期刊文献+
共找到344篇文章
< 1 2 18 >
每页显示 20 50 100
处理走航式海洋多参数剖面测量系统(MVP)温度和电导率滞后效应的方法 被引量:8
1
作者 任强 于非 +2 位作者 刁新源 司广成 魏传杰 《海洋科学》 CAS CSCD 北大核心 2014年第8期59-66,共8页
走航式海洋多参数剖面测量系统(moving vessel profiler,MVP)是一种集成程度和自动化程度都较高的海洋调查设备,能对海洋多要素进行同时观测,获得水平方向的高分辨率数据资料。由于温度和电导率传感器响应时间的不匹配,MVP下放速度过快... 走航式海洋多参数剖面测量系统(moving vessel profiler,MVP)是一种集成程度和自动化程度都较高的海洋调查设备,能对海洋多要素进行同时观测,获得水平方向的高分辨率数据资料。由于温度和电导率传感器响应时间的不匹配,MVP下放速度过快(峰值速度4 m/s)而造成非常明显的盐度尖峰现象。本研究结合Fofonoff(F)法、时间常数指数递归数字滤波(Giles and McDougall,GM)法和Grose提出的盐度尖峰订正方案,提出了一种新的方法,即MCT(match conductivity and temperature response time)法,通过对压力、温度和电导率传感器进行响应时间的匹配来减弱盐度尖峰。将SBE-9型CTD资料作为标准,发现订正后的资料与CTD盐度曲线的互相关系数为0.917,误差比订正前减小80%。对比35°N断面修正前后的盐度资料,订正后温盐跃层处出现的低盐区域消失。MVP的应用比常规海洋调查仪器CTD对于海洋现象的观测更有优势。 展开更多
关键词 走航式海洋多参剖面测量系统MVP 盐度尖峰 MCT(match CONDUCTIVITY and temperature RESPONSE time)'~r
下载PDF
Effect of gas saturation on P-wave velocity in tight sandstone
2
作者 Pan Bao-Zhi Zhou Wei-Yi +2 位作者 Guo Yu-Hang Fang Chun-Hui Zhang Li-Hua 《Applied Geophysics》 SCIE CSCD 2024年第3期487-495,617,共10页
By measuring the variation of the P-and S-wave velocities of tight sandstone samples under water saturation,it was confirmed that with the decrease in water saturation,the P-wave velocity first decreased and then incr... By measuring the variation of the P-and S-wave velocities of tight sandstone samples under water saturation,it was confirmed that with the decrease in water saturation,the P-wave velocity first decreased and then increased.The variation in velocity was influenced by the sandstone’s porosity.The commonly used Gassmann equation based on fluid substitution theory was studied.Comparing the calculated results with the measured data,it was found that the Gassmann equation agreed well with the measured data at high water saturation,but it could not explain the bending phenomenon of P-wave velocity at low saturation.This indicated that these equations could not accurately describe the relationship between fluid content and rock acoustic velocity.The reasons for this phenomenon were discussed through Taylor’s expansion.The coefficients of the fitting formula were calculated and verified by fitting the measured acoustic velocity changes of the cores.The relationship between P-wave velocity and saturation was discussed,which provides experimental support for calculating saturation using seismic and acoustic logging data. 展开更多
关键词 Tight sandstone Saturation model Reservoir parameters Acoustic wave measurement
下载PDF
Parameter Estimations of Rayleigh Distribution 被引量:20
3
作者 林金官 《Chinese Quarterly Journal of Mathematics》 CSCD 2000年第4期49-54,共6页
设随机变量X服从Rayleigh分布,其密度函数为p(x;β)=2x/βe-x^2/β,x>0,β>0为参数,对变换群G={gc;gc(x)=c^2x,c>0},本文分别在平方损失和熵损失下研究了β在G上的最优同变估计;当β有先验信息时,给出了β的Bayes估计。
关键词 Rayleigh distribution transformation group minimum risk equivariant estimations Bayesian estimations
下载PDF
Effect of geometrical parameters on forming quality of high-strength TA18 titanium alloy tube in numerical control bending 被引量:7
4
作者 方军 梁闯 +1 位作者 鲁世强 王克鲁 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第2期309-318,共10页
The forming quality of high-strength TA18 titanium alloy tube during numerical control bending in changing bending angle β, relative bending radius R/D and tube sizes such as diameter D and wall thickness t was clari... The forming quality of high-strength TA18 titanium alloy tube during numerical control bending in changing bending angle β, relative bending radius R/D and tube sizes such as diameter D and wall thickness t was clarified by finite element simulation. The results show that the distribution of wall thickness change ratio Δt and cross section deformation ratio ΔD are very similar under different β; the Δt and ΔD decrease with the increase of R/D, and to obtain the qualified bent tube, the R/D must be greater than 2.0; the wall thinning ratio Δto slightly increases with larger D and t, while the wall thickening ratio Δti and ΔD increase with the larger D and smaller t; the Δto and ΔD firstly decrease and then increase, while the Δti increases, for the same D/t with the increase of D and t. 展开更多
关键词 high-strength TA18 tube geometrical parameters forming quality finite element simulation numerical control bending
下载PDF
Application of BP neural network model with fuzzy optimization in retrieval of biomass parameters 被引量:1
5
作者 陈守煜 郭瑜 《Agricultural Science & Technology》 CAS 2005年第2期7-11,共5页
The retrieval of the biomass parameters from active/passive microwave remote sensing data (10.2 GHz) is performed based on an iterative inversion of BP neural network model with fuzzy optimization. The BP neural net... The retrieval of the biomass parameters from active/passive microwave remote sensing data (10.2 GHz) is performed based on an iterative inversion of BP neural network model with fuzzy optimization. The BP neural network is trained by a set of the measurements of active and passive remote sensing and the ground truth data versus Day of Year during growth. Once the network training is complete, the model can be used to retrieve the temporal variations of the biomass parameters from another set of observation data. The model was used in weights and microware observation data of wheat growth in 1989 to retrieve biomass parameters change of wheat growth this year. The retrieved biomass parameters correspond well with the real data of the growth, which shows that the BP model is scientific and sound. 展开更多
关键词 ANN BP model biomass parameters RETRIEVAL
下载PDF
MICRO MECHANICAL ANALYSIS OF 3-D WOVEN COMPOSITES 被引量:2
6
作者 周光明 周储伟 王新峰 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2004年第3期163-167,共5页
A micro mechanical model is carried out to predict micro stresses and macro elastic properties of 3-D woven composites. A unit cell is composed of two phases. One is fiber yarn and the other is resin or fiber yarn in ... A micro mechanical model is carried out to predict micro stresses and macro elastic properties of 3-D woven composites. A unit cell is composed of two phases. One is fiber yarn and the other is resin or fiber yarn in transverse. The additional shearing introduced by bending of fiber yarn is considered. The method to determine the microstructure is also discussed. This model is applied to the analysis of a 3-D woven graphite/epoxy composite. Micro stresses of the cell are studied, and then macro modulus is obtained by employing the average method. The predictions agree well with experimental results. 展开更多
关键词 micro mechanics 3-D woven composites Galerkin method
下载PDF
Seed Recalcitrance:a Current Assessment 被引量:4
7
作者 宋松泉 Patricia BERJAK +2 位作者 Norman PAMMENTER Tobias M.NTULI 傅家瑞 《Acta Botanica Sinica》 CSCD 2003年第6期638-643,共6页
Seeds have been categorized as orthodox, recalcitrant and intermediate seeds according to their dehydration behaviors. Identification of desiccation-tolerance and -sensitivity of seeds is the basis making storage stra... Seeds have been categorized as orthodox, recalcitrant and intermediate seeds according to their dehydration behaviors. Identification of desiccation-tolerance and -sensitivity of seeds is the basis making storage strategy of seeds and long-term conservation of species gene resources. In addition to the inherent characteristics of the species, developmental status of the seeds, dehydration rate, and the conditions under which they are dried and subsequently re-imbibed are very important factors influencing desiccation tolerance of seeds. Survival, electrolyte leakage rate, and germination/growth rate produced by survived seeds are a excellent synthetic parameter when discussing desiccation tolerance of seeds. Desiccation tolerance of seeds is a quantitative feature. The term 'critical water content' is incorrect and has caused some confusion in assessment of seed recalcitrance. A new working approach to quantify the degree of seed recalcitrance has been proposed in this paper. 展开更多
关键词 DESICCATION-TOLERANCE desiccation-sensitivity orthodox seed recalcitrant seed intermediate seed influence factor and assessment parameter of desiccation tolerance quantitative feature critical water content seed recalcitrance
下载PDF
STUDY ON THE METHOD OF CONSTRUCTING RATIONAL CUBIC CURVES AND CURVED SURFACE INCLUDING CONTROLLING PARAMETERS
8
作者 孙兰凤 高天真 +1 位作者 梁艳书 陈健 《Transactions of Tianjin University》 EI CAS 1998年第1期31-36,共6页
By adopting the method of controlling parameters this paper describes the construction of various kinds of cubic curve segment and curved surface fragment with rational and non rational parameters, and discusses the ... By adopting the method of controlling parameters this paper describes the construction of various kinds of cubic curve segment and curved surface fragment with rational and non rational parameters, and discusses the relationship between controlling parameters, weighted factors and types, kinds and characteristics of curve segments and curved surface fragments. A mathematical method is provided for CAGD with abundant connotations, broad covering region, convenience, flexibility and direct simplicity. 展开更多
关键词 controlling parameter weighted factor rational and non rational curve segment curved surface fragment matrix of parametric coefficient
下载PDF
Nonlinear Regression Fuzzy Analysis of Real Variable and Fuzzy Parameter 被引量:1
9
作者 史本广 陈守信 《Chinese Quarterly Journal of Mathematics》 CSCD 2002年第1期71-76,共6页
As far as the nonlinear regression method is concerned, the condition when both independent and dependent variable take the Fuzzy value, while the parameter, θ∈ΘR m the real value, have been discussed in . But for... As far as the nonlinear regression method is concerned, the condition when both independent and dependent variable take the Fuzzy value, while the parameter, θ∈ΘR m the real value, have been discussed in . But for most of actual conditions, the independent variable generally takes the real value, while both parameter and dependent variable take the Fuzzy value. This paper propounded a method for the latter and its relevant Fuzzy regreession model. In addition the Fuzzy observation, matrix distribution and the rational estimation of modeling parameter have also been discussed. Furthermore, the Max min estimation of modeling parameter and its corresponding calculating sequence have also been offered to and the calculating example shows the method is feasible. 展开更多
关键词 nonlinear regression parameter estimation matrix distribution
下载PDF
基坑开挖支护安全性的几个技术要点浅析
10
作者 王玉雯 王希奎 《四川建筑》 2012年第1期111-112,115,共3页
文章鉴于德州商务港基坑工程支护的成功经验,就基坑开挖工程中安全性验算、参量数确定、放坡角α计算及周边土体形变位移监测时效曲线的技术要点分析。
关键词 参量数 放坡角α 监测时效曲线
下载PDF
Asymmetry in the Strong-field Photodetachment of H- by Linearly Polarized Few-cycle Pulses
11
作者 白丽华 刘宇恒 +2 位作者 崔婷婷 王燕 张惠芳 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2011年第2期141-144,I0003,共5页
Photodetachment of H- irradiated by linearly polarized few-cycle laser field is investigated by time-dependent SchrSdinger equation numerically. The photo-electron left-right asymmetry parameter as a function of carri... Photodetachment of H- irradiated by linearly polarized few-cycle laser field is investigated by time-dependent SchrSdinger equation numerically. The photo-electron left-right asymmetry parameter as a function of carrier-envelop (CE) phase of few-cycle pulses is attained. We confirm the asymmetry of photoelectron distribution in H- photodetachment and find that the maximal asymmetry parameter of H- is equal to that of H atom under the same conditions but the corresponding CE phases are quite different. Thus a CE phase shift appears. Compared to that of H atom and field free electron, the zero asymmetry CE phase shift is sensitively affected by Coulomb field. The Coulomb effect on the asymmetry of H- photodetachment mainly behaves in the CE phase shift of H- instead of the amplitude of asymmetry parameter curve. 展开更多
关键词 Asymmetry parameter PHOTODETACHMENT Carrier-envelop phase Few-cycle pulse H-
下载PDF
Analysis and Evaluation Indicator Selection of Chilling Tolerance of Different Cotton Genotypes 被引量:2
12
作者 武辉 侯丽丽 +4 位作者 周艳飞 范志超 石俊毅 阿丽艳.肉孜 张巨松 《Agricultural Science & Technology》 CAS 2012年第11期2338-2346,共9页
[Objectivc] This study aimed to investigate the chilling tolerance of seedlings of different cotton genotypes and screen appropriate indicators for assess- ing chilling tolerance, to establish reliable mathematical ev... [Objectivc] This study aimed to investigate the chilling tolerance of seedlings of different cotton genotypes and screen appropriate indicators for assess- ing chilling tolerance, to establish reliable mathematical evaluation model for chilling tolerance of cotton, thus providing theoretical basis for breeding and promoting new chilling-tolerant cotton germplasms and large-scale evaluation of chilling tolerance of cotton varieties. [Method] Fifteen cotton varieties (lines) were used as experimental materials. The photosynthetic gas exchange parameters, chlorophyll fluorescence ki- netic parameters, chlorophyll content, relative soluble sugar content, malonaldehyde content, relative proiine content, relative conductivity and other 12 physiological indi- cators of seedling leaves under low temperature treatment (5 ℃, 12 h) and recovery treatment (25 ℃. 24 h) were determined; based on the chilling tolerance coefficient (CTC) of various individual indicators, the comprehensive evaluation of chilling toler- ance was conducled by using principal component analysis, hierarchical cluster anal- ysis and stepwise regression analysis. [Result] The results showed that the 12 indi- vidual physiological indicators could be classified into 7 independent comprehensive components by principal component analysis; 15 cotton varieties (lines) were clus- tered into three categories by using membership function method and hierarchical cluster analysis; the mathematical model for evaluating chilling tolerance of cotton seedlings was established: D =0.275 -0.244Fo1 +0.206Fv/Fm1+0.326g,%-0.056SS + 0.225MDA+O.O38REC (FF=0.995), and the evaluation accuracy of the equation was higher than 94.25%,0. Six identification indicators closely related to chilling tolerance were screened, including Fo,, Fv/Fm1, Seedling leaves of cotton varieties (lines) gs2, SS, MDA, and REC. [Conclusion] with high chilling tolerance are less dam- aged under low temperature stress, and are able to maintain relatively high photo- synthetic electron transport capacity and high stomatal conductance after recovery treatment, which is contributed to gas exchange and recovery of photosynthetic ca- pacity. Determination of the six indicators under the same stress condition can be adopted for rapid identification and prediction of the chilling tolerance of other cotton varieties, which provides basis for the breeding, promotion, identification and screen- ing of chilling tolerant germplasms. 展开更多
关键词 COTTON Chilling tolerance Principal components analysis Comprehensiveevaluation Stepwise regression analysis
下载PDF
GEOTHERMAL RESOURCES ASSESSMENT AND NUMERICAL SIMULATION IN TUANBO REGION
13
作者 朱家玲 李春华 高天真 《Transactions of Tianjin University》 EI CAS 2001年第4期251-254,共4页
This paper mainly deals with the reservoir on the heat and mass transfer and mass and energy balance in a geothermal field.On the basis of briefing the general characteristics of the reservoir and the supposition of t... This paper mainly deals with the reservoir on the heat and mass transfer and mass and energy balance in a geothermal field.On the basis of briefing the general characteristics of the reservoir and the supposition of the reservoir modeling,the paper emphasizes the mathematical descriptions of hydra thermal transportation and convection by two methods according to the different models,such as lumped parameter model and distributed parameter model.It is effective to use these models in simulating the heterogeneous,and anisotropical fracture reservoir for the designed lifetime of 15 years. 展开更多
关键词 assessment of geothermal resources mass and energy balance lumped parameter model distributed parameter model
下载PDF
Application of 3D stereotomography to the deep-sea data acquired in the South China Sea:a tomography inversion case 被引量:2
14
作者 邢逢源 杨锴 +2 位作者 薛冬 汪小将 陈宝书 《Applied Geophysics》 SCIE CSCD 2017年第1期142-153,191,192,共14页
A 3D stereotomography algorithm, which is derived from the 3D Cartesian coordinate, is applied for the first time to the deep-sea data acquired in the LH area, South China Sea, to invert a macro velocity model for pre... A 3D stereotomography algorithm, which is derived from the 3D Cartesian coordinate, is applied for the first time to the deep-sea data acquired in the LH area, South China Sea, to invert a macro velocity model for pre-stack depth migration. The successful implementation of stereotomography is highly dependent on the correct extraction of slowness components and the proper application of regularization terms. With the help of the structure tensor algorithm, a high-quality 3D stereotomography data space is achieved in a very efficient manner. Then, considering that the horizontal slowness in cross-line direction is usually unavailable for 3D narrow-azimuth data, the regularization terms must be enhanced to guarantee a stable convergence of the presented algorithm. The inverted model serves as a good model for the 3D pre-stack depth migration. The synthetic and real data examples demonstrated the robustness and effectiveness of the presented algorithm and the related schemes. 展开更多
关键词 3D stereotomography structure tensor extraction of horizontal components of slowness REGULARIZATION
下载PDF
Finite element analysis of spatial curved beam in large deformation 被引量:1
15
作者 曾森 陈少峰 +1 位作者 王焕定 曲婷 《Journal of Southeast University(English Edition)》 EI CAS 2010年第4期591-596,共6页
For the purpose of carrying out the large deformation finite element analysis of spatial curved beams,the total Lagrangian(TL)and the updated Lagrangian(UL)incremental formulations for arbitrary spatial curved bea... For the purpose of carrying out the large deformation finite element analysis of spatial curved beams,the total Lagrangian(TL)and the updated Lagrangian(UL)incremental formulations for arbitrary spatial curved beam elements are established with displacement vector interpolation,which is improved from component interpolation of the straight beam displacement.A strategy of replacing the actual curve with the isoparametric curve is used to expand the applications of the UL formulation.The examples indicate that the process of establishing the curved beam element is correct,and the accuracy with the curved beam element is obviously higher than that with the straight beam element.Generally,the same level of computational accuracy can be achieved with 1/5 as many curved beam elements as otherwise with straight beam elements. 展开更多
关键词 spatial curved beams total Lagrangian incremental formulation updated Lagrangian incremental formulation geometrical nonlinearity isoparametric curve
下载PDF
Analysis of Physical Quantities and Radar Parameters about Hail Shooting and Heavy Convective Rainfall
16
作者 陈金敏 刁秀广 《Agricultural Science & Technology》 CAS 2012年第11期2434-2437,2441,共5页
[Objective] The paper is to analyze physical quantities and radar parameter of hail shooting and heavy convective rainfall weather. [Method] Using radar data of Jinan station during 2002 and 2008, combined with soundi... [Objective] The paper is to analyze physical quantities and radar parameter of hail shooting and heavy convective rainfall weather. [Method] Using radar data of Jinan station during 2002 and 2008, combined with sounding data, the physical quantities and radar parameter of hail shooting and heavy convective rainfall weather are compared and analyzed. [Result] The smaller Sl is conducive to the generation of hail weather. When K〉 35 ~C, the probability for occurrence of heavy rainfall weather is significantly increased; when K〈20 ^(3, the probability for occurrence of heavy rainfall weather is significantly decreased. When CAPE value is greater than 1 500 J/KG, the probability for occurrence of hail weather is significantly decreased, while the probability for occurrence of heavy rainfall weather is significantly in- creased. The possibility for occurrence of hail monomer is small when the wind shear is less than 5 m/s; and it is large while wind shear is greater than 20 m/s. The radar forecasting indexes of hail monomer is as follows: VIL value reaches 35 kg/m2 (May), 43 kg/m2 (June and July), the monomer height is greater than 9 km, the maximum reflectivity factor is larger than 60 dBz, strong center height reaches 3.3 km (May), 4.3 km (June) and 5.5 km (July); VlL value of heavy rainfall monomer generally is below 25 kg/m2. [Conclusion] The paper provides basis form prediction of hail and heavy rainfall. 展开更多
关键词 HAIL Heavy convective rainfall VIL Weather radar parameter
下载PDF
Estimation of Geodetic Parameters with VLBI Data of Last 5 Years 被引量:4
17
作者 WEI Erhu LIU Jingnan SHI Chuang 《Geo-Spatial Information Science》 2007年第1期12-16,共5页
The meaning to research the potential of VLBI for geodetic applications is summarized. And the observation models and their related parameters of geodetic interest are investigated. Then, the principle and method of u... The meaning to research the potential of VLBI for geodetic applications is summarized. And the observation models and their related parameters of geodetic interest are investigated. Then, the principle and method of using the random model in VLBI data processing are investigated. With the world wide VLBI data from 2000-2004, the conditions to compute the parameters of geodetic interest are introduced, and so are the computing methods and processes. And the computed resuits of the parameters of geodetic interest are analyzed. 展开更多
关键词 VLBI observation model parameters of geodetic interest random model computation and analysis
下载PDF
Fault Diagnosis Based on Fuzzy Support Vector Machine with Parameter Tuning and Feature Selection 被引量:10
18
作者 毛勇 夏铮 +2 位作者 尹征 孙优贤 万征 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2007年第2期233-239,共7页
This study describes a classification methodology based on support vector machines(SVMs),which offer superior classification performance for fault diagnosis in chemical process engineering.The method incorporates an e... This study describes a classification methodology based on support vector machines(SVMs),which offer superior classification performance for fault diagnosis in chemical process engineering.The method incorporates an efficient parameter tuning procedure(based on minimization of radius/margin bound for SVM's leave-one-out errors)into a multi-class classification strategy using a fuzzy decision factor,which is named fuzzy support vector machine(FSVM).The datasets generated from the Tennessee Eastman process(TEP)simulator were used to evaluate the clas-sification performance.To decrease the negative influence of the auto-correlated and irrelevant variables,a key vari-able identification procedure using recursive feature elimination,based on the SVM is implemented,with time lags incorporated,before every classifier is trained,and the number of relatively important variables to every classifier is basically determined by 10-fold cross-validation.Performance comparisons are implemented among several kinds of multi-class decision machines,by which the effectiveness of the proposed approach is proved. 展开更多
关键词 fuzzy support vector machine parameter tuning fault diagnosis key variable identification
下载PDF
Influence of FSW parameters on formation quality and mechanical properties of Al 2024-T351 butt welded joints 被引量:8
19
作者 I.RADISAVLJEVIC A.ZIVKOVIC +1 位作者 N.RADOVIC V.GRABULOV 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第12期3525-3539,共15页
The influence of R/v ratio on joint quality in 2024-T351 aluminum alloy was studied. Specimens were subjected to friction stir welding with the rotation rates of 750, 950 and 1180 r/min and welding speed between 73 an... The influence of R/v ratio on joint quality in 2024-T351 aluminum alloy was studied. Specimens were subjected to friction stir welding with the rotation rates of 750, 950 and 1180 r/min and welding speed between 73 and 190 mm/min, providing R/v ratio between 5.00 and 10.27. The welded joints were tested by means of both non-destructive (visual, penetrant and X-ray inspection) and destructive (metallographic, tension and hardness) testing. In all specimens typical zones are revealed, with corresponding differences in grain size. Tensile efficiency of the joints obtained is in the range of 52.2%to 82.3%. The results show that the best quality is obtained at R/v ratio of 8.06, 10.17 and 10.27. This behavior is attributed to the assumption that the material flows around the pin with an optimal speed, i.e. sufficient amount of material is available to fill the gap and prevent tunnel formation. R/v ratio also showed influence on hardness distribution, onion features and crack initiation/propagation zones. 展开更多
关键词 Al 2024 alloy friction stir welding welding parameters heat input weld quality
下载PDF
Correlation of the quantifiable parameters of blood flow pattern derived with dynamic CT in solitary bronchogenic adenocarcinoma 被引量:8
20
作者 Shenjiang Li Xiangsheng Xiao +3 位作者 Shiyuan Liu Huimin Li Chengzhou Li Chenshi Zhang 《The Chinese-German Journal of Clinical Oncology》 CAS 2007年第4期345-349,共5页
Objective:To evaluate the correlation of the quantifiable parameters of blood flow pattern derived with dynamic CT in solitary bronchogenic adenocarcinoma(SBA).Methods:46 patients with solitary bronchogenic adenocarci... Objective:To evaluate the correlation of the quantifiable parameters of blood flow pattern derived with dynamic CT in solitary bronchogenic adenocarcinoma(SBA).Methods:46 patients with solitary bronchogenic adenocarcinomas (SBA)(diameter≤4 cm)underwent multi-location dynamic contrast material-enhanced(nonionic contrast material was administrated via the antecubital vein at a rate of 4 mL/s by using an autoinjector 90 mL,4×5 mm or 4×2.5 mm scanning mode with stable table were performed)serial CT.Precontrast and postcontrast attenuation on every scan was recorded.Perfusion (PBA),peak height(PHBA),ratio of peak height of the SPN to that of the aorta(BA-to-A ratio)and mean transit time(MTT)were calculated.The correlation between peak height of the aorta(PHA)and parameters of the SBA(PHBA,BA-to-A ratio,PBA,and MTT)and those among parameters of the SBA were assessed by means of linear regression analysis.Regression equation among parameters of the SBA were obtain by means of stepwise regression.Results:The correlation between the SBA peak height(PHBA,36.78 HU±12.02)and the aortic peak height(PHA)was significant(r=0.506,P<0.0001).No significant cor- relation was found between the BA-to-Apeak height ratio(15.33%±4.55)and the aortic peak height(r=0.130,P=0.388> 0.05)as it was between the SBA perfusion(PBA,31.86 mL/min/100 g±9.74)and the aortic peak height(r=0.049,P=0.749 >0.05).The SBA perfusion correlated with the PHBA and the BA-to-A peak height ratio(r=0.394,P=0.007<0.05;r=0.407, P=0.005<0.05).The PHBA correlated positively with the BA-to-A peak height ratio(r=0.781,P<0.0001).Mean transit time was 14.84 s±5.52.PBA=18.500+0.872×BA-to-A ratio.BA-to-A ratio=4.467+0.295×PHBA.Conclusion:The linear correlation between the SBA perfusion and BA-to-Aratio and that between BA-to-Aratio and PHBA can be expressed by equation. It is possible to design a simpler scanning procedure of investigation of bronchogenic adenocarcinoma angiogenesis. 展开更多
关键词 bronchogenic adenocarcinoma blood flow pattern CT quantifiable parameters linear correlation
下载PDF
上一页 1 2 18 下一页 到第
使用帮助 返回顶部