检索结果-南通市图书馆

New insights into the deposition of natural gas hydrate on pipeline surfaces:A molecular dynamics simulation study

Petroleum Science 2024年第1期21卷 694-704页

作者： Jun Zhang Hai-Qiang Fu Mu-Zhi Guo Zhao Wang li-wen li Qi Yin You-Guo Yan Wei Wei Wei-Feng Han Jie Zhong School of Materials Science and Engineering China University of Petroleum(East China)Qingdao 266580ShandongChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580ShandongChina Department of Alternative Energy PetroChina Research Institute of Petroleum Exploration&DevelopmentLangfang 065007HebeiChina

Natural gas hydrate(NGH)can cause pipeline blockages during the transportation of oil and gas under high pressures and low *** hydrate adhesion on pipelines is viewed as an efficient way to prevent NGH *** studies suggested the water film can greatly increase hydrate adhesion in gas-dominant ***,by performing the molecular dynamics simulations,we find in water-dominant system,the water film plays different roles in hydrate deposition on Fe and its corrosion ***,due to the strong affinity of water on Fe surface,the deposited hydrate cannot convert the adsorbed water into hydrate,thus,a water film *** water affinities decrease(Fe>Fe_(2)O_(3)>FeO>Fe_(3)O_(4)),adsorbed water would convert to amorphous hydrate on Fe_(2)O_(3)and form the ordered hydrate on FeO and Fe_(3)O_(4)after hydrate *** absorbed water film converts to amorphous or to hydrate,the adhesion strength of hydrate continuously increases(Feliquid layer,the process of which becomes harder as liquid layer *** a result,contrary to gas-dominant system,the water film plays the weakening roles on hydrate adhesion in water-dominant ***,our results can help to better understand the hydrate deposition mechanisms on Fe and its corrosion surfaces and suggest hydrate deposition can be adjusted by changing water affinities on pipeline surfaces.

关键词： Deposition Natural gas hydrate Pipelines Water affinity Adhesion strength

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

基于指纹图谱的加味葛根颗粒6种指标成分含量测定及多元统计分析

引用

中国新药杂志 2024年第9期33卷 934-941页

作者：李文莉李军鸽朱凯王永春楚云杰长春中医药大学附属医院长春130117 长春中医药大学长春130117

目的:建立加味葛根颗粒的指纹图谱,测定其中6种成分的含量,并进行正交偏最小二乘判别法分析(OPLS-DA)。方法:采用HPLC法,色谱柱为Tech Mate-C18柱,流动相为乙腈-0.05%磷酸溶液(梯度洗脱),检测波长为254 nm,柱温为35℃,流速为1 mL·min^(... 详细信息

目的:建立加味葛根颗粒的指纹图谱,测定其中6种成分的含量,并进行正交偏最小二乘判别法分析(OPLS-DA)。方法:采用HPLC法,色谱柱为Tech Mate-C18柱,流动相为乙腈-0.05%磷酸溶液(梯度洗脱),检测波长为254 nm,柱温为35℃,流速为1 mL·min^(-1)。采用《中药色谱指纹图谱相似度评价系统》2012年版进行相似度评价,确定共有峰,并测定其中6种成分的含量;采用SIMCA 14.0软件进行OPLS-DA分析,并利用分析变量重要性投影值(VIP)筛选影响其质量的标志物。结果:10批加味葛根颗粒共有14个共有峰,相似度均>0.9;共指认了6个色谱峰并分别测定了含量,各成分在考察范围内线性良好,r值在0.999 0~0.999 9之间。OPLS-DA筛选得到了6个VIP>1的共有峰(峰13、峰7、峰12、峰2、峰8、峰9),经对照品指认了其中3个差异性标志物(肉桂酸、原儿茶酸、芍药苷)。结论:结合多元统计分析,建立的指纹图谱和含量测定方法准确、稳定、可行,可用于加味葛根颗粒的质量控制。

关键词：加味葛根颗粒指纹图谱含量测定聚类分析

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

采用改进多目标灰狼算法的电力系统调度规划

引用

机械设计与制造 2024年第2期396卷 373-379页

作者：肖岚温丽丽赵静喻显茂国网四川省电力公司信息通信公司四川成都610041 国网四川省电力公司四川成都610041

对计及经济、环境因素的电力系统发电调度问题(Economic Environmental Dispatching,EED)进行研究,提出一种采用改进多目标灰狼算法的发电调度规划方案。构建基于发电燃料成本、污染气体排放量和节点电压偏移量等指标的多目标EED模型,... 详细信息

对计及经济、环境因素的电力系统发电调度问题(Economic Environmental Dispatching,EED)进行研究,提出一种采用改进多目标灰狼算法的发电调度规划方案。构建基于发电燃料成本、污染气体排放量和节点电压偏移量等指标的多目标EED模型,并采用改进的多目标灰狼算法进行求解,以得到更优的Pareto前沿和折中解。设计多度量自适应FCM算法对灰狼算法(Gray Wolf Algorithm,GWA)种群多样性进行分析,重新定义狼群层级结构和Pareto前沿规模控制策略,并在此基础上提出反向学习和变异进化策略,以提升GWA全局收敛性能。仿真结果表明,改进的GWA具有优秀全局寻优能力,而且基于改进多目标灰狼算法得到的Pareto前沿和折中解更具可行性和优越性。

关键词：发电调度帕累托最优多目标灰狼算法 FCM 折中解

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

Optimization of spray conditions in cold spraying based on numerical analysis of particle velocity

引用

中国有色金属学会会刊：英文版 2004年第z1期14卷 43-48页

作者： li wen-ya li Chang-jiu State Key Laboratory for Mechanical Behavior of Materials Xi''an Jiaotong University Xi''an 710049 China State Key Laboratory for Mechanical Behavior of MaterialsXi''an Jiaotong University Xi''an 710049 China

The effects of the parameters involved in cold spray on the acceleration of particles are systematically investigated by a CFD code in order to reveal the main factors influencing significantly particle velocity. The parameters involved include nozzle geometry parameters, processing parameters and properties of spray particles. It is found that driving gas type, operating pressure and temperature are main processing parameters which influence particle velocity. As for nozzle geometry, the expansion ratio and divergent section length of spray gun nozzle show significant effects. Moreover, the density, size and morphology of powder also have significant effects on particle velocity. The effects of those main parameters are summarized in a comprehensive equation obtained through nonlinear regression of the simulated results for the estimation of particle velocity. The interactions of the parameters on particle acceleration can be examined through the equation. Moreover, the optimization of the dimensions of spray gun nozzle and spray parameters can be realized based on the obtained results.

关键词： cold spraying numerical modeling particle acceleration impact velocity

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

用LC-MS/MS法同时测定大鼠血浆中多黏菌素B和替加环素的浓度

引用

中国临床药理学杂志 2024年第7期40卷 1049-1053页

作者：韩竺杭刘玥李文利郑天伦杨秀岭河北医科大学第二医院药学部河北石家庄050000

目的建立大鼠血浆中多黏菌素B和替加环素测定的液相色谱串联质谱(LC-MS/MS)方法,并研究其在大鼠体内的药代动力学特征。方法用3%三氯乙酸-甲醇溶液(50:50)对大鼠血浆进行沉淀蛋白处理。色谱柱:Symmetry C_(18)(150.0mm×4.6mm,3.5μm),... 详细信息

目的建立大鼠血浆中多黏菌素B和替加环素测定的液相色谱串联质谱(LC-MS/MS)方法,并研究其在大鼠体内的药代动力学特征。方法用3%三氯乙酸-甲醇溶液(50:50)对大鼠血浆进行沉淀蛋白处理。色谱柱:Symmetry C_(18)(150.0mm×4.6mm,3.5μm),流动相:0.1%甲酸水-0.1%甲酸乙腈,流速:0.6mL·min^(-1),柱温:40℃;离子源:电喷雾离子源,正离子检测模式,多反应检测。考察该方法的专属性、标准曲线和定量下限、精密度与回收率、稳定性以及重现性。结果替加环素的线性范围为25~2500ng·mL^(-1),定量下限为25ng·mL^(-1),提取回收率为95.89%~107.90%;多黏菌素B_(1+1-I)的线性范围为82~8200ng·mL^(-1),定量下限为82ng·mL^(-1),提取回收率为93.84%~97.70%;多黏菌素B_(2)的线性范围为9~900ng·mL^(-1),定量下限为9ng·mL^(-1),提取回收率为96.41%~104.80%;各个物质的日内、日间相对标准偏差均小于10%,稳定性和重现性良好。结论本方法操作简单、灵敏度高、分析时间短,适用于大鼠血浆中多黏菌素B和替加环素的血药浓度测定以及药代动力学的研究。

关键词：多黏菌素B 替加环素液相色谱串联质谱药代动力学生物样本测定

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

Formation mechanism of an aluminium-based chemical conversion coating on AZ91D magnesium alloy

引用

International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 641-647页

作者： Wei-ping li Xi-mei Wang li-qun Zhu wen li Key Laboratory of Aerospace Materials and Performance （Ministry of Education of China） School of Materials Science and EngineeringBeihang University Beijing 100083 China

An environmentally clean aluminium-based conversion coating on AZ91D magnesium alloy was studied in aluminium nitrate solutions. The morphology, composition, structure, and formation mechanism of the coating were investigated in detail using scanning electron microscopy/energy dispersion spectrometry, X-ray diffraction, transmission electron microscopy, and electrochemical corrosion tests. The results show that the conversion coating is composed of magnesium, aluminium, and oxygen, and shows an amorphous structure. In the initial stage of coating formation, the grain-like nucleus is composed of Al10O15·xH2O, （Al2O3）5.333, Al2O3, AlO（OH）, MgAl2O4, （Mg0.88Al0.12）（Al0.94Mg0.06）2O4, and （Mg0.68Al0.32）（Al0.84Mg0.16）2O4. The conversion coating formed in the 0.01 mol/L aluminium nitrate solution for 15 min can improve the corrosion resistance of the magnesium alloy greatly. The discussion reveals that the possible formation mechanism for the aluminium-based conversion coating is the reduction reaction on micro-cathodic sites due to the electrochemically heterogeneous magnesium alloy substrate.

关键词： magnesium alloys coatings aluminium nitrate corrosion resistance

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

A novel blind deconvolution algorithm using single frequency bin

引用

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1271-1276页

作者： ZHANG Gui-bao li Jia-wen li Cong-xin National Die ＆ Mold CAD Engineering Research Center Shanghai Jiao Tong University Shanghai 200030 China

Former frequency-domain blind devolution algorithms need to consider a large number of frequency bins and recover the sources in different orders and with different amplitudes in each frequency bin,so they suffer from permutation and amplitude indeterminacy troubles. Based on sliding discrete Fourier transform,the presented deconvolution algorithm can directly recover time-domain sources from frequency-domain convolutive model using single frequency bin. It only needs to execute blind sepa-ration of instantaneous mixture once there are no permutation and amplitude indeterminacy troubles. Compared with former algorithms,the algorithm greatly reduces the computation cost as only one frequency bin is considered. Its good and robust per-formance is demonstrated by simulations when the signal-to-noise-ratio is high.

关键词： Blind deconvolution Single frequency bin Convolutive mixture

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

Quantitative parameter character of choroidal melanoma in contrast-enhanced ultrasound

引用

Chinese Medical Journal 2012年第24期125卷 4440-4444页

作者： YANG wen-li WEI wen-bin li Dong-jun a Department of Ophthalmology Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing Ophthalmology & Visual Sciences Key Laboratory Beijing 100730 China

Background Choroidal melanoma is the most common intraocular malignant tumor in adults. It threatens not only the visual function but also the patient＇s life. Therefore, it is important to find a non-traumatic, quantitative and repetitive diagnostic method. This study investigated the value of quantitative analysis of contrast-enhanced ultrasound （CEUS） in the diagnosis of choroidal melanoma. Methods CEUS were performed in 51 cases of choroidal melanoma, which were diagnosed either pathologically or clinically and in 14 cases of choroidal hemangioma. The characteristics of the time-intensity curve of the contrast agent were analyzed. For the quantitative analysis, the following parameters of the contrast agent in the lesion were included： rising time （RT）, time to peak （TTP）, maximum intensity （MI） and the mean transit time （MTT）. Results Choroidal melanoma had the following characteristics on CEUS： Choroidal lesions were completely filled with contrast agent. The typical filling pattern was centripetal, with the peripheral of the choroidal lesion filled with the contrast agent first and then the center of the lesion. In some cases, areas with contrast agent filling defect were obseved in the lesions. The contrast agent filled the lesion slower than the normal eye and orbital tissue but faded faster in the lesion. Quantitative analysis showed that in choroidal melanoma, MI of contrast agent （191.31%±146.90%） was significantly more than that of the normal tissue （100.00%±0.00%）（P 〈0.05） and MTT （（63.56±26.04） seconds） was significanly less than that of the normal tissue （（149.87±182.68）seconds）（P 〈0.05）. TTP （22.80±9.85） was less than that of the normal tissue （（29.57±24.76） seconds） and RT （（18.52±7.09） seconds） was less than that of the normal tissue （（26.45±21.83） seconds）. Both the differences of TTP and RT were not statistically significant though. Logistic regression showed that to predict choroidal melanoma and choroidal hemangioma with MI and MTT, the sensi

关键词： choroidal disease malignant melanoma contrast ultrasound diagnosis

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

Layered niobium carbide enabling excellent kinetics and cycling stability of li-Mg-B-H hydrogen storage material Layered niobium carbide enabling excellent kinetics

引用

Rare Metals 2024年第3期43卷 1153-1166页

作者： li-wen Lu Hui Luo Guang-Xu li Yun li Xin-Hua Wang Cun-Ke Huang Zhi-QiangLan wen-Zheng Zhou Jin Guo Mohammad Ismail Hai-Zhen liu Guangxi Novel Battery Materials Research Center of Engineering Technology Guangxi Colleges and Universities Key Laboratory of Blue Energy and Systems IntegrationSchool of Physical Science and TechnologyGuangxi UniversityNanning530004China State Key Laboratory of Featured Metal Materials and life-Cycle Safety for Composite Structures Nanning530004China School of Mechanical and Electrical Engineering Quzhou College of TechnologyQuzhou324000China Department of Materials Science and Engineering Zhejiang UniversityHangzhou310027China Faculty of Ocean Engineering Technology and Informatics Universiti Malaysia Terengganu21030Kuala NerusTerengganuMalaysia Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Nankai UniversityTianjin300071China

The li-Mg-B-H composite(2liBH_(4)+MgH_(2))has a high capacity of 11.4 wt%as a hydrogen storage ***,the slow kinetics and poor cycling stability severely restrict its practical *** this work,a layered Nb_(2)C MXene was first synthesized and then introduced to tailor the kinetics and cycling stability of the li-Mg-B-H *** milled 2liH+MgB_(2)composites were initially hydrogenated to obtain the 2liBH_(4)+MgH_(2)*** 2liBH_(4)+MgH_(2)+5wt%Nb_(2)C can release 9.0 wt%H_(2)in 30 min at 400℃,while it is only 2.7 wt%for the undoped 2liBH_(4)+MgH_(2).The dehydrogenation activation energies of MgH_(2)and liBH_(4)are 123 and 154 kJ·mol^(-1)respectively for the 5 wt%Nb_(2)C-doped composite,lower than the undoped composite(164 and 165 kJ·mol^(-1)).The 2liBH_(4)+MgH_(2)+5 wt%Nb_(2)C possesses excellent cycling stability,with the reversible capacity only slightly reduced from 9.4 wt%for the 1st cycle to 9.3 wt%for the 20th ***_(2)C keeps stable in the composite and acts as an efficient catalyst for the li-Mg-B-H *** is believed that both the layered structure and the active Nb element contribu te to the enhanced hydrogen storage performances of the li-Mg-B-H *** work confirms that the Nb_(2)C MXene with layered stru cture has a significant enhancing impact on the li-Mg-B-H hydrogen storage materials,which is different from the bulk NbC.

关键词： Hydrogen storage lithium borohydride Magnesium hydride Nb_(2)C MXene

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

牛大力亚慢性毒性研究

引用

医学信息 2024年第7期37卷 62-68页

作者：汤莉胡帅尔陈美芬张紫虹李文立李冬利广东省疾病预防控制中心卫生毒理所五邑大学生物科技与大健康学院

目的通过开展牛大力的亚慢性毒性试验，为其安全性评价提供试验依据。方法 80只SPF级SD种大鼠(雌雄各半)分成4个组，分别为低、中、高3个剂量组[0.86、2.58、7.73 g/(kg·bw)]和阴性对照组，经口灌胃分别给予相应剂量的牛大力，阴性对... 详细信息

目的通过开展牛大力的亚慢性毒性试验，为其安全性评价提供试验依据。方法 80只SPF级SD种大鼠(雌雄各半)分成4个组，分别为低、中、高3个剂量组[0.86、2.58、7.73 g/(kg·bw)]和阴性对照组，经口灌胃分别给予相应剂量的牛大力，阴性对照组给予纯净水，连续灌胃90 d。实验结束，大鼠经腹腔麻醉后采血检测血液指标，采集脏器称重及计算脏/体比，并进行病理学检查。结果各剂量组动物生长发育良好，体重、摄食量、食物利用率、血常规、凝血、血生化指标、脏器重，以及脏/体比指标与阴性对照组比较，差异无统计学意义(P>0.05)，组织病理学观察未见与受试样品有关的病理改变。结论在本试验条件下，确定受试样品牛大力对雌、雄性大鼠的未观察到有害作用剂量(NOAEL)均为75.00 g/(kg·bw)，未见亚慢性毒性。

关键词：牛大力亚慢性毒性安全性评价有害作用剂量

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

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：