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101.
102.
为向村镇土地利用规划和管理提供合理决策依据,开展村镇土地利用空间格局变化进行模拟研究。在元胞自动机模型基础上,引入马尔科夫模型和多标准评价方法,构建元胞转移数量规则及空间位置规则,从自然环境、社会经济与政策等3方面分析土地利用影响因子,构造元胞自动机复合模型;选取北京市房山区为研究区,以村镇为单元对其土地利用空间格局进行模拟。结果显示:房山区的耕地、林地面积不断减少,建设用地占用农用地现象突出;人口集中、农业资源丰富的平原区各村镇土地利用变化明显。研究表明,多标准评价方法使元胞转移空间位置有规律可循,并有效避免模拟结果中大量错误斑点的产生;以村镇为单元进行分析,模拟的结果更加精细和合理。 相似文献
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鸭蛋动态图像预处理和获取颜色特征参数的算法 总被引:4,自引:3,他引:4
研究了动态鸭蛋图像预处理及图像颜色特征参数的提取算法。其中预处理包括去图像边缘毛刺和蛋壳污点信息;提取鸭蛋图像颜色特征参数需要通过鸭蛋轮廓识别和圆形搜索算法实现,对于鸭蛋图像的轮廓识别是以彩色图像的红色分量R来判定图像边界点,并以此计算出鸭蛋图像蛋内像素和,用圆形搜索法求出蛋芯颜色特征区域并提取图像特征颜色参数。试验结果表明,通过该算法,得到的蛋重模型相关性达到0.95,建立的颜色模型相关性达到0.92。 相似文献
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试验结果表明,单产皮棉高于2250kg/ha时,施钾肥96.0~135.6kg/ha、施锌肥34.5~51.0kg/ha、喷施稀土366.0~559.5 g/ha。 相似文献
107.
Effects of temperature and humidity on the contact angle of pesticide droplets on rice leaf surfaces
Jiantao Zhang Tengyuan Zhou Jiajun Zeng Xuanchun Yin Yubin Lan Sheng Wen 《Journal of Pesticide Science》2022,47(2):59
The effects of external factors such as temperature, humidity, pesticide formulation, and pesticide concentration on the contact angle of pesticide droplets on rice leaf surfaces were analyzed. The experiments showed that there were significant differences in the contact angles of droplets on the leaf surfaces under different temperatures and humidity. As the ambient temperature increased, the contact angle first decreased and then increased, reaching a minimum value at 25°C. With a gradual increase in humidity, the contact angle significantly increased and reached a maximum at 100% humidity. Finally, it was concluded that both the formulation and concentration of the pesticide had a significant effect on the contact angle of droplets on rice leaf surfaces. The experiments also illustrated that the effects of the pesticide formulation and concentration on the contact angle were more significant than those of temperature and humidity. 相似文献
108.
Effects of dietary macroalgae meal and lipid source on growth performance and body wall fatty acid composition of sea cucumber Apostichopus japonicus 下载免费PDF全文
Bin Wen Yong‐Jun Sun Qin‐Feng Gao Shuang‐Lin Dong Zai‐Zhong Chen Jian‐Zhong Gao 《Aquaculture Research》2018,49(2):776-785
A 70‐day experiment was conducted to examine the effects of different macroalgal meals and lipid sources on growth, body wall composition and fatty acid (FA) profile of sea cucumber Apostichopus japonicus. Two macroalgal meals including Sargassum muticum (SM) and Gracilaria lemaneiformis (GL) and two lipid sources including fish oil (FO) and vegetable oil (VO) were formulated into four diets, i.e., S. muticum and fish oil (SF), S. muticum and vegetable oil (SV), G. lemaneiformis and fish oil (GF) and G. lemaneiformis and vegetable oil (GV). The results showed that the specific growth rates (SGR) of A. japonicus fed diets containing SM were significantly higher than those fed diets containing GL. No significant differences in SGR between the FO‐based and VO‐based groups were observed. Similar results were observed in the body wall lipid content. Most body wall FAs changed to resemble the dietary FA proportions because of the dietary effect. Concentrations of 20:4n‐6 of the SF and GF groups were significantly lower than the SV and GV groups, while levels of 20:5n‐3 and 22:6n‐3 were significantly higher than the SV and GV groups. The n‐3/n‐6 polyunsaturated fatty acids (PUFA) ratios of the SF and GF groups were significantly higher than the SV and GV groups. Moreover, the SF group had significantly higher 20:5n‐3 and 22:6n‐3 contents and n‐3/n‐6 PUFAs ratio than the GF group. These findings reveal that the SF diet can show beneficial effects on both growth performance and body wall n‐3 PUFAs content of A. japonicus. 相似文献
109.
Genomic structure and molecular characterization of growth hormone and its expression response to different feed types in golden pompano Trachinotus ovatus (Linnaeus, 1758) 下载免费PDF全文
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