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压强计算中易犯的两个错误
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作者 温志勇 《沧州师范学院学报》 2002年第3期95-95,共1页
关键词 压强计算 中学 物理教学 压力 重力 物体面积
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Area-wide Detection of Anti-Toxoplasma gondii Antibodies in Dairy Animals from the Khartoum State, Sudan
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作者 Abdalla Mohamed Ibrahim Ahmed Ali Ismail +1 位作者 Tamador Elkhansa Elnour Angara Osman Mukhtar Osman 《Journal of Life Sciences》 2014年第9期723-730,共8页
Toxoplasmosis is an important cause of reproductive failure in man and farm animals resulting in significant socio-economic losses worldwide. The aim of this study was to avail large scale data-regarding the sero-prev... Toxoplasmosis is an important cause of reproductive failure in man and farm animals resulting in significant socio-economic losses worldwide. The aim of this study was to avail large scale data-regarding the sero-prevalence of T. gondii infection in dairy animals from the Khartoum State, Sudan using the commercially available Latex Agglutination Diagnostic kits. The study revealed that the overall seroprevalence of T. gondii infection at herd level of dairy animals in the State was 92.7%. The within herd seroprevalence was ranging from 8% up to 100% with mean of 51.3% in different herds of different dairy animals species in the State. Only 6 herds, 3 herds, 3 herds and 1 herd of cattle, camel sheep and goat respectively were found to be clean from anti-T, gondii antibody in the present study. Interestingly, most of the clean herds (12 herds) are located in the Khartoum district. The differences between the three districts, the seven localities and the four animal species were statistically highly significant (P 〈 0.01). The overall sero-prevalence of T. gondii infection in dairy animals--at individual level--was 45.3%. Sheep scored the highest seroprevalence rate (75.0%) followed by goats (64.0%), camels (54.1%) and cattle (40.9%) with high statistically significant differences (P 〈 0.01). The highest level of antibody titration was reported in sheep and goats. This is the first area-wide and large scale report on seroprevalence of T. gondii infection in dairy animals from the Sudan. It was concluded that dairy animals in the Sudan are widely exposed to T. gondii and people in the Sudan should be aware of the possibility of hyper-prevalence of human toxoplasmosis through these food animals. Research on clinical toxoplasmosis in dairy animals and human in the Sudan is recommended to evaluate the role T. gondii infection in economical losses in dairy farm industry and for building strategy of sustainable toxoplasmosis control. 展开更多
关键词 SEROPREVALENCE T gondii LAT dairy animals Sudan.
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Area Variation Based Color Snake Algorithm for Moving Object Tracking
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作者 Shoum-ik ROYCHOUDHURY Young-joon HAN 《Journal of Measurement Science and Instrumentation》 CAS 2010年第1期46-49,共4页
A snake algorithm has been known that it has a strong point in extracting the exact contour of an object. But it is apt to be influenced by scattered edges around the control points. Since the shape of a moving object... A snake algorithm has been known that it has a strong point in extracting the exact contour of an object. But it is apt to be influenced by scattered edges around the control points. Since the shape of a moving object in 2D image changes a lot due to its rotation and translation in the 3D space, the conventional algorithm that takes into account slowly moving objects cannot provide an appropriate solution. To utilize the advantages of the snake algorithm while minimizing the drawbacks, this paper proposes the area variation based color snake algorithm for moving object tracking. The proposed algorithm includes a new energy term which is used for preserving the shape of an object between two consecutive images. The proposed one can also segment precisely interesting objects on complex image since it is based on color information. Experiment results show that the proposed algorithm is very effective in various environments. 展开更多
关键词 color snake algorithm area variation moving object tracking snake energy SEGMENTATION
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基于物理深度学习的学生自主创新实验教学策略与实施——由“探究滑动摩擦力大小与接触面积有关吗?”引发思考 被引量:7
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作者 刘信生 张贵林 汤金波 《物理教学》 北大核心 2020年第4期25-27,14,共4页
初中物理教学中的学生自主创新实验探究是以学生物理核心素养培育与发展为路径的深度学习的具体策略与实施,以符合初中学生认知规律和能力发展水平为前提,以培养学生探究能力、实践能力和创新能力为核心。本文通过探究滑动摩擦力大小与... 初中物理教学中的学生自主创新实验探究是以学生物理核心素养培育与发展为路径的深度学习的具体策略与实施,以符合初中学生认知规律和能力发展水平为前提,以培养学生探究能力、实践能力和创新能力为核心。本文通过探究滑动摩擦力大小与接触面积是否有关等一些实验例子,让学生在"玩、学、悟、用"具体实施策略中历经曲折,既培养了科学精神又提升了物理核心素养。 展开更多
关键词 滑动摩擦力 物体间接触面积 创新应用
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Action Mechanisms of Arbuscular Mycorrhizal Fungi in Phosphorus Uptake by Capsicum annuum L. 被引量:11
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作者 M.SHARIF N.CLAASSEN 《Pedosphere》 SCIE CAS CSCD 2011年第4期502-511,共10页
A pot experiment was conducted to investigate the action mechanisms phorus (P) uptake of Capsicum annuum L. in a sterilized fossil Oxisol of arbuscular mycorrhizal (AM) fungi in phos- Three P levels of 0, 10 and 2... A pot experiment was conducted to investigate the action mechanisms phorus (P) uptake of Capsicum annuum L. in a sterilized fossil Oxisol of arbuscular mycorrhizal (AM) fungi in phos- Three P levels of 0, 10 and 200 mg kg-1 soil (P0, P10 and P200, respectively) without and with AM fungal inoculation were applied as Ca(H2PO4)2-H20. Shoot dry matter yields and shoot P uptake increased significantly (P 〉 0.05) by the inoculation of AM fungi at P0 and P10. Root length and P concentration in soil solution increased with the inoculation of AM fungi but the root:shoot ratio decreased or remained constant. Around 50% roots of inoculated plants were infected by AM and the external hyphae amounted to 20 m g^-1 soil at P10 and P200. The hyphae surface area of the infected root cylinder amounted to 11 and 2 cm^2 cm^-2 root at P0 and P10, respectively. The increased P uptake of inoculated plants was mainly because of an up to 5 times higher P influx of the infected root. Model calculations showed that the root alone could not have achieved the measured P influx in both infected and non-infected roots. But the P influx for hyphae calculated by the model was even much higher than the measured one. The P uptake capacity of hyphae introduced in the model was too high. Model calculations further showed that the depletion zone around roots or hyphae was very narrow. In the case of the root only 7% of the soil volume would contribute P to the plant, while in the case of hyphae it would be 100%. The results together with the model calculations showed that the increased P uptake of AM inoculated plants could be explained partly by the increased P concentration in the soil solution and by the increased P absorbing surface area coming from the external hyphae. 展开更多
关键词 HYPHAE mechanistic model phosphorus influx root infection root morphology
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Phase behavior and interfacial properties of symmetric polymeric ternary blends A/B/AB
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作者 LIU XiaoHan BAI ZhiQiang +2 位作者 YANG KeDa SU JiaYe GUO HongXia 《Science China Chemistry》 SCIE EI CAS 2013年第12期1710-1721,共12页
In this paper, the phase behavior and interracial properties of symmetric ternary polymeric blends A/B/AB are studied by dissipative particle dynamics (DPD) simulations. By using the structure factor and nematic ord... In this paper, the phase behavior and interracial properties of symmetric ternary polymeric blends A/B/AB are studied by dissipative particle dynamics (DPD) simulations. By using the structure factor and nematic order parameter, we carefully characterized the diversified phases and phase transitions, and established the phase diagram of such symmetric ternary blends. It can be generally divided into four regions: disordered phase (DIS) region at high temperature, ordered lameUar phase (LAM) region, bicontinuous microemulsion (BμE) channel and phase-separated phase (2P) region at low temperature with the increase of the total volume fractions of homopolymers φn, which shows good accordance with that in previous experimental and theoretical reports. Furthermore, we calculated the elastic constants of 2P and LAM phase, and discussed the transition mechanisms from 2P and LAM to BμE phase, respectively. The results show a direct relevance between the phase transitions and the change of interfacial properties. Finally, we also demonstrate that the B,uE channel becomes narrower in lower temperature caused by the temperature dependence of interfacial properties of ternary blends. 展开更多
关键词 symmetric ternary blend phase behavior bicontinuous microemulsion dissipative particle dynamics
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