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111.
In the current keypoint-based image matching methods, not all the keypoints can be reliably matched because of the influence of noise, illumination, and image distortion. In the paper, we propose a novel method based on the Delaunay triangulation to detect and remove possible mismatches. Given previously matched keypoints by a detector in two images, the proposed method utilizes four steps to remove the mismatched point pairs: first, triangulating keypoints in the reference image, and producing a graph consisting of edges that connects the keypoints; second, drawing a graph in the test image by connecting the corresponding points as same as in the reference image; third, detecting abnormal edges in the test image using special constraints; fourth, detecting and removing mismatched point pairs based on the abnormal edges. The experimental results show that the method can detect the mismatches accurately and improve the robustness of current matching algorithms.  相似文献   
112.
Y-Riemannian metric gY is an important tool in Finsler geometry, where Y is a smooth non-zero vector field on Finsler manifold. If Y is a geodesic field, it is very effective to study flag curvature using Y-Riemann metric. In this paper, using a special Y-Riemann metric ( that is, so called v-Riemann metric ), we study hyperspheres in a Minkowski space and give some characteristics of hyperspheres in a Minkowski space.  相似文献   
113.
受体介导的内吞是细胞与外界物质交换的常见方式. 采用配体修饰表面的纳米脂质体颗粒,将药物有针对性地投放到肿瘤细胞 以提高药物传输的效率,是药物传 输系统设计中的核心问题之一. 本文假设内吞是准静态过程,采用三维数学模型来模拟球状纳米颗粒的内吞,建立了包含绑定键的系统变形能方程,通过求 解能量方程的最小值,得到药物在每个内吞包裹阶段的变形以及药物的被动内吞所需最小能量,分析不同药物半径对内吞所 需最小能量的影响. 研究表明,细胞膜变形能与绑定键变形能占总能量的绝大部分,各组分随着包裹区域增加均有变化;在给定细胞膜和药物颗 粒的硬度、绑定键强度等物理特性下存在最优药物尺寸,使得内吞过程中总能耗最小;在药物内吞进行的后期,包裹区域边 缘的绑定键因伸长过大发生断裂,影响内吞的顺利完成. 本研究为受体介导的高效药物设计提供了理论支撑.   相似文献   
114.
A class of Finsler metrics with isotropic S-curvature   总被引:3,自引:0,他引:3  
In this paper, we study a class of Finsler metrics defined by a Riemannian metric and a 1-form. We characterize these metrics with isotropic S-curvature. Supported by a NNSFC grant (10671214) and by the NSF project of CQ CSTC. Supported by a NNSFC grant (10671214), a NSF grant (DMS-0810159) and the C. K. Chao Foundation for Advanced Research  相似文献   
115.
Journal of Thermal Analysis and Calorimetry - The bifunctional Ga/HZSM-5 catalyst has been proven having the capability to increase the selectivity of aromatics production during catalytic...  相似文献   
116.
Heparin is a highly sulfated, complex polysaccharide and widely used anticoagulant pharmaceutical. In this work, we chemoenzymatically synthesized perdeuteroheparin from biosynthetically enriched heparosan precursor obtained from microbial culture in deuterated medium. Chemical de‐N‐acetylation, chemical N‐sulfation, enzymatic epimerization, and enzymatic sulfation with recombinant heparin biosynthetic enzymes afforded perdeuteroheparin comparable to pharmaceutical heparin. A series of applications for heavy heparin and its heavy biosynthetic intermediates are demonstrated, including generation of stable isotope labeled disaccharide standards, development of a non‐radioactive NMR assay for glucuronosyl‐C5‐epimerase, and background‐free quantification of in vivo half‐life following administration to rabbits. We anticipate that this approach can be extended to produce other isotope‐enriched glycosaminoglycans.  相似文献   
117.
Ten novel PEG-modified nitroimidazole derivatives labeled with 18F were synthesized via “hot-click” reaction and evaluated as PET tumor tracers. The radiolabeling method was convenient and efficient, all compounds displayed high radiochemical purity (>95%), high yield (30–50%) and good stability in saline and human serum. The biodistribution studies in EMT-6 tumor-bearing mice demonstrated their tumor uptake values at 60 min postinjection were 1.46–2.99%ID/g, which were lower than [18F]FMISO (5.43%ID/g), their tumor-to-liver ratios were 0.73–1.07, higher than [18F]FMISO (0.69). In vitro MCF-7 cell uptake studies showed their uptake values have no significant difference between hypoxic and aerobic cells.  相似文献   
118.
二氧化硅(SiO2)气凝胶是一种拥有三维骨架网络结构的纳米多孔材料,具有高孔隙率、低密度和低热导率等许多独特的性能.但是由于二氧化硅气凝胶本身的脆性及高温稳定性差等原因,限制了其大规模应用.二氧化硅气凝胶的热力学性能与其内部的三维骨架和孔结构紧密相关,掌握二氧化硅气凝胶内部微结构演化规律与宏观性能的关联,是改善其热力学...  相似文献   
119.
Glycals are highly versatile and useful building blocks in the chemistry of carbohydrate and natural products. However, the practical synthesis of glycals remains a long-standing and mostly unsolved problem in synthetic chemistry. Herein, we present an unprecedented approach to make a variety of glycals using phosphonium hydrolysis-induced, P(v) intermediate-mediated E1cB elimination. The method provides a highly efficient, practical and scalable strategy for the synthesis of glycals with good generality and excellent yields. Furthermore, the strategy was successfully applied to late-stage modification of complex drug-like molecules. Additionally, the corresponding 1-deuterium-glycals were produced easily by simple tBuONa/D2O-hydrolysis–elimination. Mechanistic investigations indicated that the oxaphosphorane intermediate-mediated E1cB mechanism is responsible for the elimination reaction.

A novel glucosylphosphonium-hydrolysis induced E1cB-elimination provides a highly efficient, practical and scalable method for the synthesis of glycals with good compatibility and excellent yields.  相似文献   
120.
氧化镓(β-Ga2O3)是一种超宽禁带氧化物半导体材料,其相关研究起源于日本。21世纪初,日本东北大学利用浮区法获得了多晶向的高质量β-Ga2O3单晶晶圆,京都大学开展了β-Ga2O3薄膜外延研究并获得了高质量的同质外延片。在此基础上,日本信息通信研究机构于2012年构建了第一个β-Ga2O3金属半导体场效应晶体管(MESFET),证明了β-Ga2O3在功率器件领域拥有巨大潜能,开启了β-Ga2O3研发的新纪元。此后,国际上众多机构加入了β-Ga2O3单晶、外延、器件的研发潮流。随着研发工艺的进步,β-Ga2O3基功率器件的耐压上限一次次被刷新。本文梳理了β-Ga2O3单晶、外延、器件发展的时间线,汇总分析了β-Ga2O3功率器件的研究现状,指出存在的问题和可能的解决方案,并对其未来进行了展望,期望为以后的技术发展提供参考。  相似文献   
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