共查询到20条相似文献，搜索用时 78 毫秒
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单一闭合导线是由一已知点出发,布置成闭合多边形扣到起始点的闭合导线(图1)。在测量中常布设闭合导线作控制测量,常规的闭合导线手工平差及面积求算,计算量大,步骤烦琐,在计算中难免出错、影响精度;用计算机进行运算,能省时省工,确保运算结果的 相似文献
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手持GPS和罗盘仪在涉案林地面积测量中的精度分析 总被引：3，自引：0，他引：3
通过在南京中山陵风景区不同林地条件下及南京森林公安学校校园内选设的多个点进行面积测量,以全站仪测量结果为真值,对比分析手持GPS和罗盘仪在林地面积测量中的精度问题,为森林公安人员在办理森林案件中测算林地面积提供参考。 相似文献
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《中南林业科技大学学报(自然科学版)》2016,(8)
立木胸径是森林资源清查中的一项重要指标,它是计算森林蓄积量和衡量林木生长状况的重要依据。三维重建测量物体是近年来计算机视觉领域研究的新热点。将低成本的USB摄像头双目视觉尝试运用到立木胸径测量中,通过摄像机标定参数和视差图获取三维点云,用C++语言结合Open CV实现了从三维点云中提取和计算胸径的方法。并选取华北落叶松进行胸径测量,将测量结果与胸径尺进行比较结果表明胸径测量精度可达到95.3%,可满足国家对森林资源清查的精度要求。 相似文献
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介绍了悬高测量的方法、原理,对TOPCON GTS-211D全站仪悬高测量精度及其测量结果的可靠性进行了分析,并指出在测量过程中如何正确投点以减小悬高测量误差. 相似文献
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以环球法测定松香软化点为评定对象,对测量结果的各种影响因素进行了不确定度分析。评定结果定量表征了检测结果的质量,说明了环球法测定松香软化点检测结果的可用性,同时说明温度计的准确度对软化点测量结果的影响最大,为实验室在相关检测过程中进一步提高检测数据的可靠性和一致性提供参考。 相似文献
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《Southern Forests》2013,75(3):247-253
Genetic materials interact with the environment in specific ways, therefore their responses in wood need to be better understood. The present study sought to evaluate the influence of different climatic conditions in Minas Gerais, Brazil on Eucalyptus grandis × Eucalyptus urophylla wood. Two six-year-old clones were cultivated in Belo Oriente, Ferros, Santa Bárbara, Itabira and Peçanha. Five trees from each clone were sampled from the base to top direction. Wood density, heartwood/sapwood ratio, vessels, fibres, and extractive and lignin contents were determined, as well as their correlation with environmental variables. Vessel diameters, heartwood/sapwood ratio, and extractive and lignin contents all increased due to higher water availability in Santa Bárbara and Itabira. In both genetic materials, the variables linked to growth and wood quality were related to environmental factors. 相似文献
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无人机在我国林业上应用概述 总被引：1，自引：0，他引：1
文章对无人机在我国林业上的应用做一归类,主要包括在森林资源调查、森林资源监测、森林信息提取等方面的应用,并提出无人机在我国林业上应用存在的问题及建议。 相似文献
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锰在植物体内生理功能研究进展 总被引：35，自引：0，他引：35
从锰胁迫对植物的影响、锰在植物的光合作用、氟化还原和多种酶活化中的作用及锰与其它元素的关系等方面综述了锰在植物体内的主要生理功能，为植物锰营养研究提供研究资料。 相似文献
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Nicolas Desneux Jean-Michel Rabasse Yannick Ballanger Laure Kaiser 《Journal of pest science》2006,79(2):95-102
In light of a recent increase in the aphid populations on young canola (Brassica napus) in autumn in Northwestern Europe, we carried out a survey of their parasitoid species during this season. The study was
done in France from 1998 to 2001 using different sampling methods. Results highlighted the presence of two main species of
Aphidiinae, Aphidius matricariae and Diaeretiella rapae (and to a lesser extent Aphidius ervi) on Myzus persicae, and of D. rapae on Brevicoryne brassicae. Nine other Aphidiinae species were found occasionally as well as some Aphelinidae parasitoids and hyperparasitoids. There
was no difference in parasitoid species pattern between fields in Northern and Southern France. The principal parasitoid species
found in the fields were reared in the laboratory to confirm their ability to develop on the canola aphids. Aphidius matricariae and D. rapae were reared successfully on M. persicae, but a low parasitism rate was obtained for A. ervi on this aphid. This study showed that A. matricariae and D. rapae could develop on aphids on canola and that they are present naturally in canola in autumn. However, the parasitism rate is
low in autumn, so the options could be the use of these parasitoids in augmentative release biological control programs or
in an IPM project on canola fields during this time of the year. 相似文献
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乌兰察布市兴和县山区春季雨季造林与管理措施的浅析 总被引：1，自引：0，他引：1
文章针对乌兰察布市兴和县山区利用春季雨季的有利时机,搞好造林,提高造林成活率,春季雨季造林技术及管理粗浅的想法。 相似文献
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文章记述了内蒙古大兴安岭林区鳞翅目粉蝶科已知19种,包括斑缘豆粉蝶Colias erate Esper、北黎豆粉蝶Colias viluiensis Men、黑缘豆粉蝶Colias palaeno Linnaeus、黎明豆粉蝶Colias aurora Esp、北方豆粉蝶Colias melinos Ev、兴安豆粉蝶Colias tychede Boeber、橙黄豆粉蝶Colias fieldii Menetries、镏金豆粉蝶Colias chrysoheme Esper、绢粉蝶Aporia crataegiL、菜粉蝶Pieris rapaeL、东方菜粉蝶Pieris canidia Sparrman、暗脉粉蝶Pieris napiL、黑纹粉蝶Pieris melete Menetries、云粉蝶Pontia daplidiceL、绿云粉蝶Pontia chloridice Hubner、钩粉蝶Gonepteryx rhamniL、尖钩粉蝶Gonepteryx aspsiaMen、莫氏小粉蝶Leptidea morsei Fenton和突角小粉蝶Leptidea amurensis Mentries。并对其形态特征、习性、寄主和分布进行了简要介绍。 相似文献
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