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Toroidal torques due to n=1 magnetic perturbations in ITER baseline scenario
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作者 Jingwei LI Li LI +5 位作者 Yueqiang LIU Yunfeng LIANG Yanfei WANG Lu TIAN Zhongqing LIU Fangchuan ZHONG 《Plasma Science and Technology》 2025年第1期39-51,共13页
Toroidal torques,generated by the resonant magnetic perturbation(RMP)and acting on the plasma column,are numerically systematically investigated for an ITER baseline scenario.The neoclassical toroidal viscosity(NTV),i... Toroidal torques,generated by the resonant magnetic perturbation(RMP)and acting on the plasma column,are numerically systematically investigated for an ITER baseline scenario.The neoclassical toroidal viscosity(NTV),in particular the resonant portion,is found to provide the dominant contribution to the total toroidal torque under the slow plasma flow regime in ITER.While the electromagnetic torque always opposes the plasma flow,the toroidal torque associated with the Reynolds stress enhances the plasma flow independent of the flow direction.A peculiar double-peak structure for the net NTV torque is robustly computed for ITER,as the toroidal rotation frequency is scanned near the zero value.This structure is found to be ultimately due to a non-monotonic behavior of the wave-particle resonance integral(over the particle pitch angle)in the superbanana plateau NTV regime in ITER.These findings are qualitatively insensitive to variations of a range of factors including the wall resistivity,the plasma pedestal flow and the assumed frequency of the rotating RMP field. 展开更多
关键词 toroidal torques resonant magnetic perturbation fieds plasma flow ITER baseline scenario
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Vibration analysis of nano-structure multilayered graphene sheets using modified strain gradient theory
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作者 Amir ALLAHBAKHSHI Masih ALLAHBAKHSHI 《Frontiers of Mechanical Engineering》 SCIE CSCD 2015年第2期187-197,共11页
In this paper, for the first time, the modified strain gradient theory is used as a new size-dependent Kirchhoff micro-plate model to study the effect of interlayer van der Waals (vdW) force for the vibration analys... In this paper, for the first time, the modified strain gradient theory is used as a new size-dependent Kirchhoff micro-plate model to study the effect of interlayer van der Waals (vdW) force for the vibration analysis of multilayered graphene sheets (MLGSs). The model contains three material length scale parameters, which may effectively capture the size effect. The model can also degenerate into the modified couple stress plate model or the classical plate model, if two or all of the material length scale parameters are taken to be zero. After obtaining the governing equations based on modified strain gradient theory via principle of minimum potential energy, as only infinitesimal vibration is considered, the net pressure due to the vdW interaction is assumed to be linearly proportional to the deflection between two layers. To solve the goveming equation subjected to the boundary conditions, the Fourier series is assumed for w = w(x, y). To show the accuracy of the formulations, present results in specific cases are compared with available results in literature and a good agreement can be seen. The results indicate that the present model can predict prominent natural frequency with the reduction of structural size, especially when the plate thickness is on the same order of the material length scale parameter. 展开更多
关键词 GRAPHENE van der Waals (vdW) force modi- fied strain gradient elasticity theory size effect parameter
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Genesis of the Jiuqu gold deposit, Jiaodong gold province, China: Constraints on the texture, mineral geochemistry, and sulfur isotope of pyrite
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作者 Senmiao Xue Yayun Liang +6 位作者 Lei Shu Wenhao Xue Chenxi Zhang Chonghui Shen Bi He Haiyi Wang Yayi Fang 《Acta Geochimica》 2025年第3期631-647,共17页
The Linglong gold ore field is situated in the northwestern region of the Jiaodong gold province,China,with over 1000 tons of gold resources.Although the metallogenic mechanism and fluid sources of the Linglong gold d... The Linglong gold ore field is situated in the northwestern region of the Jiaodong gold province,China,with over 1000 tons of gold resources.Although the metallogenic mechanism and fluid sources of the Linglong gold deposit have been the subject of extensive discussion and analyzed by numerous scholars,a definitive conclusion remains elusive.The Jiuqu Au deposit is a significant metallogenic area in the eastern part of the Linglong gold ore field,characterized as a quartz vein-type gold deposit.Gold mineralization in the Jiuqu gold deposit is classified into four stages,primarily occurring within the Late Jurassic Linglong granite and Early Cretaceous Guojialing granodiorite.Pyrite,the primary gold-bearing mineral at the Jiuqu Gold Mine,has been present throughout the metallogenic period,is rich in a variety of trace elements and is closely related to the formation of gold ore.This study focused on evaluating pyrite from the essential metallogenic stages(Stages Ⅰ-Ⅲ)of the Jiuqu gold deposit using scanning electron microscopy(SEM),electron microprobe analysis(EMPA),laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS) and laser ablation multi-collector inductively coupled plasma mass spectrometry(LA-MC-ICP-MS) sulfur isotope analysis and detection.The work aimed to reconstruct the origin of metallogenic materials and the evolution of ore-forming fluids and to restrict the genesis of the deposit.Pyrite exhibits discernible alterations in both shape and crystal structure as it progresses through its ore-forming stages.The aforementioned stages can be delineated as follows:type 1 pyrite(PyⅠ),developed in the initial ore stage,is characterized by coarse-to-medium-grained euhedral pyrite in Stage Ⅰ;type 2 pyrite(PyⅡ),developed in the second ore stage,appears during the middle stage of mineralization and is characterized by subhedral or anhedral pyrite;type 3 pyrite(PyⅢ),developed in the third ore stage,primarily occurred in the late-middle stages of mineralization.It is fragmented and coexists with various metal sulfides,including chalcopyrite,sphalerite and galena.The in situ major and elemental compositions of pyrites at Jiuqu indicate that Au,in the form of visible gold,exists in pyrites with low Au and Ag contents throughout all stages.PyⅠ had lower Pb,Bi,Co and Ni contents than those of PyⅡ.PyⅢ displayed decreased Pb,Bi,Co and Ni levels compared with PyⅡ.The δ34S values of the PyⅠ,PyⅡ and PyⅢ pyrite stages ranged from 7.19% to 8.71%,6.24% to 7.68% and 7.66% to 8.07%,respectively.According to the structural and geochemical analysis of pyrite,the ore-forming fluid of the Jiuqu gold deposit was derived from a magmatic-hydrothermal formation created by enriched lithospheric mantle-derived magma,mixing S from Precambrian metamorphic rocks.Previous studies on the H-O isotopes of quartz in the region's ores have indicated the presence of primary magma water.Additionally,studies concerning the C-O isotopes of carbonate minerals in ores have suggested that C may have originated from the mantle.Fluid migration and water-rock interaction resulted in sulfide and gold precipitation.In the Late Meosozoic,lithospheric thinning of eastern North China Craton led to up welling of astheno spheric mantle and partial melting of lithospheric mantle in the Jiaodong area.Under tectonic changes,magmatic-hydro thermal fluid migrated upward along fault structures to form a gold province. 展开更多
关键词 Jiaodong gold province Linglong gold ore fi eld PYRITE Source of ore-forming fl uids Gold precipitation
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Genetic liability to atrial fibrillation,aortic valve disease,and mitral valve disease:a two-sample Mendelian randomization study
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作者 Yun Zhang Chengui Zhuo +1 位作者 Ting Chen Xiaosheng Hu 《World Journal of Emergency Medicine》 2025年第5期475-480,共6页
BACKGROUND:Research has revealed a relationship between atrial fi brillation(AF)and valvular heart disease;however,the causality remains largely unknown.This study explored whether a causal association between AF and ... BACKGROUND:Research has revealed a relationship between atrial fi brillation(AF)and valvular heart disease;however,the causality remains largely unknown.This study explored whether a causal association between AF and non-rheumatic aortic valve disease(AVD)and mitral valve disease(MVD)could be found.METHODS:A two-sample Mendelian randomization(TSMR)method was applied to determine the causal eff ect of AF on AVD,mitral regurgitation,and MVD.The inverse variance weighted(IVW)method was used as the primary analytical approach,and several complementary analyses were conducted.Outliers were detected using the Mendelian Randomization Pleiotropy RESidual Sum and Outlier(MR-PRESSO)and radial Mendelian randomization(MR)methods.RESULTS:Genetically predicted AF was found to be causally associated with the risk of MVD(odds ratio[OR]=1.001;95%confi dence interval[CI]:1.000-1.001;P=1.33×10-6)and mitral regurgitation(OR=1.001;95%CI:1.000-1.002;P=0.009).However,no signifi cant causal associations between AF and AVD were detected(OR=1.000;95%CI:0.999-1.000;P=0.804).Causal eff ects were still detected,even after adjusting for potential risk factors or removing the identifi ed outliers.Reverse MR analyses revealed no signifi cant causal eff ect of valvular heart disease on AF.CONCLUSION:Our findings demonstrate a positive causal association between AF,MVD,and mitral regurgitation,but not AVD.Further research and an aggressive AF management strategy should be explored as potential measures for preventing MVD. 展开更多
关键词 Atrial fi brillation Valvular heart disease Mitral valve disease
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Diagnosis of focal spots at relativistic intensity utilizing coherent radiation from laser-driven flying electron sheets
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作者 Shirui Xu Zhuo Pan +22 位作者 Ying Gao Jiarui Zhao Shiyou Chen Zhusong Mei Xun Chen Ziyang Peng Xuan Liu Yulan Liang Tianqi Xu Tan Song Qingfan Wu Yujia Zhang Zhipeng Liu Zihao Zhang Haoran Chen Qihang Han Jundong Shen Chenghao Hua Kun Zhu Yanying Zhao Chen Lin Xueqing Yan Wenjun Ma 《Matter and Radiation at Extremes》 2025年第2期16-23,共8页
Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challe... Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challenges.In this work,we demonstrate for the firs time that the coherent radiation farfiel patterns from laser–foil interactions can serve as an in situ,real-time,and easy-to-implement diagnostic for an ultraintense laser focus.The laser-driven electron sheets,curved by the spatially varying laser fiel and leaving the targets at nearly the speed of light,produce doughnut-shaped patterns depending on the shapes of the focal spot and the absolute laser intensities.Assisted by particle-in-cell simulations,we can achieve measurements of the intensity and the focal spot,and provide immediate feedback to optimize the focal spots for extremely high intensity. 展开更多
关键词 diagnosis focal spot peak intensity laser foil interactions laser fi coherent radiation farfiel patterns laser driven electron sheets experimental validation laser intensity focal spot coherent radiation
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关于FBZ-代数的一些结果
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作者 邓方安 《模糊系统与数学》 北大核心 2024年第4期21-26,共6页
本文进一步探讨了FBZ-代数的基本性质,刻画了FBZ-代数与BCI代数、模糊蕴涵(FI)代数及W_(d)-模糊蕴涵代数的关系;给出了FBZ-代数一个等价公理系统。最后,证明了FBZ-代数构成模糊蕴涵(FID)代数与W_(d)-模糊蕴涵代数的相关命题。
关键词 FBZ-代数 模糊蕴涵(FI)代数 Wd-模糊蕴涵代数
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基于OBE理念的英语专业口语课程混合式教学改革探析 被引量:2
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作者 彭宁红 《湖南科技学院学报》 2024年第2期105-108,共4页
OBE即成果导向教育,是一种以学习成果为导向的教育理念。针对目前英语专业口语课程教学中存在的问题,在OBE理念指导下,以学生为中心,以“口语产出”为导向,依托Fi F口语训练系统,进行英语专业口语课程线上线下混合式教学改革,确保学生... OBE即成果导向教育,是一种以学习成果为导向的教育理念。针对目前英语专业口语课程教学中存在的问题,在OBE理念指导下,以学生为中心,以“口语产出”为导向,依托Fi F口语训练系统,进行英语专业口语课程线上线下混合式教学改革,确保学生达成课程目标,提升英语口语能力和英语交际能力,为未来职业的成功打下良好基础。 展开更多
关键词 OBE理念 英语专业口语课程 混合式教学 Fi F口语训练系统
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烯烃聚合FI催化剂研究进展
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作者 姜如愿 郑鹏程 +1 位作者 路宝翠 许胜 《化学反应工程与工艺》 2024年第6期561-574,共14页
综述了FI催化剂发展史以及独特的化学特性,详细地叙述了FI催化剂结构性能、合成路线以及配体上各种取代基对催化剂活性的影响,通过对催化剂结构的优化设计,可实现活性聚合产物的高效率合成。另外,通过分析总结FI催化剂在催化丙烯均聚、... 综述了FI催化剂发展史以及独特的化学特性,详细地叙述了FI催化剂结构性能、合成路线以及配体上各种取代基对催化剂活性的影响,通过对催化剂结构的优化设计,可实现活性聚合产物的高效率合成。另外,通过分析总结FI催化剂在催化丙烯均聚、乙烯均聚、乙烯和丙烯共聚、乙烯和长链α-烯烃共聚等聚合方面的应用,以及催化剂对烯烃嵌段共聚物结构与性能的影响,为高性能FI催化剂的开发提供了新思路。 展开更多
关键词 FI催化剂 烯烃聚合 配体合成
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Olefin Polymerization Behavior of Titanium(IV) Complexes with Fluorinated and Non-fluorinated Aliphatic Phenoxyimine Ligands
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作者 Vladislav A.Tuskaev Kasim F.Magomedov +9 位作者 Svetlana Ch.Gagieva Dmitry A.Kurmaev Yulia V.Nelyubina Evgenii K.Golubev Maria D.Evseeva Viktor G.Vasil'ev Galina G.Nikiforova Mikhail I.Buzin Vyacheslav S.Bogdanov Boris M.Bulychev 《Chinese Journal of Polymer Science》 SCIE EI CAS CSCD 2024年第1期52-62,I0007,共12页
A series of Ti(Ⅳ) dichloride and dialkoxide com plexes with phenoxyimine ligands containing fluorinated and nonfluorinated aliphatic imine fragments have been synthesized.The molecular structures of complexes 1 and 4... A series of Ti(Ⅳ) dichloride and dialkoxide com plexes with phenoxyimine ligands containing fluorinated and nonfluorinated aliphatic imine fragments have been synthesized.The molecular structures of complexes 1 and 4 were established by single-crystal X-ray diffraction studies.The complexes adopt a distorted octahedral coordination structure around the titanium atom and two oxygen atoms are situated in trans position while two nitrogen atoms and two outgoing ligands(Cl or iPrO) are situated in cis position.Effect of activators(MMAO-12 and combinations Et_nAICl_(3-n)+Bu_(2)Mg) and outgoing ligand(Cl or iPrO) nature on the catalytic activity and properties of the resulting polymers was studied.The Ti complexes,despite the nature of the outgoing ligands(Cl or iPrO) in the presence of Al/Mg activators,was found to display a high ethylene polymerization activity in the range 1600-3830 kg_(polymer)·mol_(Ti)^(-1)·h^(-1)·atm^(-1) with a viscosity average molecular weight(M_v) value in the range 1.1×10~6-7.1×10~6 Dalton(Da).The resulting UHMWPE can be processed by a solventless method into high-strength and high-modulus oriented films.The rheological characteristics of a polymer melt have been studied.The absence of a cross-over point did not allow to compare the values of the molecular weight distribution of polymers obtained on fluorinated and non-fluorinated pre-catalysts,however,the estimation of the entanglement density is in good agreement with the mechanical characteristics of oriented film s.Upon activation with methylalumoxane,the activity of the com plexes decreased very significantly;however,a polymer with a molecular weight of about 12 million Da was obtained.In the process of ethylene/octene-1 copolymerization,fluorine-containing precatalysts showed a clear advantage over non-fluorinated analogues both in activity and in comonomer content. 展开更多
关键词 FI catalysts Titanium(IV) (Co)polymerization Al/Mg co-catalyst Ultra-high molecular weight polyethylene
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Accelerating Electrocatalytic Nitrate Reduction to Ammonia via Weakening of Intermediate Adsorption on Cu-Based Catalyst
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作者 Yizhu Chen Ang Ma +9 位作者 Lei Chen Xinyang Liu Yan Li Yan Hong Yushuo Zhang Yunyi Liu Lixin Wei Yudong Li Siqi Li Song Liu 《Transactions of Tianjin University》 EI CAS 2024年第6期488-497,共10页
Cu-based materials are commonly used in electrocatalytic nitrate reduction reactions(NO 3 RR).NO 3 RR is a“two birds,one stone”approach,simultaneously removing NO 3−pollutants and producing valuable ammonia(NH 3).Ho... Cu-based materials are commonly used in electrocatalytic nitrate reduction reactions(NO 3 RR).NO 3 RR is a“two birds,one stone”approach,simultaneously removing NO 3−pollutants and producing valuable ammonia(NH 3).However,the strong coordination between the NO 3−intermediate and the catalytic active sites seriously hinders the conversion effi ciency.Here,we determined that,through encapsulation strategies,the carbon layer could weaken the NO 3−intermediate binding to active sites,resulting in higher NH 3 yields.We experimentally fabricated electrocatalysts,i.e.,Cu nanoparticles encapsulating(or loaded on)N-doped carbon nanofi bers(NCNFs)called Cu@NCNFs(Cu-NCNFs),using electrostatic spinning.As a result,Cu@NCNFs can achieve NH 3 yields of 17.08 mg/(h·mg cat)at a voltage of−0.84 V and a Faraday effi ciency of 98.15%.Meanwhile,the electrochemical properties of the Cu nanoparticles on the surface of carbon fi bers(Cu-NCNFs)are lower than those of the Cu@NCNFs.The in situ Raman spectra of Cu@NCNFs and Cu-NCNFs under various reduction potentials during the NO 3 RR process show that catalyst encapsulation within carbon layers can eff ectively reduce the adsorption of N species by the catalyst,thus improving the catalytic performance in the nitrate-to-ammonia catalytic conversion process. 展开更多
关键词 Electrocatalytic nitrate reduction reactions Ammonia synthesis Copper-based electrocatalysts·Electrostatically spun carbon fi ber Regulated adsorption
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中国石化开发出聚乙烯用改性催化剂及其制备方法
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作者 燕丰 《合成树脂及塑料》 CAS 北大核心 2024年第4期23-23,共1页
中国石油化工股份有限公司(简称中国石化)开发出一种聚乙烯用改性催化剂及其制备方法。该催化剂包括主催化剂和改性剂,两者质量比为100.0∶(0.1~30.0)。主催化剂为Ziegler-Natta催化剂、茂金属催化剂、后过渡金属催化剂、FI催化剂、铬... 中国石油化工股份有限公司(简称中国石化)开发出一种聚乙烯用改性催化剂及其制备方法。该催化剂包括主催化剂和改性剂,两者质量比为100.0∶(0.1~30.0)。主催化剂为Ziegler-Natta催化剂、茂金属催化剂、后过渡金属催化剂、FI催化剂、铬基催化剂中的一种,改性剂为硅氧烷、苯乙烯基聚合物中的至少一种。该方法通过将改性剂引入主催化剂中,改变了主催化剂原有活性位点的分布和催化特性,进而可以改变聚乙烯活性链的生长和结晶行为,提高了聚乙烯的相对分子质量分布。 展开更多
关键词 后过渡金属催化剂 茂金属催化剂 主催化剂 相对分子质量分布 改性催化剂 铬基催化剂 乙烯基聚合物 FI催化剂
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Progress on the mechanism of food polyphenols in the prevention of liver fi brosis
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作者 Jianye Dai Man Zhang +3 位作者 Yipeng Wang Jiaoying Liu Junyan Shan Guangyue Su 《Journal of Polyphenols》 2024年第4期150-164,共15页
Liver fibrosis is the formation of extracellular matrix deposits due to excessive repair of chronic liver damage.Liver fi brosis is a necessary stage in the progression of cirrhosis,and timely intervention reverses th... Liver fibrosis is the formation of extracellular matrix deposits due to excessive repair of chronic liver damage.Liver fi brosis is a necessary stage in the progression of cirrhosis,and timely intervention reverses the pathogenesis.Liver fi brosis is a dynamic and highly integrated molecular,cellular and organisational process.Currently,no specifi c drug is used to treat liver fi brosis,and liver transplantation is the main clinical treatment for cirrhosis.Chemical drugs are often designed to target individual genes or proteins,with kinds of side eff ects.Food polyphenols,which are available and safe,have unique advantages and great potential in the treatment with the liver fibrosis.This review summarizes the pathogenesis of liver fi brosis and provides examples of food polyphenols’anti-liver fi brosis mechanisms that have been identifi ed in recent studies,and provides some sights for the development of anti-liver fi brosis drugs. 展开更多
关键词 food polyphenols liver fi brosis MECHANISM
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用FPGA实现嵌入式视频图像信号实时采集 被引量:2
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作者 刘超 钱光弟 《实验科学与技术》 2005年第2期12-15,共4页
提出了一种基于FPGA的嵌入式视频图像信号实时采集系统,采用SAA7111A对信号进行A/D变换,并用FPGA与SDRAM实现大容量的双帧缓存。详细说明双口存储器、有限状态机的实现及隔行扫描到逐行扫描的转换、乒乓互锁工作机制等。本系统可用在安... 提出了一种基于FPGA的嵌入式视频图像信号实时采集系统,采用SAA7111A对信号进行A/D变换,并用FPGA与SDRAM实现大容量的双帧缓存。详细说明双口存储器、有限状态机的实现及隔行扫描到逐行扫描的转换、乒乓互锁工作机制等。本系统可用在安全监控、工业图像检测、机器视觉等领域。 展开更多
关键词 现场可编程门序列FPGA(fied Programmable Gate Array) 同步动态随机存取存储器SDRAM(Synchronous Dynamic Random Access Memory) 视频图像采集 双口存储器 SAA7111A
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基于物联网的智能高压开关柜设计 被引量:31
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作者 黄新波 方寿贤 +3 位作者 王霄宽 王红亮 李小博 李文静 《电力自动化设备》 EI CSCD 北大核心 2013年第2期147-151,共5页
设计了一种基于物联网技术的智能开关柜。智能开关柜IED采用DSP+ARM双CPU的结构,通过CAN总线、RS-485总线、ZigBee技术等接收智能监测单元监测到的信息,按照IEC61850协议与站控层服务中心进行通信,实现远程监控功能。智能控制单元对柜... 设计了一种基于物联网技术的智能开关柜。智能开关柜IED采用DSP+ARM双CPU的结构,通过CAN总线、RS-485总线、ZigBee技术等接收智能监测单元监测到的信息,按照IEC61850协议与站控层服务中心进行通信,实现远程监控功能。智能控制单元对柜内开关量、温度、湿度等进行监测,并通过液晶屏、高亮指示条和指示灯显示开关柜状态,同时负责实现开关柜电动操作控制。智能识别单元将设备信息以电子标签的形式预埋在设备中,通过无线射频识别(RFID)技术直接将设备信息传递给智能开关柜IED,由开关柜上传到一体化信息平台,对设备进行准确定位、跟踪。所设计的智能开关柜已成功应用于唐山虹桥变电站,现场工作正常。 展开更多
关键词 物联网 无线射频识别 IEC61850 智能电子设备 Wi—Fi 监控 智能控制 通信
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基于生态位适宜度的耕地可持续利用评价 被引量:46
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作者 牛海鹏 赵同谦 +1 位作者 张安录 李明秋 《生态学报》 CAS CSCD 北大核心 2009年第10期5535-5543,共9页
耕地可持续利用评价是土地利用研究的重要内容。基于生态位理论,从区域耕地生态系统整体性出发,提出耕地生态元和耕地生态位的概念,并在此基础上构建了耕地可持续利用生态位适宜度评价模型(Fi模型)。然后,将所构建模型应用于河南省焦作... 耕地可持续利用评价是土地利用研究的重要内容。基于生态位理论,从区域耕地生态系统整体性出发,提出耕地生态元和耕地生态位的概念,并在此基础上构建了耕地可持续利用生态位适宜度评价模型(Fi模型)。然后,将所构建模型应用于河南省焦作市耕地可持续利用评价之中,测度了1997~2006年期间焦作市耕地可持续利用生态位适宜度Fi值。为了便于对照分析,采用限制因子模型(NFmin-i模型)和希尔伯脱空间模型(CHi模型)进行耕地可持续利用生态位适宜度NFmin-i值和CHi值的测算。测算结果表明:(1)1997~2006年期间,Fi值总体上呈递增趋势,从1997年的0.5088增加到2006年的0.6503,表明支撑焦作市耕地可持续利用的自然、经济和社会因子总体上呈良性发展趋势,即耕地可持续利用现实生态位趋于最适生态位。(2)1997~2006年期间,Fi与CHi值各年间的变化规律一致,与NFmin-i值总体变化规律一致,表明运用Fi模型进行耕地可持续利用评价具有较强的科学性和现实性。同时,Fi值有利于从综合角度表征区域耕地总体可持续利用水平。(3)利用最适生态位解释区域耕地可持续利用评价标准,以及运用n维资源(条件)生态位与最适生态位的匹配这一基本思想进行区域耕地可持续利用评价,生态意义明确,便于依据生态位适宜度值的大小及其变化制定区域耕地利用方案和措施。 展开更多
关键词 耕地可持续利用 生态位适宜度 现实生态位 最适生态位 Fi值
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广西隆林县首起鼠疫暴发流行的特征及原因分析 被引量:30
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作者 林新勤 杨进业 +18 位作者 梁江明 董柏青 陈杰 秦石英 周树武 鲁翠芳 韦锦平 杨勤保 姜超穗 梁少生 黄建财 农智 蒙礼坚 王贵贤 杨永群 龚永超 廖生华 王利荣 陆胜忠 《中国地方病学杂志》 CAS CSCD 北大核心 2002年第3期205-207,共3页
目的 了解广西 2 0 0 0年发生鼠疫暴发流行的特征 ,初步分析流行原因。方法 以普查、医学观察和追踪调查相结合对人群进行调查 ,用 IHA(间接血凝法 ,Indirect hem agglutination assay,IHA)法测定鼠疫 FI抗体 ,按国家鼠疫诊断标准诊... 目的 了解广西 2 0 0 0年发生鼠疫暴发流行的特征 ,初步分析流行原因。方法 以普查、医学观察和追踪调查相结合对人群进行调查 ,用 IHA(间接血凝法 ,Indirect hem agglutination assay,IHA)法测定鼠疫 FI抗体 ,按国家鼠疫诊断标准诊断病人。结果 疫情波及天生桥库区周围 2个乡镇 15个自然屯或单位 ,发生腺型鼠疫病人 4 2例 ,发病率为 1.10 % ,隐性感染率 2 .78% ,第 2代发病率 2 .76 %。流行时间为 3~ 10月。人间鼠疫发病年龄以青少年多见。结论 疫点分布于天生桥库区周围 ,库区鼠、蚤密度增高 。 展开更多
关键词 隆林县 鼠疫 流行特征 间接血凝法 IHA 菌荚膜抗体 FI 流行原因 疫情分析
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华北区年高温日数区域平均方法及趋势分析 被引量:29
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作者 张德宽 姚华栋 +1 位作者 杨贤为 廖要明 《高原气象》 CSCD 北大核心 2006年第4期750-753,共4页
利用华北地区33个代表站1961—2002年间的年高温日数序列,采用均生函数和最优子集回归法,设计出具有较强拟合能力和未来趋势预测的数理统计模型。该模型能较好地拟合历史实况,其信度达到了99%;也使用该模型做出华北地区2003—2005年3年... 利用华北地区33个代表站1961—2002年间的年高温日数序列,采用均生函数和最优子集回归法,设计出具有较强拟合能力和未来趋势预测的数理统计模型。该模型能较好地拟合历史实况,其信度达到了99%;也使用该模型做出华北地区2003—2005年3年的高温日数趋势预测,对2003年和2004年做出的趋势预测效果较好。 展开更多
关键词 华北区 高温FI数 区域平均 最优插值
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低温条件下絮体破碎再絮凝去除水中颗粒的研究 被引量:17
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作者 俞文正 杨艳玲 +1 位作者 卢伟 李圭白 《环境科学学报》 CAS CSCD 北大核心 2009年第4期791-796,共6页
为了了解低温条件下絮体的形成/破碎/再絮凝过程在适当条件下对絮凝去除水中颗粒物的强化效果,采用PDA2000透光率脉动检测仪对絮凝破碎再絮凝过程进行了在线监测.研究结果表明,当电中和机理占主导作用时(混凝剂投加量小于0.1mmo.lL-1),... 为了了解低温条件下絮体的形成/破碎/再絮凝过程在适当条件下对絮凝去除水中颗粒物的强化效果,采用PDA2000透光率脉动检测仪对絮凝破碎再絮凝过程进行了在线监测.研究结果表明,当电中和机理占主导作用时(混凝剂投加量小于0.1mmo.lL-1),絮体破碎后能重新絮凝,絮体大小能恢复到破碎之前;而当网捕卷扫机理占主导作用时(混凝剂投加量大于0.2mmol.L-1),絮体的恢复情况不如电中和条件,再絮凝能力降低.投加适量的腐殖酸会增加絮体破碎前后的分形维数,但过量的腐殖酸则会降低破碎前后絮体的分形维数.絮体破碎再絮凝后其分形维数比破碎前高.腐殖酸的投加量并不会明显影响絮凝和破碎后再絮凝的FI指数.电中和絮体破碎前初始絮凝时间越长破碎后沉后水浊度越低,破碎后其浊度会比破碎前显著减小.较低投量的铝盐就能使得沉后水浊度降到很低,因此可以降低混凝剂投量而达到更好的水处理效果. 展开更多
关键词 絮体破碎 重新絮凝 FI指数 电中和 网捕卷扫
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采用膜污染指数评估天然有机物在低压超滤膜中的污染行为 被引量:23
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作者 肖萍 肖峰 +4 位作者 赵锦辉 秦潼 王东升 冯金荣 许光 《环境科学》 EI CAS CSCD 北大核心 2012年第12期4322-4328,共7页
针对超滤膜的过滤特性,采用膜污染指数(FI)来研究天然有机物(NOM)的膜污染行为.实验中,腐殖酸(HA)、牛血清蛋白(BSA)以及海藻酸钠(NaAlg)被用作模型有机物进行超滤膜污染研究.结果表明,NOM-膜滤先后经过快反应和慢反应污染阶段,其中快... 针对超滤膜的过滤特性,采用膜污染指数(FI)来研究天然有机物(NOM)的膜污染行为.实验中,腐殖酸(HA)、牛血清蛋白(BSA)以及海藻酸钠(NaAlg)被用作模型有机物进行超滤膜污染研究.结果表明,NOM-膜滤先后经过快反应和慢反应污染阶段,其中快反应膜污染指数(TFIF)远大于慢反应膜污染指数(TFIS).说明短时间内NOM容易在低压膜上积累,造成通量迅速下降,引起较为严重的污染.因此,反应最初阶段,低压膜与有机物的作用决定了整个膜污染的趋势.经过水力清洗,通量有一定恢复,膜阻力降低,能够去除部分污染物,但仍有少量有机物附着在膜丝,从而造成不可逆污染.3种有机物造成的不可逆污染比例依次为BSA>HA>NaAlg,而通过化学清洗后,其不可逆污染比例依次为:NaAlg>BSA>HA,腐殖酸和蛋白容易造成不可逆污染,但碱洗易于除去,多糖造成的不可逆污染相对较轻,但碱洗难以去除.污染物与膜之间的相互作用可能是造成污染的主要原因.总的说来,FI计算方法简单,能够综合描述膜污染情况,具有一定的应用价值. 展开更多
关键词 天然有机物(NOM) 低压超滤膜 腐殖酸(HA) 牛血清蛋白(BSA) 海藻酸钠(NaAlg) 膜污染指数(FI)
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日本FI/F-term分类体系在专利技术/功效矩阵中的应用研究 被引量:20
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作者 霍翠婷 蒋勇青 +1 位作者 凌锋 刘会景 《情报杂志》 CSSCI 北大核心 2013年第11期140-144,共5页
随着创新型企业对专利信息服务品质和服务深度提出越来越高的要求,基于数理统计的基本专利分析方法已经不能满足实际应用需求,针对技术层面深度剖析的专利技术/功效矩阵分析成为能够为企业技术创新提供有力支撑的重要有效手段。本研究... 随着创新型企业对专利信息服务品质和服务深度提出越来越高的要求,基于数理统计的基本专利分析方法已经不能满足实际应用需求,针对技术层面深度剖析的专利技术/功效矩阵分析成为能够为企业技术创新提供有力支撑的重要有效手段。本研究根据专利技术/功效矩阵的制作流程,探索性利用日本专利检索体系中的FI/Fterm分类体系进行数据分类标引预处理,并基于实例进行实际应用可行性验证,从而形成面向特定技术主题的专利技术/矩阵分析方法。最后,简单阐述该方法的相关注意事项以及应用前景。 展开更多
关键词 专利FI F-term分类体系 主题分类应用流程技术 功效矩阵 多点触控
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