期刊文献+
共找到4篇文章
< 1 >
每页显示 20 50 100
塿土和黑土不同层次钾运移研究 被引量:5
1
作者 冯建 赵玉安 丁晋丽 《甘肃农业科技》 2006年第12期6-8,共3页
以采自陕西省杨凌区西北农林科技大学农作一站的土娄土和黑龙江省农业科学院土壤肥料研究所试验田的黑土为研究对象,通过饱和稳定流土柱运移实验,测定不同层次土壤钾运移穿透曲线;应用对流、扩散模型,对测试穿透曲线进行拟合,反求其运... 以采自陕西省杨凌区西北农林科技大学农作一站的土娄土和黑龙江省农业科学院土壤肥料研究所试验田的黑土为研究对象,通过饱和稳定流土柱运移实验,测定不同层次土壤钾运移穿透曲线;应用对流、扩散模型,对测试穿透曲线进行拟合,反求其运移参数D、R,结果表明:钾在土娄土和黑土不同层次的运移均受到强烈的阻滞作用。土娄土的阻滞因子与土层的粘粒含量呈显著正相关;黑土对钾运移的阻滞作用是土壤质地、有机质含量、矿物组成等因子综合作用的结果。土娄土和黑土的扩散、弥散系数与平均孔隙水流速均呈极显著的线性关系。 展开更多
关键词 塿土 黑土 钾运移 穿透曲线 扩散弥散系数
下载PDF
Diffusion-weighted imaging of biliopancreatic disorders:Correlation with conventional magnetic resonance imaging 被引量:8
2
作者 Nam Kyung Lee Suk Kim +5 位作者 Gwang Ha Kim Dong Uk Kim Hyung Il Seo Tae Un Kim Dae Hwan Kang Ho Jin Jang 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第31期4102-4117,共16页
Diffusion-weighted magnetic resonance imaging(DWI)is a well established method for the evaluation of intracranial diseases,such as acute stroke.DWI for extracranial application is more difficult due to physiological m... Diffusion-weighted magnetic resonance imaging(DWI)is a well established method for the evaluation of intracranial diseases,such as acute stroke.DWI for extracranial application is more difficult due to physiological motion artifacts and the heterogeneous composition of the organs.However,thanks to the newer technical development of DWI,DWI has become increasingly used over the past few years in extracranial organs including the abdomen and pelvis.Most previous studies of DWI have been limited to the evaluation of diffuse parenchymal abnormalities and focal lesions in abdominal organs,whereas there are few studies about DWI for the evaluation of the biliopancreatic tract.Although further studies are needed to determine its performance in evaluating bile duct,gallbladder and pancreas diseases,DWI has potential in the assessment of the functional information on the biliopancreatic tract concerning the status of tissue cellularity,because increased cellularity is associated with impeded diffusion,as indicated by a reduction in the apparent diffusion coefficient.The detection of malignant lesions and their differentiation from benign tumor-like lesions in the biliopancreatic tract could be improved using DWI in conjunction with findings obtained with conventional magnetic resonance cholagiopancreatography.Additionally,DWI can be useful for the assessment of the biliopancreatic tract in patients with renal impairment because contrast-enhanced computed tomography or magnetic resonance scans should be avoided in these patients. 展开更多
关键词 Magnetic resonance imaging Diffusion-weighted imaging Biliary tract GALLBLADDER PANCREAS
下载PDF
Image Quality Stability of Whole-body Diffusion Weighted Imaging 被引量:1
3
作者 Yun-bin Chen Chun-miao Hu +1 位作者 Jing Zhong Fei Sun 《Chinese Medical Sciences Journal》 CAS CSCD 2009年第2期122-126,共5页
Objective To assess the reproducibility of whole-body diffusion weighted imaging(WB-DWI) technique in healthy volunteers under normal breathing with background body signal suppression.Methods WB-DWI was performed on 3... Objective To assess the reproducibility of whole-body diffusion weighted imaging(WB-DWI) technique in healthy volunteers under normal breathing with background body signal suppression.Methods WB-DWI was performed on 32 healthy volunteers twice within two-week period using short TI inversion-recovery diffusion-weighted echo-planar imaging sequence and built-in body coil.The volunteers were scanned across six stations continuously covering the entire body from the head to the feet under normal breathing.The bone apparent diffusion coefficient(ADC) and exponential ADC(eADC) of regions of interest(ROIs) were measured.We analyzed correlation of the results using paired-t-test to assess the reproducibility of the WB-DWI technique.Results We were successful in collecting and analyzing data of 64 WB-DWI images.There was no significant difference in bone ADC and eADC of 824 ROIs between the paired observers and paired scans(P>0.05).Most of the images from all stations were of diagnostic quality.Conclusion The measurements of bone ADC and eADC have good reproducibility.WB-DWI technique under normal breathing with background body signal suppression is adequate. 展开更多
关键词 whole-body diffusion weighted imaging REPRODUCIBILITY BONE apparent diffusion coefficient exponential apparent diffusion coefficient
下载PDF
Usefulness of DWI in the evaluation of pulmonary isolated lesions 被引量:1
4
作者 Zhiyong Li Tingting Zhang Bin Xu Qiang Wei Rui Han Wei Liu Jianlin Wu 《The Chinese-German Journal of Clinical Oncology》 CAS 2010年第7期388-390,共3页
Objective: The aim of our study was to investigate the value of Diffusion-weighted MR imaging (DWl) for evaluating differential diagnosis of pulmonary isolated lesions. Methods: Twenty-seven consecutive patients e... Objective: The aim of our study was to investigate the value of Diffusion-weighted MR imaging (DWl) for evaluating differential diagnosis of pulmonary isolated lesions. Methods: Twenty-seven consecutive patients enrolled in this study, all of whom underwent single direction DWl examinations and received a histologic and clinical diagnosis. Diffusion factor B value was 300, 500, 800 s/mm2, respectively. DWl images of twenty cases could be satisfied to measurement and diagnosis and success rate was percent 74. Among these, lung tuberculoma 5 cases, harmatoma 3 cases, peripheral lung cancer 12 cases. The apparent diffusion coefficient (ADC) values of the lesions were measured. Statistical analyses were performed with the independent samples t test for comparing difference of ADC values between malignant nodules and benign nodules at different 8 value. Results: DWI images of twenty cases could be satisfied and its success rate was percent 74. When B value was 300 s/mm2, ADC values of malignant nodules and benign nodules were 0.002192±0.0006091 mm2/s, 0.002454 ± 0.0007892 mm2/s, respectively, and P = 0.442. When B value was 500 s/mm2, ADC value of malignant nodules and benign nodules were 0.002065 ± 0.0006769 mm2/s, 0.002871± 0.0007746 mm2/s, respectively, and P = 0.033. When B value was 800 s/mm2, ADC value of malignant nodules and benign nodules were 0.001646 ± 0.0004292 mm2/s, 0.002651 + 0.0008041 mm2/s, respectively, and P = 0.009. There were the most different between malignant nodules and benign nodules at B value 800 and statistical significance. Conclusion: Lung DWl imaging is helpful to diagnosis and differential diagnosis between malignant and benign isolated nodules. The ADC value of benign lesions was statistically higher than that of malignant tumors. 展开更多
关键词 diffusion imaging NEOPLASM diagnosis
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部