基于距离相关系数和KNN回归模型的森林蓄积量估测研究

【目的】探究Landsat8 OLI数据和KNN算法在森林蓄积量估测中的潜力。【方法】以湖南省湘潭县为研究区,采用Landsat8 OLI数据和同时期的二类调查数据,通过距离相关系数筛选特征,分别采用线性回归模型(MLR)、K-近邻模型(KNN)、距离加权KNN模型(DW-KNN)和优化欧式KNN模型(FW-KNN)对森林蓄积量进行估测。使用十折交叉方法进行精度检验,对检验结果进行对比分析。【结果】3种KNN模型的估测结果均高于传统的线性模型,并且在3种KNN模型中,FW-KNN算法效果最好,决定系数达到0.69,为3种模型中最高;3种KNN模型中,本研究优化欧氏距离KNN模型的估测精度最高,其均方根误差为30.3%,相比于传统KNN模型的均方根误差降低了5.1%,相比于DW-KNN模型降低了3.3%。【结论】采用DW-KNN蓄积量估测结果明显优于其他两种模型,说明通过特征与蓄积量的相关性优化样本间的距离是一种可行的KNN优化方法。     

根据盗伐、滥伐林木现场树坑作相应林木材积估测

介绍了在盗伐、滥伐林木现场仅有树坑的情况下，利用相应小班森林资源规划设计调查资料或相近林分调查资料对被盗伐、滥伐林木作材积估测的方法，并举例说明。     

进口木地板坯料应注意的问题

本文提出了进口木地板坯料时应考虑南北气候差异及木材密度等材性差异来确定留有不同的加工余量，并建议海关按照国际惯例制定以净尺寸材积作为计税材积的标准，避免各港口实行不同征税标准，给企业进口地板坯料带来诸多困难。该建议已引起海关总署重视，并委托国家林业局起草单耗标准。     

Application of acoustic Doppler current profiler combined with a scientific echo sounder for krill Euphausia pacifica density estimation

ABSTRACT:   An application of the acoustic Doppler current profiler (ADCP, 153.6 kHz) in combination with a scientific echo sounder (EK60, 38 and 200 kHz) was investigated to estimate the density of krill Euphausia pacifica . The acoustic backscattering strength from sound scattering layers was compared with biomass estimates from midwater trawls. Euphausia pacifica was targeted among mixed species populations in the sound scattering layer in the offshore Funka Bay area of Hokkaido, Japan. The frequency characteristics of acoustic backscattering by krill were calculated using a distorted wave Born approximation scattering model at three frequencies. Krill aggregations identified from the EK60 data were extracted as the mean volume backscattering strength difference between two frequencies. They were then used to identify similar aggregations in the ADCP data by matching observation times and depths for the two methods, which were applied simultaneously. Results from the comparison of the mean volume backscattering strength and the density calculated from the ADCP and EK60 showed that ADCP can be used to measure density and spatial–temporal distribution of krill aggregations. Current speed and direction at the study site were found to be 16.1 cm/s and 187.0°, respectively, and krill speed and direction (including the current component) were found to be 19.8 cm/s and 172.2°, respectively. Based on the ADCP data, the net speed and direction of the krill aggregations were found to be 5.9 cm/s and 128.0°, respectively.     

棉花黄萎病菌毒素结合位点初探

以纯化的棉花黄萎病菌毒素(PLPC)免疫新西兰白兔制备了PLPC特异性抗血清。将PLPC(15μg·ml 1)用不同浓度的抗体(1～20μg·ml 1IgG)吸附后处理泗棉3号的切根苗,毒素所引起的症状都有不同程度的减轻。表明所制备的抗体在与毒素发生特异性免疫学反应的同时,可部分封闭毒素分子上与毒素受体结合的位点。利用竞争ELISA测定了泗棉3号幼苗子叶的质膜制剂与PLPC的结合活性。结果表明,质膜制剂与毒素结合后能部分阻断毒素与其抗体的免疫学反应,即质膜制剂中含有毒素的结合位点。分别用胰蛋白酶和煮沸处理质膜制剂后,质膜制剂对毒素与其抗体的反应的抑制作用消失,初步表明质膜制剂中与毒素结合的是蛋白质。     

Identification by isoelectric focusing of creatine kinase-MM isoforms in the plasma and striated muscle of pigs

Total creatine kinase (CK) and CK-MM isoforms were determined in plasma and longissimus dorsi muscle extracts from normal pigs. Based on their total CK activity, the pigs were divided into two groups. Pigs of group 1 (n=16) had a mean plasma total CK of 298±16 U/L and the distribution of the CK-MM isoforms was 65.7±2.5% CK-MM₃, 18.9±1.6% CK-MM₂ and 15.3±1.5% CK-MM. In group 2 (n=18; 826±75 U/L total CK) four isoforms were observed: 3.1±0.9% CK-MM, 67.9±3.0% CK-MM₃, 21.5±2.3% CK-MM₂ and 7.5±1.3% CK-MM₁. The differences between the two groups of pigs were significant (p<0.001) for CK-MM₁ and the presence of CK-MM. Four CK-MM isoforms were also detected in longissimus dorsi muscle homogenates: 45.6±8.1% CK-MM, 32.6±11.7% CK-MM₃, 16.6±2.3% CK-MM₂ and 5.1±2.8% CK-MM₁. The release of CK-MM isoforms from muscle into plasma seems to be unrelated to the concentration of these isoforms in striated muscle.     

猪血浆蛋白(酶)多态性与杂种优势的关系

为探讨血浆蛋白 (酶 )多态性与杂种优势的关系 ,测定了杜洛克、长白、大白、杜×长大、大×长大、长×大、大×长共 7个品种 (组合 )的 8个血浆蛋白 (酶 )位点的多态性及部分生长和胴体性状 ,计算了平均基因杂合度与部分经济性状实测值和杂优率的相关关系 .结果表明 ,平均基因杂合度与遗传距离呈正相关 ,与日增重、屠宰率、背膘厚、后腿比例的实测值或杂优率呈正相关 ,与眼肌面积的实测值和杂优率呈负相关 .平均基因杂合度和亲本间遗传距离可为预测杂种优势提供依据 .     

溴隐停对惠州麻肉种鸡产蛋性能的影响

研究目的在于探讨多巴胺受体激动剂(溴隐停)对地方良种肉鸡繁殖性能的影响。方法从628只28周龄健康的“惠州麻”黄羽肉种鸡群中随机选取1组鸡笼内的40鸡作为实验组,其余的作为对照组。实验组鸡群喂服溴隐停,每只鸡每天1.25mg,连用4d,停用4d后再用4d,对照组不使用。结果在4周的实验期内实验组和对照组的产蛋率分别为83.86%和69.96%;破蛋率分别为1.28%和1.69%,畸形蛋率分别为4.33%和1.19%;实验组平均每只鸡的产蛋总数比对照组多3.89个、合格种蛋数多3.26个;药物处理对平均蛋重无显著影响;使用溴隐停能够提高鸡血液中的雌激素水平。结论溴隐停能够通过抑制地方良种肉鸡体内促乳素的合成与分泌,减少抱窝现象的发生,提高其繁殖性能。     

河南省杨树材种出材率表的研编

用削度方程和单株带皮—去皮胸径的转换关系式两个模型对河南省杨树进行计算机理论造材．经精度检验，满足要求，方法可行，依此编制了河南省杨树材种出材率表。