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Assumption of E-commerce Platform of Agricultural Products Based on F2C2B Mode
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作者 KeweiZhu 《International Journal of Technology Management》 2017年第4期86-88,共3页
This paper proposes the assumption of E-commerce platform of the agricultural products based on the F2C2B mode. The whole e-commerce model is guided by the idea of the supply chain management from the perspective of t... This paper proposes the assumption of E-commerce platform of the agricultural products based on the F2C2B mode. The whole e-commerce model is guided by the idea of the supply chain management from the perspective of the modern system, and the e-commerce integration model from customer to supplier is implemented, and the whole is optimized. E-commerce to cloud computing as the basic environment, the construction of public cloud services and private cloud resources, based on public cloud to the SaaS way to provide services to customers, focus on business search and business collaboration, make full use of the lnternet, modern communications technology to provide the real- service. The development of agricultural economy, no longer depends only on the number of some traditional agricultural resources, but also depends on the modern technology, information access and use. Through the development of basic network technology, by virtue of some modern electronic information technology and some other means that can improve the intelligence of agricultural use of the information resources, the proposed model provides the new methodology of the solution. 展开更多
关键词 f2C2B Mode e-commerce Platform Agricultural Products.
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实验性颈动脉粥样硬化模型中血栓素B2和6-酮-前列腺素F1α与抗凝血酶Ⅲ和纤溶酶原活性的改变 被引量:8
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作者 王明山 张磊 +3 位作者 郑荣远 谢淑萍 王拥军 高申孟 《中国动脉硬化杂志》 CAS CSCD 2001年第2期112-114,共3页
为研究高脂饲料加空气干燥术制作的家兔颈动脉粥样硬化模型中血栓素B2和 6 -酮 -前列腺素F1α(简称为前列腺素F)与抗凝血酶Ⅲ和纤溶酶原活性改变的关系。采用 5 4只日本大耳白兔分为 3组 ,分别给予高脂饲料加空气干燥术 (n =2 4)、单纯... 为研究高脂饲料加空气干燥术制作的家兔颈动脉粥样硬化模型中血栓素B2和 6 -酮 -前列腺素F1α(简称为前列腺素F)与抗凝血酶Ⅲ和纤溶酶原活性改变的关系。采用 5 4只日本大耳白兔分为 3组 ,分别给予高脂饲料加空气干燥术 (n =2 4)、单纯高脂饲料 (n =2 4)和正常饲料 (n =6 )喂养。在实施空气干燥术后的第 3天、第 1周、第 2周和第 4周分别处死动物 ,观察颈动脉病理改变和血液中血栓素B2和前列腺素F与抗凝血酶Ⅲ和纤溶酶原活性改变的关系。结果发现 ,高脂饲料加空气干燥术组动物第 4周时抗凝血酶Ⅲ活性明显降低 ,而纤溶酶原活性明显升高。高脂饲料加空气干燥术组与单纯高脂饲料组的血栓素B2和血栓素B2 前列腺素F比值均较正常饲料组升高 ,差异有显著性。结果提示 ,高脂饲料加空气干燥术法可以形成典型的颈动脉粥样硬化病变 ,病变与内皮细胞损害后血栓素和前列腺素改变及抗凝血酶Ⅲ和纤溶酶原活性改变密切相关。 展开更多
关键词 动脉粥样硬化 颈动脉 疾病模型 血栓素B2 前列腺素f 纤溶酶原 抗凝血酶Ⅲ
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寒喘平、热喘平对哮喘模型豚鼠血浆TXB_2和6-keto-PGF_(1α)的影响
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作者 倪荷芳 许惠琴 +1 位作者 王志英 张旭 《中药新药与临床药理》 CAS CSCD 2000年第6期345-346,共2页
目的 :观察寒喘平、热喘平对哮喘模型豚鼠血浆TXB2 、 6-keto -PGF1α的影响。方法 :用 1 0 %卵白蛋白液致敏豚鼠 ,两周后再用 1 %该溶液雾化吸入 ,以诱发豚鼠哮喘 ,测定豚鼠血浆TXB2 、 6-keto -PGF1α水平。结果 :模型组豚鼠 6-keto -... 目的 :观察寒喘平、热喘平对哮喘模型豚鼠血浆TXB2 、 6-keto -PGF1α的影响。方法 :用 1 0 %卵白蛋白液致敏豚鼠 ,两周后再用 1 %该溶液雾化吸入 ,以诱发豚鼠哮喘 ,测定豚鼠血浆TXB2 、 6-keto -PGF1α水平。结果 :模型组豚鼠 6-keto -PGF1α降低 ,TXB2 升高 ,与正常组比较具有显著性差异 (P <0 .0 1 )。而寒喘平、热喘平组能够明显升高血浆 6-keto -PGF1α、降低血浆TXB2 ,与模型组比较具有显著性差异 (P <0 .0 5,0 .0 1 )。结论 :寒喘平、热喘平升高PGI2 和降低TXA2 可能是治疗哮喘的作用机理之一。 展开更多
关键词 寒喘平 药理学 热喘平 血检素B2 前列腺素f 哮喘
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电子束泵浦三原子Kr_2F准分子激光的一维动力学研究 被引量:1
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作者 冯国刚 王璞 《强激光与粒子束》 EI CAS CSCD 北大核心 1997年第2期293-297,共5页
应用一维动力学模型,对电子束泵浦Ar/Kr/F2混合气体产生的三原子Kr2F准分子激光进行了理论模拟研究,指出了提高三原子Kr2F准分子激光能量的实验方向,激光能量输出可达毫焦耳量级。
关键词 反应动力学 Kr2f激光 电子束泵浦 激光 准分子
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Expression of cyclooxygenase-2 and its pathogenic effects in nonalcoholic fatty liver disease 被引量:7
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作者 Mingbo Cao Lei Dong Xiaolan Lu Jinyan Luo 《Journal of Nanjing Medical University》 2008年第2期111-116,共6页
Objective:To investigate the expression of cyclooxygenase-2 and its pathological effect in the experimental nonalcoholic fatty liver of rats, and to explore its possible mechanism. Methods:The rat NAFLD model was es... Objective:To investigate the expression of cyclooxygenase-2 and its pathological effect in the experimental nonalcoholic fatty liver of rats, and to explore its possible mechanism. Methods:The rat NAFLD model was established by giving a fat-enriched diet. The blood samples were obtained form abdominal aorta and the levels of serum ALT, AST and IL-1, changes in the hepatic tissue 6-k-PGF1 α TXB2 were measured. The expression level of COX-2 in rats livers were assayed by immunohistochemistry, RT-PCR and Westernblot. Results: Light microscope analysis revealed that hepatocytes were injured in the model group and slightly in the treatment group. The levels of serum TXB2 and IL-1 in the fatty liver rats were increased. Compared with the model group, the IL-1 and TXB2 increased significantly(P〈 0.05), on the contrary, compared with the normal group, the hepatic tissue 6-Keto-prostagland decreased significantly in the model group(P 〈 0.05), the treatment group also increased but P 〉 0.05. There was no positive expression of COX-2 in hepatic tissue of normal rats. In the model group, there was positive expression of COX-2 antigen and the number of COX positive cells progressively increased at 4, 8, 12 wks. The intensity of expression of COX-2 had significantly increased(P 〈 0.05 ) and the intensity of COX-2 expression in the treated group decreased remarkably compared with the model group(P 〈 0.05). The expression of COX-2 mRNA and the level of COX-2 protein were significantly stronger in the liver of model rats compared with normal rats, and significantly weaker in treated rats, than in 8W and 12W model rats(P 〈 0.05). Conclusion:The increase of COX-2 expression in NAFLD is closely associated with the severity of liver inflammation and damage. COX-2 may play an important role in the progression of rat NAFLD, and the expression of COX-2 mRNA is downregulated by cyclooxygenase-2 inhibitor, which can depress the oxidative stress and control inflammatory response efficiently. 展开更多
关键词 fatty liver non-alcoholic CYCLOOXYGENASE-2 INTERLEUKIN-1 6-Keto-prostaglandin f1 alpha thromboxane B2 animal disease model
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Peak of Electron Density in F2-Layer Parameters Variability at Quiet Days on Solar Minimum 被引量:2
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作者 Emmanuel Nanéma Moustapha Konaté Frédéric Ouattara 《Journal of Modern Physics》 2019年第3期302-309,共8页
This study deals with Peak of electron density in F2-layer sensibility scale during quiet time on solar minimum. Peaks of electron density in F2-layer (NmF2) values at the quietest days are compared to those carried o... This study deals with Peak of electron density in F2-layer sensibility scale during quiet time on solar minimum. Peaks of electron density in F2-layer (NmF2) values at the quietest days are compared to those carried out from the two nearest days (previous and following of quietest day). The study uses International Reference Ionosphere (IRI) for ionosphere modeling. The located station is Ouagadougou, in West Africa. Solar minimum of phase 22 is considered in this study. Using three core principles of ionosphere modeling under IRI running conditions, the study enables to carry out Peak of electron density in F2-layer values during the quietest days of the characteristic months for the four different seasons. These parameters are compared to those of the previous and the following of the quietest days (the day before and following each quietest selected day) at the same hour. The knowledge of NmF2 values at the quietest days and at the two nearest days enables to calculate the relative error that can be made on this parameter. This calculation highlights insignificant relative errors. This means that NmF2 values at the two nearest days of each quietest day on solar minimum can be used for simulating the quietest days’ behavior. NmF2 values obtained by running IRI model have good correlation with those carried out by Thermosphere-Ionosphere-Electrodynamics-General Circulation Model (TIEGCM). 展开更多
关键词 IONOSPHERE PEAK of Electron Density in f2-Layer Solar Cycle QUIET Day International Reference IONOSPHERE model
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Theoretical Design of Catalytic Domain of Abzyme Se-scFv2F3 by Introducing a Catalytic Triad
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作者 LUO Quan ZHOU Yi-han YAO Yuan LI Ze-sheng 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2010年第1期118-121,共4页
The single chain antibody scFv2F3 can be converted into selenium-containing Se-scFv2F3 by chemical mutation of the Ser residues. With antibody fragment 1NQB as a template, the catalytic domain of scFv2F3 was built by ... The single chain antibody scFv2F3 can be converted into selenium-containing Se-scFv2F3 by chemical mutation of the Ser residues. With antibody fragment 1NQB as a template, the catalytic domain of scFv2F3 was built by using homology modeling and molecular dynamics(MD) simulations. On the basis of the 3D model, we discussed the importance of Ser52 as the chemical modification site and redesigned the protein groups nearby Ser52 via intro- ducing a catalytic triad. The following 10 ns MD results show that the designed Ser52-Trp29-Gln72 catalytic triad is stable enough and high close to the local structural features of native glutathione peroxidases(GPX). Our results may be useful for creating a new abzyme with higher catalytic efficiency and stability. 展开更多
关键词 Ahzyme scfv2f3 Homotogy modeling Molecular dynamics simulation
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Electron Bulk Surface Density Effect on Critical Frequency in the F2-Layer
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作者 Emmanuel Nanéma Issaka Ouédraogo +1 位作者 Christian Zoundi Frédéric Ouattara 《International Journal of Geosciences》 2018年第9期572-578,共7页
Ionosphere layer is the atmosphere region which reflects radio waves for telecommunication. The density in particles in this layer influences the quality of communication. This study deals with the effects of Total El... Ionosphere layer is the atmosphere region which reflects radio waves for telecommunication. The density in particles in this layer influences the quality of communication. This study deals with the effects of Total Electron Contents (TEC) on the critical frequency of radio waves in the F2-layer. Total Electron Contents parameter symbolizes electron bulk surface density in ionosphere layer. Above critical frequency value in F2 layer (foF2), radio waves pass through ionosphere. The knowledge of this value enables to calibrate transmission frequencies. In this study, we consider TEC effects on foF2 under quiet time conditions during the maximum and the minimum of solar cycle 22, at Ouagadougou station, in West Africa. The study also considers the effects of seasons and the hourly variability of TEC and foF2. This work shows winter anomaly on foF2 and TEC on minimum and maximum of solar cycle phase respectively. Running International Reference Ionosphere (IRI) model enables to carry out the effects of TEC on foF2 by use of their monthly average values. This leads to a new approach to calibrate radio transmitters. 展开更多
关键词 IONOSPHERE Total ELECTRON CONTENTS Critical frequency in f2-Layer Solar Cycle Phase International Reference IONOSPHERE model
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Gastrodin protects neonatal rat brain against hypoxic-ischemic encephalopathy Acute therapeutic drug effects
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作者 Yanjun Niu Zhengyong Jin 《Neural Regeneration Research》 SCIE CAS CSCD 2008年第2期196-199,共4页
BACKGROUND: Pharmacological experiments have demonstrated that gastrodin has a protective effect on neonatal rat brain subjected to hypoxia-ischemia; however, the underlying mechanism has not been fully elucidated. O... BACKGROUND: Pharmacological experiments have demonstrated that gastrodin has a protective effect on neonatal rat brain subjected to hypoxia-ischemia; however, the underlying mechanism has not been fully elucidated. OBJECTIVE: The aim of this study was to investigate the acute therapeutic effects of gastrodin by observing prostaglandin B2 and 6-keto-prostaglandin F 1 a in brain tissue of neonatal rats that received gastrodin injections immediately after hypoxia-ischemia. DESIGN: Single-factor design. SETTING: Department of Pediatrics, Affiliated Hospital of Yanbian University. MATERIALS: This study was performed in the Laboratory of the Department of Pediatrics, Affiliated Hospital of Yanbian University (key laboratory of provincial Health Department) from April to December 2003. Fifty-five Wistar rats of either gender, aged 7 days, were provided by the Laboratory Animal Center of Affiliated Hospital of Yanbian University. The rats were randomly divided into normal control (n =10), model (n = 15), gastrodin-treated (n = 15), and Danshen-treated (n = 15) groups. The protocol was performed in accordance with guidelines from the Institute of Health Sciences for the use and care of animals. The following reagents were. used: Gastrodin (Sancai Medicine Group Co., Ltd., Zhongshan, Guangdong Province, China; component: gastrodin), Danshen (Conba Stock Company, Jinhua, Zhengjiang Province, China; component: salvia miltiorrhiza), and reagent kits for ^125I-prostaglandin B2 and ^125I-6-prostaglandin F l a (Research and Development Center for Science and Technology, General Hospital of Chinese PLA). METHODS: Rats in the normal control group received no treatment. Rats in the remaining 3 groups were anesthetized, followed by ligation of the left common carotid artery. One hour later, the rats were placed in a closed hypoxic box and allowed to inhale 8% oxygen-air (2.0 3.0 L/min) for 2 hours to develop hypoxic-ischemic encephalopathy. Immediately after lesion, rats in the gastrodin and Danshen-treated groups were intraperitoneally injected with l g gastrodin (10 mL/kg) and 15 g Danshen (l 5 mL/kg), respectively. MAIN OUTCOME MEASURES: Forty-eight hours after lesion, the left brain hemisphere was removed and homogenized to test the levels of prostaglandin B2 and 6-keto-prostaglandin F 1 a by radioimmunoassay. RESULTS: Forty successfully lesioned neonatal rats from the model, gastrodin-treated, and Danshen-treated groups, and ten rats from the control group, were included in the final analysis. Levels of prostaglandin B2 and 6-keto-prostaglandin F 1 a in brain tissue of neonatal rats were significantly higher in the model group than in the control group (both P 〈 0.01). Levels of prostaglandin B2 and 6-keto-prostaglandin F 1 a were significantly lower in the gastrodin-treated and the Danshen-treated groups compared to the model group (all P 〈 0.01). However, there were no significant differences in levels of prostaglandin B2 and 6-keto-prostaglandin F 1 a between the gastrodin-treated and the Danshen-treated groups (P 〉 0.05). CONCLUSION: Gastrodin decreased prostaglandin and thromboxan levels in neonatal rat brains subjected to hypoxia-ischemia. 展开更多
关键词 rat model neonatal hypoxia-ischemia prostaglandin B2 6-keto-prostaglandin f
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基于神经F波参数构建2型糖尿病周围神经病变的风险预测模型
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作者 庄丽 何帆 聂瑶瑶 《中国医药导报》 2025年第33期85-89,95,共6页
目的探究基于神经F波参数构建2型糖尿病(T2DM)患者并发糖尿病周围神经病变(DPN)的风险预测模型的临床价值。方法回顾性分析2023年1月至2024年12月江苏省中医院收治的186例T2DM患者的临床资料,根据是否并发DPN将患者分为T2DM组(71例)和DP... 目的探究基于神经F波参数构建2型糖尿病(T2DM)患者并发糖尿病周围神经病变(DPN)的风险预测模型的临床价值。方法回顾性分析2023年1月至2024年12月江苏省中医院收治的186例T2DM患者的临床资料,根据是否并发DPN将患者分为T2DM组(71例)和DPN组(115例)。收集两组患者临床资料,采用多因素logistic回归模型分析影响T2DM并发DPN的因素。基于影响因素构建预测T2DM并发DPN的风险预测模型,受试者工作特征曲线(ROC)及校准曲线对该模型进行验证。结果DPN组年龄≥60岁的占比高于T2DM组,糖尿病病程长于T2DM组,糖化血红蛋白(HbA1c)水平高于T2DM组(P<0.05)。DPN组正中神经、胫神经F波传导速度小于T2DM组,正中神经、胫神经F波潜伏期长于T2DM组(P<0.05)。多因素logistic回归分析显示,年龄≥60岁、糖尿病病程长、Hb A_(1c)高水平、正中神经F波潜伏期延长是T2DM患者并发DPN的危险因素(P<0.05),正中神经F波传导速度快是T2DM患者并发DPN的保护因素(P<0.05)。基于影响因素构建列线图模型,ROC结果显示,该模型预测T2DM患者并发DPN的曲线下面积为0.893(95%CI:0.839~0.934),灵敏度为83.48%、特异度为91.55%、约登指数为0.750;Bootstrap校准曲线显示,该预测模型的校准曲线与实际曲线接近重合,Hosmer-Lemeshowχ^(2)=0.749,P=0.527。结论基于神经F波参数构建的风险预测模型对于T2DM患者并发DPN具有较高的预测效能,可有效识别DPN早期进展的高风险人群,为临床实施神经保护性干预提供时间窗。 展开更多
关键词 f 2型糖尿病 糖尿病周围神经病变 预测模型
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A MODEL FOR THE VARIATIONS OF THE CRITICAL FREQUENCY OF F_2 LAYER DURING THE NEGATIVE PHASES OF IONOSPHERIC STORMS
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作者 涂传诒 贾志华 《Science China Mathematics》 SCIE 1983年第5期549-560,共12页
A model for the negative phase of ionospheric storms in middle latitudes is presented. It is assumed that there will be molecule enriched air in the thermosphere above the auroral oval during the period of the main ph... A model for the negative phase of ionospheric storms in middle latitudes is presented. It is assumed that there will be molecule enriched air in the thermosphere above the auroral oval during the period of the main phase of a magnetic storm. The molecule enriched air is carried to the middle latitudes by thermospheric neutral wind, and at the same time it diffuses away. When the molecule enriched air arrives at the F2 layer above a station, the electron loss rate in the F2 layer increases, the electron density decreases and then the negative phase at the station begins. We have calculated the variations of the fo F2 following magnetic storms for Manzhouli (29.5°N, 117.5°E), Freiburg (48°N, 07°E) and Billerica (43°N, 71°W) respectively. The results agree very well with typical events observed at the three stations and can be used to explain some average features of negative phase ionospheric storms in middle latitudes. 展开更多
关键词 A model fOR THE VARIATIONS Of THE CRITICAL fREQUENCY Of f2 LAYER DURING THE NEGATIVE PHASES Of IONOSPHERIC STORMS
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Identification of Non-Varying Coefficients in Varying-Coefficient Models 被引量:1
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作者 Chang-linMei Chun-xiaZhang 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2005年第1期135-144,共10页
A partially varying-coefficient model is one of the useful modelling tools.In this model, some coefficients of a linear model are kept to be constant whilst the others areallowed to vary with another factor. However, ... A partially varying-coefficient model is one of the useful modelling tools.In this model, some coefficients of a linear model are kept to be constant whilst the others areallowed to vary with another factor. However, rarely can the analysts know a priori whichcoefficients can be assumed to be constant and which ones are varying with the given factor.Therefore, the identification problem of the constant coefficients should be solved before thepartially varying-coefficient model is used to analyze a real-world data set. In this article, asimple test method is proposed to achieve this task, in which the test statistic is constructed asthe sample variance of the estimates of each coefficient function in a well-knownvarying-coefficient model. Moreover two procedures, called F-approximation and three-moment χ~2approximation, are employed to derive the p-value of the test. Furthermore, some simulations areconducted to examine the performance of the test and the results are satisfactory. 展开更多
关键词 varying-coefficient model partially varying-coefficient model local linearfitting three-moment χ~2 approximation f-approximation
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基于稀疏变换的地震数据重构方法 被引量:5
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作者 路交通 曹思远 +1 位作者 董建华 张 《物探与化探》 CAS CSCD 2013年第1期175-179,共5页
缺失地震数据重构恢复是后期地震资料处理取得良好效果的前提。笔者通过研究稀疏变换(F-K变换、Cur-velet变换)与最近流行的压缩感知理论,将两者结合起来,建立基于稀疏变换的地震数据重构模型。F-K变换是将地震数据由时间—空间域变换... 缺失地震数据重构恢复是后期地震资料处理取得良好效果的前提。笔者通过研究稀疏变换(F-K变换、Cur-velet变换)与最近流行的压缩感知理论,将两者结合起来,建立基于稀疏变换的地震数据重构模型。F-K变换是将地震数据由时间—空间域变换到稀疏域频率—波数域,Curvelet变换由于其良好的方向性、局部性以及各向异性,能够将地震数据进行更优的稀疏表达。基于重构模型,分别采用这两种稀疏变换对地震数据进行重构,并且比较两者的重构效果,证实Curvelet变换重构效果优于F-K变换。最终通过Marmousi 2模型以及实际地震资料处理分析,证明该重构模型的正确性和有效性。 展开更多
关键词 地震数据重构 f-K变换 CURVELET变换 压缩感知 Marmousi2模型
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干预协同刺激分子CD86对生殖道沙眼衣原体感染小鼠妊娠结局的影响
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作者 肖国宏 侯棚钟 +4 位作者 陈敦金 孙利华 杨智莺 郑和平 薛耀华 《中国现代医学杂志》 CAS CSCD 北大核心 2011年第35期4400-4404,共5页
目的了解小鼠感染沙眼衣原体后的妊娠结局,以及CD86 mAb干预治疗后对妊娠结局的影响及与体内Th1型、Th2型细胞因子水平的关系。方法建立小鼠沙眼衣原体生殖道感染模型,合笼受孕后为模型组,受孕后孕4 d腹腔注射CD86 mAb100μg作为治疗组... 目的了解小鼠感染沙眼衣原体后的妊娠结局,以及CD86 mAb干预治疗后对妊娠结局的影响及与体内Th1型、Th2型细胞因子水平的关系。方法建立小鼠沙眼衣原体生殖道感染模型,合笼受孕后为模型组,受孕后孕4 d腹腔注射CD86 mAb100μg作为治疗组,将未受衣原体感染孕鼠作为对照组。孕12 d用酶联免疫法检测各组小鼠血清中Th1型(IFN-γ)和Th2型(IL-4)细胞因子的表达水平。结果①模型组Th1型细胞因子(IFN-γ)上升,较对照组和治疗组差异有统计学意义(P<0.05),②模型组胚胎吸收率升高,较对照组和治疗组差异有统计学意义(P<0.05)。③3组的受孕情况、胚重、孕期体质量增加量差异无统计学意义。结论小鼠感染沙眼衣原体后体内Th1细胞因子IFN-γ增加,形成Th1型偏倚,增加了胚胎吸收率;CD86 mAb干预可降低Th1型偏倚程度,降低小鼠胚胎吸收率。 展开更多
关键词 沙眼衣原体f型株 CD86mAb TH1/TH2型细胞因子 小鼠 动物模型
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建筑物顶部锥形涡空间演化的数值模拟 被引量:2
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作者 李鹏年 邹正平 +1 位作者 陈学锐 顾志福 《航空动力学报》 EI CAS CSCD 北大核心 2006年第5期891-896,共6页
运用通用流体力学计算软件FLUENT,对建筑物表面风荷载问题进行了数值模拟,讨论和分析了采用不同湍流模型获得的结果差异。通过与风洞实验结果的对比,选择了v2-f湍流模型对40°风向角建筑物顶面出现锥形涡现象进行了成功的模拟。进... 运用通用流体力学计算软件FLUENT,对建筑物表面风荷载问题进行了数值模拟,讨论和分析了采用不同湍流模型获得的结果差异。通过与风洞实验结果的对比,选择了v2-f湍流模型对40°风向角建筑物顶面出现锥形涡现象进行了成功的模拟。进而利用数值模拟的优势给出了典型建筑物顶面锥形涡的空间演化规律及其和侧面脱体涡的相互作用。还获得了锥形涡的演化、强度和位置与建筑物表面压力分布的内在联系。 展开更多
关键词 航空 航天推进系统 κ-ε湍流模型 v^2-f湍流模型 锥形涡 数值模拟
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斑岩铜矿蚀变分带与成矿机制:玉龙矿床水-岩反应热力学平衡模拟例析 被引量:4
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作者 张少颖 和文言 +2 位作者 高雪 田成华 肖仪武 《岩石学报》 SCIE EI CAS CSCD 北大核心 2024年第6期1837-1852,共16页
蚀变分带和成矿机制的准确厘定是建立斑岩成矿模型与找矿预测的关键。本文以新生代金沙江-哀牢山成矿带的玉龙斑岩铜矿为例,通过质量作用定律(LMA)和吉布斯自由能最小化模型(GEM),构建含矿热液与斑岩侵入体的pH-f O 2相图和动态传输模型... 蚀变分带和成矿机制的准确厘定是建立斑岩成矿模型与找矿预测的关键。本文以新生代金沙江-哀牢山成矿带的玉龙斑岩铜矿为例,通过质量作用定律(LMA)和吉布斯自由能最小化模型(GEM),构建含矿热液与斑岩侵入体的pH-f O 2相图和动态传输模型,以揭示蚀变分带成因和金属成矿机制。LMA与GEM结果显示初始成矿流体pH值为4.7,logf_(O2)=-23.0(ΔFMQ=+2.7),且溶解Cu含量为1138×10^(-6),Mo为1.2×10^(-6)。研究表明,当该酸性及强氧化性流体流入二长花岗斑岩体时,在温度为450~360℃范围内,代表钾硅酸盐化蚀变的钾长石、黑云母、硬石膏、赤铁矿和磁铁矿的矿物逐渐沉淀,且与钾硅酸盐化蚀变相关流体具有较高pH值(5.0~7.0)和氧逸度(ΔFMQ=+2.9~+3.6)特征;当温度在360~320℃范围时,代表青磐岩化蚀变阶段的典型矿物如绿帘石、铁绿泥石和斜绿泥石等逐渐形成,流体pH值(5.0~6.4)和氧逸度(ΔFMQ=+1.1)均有所下降;当温度进一步从320℃下降到200℃时,流体pH值(5.0~5.7)进一步小幅下降,而氧逸度则(ΔFMQ=+1.7)略有回升,在此期间,绢云母和方解石等开始沉淀并形成典型的绢英岩化蚀变。此外,以HMoO_(4)^(-)和MoO_(4)^(2-)为载体的Mo在狭窄高温区间(450~370℃)内沉淀,而以CuCl(CuCl_(4)^(3-)、CuCl_(2)^(-)、CuCl)为主要载体的Cu则在在中、高温(450~300℃)范围中沉淀。通过利用LMA反演及GEM正演相结合定量化地刻画了玉龙斑岩铜矿水岩反应过程,由此揭示了斑岩矿床蚀变分带是逐渐冷却的单一岩浆热液与斑岩体不断反应的结果,且不同温度窗口对应着钾硅酸盐化(450~360℃)、青磐岩化(360~320℃)和绢英岩化(320~200℃)蚀变矿物的形成,故含矿流体温度的快速下降可能是玉龙铜矿蚀变叠加的重要因素。此外,Cu、Mo络合离子溶解度对温度变化的差异响应,导致了Mo矿化主要发育于靠近斑岩体的高温区域,而Cu则以网脉状-浸染状叠加到Mo矿化之上,并广泛分布于斑岩体周边的高-中温区域。 展开更多
关键词 水岩反应 热力学平衡模拟 玉龙斑岩铜矿 pH-f O 2相图 动态传输模型
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二代粘虫发生趋势的预测方法
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作者 龙玲 莫纯碧 《贵州农业科学》 CAS 2002年第2期14-16,共3页
根据 198 6~ 1999年二代粘虫系统测报数据及有关气象资料 ,组建 Fuzzy综合评判模型 ,对二代粘虫发生情况作预测的历史符合率达 92 .86 % ,对 2 0 0 0年和 2 0 0 1年二代粘虫发生趋势试报的结果与实况吻合。
关键词 发生趋势 预测方法 二代粘虫 fuzzy综合评判模型 农业害虫 预报因子
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状态饱和2-D离散系统的稳定性分析 被引量:1
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作者 陈东彦 于浍 《系统科学与数学》 CSCD 北大核心 2014年第2期171-178,共8页
研究由Fornasini-Marchesini(简记F-M)第二模型描述的状态饱和2-D离散系统的渐近稳定性.定义参数s_i将系统表示成部分状态饱和2-D离散系统;构造具有较少限制的矩阵Q并引入参数β,利用Lyapunov方法给出了系统全局渐近稳定性的新的判别条... 研究由Fornasini-Marchesini(简记F-M)第二模型描述的状态饱和2-D离散系统的渐近稳定性.定义参数s_i将系统表示成部分状态饱和2-D离散系统;构造具有较少限制的矩阵Q并引入参数β,利用Lyapunov方法给出了系统全局渐近稳定性的新的判别条件;设计了基于线性矩阵不等式的求解算法,并通过数值算例验证了算法的有效性. 展开更多
关键词 2-D离散系统 f-M第二模型 状态饱和 渐近稳定性
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食管癌容积旋转调强与动态调强放疗计划的等效生物剂量分布比较 被引量:10
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作者 陈翠 张广顺 +1 位作者 卢丽霞 邓小武 《中华肿瘤防治杂志》 CAS 北大核心 2018年第15期1075-1080,共6页
目的食管癌使用不同调强放射治疗技术会得到不同物理剂量和等效生物剂量分布。使用等效生物剂量评估可以更好预测放疗效果。本研究比较使用容积旋转调强(volumetric modulated arc therapy,VMAT)和5野、7野、9野动态调强(5F-,7F-,9F-dyn... 目的食管癌使用不同调强放射治疗技术会得到不同物理剂量和等效生物剂量分布。使用等效生物剂量评估可以更好预测放疗效果。本研究比较使用容积旋转调强(volumetric modulated arc therapy,VMAT)和5野、7野、9野动态调强(5F-,7F-,9F-dynamic MLC-IMRT)4种技术在食管癌放疗计划中的等效生物剂量(equivalent dose in 2Gy/f,EQD2)与物理剂量的分布差别,为临床选择最佳放疗技术提供依据。方法选择中山大学肿瘤防治中心2015-03-05-2015-06-27收治的20例食管癌患者,分别使用5F-、7F-、9F-dMLC-IMRT和VMAT技术各设计4套计划,所有计划使用相同的临床目标和剂量限制条件,肿瘤靶区的处方剂量均为60Gy/28f。根据各器官的α/β值和线性二次(linearquadratic,L-Q)模型,采用自编软件对治疗计划所有体素点物理剂量进行转换,得到治疗计划各体素点的EQD2剂量、以及靶区和危及器官的生物等效剂量体积(DVHEQD2)数据。比较不同调强放疗技术物理剂量和生物等效剂量体积参数差异,包括靶区相关剂量参数、适形指数(conformal index,CI)、均匀性指数(homogeneity index,HI)和脊髓、肺、心脏等危及器官体积剂量参数,并根据EQD2剂量分布综合结果选择最佳放疗技术。结果肿瘤区和预防照射区剂量体积参数中生物等效剂量(DEQD2)与物理剂量(DPhys)差别<3.5%;各危及器官的剂量参数中,DEQD2低于DPhys,均>10%。使用DEQD2对4种调强放疗技术进行比较,肿瘤区的处方剂量包绕体积均>98%,差别没有统计学意义(P>0.05),VMAT的靶区适形性(适形指数CI=0.554)高于动态调强技术技术(适形指数CI9F、CI7F和CI5F分别为0.535、0.473和0.408),P<0.001;危及器官的剂量参数中,脊髓最大量、心脏的平均剂量、肺的平均剂量和体积剂量VEQD2-20Gy和VEQD2-30Gy在不同调强技术之间差异<3%。VMAT技术肺的VEQD2-5Gy比5F-IMRT高4.51%,低于使用物理剂量评估时的7.58%。结论综合比较4组不同调强计划的剂量体积参数,食管癌调强放疗使用VMAT技术在EQD2的分布上比其他3种技术更有优势。 展开更多
关键词 食管癌 调强放射治疗 等效生物剂量 线性二次模型
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