期刊文献+
共找到5,035篇文章
< 1 2 250 >
每页显示 20 50 100
Establishment of a humanized ST6GAL1 mouse model for influenza research
1
作者 Lyu Chao Han Feng +10 位作者 Gao Qian Lv Limin Lu Ziwei Lu Shuangshuang Li Xiaoyan Hu Yuechao Yang Mengjie Zhao Yingze Liu Jun Lu Xuancheng Duo Shuguang 《Animal Models and Experimental Medicine》 CAS CSCD 2024年第3期337-346,共10页
Background:This study aimed to construct and characterize a humanized influenza mouse model expressing hST6GAL1.Methods:Humanized fragments,consisting of the endothelial cell-specific K18 promoter,human ST6GAL1-encodi... Background:This study aimed to construct and characterize a humanized influenza mouse model expressing hST6GAL1.Methods:Humanized fragments,consisting of the endothelial cell-specific K18 promoter,human ST6GAL1-encoding gene,and luciferase gene,were microinjected into the fertilized eggs of mice.The manipulated embryos were transferred into the oviducts of pseudopregnant female mice.The offspring were identified using PCR.Mice exhibiting elevated expression of the hST6GAL1 gene were selectively bred for propagation,and in vivo analysis was performed for screening.Expression of the humanized gene was tested by performing immunohistochemical(IHC)analysis.Hematologic and biochemical analyses using the whole blood and serum of humanized hST6GAL1 mice were performed.Results:Successful integration of the human ST6GAL1 gene into the mouse genome led to the overexpression of human SiaT ST6GAL1.Seven mice were identified as carrying copies of the humanized gene,and the in vivo analysis indicated that hST6GAL1gene expression in positive mice mirrored influenza virus infection characteristics.The IHC results revealed that hST6GAL1 was expressed in the lungs of humanized mice.Moreover,the hematologic and biochemical parameters of the positive mice were within the normal range.Conclusion:A humanized influenza mouse model expressing the hST6GAL1 gene was successfully established and characterized. 展开更多
关键词 hST6GAL1 humanized mice influenza animal model
下载PDF
Tidal modeling based on satellite altimetry observations of TOPEX/ Poseidon, Jason1, Jason2, and Jason3 with high prediction capability: A case study of the Baltic Sea
2
作者 Alireza A.Ardalan Asiyeh Hashemifaraz 《Geodesy and Geodynamics》 EI CSCD 2024年第4期404-418,共15页
This research aims to optimize the utilization of long-term sea level data from the TOPEX/Poseidon,Jason1,Jason2,and Jason3 altimetry missions for tidal modeling.We generate a time series of along-track observations a... This research aims to optimize the utilization of long-term sea level data from the TOPEX/Poseidon,Jason1,Jason2,and Jason3 altimetry missions for tidal modeling.We generate a time series of along-track observations and apply a developed method to produce tidal models with specific tidal constituents for each location.Our tidal modeling methodology follows an iterative process:partitioning sea surface height(SSH)observations into analysis/training and prediction/validation parts and ultimately identi-fying the set of tidal constituents that provide the best predictions at each time series location.The study focuses on developing 1256 time series along the altimetry tracks over the Baltic Sea,each with its own set of tidal constituents.Verification of the developed tidal models against the sSH observations within the prediction/validation part reveals mean absolute error(MAE)values ranging from 0.0334 m to 0.1349 m,with an average MAE of 0.089 m.The same validation process is conducted on the FES2014 and EOT20 global tidal models,demonstrating that our tidal model,referred to as BT23(short for Baltic Tide 2023),outperforms both models with an average MAE improvement of 0.0417 m and 0.0346 m,respectively.In addition to providing details on the development of the time series and the tidal modeling procedure,we offer the 1256 along-track time series and their associated tidal models as supplementary materials.We encourage the satellite altimetry community to utilize these resources for further research and applications. 展开更多
关键词 Satellitealtimetry Baltic Sea Ocean tide modeling Jason3 Jason2 Jason1 TOPEX/POSEIDON EOT20 FES2014
下载PDF
An approach to estimate tree height using PolInSAR data constructed by the Sentinel-1 dual-pol SAR data and RVoG model
3
作者 Yin Zhang Ding-Feng Duan 《Journal of Electronic Science and Technology》 EI CAS CSCD 2024年第3期69-79,共11页
We estimate tree heights using polarimetric interferometric synthetic aperture radar(PolInSAR)data constructed by the dual-polarization(dual-pol)SAR data and random volume over the ground(RVoG)model.Considering the Se... We estimate tree heights using polarimetric interferometric synthetic aperture radar(PolInSAR)data constructed by the dual-polarization(dual-pol)SAR data and random volume over the ground(RVoG)model.Considering the Sentinel-1 SAR dual-pol(SVV,vertically transmitted and vertically received and SVH,vertically transmitted and horizontally received)configuration,one notes that S_(HH),the horizontally transmitted and horizontally received scattering element,is unavailable.The S_(HH)data were constructed using the SVH data,and polarimetric SAR(PolSAR)data were obtained.The proposed approach was first verified in simulation with satisfactory results.It was next applied to construct PolInSAR data by a pair of dual-pol Sentinel-1A data at Duke Forest,North Carolina,USA.According to local observations and forest descriptions,the range of estimated tree heights was overall reasonable.Comparing the heights with the ICESat-2 tree heights at 23 sampling locations,relative errors of 5 points were within±30%.Errors of 8 points ranged from 30%to 40%,but errors of the remaining 10 points were>40%.The results should be encouraged as error reduction is possible.For instance,the construction of PolSAR data should not be limited to using SVH,and a combination of SVH and SVV should be explored.Also,an ensemble of tree heights derived from multiple PolInSAR data can be considered since tree heights do not vary much with time frame in months or one season. 展开更多
关键词 Constructed polarimetric SAR data Dual polarization Sentinel-1 SAR data Polarimetric interferometric SAR Random volume over the ground model Tree height estimation
下载PDF
Numerical Models and Methods of Atmospheric Parameters Originating in the Formation of the Earth’s Climatic Cycle
4
作者 Wend Dolean Arsène Ilboudo Kassoum Yamba +1 位作者 Windé Nongué Daniel Koumbem Issaka Ouédraogo 《Atmospheric and Climate Sciences》 2024年第2期277-286,共10页
Atmospheric models are physical equations based on the ideal gas law. Applied to the atmosphere, this law yields equations for water, vapor (gas), ice, air, humidity, dryness, fire, and heat, thus defining the model o... Atmospheric models are physical equations based on the ideal gas law. Applied to the atmosphere, this law yields equations for water, vapor (gas), ice, air, humidity, dryness, fire, and heat, thus defining the model of key atmospheric parameters. The distribution of these parameters across the entire planet Earth is the origin of the formation of the climatic cycle, which is a normal climatic variation. To do this, the Earth is divided into eight (8) parts according to the number of key parameters to be defined in a physical representation of the model. Following this distribution, numerical models calculate the constants for the formation of water, vapor, ice, dryness, thermal energy (fire), heat, air, and humidity. These models vary in complexity depending on the indirect trigonometric direction and simplicity in the sum of neighboring models. Note that the constants obtained from the equations yield 275.156˚K (2.006˚C) for water, 273.1596˚K (0.00963˚C) for vapor, 273.1633˚K (0.0133˚C) for ice, 0.00365 in/s for atmospheric dryness, 1.996 in<sup>2</sup>/s for humidity, 2.993 in<sup>2</sup>/s for air, 1 J for thermal energy of fire, and 0.9963 J for heat. In summary, this study aims to define the main parameters and natural phenomena contributing to the modification of planetary climate. . 展开更多
关键词 Atmospheric Parameter 1 Climatic Cycle 2 Numerical models 3
下载PDF
成纤维细胞生长因子受体1 抑制剂对胶原诱导关节炎模型大鼠骨破坏的影响
5
作者 韩海慧 孟晓辉 +3 位作者 徐博 冉磊 施杞 肖涟波 《中国组织工程研究》 CAS 北大核心 2025年第5期968-977,共10页
背景:课题组前期的研究表明靶向成纤维细胞生长因子受体1(fibroblast growth factor receptor 1,FGFR1)可能是治疗类风湿性关节炎的有效靶点。目的:探讨FGFR1抑制剂(PD173074)对胶原诱导关节炎模型大鼠骨破坏的影响。方法:将25只雌性SD... 背景:课题组前期的研究表明靶向成纤维细胞生长因子受体1(fibroblast growth factor receptor 1,FGFR1)可能是治疗类风湿性关节炎的有效靶点。目的:探讨FGFR1抑制剂(PD173074)对胶原诱导关节炎模型大鼠骨破坏的影响。方法:将25只雌性SD大鼠随机分为5组,正常对照组、模型组、甲氨蝶呤组、PD173074低剂量组、PD173074高剂量组。除正常对照组外,其余各组大鼠建立Ⅱ型胶原诱导关节炎模型。造模成功后正常组及模型组大鼠腹腔注射无菌PBS,甲氨蝶呤组药物注射剂量为1.04 mg/kg,PD173074低剂量组和高剂量组药物注射剂量分别为5,20 mg/kg,1次/周。给药4周后取材,观察大鼠临床症状以及关节肿胀情况,踝关节Micro-CT三维重建及分析,观察踝关节病理变化,检测关节周围血管生成情况及核因子κB受体活化因子配体的表达,检测关节滑膜中p-FGFR1、血管内皮生长因子A、抗酒石酸酸性磷酸酶的表达,观察肝、脾、肾病理变化并计算肝、脾、肾指数。结果与结论:①PD173074能够减轻模型大鼠踝关节临床症状及关节肿胀,延缓骨质丢失,改善骨结构,减轻关节滑膜侵袭以及软骨骨侵蚀,降低关节周围破骨细胞数量,抑制关节滑膜组织中的血管生成,降低核因子κB受体活化因子配体的表达,抑制FGFR1磷酸化蛋白、抗酒石酸酸性磷酸酶和血管内皮生长因子A的蛋白表达。②大鼠肝、脾、肾病理观察表明经过PD173074治疗后无明显的毒副作用。③研究证明了FGFR1抑制剂能够延缓Ⅱ型胶原诱导关节炎模型大鼠关节炎症及骨破坏的进展,并抑制血管的生成。初步验证了PD173074在Ⅱ型胶原诱导关节炎模型中的治疗作用,其可能是通过抑制FGFR1磷酸化发挥作用,为寻找类风湿性关节炎新的治疗靶点提供了方向。 展开更多
关键词 类风湿关节炎 PD173074 成纤维细胞生长因子受体1 胶原诱导型关节炎 动物模型 骨破坏 血管生成
下载PDF
Application of Modelica Based Multi- Domain Modeling and Simulation for Gravity-1
6
作者 ZHANG Chi BU Xiangwei +3 位作者 XU Lijie WU Kao HOU Shiyuan XU Guoguang 《Aerospace China》 2024年第1期47-55,共9页
In the R&D phase of Gravity-1(YL-1), a multi-domain modeling and simulation technology based on Modelica language was introduced, which was a recent attempt in the practice of modeling and simulation method for la... In the R&D phase of Gravity-1(YL-1), a multi-domain modeling and simulation technology based on Modelica language was introduced, which was a recent attempt in the practice of modeling and simulation method for launch vehicles in China. It realizes a complex coupling model within a unified model for different domains, so that technologists can work on one model. It ensured the success of YL-1 first launch mission, supports rapid iteration, full validation, and tight design collaboration. 展开更多
关键词 modelICA Gravity-1 simulation modeling launch vehicle model
下载PDF
Exploiting fly models to investigate rare human neurological disorders
7
作者 Tomomi Tanaka Hyung-Lok Chung 《Neural Regeneration Research》 SCIE CAS 2025年第1期21-28,共8页
Rare neurological diseases,while individually are rare,collectively impact millions globally,leading to diverse and often severe neurological symptoms.Often attributed to genetic mutations that disrupt protein functio... Rare neurological diseases,while individually are rare,collectively impact millions globally,leading to diverse and often severe neurological symptoms.Often attributed to genetic mutations that disrupt protein function or structure,understanding their genetic basis is crucial for accurate diagnosis and targeted therapies.To investigate the underlying pathogenesis of these conditions,researchers often use non-mammalian model organisms,such as Drosophila(fruit flies),which is valued for their genetic manipulability,cost-efficiency,and preservation of genes and biological functions across evolutionary time.Genetic tools available in Drosophila,including CRISPR-Cas9,offer a means to manipulate gene expression,allowing for a deep exploration of the genetic underpinnings of rare neurological diseases.Drosophila boasts a versatile genetic toolkit,rapid generation turnover,and ease of large-scale experimentation,making it an invaluable resource for identifying potential drug candidates.Researchers can expose flies carrying disease-associated mutations to various compounds,rapidly pinpointing promising therapeutic agents for further investigation in mammalian models and,ultimately,clinical trials.In this comprehensive review,we explore rare neurological diseases where fly research has significantly contributed to our understanding of their genetic basis,pathophysiology,and potential therapeutic implications.We discuss rare diseases associated with both neuron-expressed and glial-expressed genes.Specific cases include mutations in CDK19 resulting in epilepsy and developmental delay,mutations in TIAM1 leading to a neurodevelopmental disorder with seizures and language delay,and mutations in IRF2BPL causing seizures,a neurodevelopmental disorder with regression,loss of speech,and abnormal movements.And we explore mutations in EMC1 related to cerebellar atrophy,visual impairment,psychomotor retardation,and gain-of-function mutations in ACOX1 causing Mitchell syndrome.Loss-of-function mutations in ACOX1 result in ACOX1 deficiency,characterized by very-long-chain fatty acid accumulation and glial degeneration.Notably,this review highlights how modeling these diseases in Drosophila has provided valuable insights into their pathophysiology,offering a platform for the rapid identification of potential therapeutic interventions.Rare neurological diseases involve a wide range of expression systems,and sometimes common phenotypes can be found among different genes that cause abnormalities in neurons or glia.Furthermore,mutations within the same gene may result in varying functional outcomes,such as complete loss of function,partial loss of function,or gain-of-function mutations.The phenotypes observed in patients can differ significantly,underscoring the complexity of these conditions.In conclusion,Drosophila represents an indispensable and cost-effective tool for investigating rare neurological diseases.By facilitating the modeling of these conditions,Drosophila contributes to a deeper understanding of their genetic basis,pathophysiology,and potential therapies.This approach accelerates the discovery of promising drug candidates,ultimately benefiting patients affected by these complex and understudied diseases. 展开更多
关键词 ACOX1 Drosophila melanogaster GLIA lipid metabolism model organisms NEUROINFLAMMATION neurologic disorders NEURON rare disease VLCFA
下载PDF
GM(1,1)与Verhulst模型在地基沉降预测中的适用性比较 被引量:15
8
作者 张庆伟 肖建清 《沈阳工业大学学报》 EI CAS 北大核心 2014年第6期716-720,共5页
为比较灰色Verhulst模型和GM(1,1)模型在地基沉降预测中的适用性,对某工程实例复合地基的沉降进行分析,并与实测沉降数据进行对比.结果表明:灰色Verhulst模型比GM(1,1)模型更适用,Verhulst模型预测结果更接近实测值,预测精度也更高;Verh... 为比较灰色Verhulst模型和GM(1,1)模型在地基沉降预测中的适用性,对某工程实例复合地基的沉降进行分析,并与实测沉降数据进行对比.结果表明:灰色Verhulst模型比GM(1,1)模型更适用,Verhulst模型预测结果更接近实测值,预测精度也更高;Verhulst模型不仅能够预测最终沉降量,也能很好地反映全过程的沉降与时间的关系.两种灰色模型中,Verhulst模型预测精度高,更适合应用于地基沉降预测,值得在实际工程中推广运用. 展开更多
关键词 地基沉降 灰色理论 沉降预测 verhulst模型 GM(1 1)模型 固结 全过程 精度
下载PDF
Study on the Prediction of Rice Blast Based on the Unbiased GM (1,1) Model 被引量:1
9
作者 魏代俊 曾艳敏 邹迎春 《Plant Diseases and Pests》 CAS 2010年第6期4-6,共3页
To create a new prediction model, the unbiased GM (1,1) model is optimized by the five-point slide method in this paper. Then, based on the occurrence areas of dce blast in Enshi District during 1995 -2004, the new ... To create a new prediction model, the unbiased GM (1,1) model is optimized by the five-point slide method in this paper. Then, based on the occurrence areas of dce blast in Enshi District during 1995 -2004, the new model and unbiased GM (1, 1 ) model are applied to predict the occurrence areas of rice blast during 2005 -2010. Predicting outcomes show that the prediction accuracy of five-point unbiased sliding optimized GM (1, 1 ) model is higher than the unbiased GM (1,1) model. Finally, combined with the prediction results, the author provides some suggestion for Enshi District in the prevention and control of rice blast in 2010. 展开更多
关键词 Unbiased GM 1 1 model Five-point slide method Optimization PREDICTION Rice blast
下载PDF
用GM(1,1)模型和Verhulst模型进行建筑物沉降预测 被引量:3
10
作者 郭广猛 《矿产勘查》 2000年第10期33-37,共2页
采用GM( 1 ,1 )模型和Verhulst模型对建筑物进行沉降预测 ,对二者进行对比 ,指出其优缺点 ,最后指出使用Verhulst模型预测沉降效果较好。
关键词 沉降 预测 GM(1 1)模型 verhulst模型
下载PDF
改进的灰色Verhulst GM(1,1)建筑物沉降模型 被引量:16
11
作者 刘玉成 《中国地质灾害与防治学报》 CSCD 2006年第4期61-63,共3页
造成建筑物的沉降因素是复杂多样,沉降机理与过程是非线性的,从理论上给出符合实际的建筑物沉降公式很困难,许多安全等级很高的重要建筑物在施工期间均需进行沉降观测,以保证建筑物的安全而及时修改设计。根据建筑物沉降观测数据列特征... 造成建筑物的沉降因素是复杂多样,沉降机理与过程是非线性的,从理论上给出符合实际的建筑物沉降公式很困难,许多安全等级很高的重要建筑物在施工期间均需进行沉降观测,以保证建筑物的安全而及时修改设计。根据建筑物沉降观测数据列特征,综合分析了影响建筑物沉降的因素,应用灰色理论关于连续非线性数据列的建模方法,经过二次拟合,建立了能描述高层建筑沉降过程的非等间距灰色Verhulst GM(1,1)模型。该模型经重庆地区某高层建筑沉降观测实例验证,能较准确预测建筑物的沉降过程和最终沉降量。表明利用少数高层建筑沉降的观测数据建立非等间距的灰色Verhulst GM(1,1)模型能较准确模拟建筑物沉降过程和预测最终沉降量,其建模方法较简单、精度高,具有一定的实用性。 展开更多
关键词 建筑物 沉降 非等问距 灰色verhulst GM(1 1)模型 预测
下载PDF
灰色GM(1,l)和Verhulst模型在吹填土地基沉降中的应用 被引量:1
12
作者 韩鹏 朱平 +1 位作者 张文振 陈少青 《港工技术》 2014年第1期52-56,共5页
在利用灰色GM(1,l)和Verhulst模型预测真空预压加固吹填土地基的最终沉降量时,建模序列直接影响预测结果的精度。结合某吹填土地基加固工程的沉降监测数据,探讨监测序列长度、建模序列长度对上述2种模型最终沉降量预测值及预测精度的影... 在利用灰色GM(1,l)和Verhulst模型预测真空预压加固吹填土地基的最终沉降量时,建模序列直接影响预测结果的精度。结合某吹填土地基加固工程的沉降监测数据,探讨监测序列长度、建模序列长度对上述2种模型最终沉降量预测值及预测精度的影响,总结出不同模型预测地基最终沉降量时建模序列的选取规律。研究结果表明,上述2种模型预测地基最终沉降量的误差均小于1.0%,灰色GM(1,l)模型的适应性更好。 展开更多
关键词 灰色GM(1 l)模型 verhulst模型 吹填土地基 最终沉降量 预测 GREY GM model(1 1)
下载PDF
GM(1,1)模型和Verhulst模型在人口预测中的应用 被引量:12
13
作者 刘文 王振环 刘勇 《孝感学院学报》 2008年第3期27-30,共4页
为提高我国人口预测模型的预测精度,分析了GM(1,1)和Verhulst预测模型的特点,并分别利用GM(1,1)和Verhulst模型对我国人口的变化情况进行了预测,发现灰色Verhulst模型有更高的预测精度和可靠性,更适合于我国人口的预测。
关键词 灰色GM(1 1)模型 灰色verhulst模型 人口预测
下载PDF
基于GM(1,1)模型与灰色Verhulst模型的风速预测 被引量:4
14
作者 靳小钊 王娟娟 赵闻蕾 《电器与能效管理技术》 2015年第4期46-48,共3页
在阐述灰色系统理论的基础上,将GM(1,1)模型与灰色Verhulst模型应用至风力发电预测中,最终利用这两种模型分别对某日10:20至11:00的风速数据进行分析建模,预测11:10与11:20的风速。最后通过残差分析得出Verhulst模型的预测精度更高,更... 在阐述灰色系统理论的基础上,将GM(1,1)模型与灰色Verhulst模型应用至风力发电预测中,最终利用这两种模型分别对某日10:20至11:00的风速数据进行分析建模,预测11:10与11:20的风速。最后通过残差分析得出Verhulst模型的预测精度更高,更适合应用于风速预测分析。 展开更多
关键词 GM(1 1)模型 verhulst模型 风速预测 残差分析
下载PDF
基于GM(1,1)和Verhulst模型的广西边贸物流预测比较研究 被引量:3
15
作者 朱念 《广西经济管理干部学院学报》 2017年第3期1-8,共8页
为更好地掌握广西边贸物流的发展态势,从而为制定边贸发展的政策提供科学依据,文章在分析广西边贸物流现状的基础上,运用灰色系统理论和方法建立广西边贸物流的灰色GM(1,1)和Verhulst模型,在MATLAB环境下对该模型精度以及误差进行分析,... 为更好地掌握广西边贸物流的发展态势,从而为制定边贸发展的政策提供科学依据,文章在分析广西边贸物流现状的基础上,运用灰色系统理论和方法建立广西边贸物流的灰色GM(1,1)和Verhulst模型,在MATLAB环境下对该模型精度以及误差进行分析,并利用模型对广西边贸物流发展趋势进行预测。预测结果表明,GM(1,1)和Verhulst模型都适合预测广西边贸物流的精度,但是GM(1,1)模型更能明显地提高广西边贸物流预测的精度,增加预测的可靠性。最后提出了采用统一的"国际边贸物流统一标准"、构建更便捷的"黄金通道"、打造广西边贸与边贸物流升级版、培养与引进边贸物流专业型人才、制定边贸物流可持续发展战略计划等对策建议。 展开更多
关键词 灰色系统 GM(1 1)模型 verhulst模型 边贸物流
下载PDF
Protective Effects of Oral Fructose-1, 6-diphosphate on Liver Injury in Animal Models
16
作者 刘晓岩 李凤云 +1 位作者 池志宏 王银叶 《Journal of Chinese Pharmaceutical Sciences》 CAS 2006年第3期188-193,共6页
Aim To investigate the effects of FDP on different liver injury models to explore the possibility of FDP used as an oral liver protective agent. Methods Chronic liver injury model in rats was induced by carbon tetrach... Aim To investigate the effects of FDP on different liver injury models to explore the possibility of FDP used as an oral liver protective agent. Methods Chronic liver injury model in rats was induced by carbon tetrachloride ( CCl4 ) ; Acute liver injury model in mice was induced by aminogalactose (GAIN) or lipopolysaccharide (LPS). Results In CCl4-induced chronic liver injury model, FDP (1 , 4 g·kg^-1·d^-1, q.d., for 10 weeks) significantly lowered ALT, AST,γ-glutamyl transpeptidase (γ-GT), alkaline phosphatase (ALP), and total bilirubin (T-BIL) in serum compared with vehicle; simultaneously it evidently elevated abnormal total protein (TP), albumin (ALB) and total cholesterol ( T-CHO ) levels in serum; it also dose-dependently reduced hydroxyproline contents in hepatic tissue. 4 g·kg^-1·d^-1 of FDP apparently decreased incidence of hepatic cirrhosis, and alleviated pathological changes of liver tissue. In GaiN-induced model, 1.0 - 4. 0 g·kg^-1·d^-1 of FDP ( bid, for 3 d ) significantly lowered alanine aminotransferase ( ALT ) and aspartate aminotransferase ( AST ) levels in serum ; it also decreased liver coefficient. 4. 0 g·kg^-1·d^-1 of FDP significantly alleviated pathological changes of cell ultra-structures. In LPS-induced model, only high dose of FDP (4. 0 g·kg^-1·d^-1, bid, for 12 d) significantly decreased ALT level in serum. Conclusion This study first demonstrated the protective effect of oral FDP on chronic liver injury caused by CCl4, and confirmed its effect on acute liver injury at the same time, suggesting that Long-term oral FDP is efficacious against liver injury induced by different factors and can be used as an oral liver protective agent in clinic. 展开更多
关键词 liver injury oral fructose-1 6-diphosphate animal models
下载PDF
GM(1,1)模型和Verhulst模型的改进及其应用 被引量:5
17
作者 肖岚菁 刘红良 《吉首大学学报(自然科学版)》 CAS 2013年第5期16-20,共5页
基于残差修正对GM(1,1)模型和Verhulst模型进行改进,利用所改进的模型分别对湖南省固定资产投资和水稻产量进行预测.预测结果表明,改进后的模型模拟精度明显优于原来模型模拟精度,改进的方法分别更适合于固定资产投资和水稻产量的预测.
关键词 回归分析 灰色预测 GM(1 1)模型 verhulst模型
下载PDF
灰色GM(1,1)模型和Verhulst模型在青岛市海水养殖产量预测中的应用 被引量:6
18
作者 杜小伟 刘群 《浙江海洋学院学报(自然科学版)》 CAS 2011年第5期420-425,共6页
灰色预测是建立从过去引申到将来的灰色预测模型(Grey Prediction Model),从而确定所研究系统未来发展变化的趋势,为决策者提供科学依据。以青岛市1998-2007年海水养殖产量统计数据为基础,分别利用灰色GM(1,1)模型和Verhulst模型对该市... 灰色预测是建立从过去引申到将来的灰色预测模型(Grey Prediction Model),从而确定所研究系统未来发展变化的趋势,为决策者提供科学依据。以青岛市1998-2007年海水养殖产量统计数据为基础,分别利用灰色GM(1,1)模型和Verhulst模型对该市传统海水养殖产量变化作预测。预测结果表明,GM(1,1)模型和Verhulst模型都显示了青岛市海水养殖产量在未来5年呈逐年递增的趋势。但通过对GM(1,1)模型和Verhulst模型的模拟精度验证和模拟预测结果的比较,发现灰色Verhulst模型预测精度较高,Verhulst模型更适合对该市未来几年的海水养殖产量进行预测。该研究结果可为青岛市合理保护和利用海水养殖资源、制定海水养殖规划提供参考依据。 展开更多
关键词 青岛市 海水养殖产量 灰色预测 GM(1 1)模型 verhulst模型
下载PDF
灰色GM(1,1)模型和Verhulst模型在喀斯特地区耕地预测中的应用——以毕节生态试验区为例 被引量:3
19
作者 杜江 安裕伦 袁士聪 《中国岩溶》 CAS CSCD 2009年第4期426-431,共6页
毕节生态试验区是典型的喀斯特地区,人口密度大,生态环境脆弱,水土流失严重,耕地保护尤为重要。本文以毕节地区1998-2006年常用耕地面积统计数据为基础,分别利用灰色GM(1,1)模型和Verhulst模型对该喀斯特地区常用耕地面积变化作预测。... 毕节生态试验区是典型的喀斯特地区,人口密度大,生态环境脆弱,水土流失严重,耕地保护尤为重要。本文以毕节地区1998-2006年常用耕地面积统计数据为基础,分别利用灰色GM(1,1)模型和Verhulst模型对该喀斯特地区常用耕地面积变化作预测。预测结果表明,GM(1,1)模型和Verhulst模型都揭示了毕节地区常用耕地面积在未来几年呈逐年递减的趋势。但是通过模拟精度验证,研究区耕地面积原始数据变化曲线呈S型,就灰色GM(1,1)模型与Verhulst模型模拟预测结果相比较,对于原始数据的模拟,GM(1,1)模型预测精度较高,而Verhulst模型更适合研究区未来几年耕地面积变化的预测。该研究结果可为区域合理利用土地资源、编制土地利用规划和耕地保护提供依据。 展开更多
关键词 灰色预测 GM(1 1)模型 verhulst模型 喀斯特 耕地面积变化
下载PDF
基于Sentinel-1/2改进极化指数和纹理特征的土壤含盐量反演模型 被引量:1
20
作者 张智韬 贺玉洁 +3 位作者 殷皓原 项茹 陈俊英 杜瑞麒 《农业机械学报》 EI CAS CSCD 北大核心 2024年第1期175-185,共11页
目前Sentinel-1/2协同反演植被土壤含盐量的研究大多是基于Sentinel-2光谱信息和Sentinel-1后向散射系数,没有考虑Sentinel-2光谱信息容易受土壤亮度等信息影响,Sentinel-1后向散射系数容易受土壤粗糙度和水分影响。为进一步提高Sentine... 目前Sentinel-1/2协同反演植被土壤含盐量的研究大多是基于Sentinel-2光谱信息和Sentinel-1后向散射系数,没有考虑Sentinel-2光谱信息容易受土壤亮度等信息影响,Sentinel-1后向散射系数容易受土壤粗糙度和水分影响。为进一步提高Sentinel-1/2协同反演植被土壤含盐量的精度,用水云模型对雷达卫星后向散射系数进行校正,消除植被影响;然后协同Sentinel-2纹理特征,基于VIP、OOB、PCA 3种变量筛选和RF、ELM、Cubist 3种机器学习回归模型构建植被土壤含盐量反演模型。研究结果表明:经过水云模型去除植被影响后的雷达后向散射系数及其极化组合指数与土壤含盐量的相关性有一定程度的提高。不同变量选择方法与不同机器学习方法耦合模型在反演土壤含盐量中,OOB变量筛选方法与RF、ELM和Cubist 3种机器学习方法的耦合模型精度最佳,建模集和验证集的R2都在0.750以上,且验证集的RMSE和MAE均最小;其中OOB-Cubist耦合模型精度最高,且R_(v)^(2)/R_(c)^(2)为0.955,具有良好的鲁棒性。研究可为机器学习协同物理模型、光学卫星协同雷达卫星在土壤含盐量反演中的进一步应用提供思路。 展开更多
关键词 土壤含盐量 Sentinel-1/2 纹理特征 水云模型 机器学习 改进极化指数
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部