportunities for OER electrocatalysts are provided with the aim to promote the development of next-generation catalysts with high activity and excellent stability.

关键词： Oxygen evolution reaction Ru-based electrocatalysts Acidic solutions Mechanism Proton-exchange membranes

Reflection separation technology based on polarization characteristics

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2022年第5期33卷 1032-1042页

作者： ZHANG Yan ZHANG Jinghua shi Zhiguang ZHANG Yu LING Feng National Key Laboratory of Science and Technology on Automatic Target Recognition College of Electronic Science and EngineeringNational University of Defense TechnologyChangsha 410073China

Specific to the reflected light problem on the surface of transparent body,the polarization characteristics of the reflection region are analyzed,and a polarization characterization model combining the reflection and transmission effects is *** the basis of the polarization characteristic analysis,the minimum value of normalized cross-correlation(NCC)coefficient between transmission and reflection images is solved through the gradient descent method,and their polarization degrees under the minimum correlation are *** to the distribution relations of the transmitted and reflected lights in perpendicular and parallel directions,reflection separation is realized via the polarized orthogonality difference algorithm based on the degree of reflection polarization and the degree of transmission polarization.

关键词： reflection separation transparent object correlation polarization characteristics

Low-Power CMOS VCO with Dual-Band Local Oscillating Signal Outputs for 5/2.5-GHz WLAN Transceivers

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2003年第2期8卷 121-125页

作者： CHI Baoyong(池保勇) shi Bingxue(石秉学) Institute of Microelectronics Tsinghua University Beijing 100084 China Institute of Microelectronics Tsinghua University Beijing 100084 China

The paper describes a low-power CMOS voltage-controlled oscillator (VCO) with dual-band local oscillating (LO) signal outputs for 5/2.5-GHz wireless local area network (WLAN) transceivers. The VCO is based on an on-chip symmetrical spiral inductor and a differential varactor. The 2.5-GHz quadrature LO signals are generated using the injection-locked frequency divider (ILFD) technique. The ILFD structure is similar to the VCO structure with its wide tracking range. The design tool ASITIC was used to optimize all on-chip symmetrical inductors. The power consumption was kept low with differential LC tanks and the ILFD technique. The circuit was implemented in a 0.18-μm CMOS process. Hspice and SpectreRF simulations show the proposed circuit could generate low phase noise 5/2.5-GHz dual band LO signals with a wide tuning range. The 2.5-GHz LO signals are quadrature with almost no phase and amplitude errors. The circuit consumes less than 5.3 mW in the tuning range with a power supply voltage of 1.5 V. The die area is only 1.0 mm×1.0 mm.

关键词： CMOS integrated circuits Frequency dividing circuits Transceivers Variable frequency oscillators

Usefulness of dobutamine stress myocardial contrast echocardiography for assessing coronary artery disease

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2005年第21期118卷 1766-1772页

作者： GUO shi-zun shu Xian-hong PAN Cui-zhen LI Yan-lin GE Jun-bo CHEN Hao-zhu Institute of Cardiovascular Diseases Zhongshan Hospital Fudan University Shanghai 200032 China

Background Quantitatively assessing myocardial perfusion and its reserve is of great importance for the diagnosis and stratification of patients with coronary artery disease （ CAD）, and represents an important goal of myocardial contrast echocardiography. In this study we sought to test the usefulness of low dose dobutamine stress real-time myocardial contrast echocardiography （RT-MCE） in the assessment of CAD, and to explore the relationship between perfusion reserve and contractile reserve. Methods Twenty-six patients with suspected or clinical diagnosed CAD were enrolled and underwent RT-MCE at baseline and under low dose dobutamine stress, and subsequent coronary angiography. RT-MCE images were analyzed quantitatively from microbubble replenishment curves for myocardial perfusion and its reserve. Results At baseline, significant differences in beta （0.28± 0. 12, 0. 25± 0. 09, 0.22 ± 0. 06, 0. 20± 0.07 respectively, P 〈0. 01） and A x beta （1.37 ±0. 46, 1.28±0. 47, 1. 13 ±0. 37, 0.91±0. 32, respectively, P 〈0. 01 ） were observed among four segment groups with graded coronary artery stenosis severity （normal; 30% -69% stenosis; 70% -90% stenosis; and beyond 90% stenosis） , but not observed in parameter A. When under stress, significant differences in A （5.73 ± 1.28, 5.63 ± 1.01,4.96 ±0.81,4.57 _＋0.62, respectively, P〈0.01）, beta （0.67 ±0. 17, 0.55 ±0. 19, 0.32 ±0. 13, 0.25 ±0.08, respectively, P 〈0.01） and A x beta （3.81 ± 1.20, 3. 11±1.17, 1.59 ±0. 82, 1. 12 _＋0. 37, respectively, P 〈0. 01 ） were observed among the formerly mentioned groups. Graded decreases in A reserve （ 1.20 ±0. 53, 1.11 ±0. 16, 0.98 ±0. 12, 0. 99 ±0.13, respectively, P〈0.01）, beta reserve （2.65 ±1.07, 2. 32±0.82, 1.44±0.40, 1.29±0.34, respectively, P〈0.01） and A xbeta reserve （3.05 ± 1.63, 2.59 ±1.01, 1.42 ±0.44, 1.27±0.34, respectively, P 〈 0. 01 ） could also be observed with increasing coronary stenosis severity. In five segments groups scored by WMS （ 1 - 5 ） , concordance between contracti

关键词： echocardiography contrast media coronary disease myocardial reperfusion dobutamine