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1.
We model developable surfaces by wrapping a planar figure around cones and cylinders. Complicated developables can be constructed by successive mappings using cones and cylinders of different sizes and shapes. We also propose an intuitive control mechanism, which allows a user to select an arbitrary point on the planar figure and move it to a new position. Numerical techniques are then used to find a cone or cylinder that produces the required mapping. Several examples demonstrate the effectiveness of our technique. 相似文献
2.
Most researches on graphene/polymer composites are focusing on improving the mechanical and electrical properties of polymers at low graphene content instead of paying attention to constructing graphene’s macroscopic structures. In current study the homo-telechelic functionalized polyethylene glycols (FPEGs) were tailored with π-orbital-rich groups (namely phenyl, pyrene and di-pyrene) via esterification reactions, which enhanced the interaction between polyethylene glycol (PEG) molecules and chemical reduced graphene oxide (RGO) sheets. The π–π stacking interactions between graphene sheets and π-orbital-rich groups endowed the composite films with enhanced tensile strength and tunable electrical conductivity. The formation of graphene network structure mediated by the FPEGs fillers via π–π stacking non-covalent interactions should account for the experimental results. The experimental investigations were also complemented with theoretical calculation using a density functional theory. Atomic force microscope (AFM), scanning electron microscope (SEM), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), thermal gravimetric analysis (TGA), UV–vis and fluorescence spectroscopy were used to monitor the step-wise preparation of graphene composite films. 相似文献
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应用不同剂量的~(60)Coγ射线照射含NT株弓形虫包囊的鼠脑匀浆后,以0.4%胰蛋白酶液消化,使弓形虫缓殖子从包囊中释放出来,并用生理盐水作连续10倍稀释,使成为含不同数量缓殖子的悬液,将此悬液接种小鼠,用生物检测方法确定其感染性。另设未经照射处理的缓殖子悬液感染小鼠的对照组。结果表明,γ射线0.55kGy剂量为控制鼠脑中NT株弓形虫感染性的最小有效剂量。γ射线0.1kGy剂量对弓形虫缓殖子感染性无明显影响,而0.45kGy照射后,其感染性较前者下降了10~4倍。 相似文献
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In this paper, a novel binary classifier coined projection twin support vector machine (PTSVM) is proposed. The idea is to seek two projection directions, one for each class, such that the projected samples of one class are well separated from those of the other class in its respective subspace. In order to further boost performance, a recursive algorithm for PTSVM is proposed to generate more than one projection axis for each class. To overcome the singularity problem, principal component analysis (PCA) is utilized to transform the data in the original space into a low-dimensional subspace wherein the optimization problem of PTSVM is convex and can be solved efficiently. The experimental results on several UCI benchmark data sets and USPS digit database show the feasibility and effectiveness of the proposed method. 相似文献
6.
柳叶腊梅中总香豆素的提取工艺研究及纯化 总被引:1,自引:0,他引:1
研究畲药柳叶腊梅中总香豆素类化合物的超声辅助提取工艺和液液萃取纯化技术,建立一种简便、快速、廉价、无污染的工艺方法.利用超声的空化作用的液液萃取方法,在单因素实验的基础上,应用正交分析法进行三因素三水平实验研究,最后通过萃取技术得到纯度较高的香豆素类化合物.通过该工艺,利用正交分析的最优条件制备得到提取物中6,7-二甲氧基香豆素(化合物1)和6,7,8-三甲氧基香豆素(化合物2),提取量分别达到0.23 mg/g和0.76mg/g.纯化工艺采用乙醇超声辅助技术和萃取技术,可以快速、方便的提取出目的化合物.该工艺科学合理,适于大规模生产. 相似文献
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《Materials Letters》2005,59(29-30):3861-3865
A coordinated iron phosphate, Fe(bipy)(HPO4)(H2PO4) (I), has been hydrothermally synthesized and characterized by elemental analysis, thermogravimetric analysis, and single crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P21/n (No. 14), with cell parameters M = 405.00, a = 10.904(4) Å, b = 6.4210(2) Å, c = 19.294(9) Å, β = 101.24(4) Å3, V = 1324.9(9) Å3, Z = 4, R1 [I > 2((I)) = 0.0357, wR2 [I > 2((I)) = 0.0717. This compound displays a new structure of ladder-like chains, in which each one-dimensional chain is constituted by the distorted octahedral units of Fe3+ bridged through PO4 tetrahedra. The bipy ligands in the compound bind in a bidentate fashion to the iron atoms and the ladder-like structure of the compound extends into a three-dimensional supramolecular array via π–π stacking interactions of bipy ligands and strong hydrogen bonding between the chains. Mössbauer spectroscopy shows the presence of Fe3+ in the octahedral coordination. Magnetic susceptibility measurements show that this material may model as anti-ferromagnetic. 相似文献
8.
茶尺蠖蛹的耐冷藏性研究 总被引:1,自引:0,他引:1
模拟茶尺蠖蛹的越冬环境,研究了不同蛹龄的蛹在4℃下冷藏15、20、25、30 d,对蛹羽化、成虫产卵和幼虫生长发育的影响。结果表明,同一蛹龄,随着冷藏时间的延长,蛹羽化率下降,成虫发育畸形率增加.蛹龄1 d的蛹冷藏15~30 d,蛹羽化率为42.5%~52.5%,成虫发育畸形率为8.3%~29.3%。蛹龄2 d的蛹冷藏15~30 d,蛹羽化率为62.5%~75%,成虫发育畸形率为53.3%~75.3%。蛹龄3~4 d的蛹冷藏15~30 d,蛹羽化率急剧下降,而且羽化的成虫全部发育不正常。冷藏30 d的蛹羽化的雌成虫与未冷藏的蛹羽化后的雄成虫交配或者冷藏15 d的蛹羽化的雌、雄成虫交配,均能正常产卵、孵化和生长发育;冷藏30 d的蛹羽化的雄成虫与未冷藏的蛹羽化后的雌成虫交配或者冷藏20~30 d的蛹羽化的雌、雄成虫交配,能产卵,但卵均不能孵化。这说明,茶尺蠖雌蛹的耐冷能力较强,至少可达30 d以上,雄蛹则只能冷藏15 d左右。 相似文献
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