951 resultados para Li MRI


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本文报道了太行花属(Taihangia Yu et Li)的种群分布、生物学特性和离体培养的初步结果。 太行花种群由于环境和生物等方面的原因仅在太行山区有狭小分布。来源于不同地区种群的太行花其形态特征具有丰富的表型,在引种条件下更为显著。而酯酶同工酶和过氧化物酶同工酶分析进一步证实了其遗传的稳定性和同源性。 实验表明,太行花在北纬39°58',最低温度-11℃的北京北京植物园,露地越冬正常。温度提高至40℃时生长发育受抑制而迟滞,以25℃最为适宜,增殖率最高。太行花对土壤的适应范围较广,在泥炭培养土上移殖的幼苗成活率达97.20%,主根须根发达,叶生长良好。不同强度光照处理12000Lux效果最好。 太行花生育期为230多天,生长积温为3763℃左右。物候期受环境条件和当年气候的影响,不同种群和个体之间有一定的差异。花的性别、花期和开花量等与纬度、海拔主要与温湿度相关。 太行花的茎尖、花芽、花梗、萼片、花瓣和叶子等外植体均能在MS附加不同种类和浓度植物激素的培养基中分化,其分化途径和分化效果因附加成分、外植体类别而异。在含有0.1mg/L IAA和0.5mg/L 6-BA的培养基中,不但能启动花芽正常生长、开花、形成合子胚,而且也能诱导花芽、花梗、茎尖产生花芽和营养芽。在芽的继代培养中,细胞分裂素能大量诱导芽的分化,最好的配比是0.5mg/L 6-BA、0.1mg/L ZJ;只含生长素时可以诱导生根或脱分化,其中生根最好的是0.5mg/L IAA;2.4-D单独使用时,能较好地使花芽、叶等脱分化,其最佳浓度为1.0mg/L。

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In this paper a novel visualisation method for diffusion tensor MRI datasets is introduced. This is based on the use of Complex Wavelets in order to produce "stripy" textures which depict the anisotropic component of the diffusion tensors. Grey-scale pixel intensity is used to show the isotropic component. This paper also discusses enhancements of the technique for 3D visualisation. © 2004 IEEE.

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Computational fluid dynamics (CFD) simulations are becoming increasingly widespread with the advent of more powerful computers and more sophisticated software. The aim of these developments is to facilitate more accurate reactor design and optimization methods compared to traditional lumped-parameter models. However, in order for CFD to be a trusted method, it must be validated using experimental data acquired at sufficiently high spatial resolution. This article validates an in-house CFD code by comparison with flow-field data obtained using magnetic resonance imaging (MRI) for a packed bed with a particle-to-column diameter ratio of 2. Flows characterized by inlet Reynolds numbers, based on particle diameter, of 27, 55, 111, and 216 are considered. The code used employs preconditioning to directly solve for pressure in low-velocity flow regimes. Excellent agreement was found between the MRI and CFD data with relative error between the experimentally determined and numerically predicted flow-fields being in the range of 3-9%. © 2012 American Institute of Chemical Engineers (AIChE).

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We propose a new approach for quantifying regions of interest (ROIs) in medical image data. Rotationally invariant shape descriptors (ISDs) were applied to 3D brain regions extracted from MRI scans of 5 Parkinson's patients and 10 control subjects. We concentrated on the thalamus and the caudate nucleus since prior studies have suggested they are affected in Parkinson's disease (PD). In the caudate, both the ISD and volumetric analyses found significant differences between control and PD subjects. The ISD analysis however revealed additional differences between the left and right caudate nuclei in both control and PD subjects. In the thalamus, the volumetric analysis showed significant differences between PD and control subjects, while ISD analysis found significant differences between the left and right thalami in control subjects but not in PD patients, implying disease-induced shape changes. These results suggest that employing ISDs for ROI characterization both complements and extends traditional volumetric analyses. © 2006 IEEE.

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Within the spectrum of extratesticular mesenchymal tumors in the scrotum and perineum lies cellular angiofibroma, also known as angiomyofibroblastoma-like tumor, a rare lesion originally described to almost exclusively occur in the vulva, perineum, and pelvis of women. We report a case of this tumor, with an adjacent scrotal lipoma, occurring in a 60-year-old male who presented to our department with a firm palpable scrotal mass. To our knowledge, the MRI findings of this entity have yet to be described in the radiological literature. We present the MRI features of cellular angiofibroma that are consistent with the pathological characteristics of this entity-a benign cellular and fibrous tumor with prominent vascularity.

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Redescription of Balantidium polyvacuolum Li 1963, collected from the hindgut of Xenocypris davidi and Xenocypris argentea, from Niushan Lake Fishery (30A degrees 19' N, 114A degrees 31' E) in Wuhan City, Hubei Province, China in April and June 2007 is presented in this paper to complete Li's description at both light and scanning electronic microscopic levels. The unique body shape of B. polyvacuolum-highly arched dorsal side and flattened ventral surface-as well as its remarkable concave platelet present in the centroventral were well described and compared with other close Balantidium species. Besides, two types of vestibulum shape are observed in our present work, which may suggest the existence of two subspecies or genotype species of these balantidia.

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The morphology of Gomphonema kaznakowi Mereschkowsky was investigated using light microscopy. This species has two morphologically distinct areas near the headpole; an unornamented and an ornamented area. The two areas are distinguished from each other by the combination of size and striae number. A new species, Gomphonema yangtzensis Li nov. sp. is identified based on an ornamented area near the headpole. G. kaznakowi is reported from the upper and middle part of the Yangtze River, and was also found in the upper section of the Yellow River. G. yangtzensis was found in the upper area of the Yellow River and the middle of the Yangtze River. Their limited distribution may be due to certain environmental conditions or a different dispersal rate. Both species are illustrated.