首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   59篇
  免费   3篇
儿科学   2篇
基础医学   12篇
口腔科学   1篇
临床医学   2篇
内科学   3篇
神经病学   2篇
特种医学   24篇
外科学   6篇
药学   2篇
肿瘤学   8篇
  2023年   2篇
  2022年   1篇
  2017年   1篇
  2016年   2篇
  2015年   1篇
  2014年   2篇
  2013年   1篇
  2012年   6篇
  2011年   3篇
  2010年   3篇
  2008年   4篇
  2007年   3篇
  2006年   4篇
  2005年   1篇
  2004年   3篇
  2003年   1篇
  2002年   4篇
  2001年   2篇
  2000年   2篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   1篇
  1993年   3篇
  1992年   1篇
  1991年   2篇
  1989年   3篇
  1988年   1篇
排序方式: 共有62条查询结果,搜索用时 31 毫秒
1.
Childhood moyamoya disease: hemodynamic MRI   总被引:2,自引:0,他引:2  
Background. Childhood moyamoya disease is a rare progressive cerebrovascular disease. Objective. To evaluate cerebral hemodynamics using dynamic Gd-DTPA-enhanced imaging in children with moyamoya disease. Materials and methods. Eight children (2–11 years of age) with the clinical and angiographic findings typical of moyamoya disease, before and/or after surgical intervention (pial synangiosis), underwent conventional MR imaging (MRI) and hemodynamic MR imaging (HMRI). HMRI used a spoiled gradient-echo with low flip angle (10 deg) and long TE (TR/TE = 24/15 ms) to minimize T 1 effects and emphasize T 2* weighting. Raw and calculated hemodynamic images were reviewed. Three-dimensional time-of-flight MR angiography (MRA) and perfusion brain single photon emission computed tomography (SPECT) were also performed. Results. Abnormal hemodynamic maps resulting from vascular stenosis or occlusion and basal collaterals were observed in six patient studies. HMRI depicted perfusion dynamics of affected cerebrovascular territories, detected cortical perfusion deficits, and complemented conventional MRI and MRA. HMRI findings were consistent with those of catheter angiography and perfusion SPECT. Conclusion. Our preliminary experience suggests that HMRI may be of value in the preoperative and postoperative evaluation of surgical interventions in moyamoya disease. Received: 20 February 1996 Accepted: 4 February 1997  相似文献   
2.
Twelve Yucatan micropigs (3 controls; 3 sham-operated; 6 with unilateral obstruction) were studied to assess the value of noncontrast and contrast-enhanced (Gadolinium-DTPA) magnetic resonance (MR) imaging in the evaluation of partial ureteral obstruction. MR findings were correlated with findings of quantitative (Tc-99m-DMSA) scintigraphy, and histology. On noncontrast T1-weighted images, the normal porcine kidney demonstrated good corticomedullary contrast (CMC = 16.8% +/- 5.0). Five minutes after administration of Gd-DTPA, there was enhancement of the renal cortex (+24.4% and medulla (+46.2%), and CMC was no longer discernible. Enhancement of the urine within the collecting system (+119.1%) was also observed. The obstructed kidneys demonstrated marked thinning of the renal parenchyma and decreased signal intensity on noncontrast T1- and T2-weighted images (P less than 0.01). Urine in the dilated collecting system did not differ significantly from urine in controls except in the three animals with urinary tract infection (P less than 0.05). Five minutes following injection of Gd-DTPA, there was enhancement of the renal parenchyma in all kidneys. Excretion was seen in three pigs and no excretion in two. Thus, useful information can be obtained in partial ureteral obstruction from both pre-contrast and Gd-DTPA-enhanced MR images of the kidney.  相似文献   
3.
4.
Iron-dextran (1 mmol Fe/kg) was used as an intravascular, paramagnetic contrast agent in rat and cat brain in conventional spin-echo T2-weighted (TR 2800/TE 100) 1H magnetic resonance imaging. The resulting images displayed differential decreases (30-50%) in intensity whose pattern was similar to that obtained with the superparamagnetic particulate iron oxide AMI-25 (0.18 mmol Fe/kg). Postcontrast images displayed improved anatomic detail, and contrast effects were observed to be greater in cortical and subcortical gray matter than in adjacent white matter. Intravenous injection of acetazolamide after administration of iron-dextran caused a small additional decrease in image intensity. Measurement of whole blood and plasma at 5 min postinjection of either contrast agent revealed significant increases in their volume magnetic susceptibilities. The contrast effect appears to be related to magnetic susceptibility changes brought about by the iron-dextran; it has both blood volume and blood flow components. The static model of magnetic susceptibility effects in brain capillaries is modified to include bolus flow of erythrocytes, providing a mechanism for the observed flow effects.  相似文献   
5.
6.
7.
Magnetic resonance (MR) techniques offer a non-invasive, non-irradiating yet sensitive approach to diagnose and monitor cancer, which encompasses diverse processes affecting various aspects of pathophysiology. Techniques such as MR spectroscopy (MRS) have been developed and applied to monitor the metabolic aspects of cancer. Given that cancer is such a variable disease, biomarkers identified using MRS represent a promising advance and may suggest appropriate therapy, especially when diagnostic biopsies are not feasible. This article will focus on proton MRS, which appears to be the most promising MR method and is complementary to existing diagnostic methods that may be used to characterize and monitor cancer processes. We further focus on applying the MRS technology to pediatric brain tumors, the leading cause of pediatric cancer mortality.  相似文献   
8.
Burn injury causes mitochondrial dysfunction in skeletal muscle   总被引:6,自引:0,他引:6       下载免费PDF全文
Severe burn trauma is generally followed by a catabolic response that leads to muscle wasting and weakness affecting skeletal musculature. Here, we perform whole-genome expression and in vivo NMR spectroscopy studies to define respectively the full set of burn-induced changes in skeletal muscle gene expression and the role of mitochondria in the altered energy expenditure exhibited by burn patients. Our results show 1,136 genes differentially expressed in a mouse hind limb burn model and identify expression pattern changes of genes involved in muscle development, protein degradation and biosynthesis, inflammation, and mitochondrial energy and metabolism. To assess further the role of mitochondria in burn injury, we performed in vivo (31)P NMR spectroscopy on hind limb skeletal muscle, to noninvasively measure high-energy phosphates and the effect of magnetization transfer on inorganic phosphate (P(i)) and phosphocreatine (PCr) resonances during saturation of gammaATP resonance, mediated by the ATP synthesis reactions. Although local burn injury does not alter high-energy phosphates or pH, apart from PCr reduction, it does significantly reduce the rate of ATP synthesis, to further implicate a role for mitochondria in burn trauma. These results, in conjunction with our genomic results showing down-regulation of mitochondrial oxidative phosphorylation and related functions, strongly suggest alterations in mitochondrial-directed energy expenditure reactions, advancing our understanding of skeletal muscle dysfunction suffered by burn injury patients.  相似文献   
9.
10.
BACKGROUND: In vivo biomarkers to predict progression of brain tumors are of great value in clinical practice. Therefore, the authors tested the hypothesis that changes in choline ratios by magnetic resonance (MR) spectroscopic imaging and/or relative tumor blood volume (rTBV) can differentiate clinically stable from progressive pediatric brain tumors. METHODS: MR spectroscopic imaging examinations were performed on 27 children with neuroglial brain tumors during therapy on a 1.5-Tesla MR system. Normalized rTBV values were measured in 11 of 27 patients. Each examination was rated as stable or progressive by clinical and imaging criteria. RESULTS: The percent change in normalized choline (Cho) was significantly greater in patients who had progressive examinations compared with patients who had stable examinations (P = 0.03). The percent change in Cho/N-acetylaspartate (Cho/NAA) was significantly higher in patients who had progressive outcomes (n = 18 patients) compared with patients who had stable outcomes (n = 32 patients; P < 0.001; sensitivity, 0.89; specificity, 0.88) and was identified as the most important prognostic indicator of tumor progression by logistic regression (likelihood ratio test, 33.4; P < 0.001). The odds of tumor progression were approximately 55 times greater for patients who showed at least a 20% change in Cho/NAA. rTBV distinguished between progressing and stable tumors (P = 0.03), and Cho/NAA and rTBV values showed interaction to predict the probability of a progressing clinical outcome. CONCLUSIONS: The percent change in Cho/NAA by proton MR spectroscopic imaging, assisted by rTBV, was useful in predicting tumor progression in children with brain tumors.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号