云南撒坝猪H-FABP基因多态性及与部分生产性能的关系     

李国治  连林生  鲁绍雄  严达伟  苟潇  赵桂英 《家畜生态》2008,(6)

采用PCR-RFLP技术检测H-FABP基因5′上游区1125~1817区段HinfⅠ酶切位点在撒坝猪群体中的多态性分布,并采用最小二乘分析模型初步统计分析检测位点多态性与部分生产性能的相关性。结果表明,H-FABP基因等位基因H及基因型Hh在群体中占优势,频率分别为0.6022和0.4194;H-FABP基因在群体中处于Hardy-Weinberg平衡状态;H-FABP基因检测位点基因型间在生长和繁殖性状上不存在不利影响。  相似文献   

2022年夏季汉江中下游水华生消驱动因子及其贡献率量化研究          下载免费PDF全文

查悉妮  辛小康  付婷  李建  白凤朋  林枭  舒鹏 《水生态学杂志》2024,45(1):143-151

2022年夏季，长江流域遭遇了罕见的“汛期反枯”极端水文事件，在此期间，汉江中下游首次发现了蓝藻水华。本研究选取叶绿素a浓度作为衡量水华的关键指标，基于偏最小二乘回归（Partial least squares regression，PLSR）量化了不同环境因子对2022年夏季汉江中下游（仙桃、宗关断面）水华生消的贡献率。结果表明：（1）仙桃和宗关断面叶绿素a浓度与溶解氧、pH值和水温均呈现出显著的正相关关系。溶解氧、pH值和水温对2022年夏季汉江中下游水华生消的贡献程度最高，三者对仙桃和宗关断面水华生消的贡献率分别为15.18%、13.68%、14.50%和18.06%、15.93%、15.65%。（2）基于偏最小二乘路径模型（Partial Least Squares Path Modeling，PLS-PM），本研究进一步解析了各环境因子对叶绿素a浓度变化的影响路径。结果表明气象因子是2022年夏季汉江中下游蓝藻水华暴发的诱导因子，高温无雨的极端天气导致水温和pH上升，加速了藻类的代谢反应速率。同时，河道流量减小延长了有机物和营养盐的传输和滞留时间，为藻类生长提供了稳定的营养条件。并且水华“萌发”时段可能与汉江中下游“涝旱急转”时段重叠。因此，本文建议下一步研究应结合准确的中长期气象预报信息，在“涝旱急转”时段实时优化汉江中下游水华防控调度的下泄流量与下泄时机，这将有可能大大提高水华防控的效率和效果。  相似文献   

Prediction of watermelon quality based on vibration spectrum     

《Postharvest Biology and Technology》2013

Judging watermelon quality based on its apparent properties such as size or skin color is difficult. A non-destructive method is employed here, based on vibrational response spectrum, to determine the quality indices of watermelon (Charleston gray). The responses of samples to vibration excitation were recorded by laser Doppler vibrometry (LDV). The phase shift between input and output signals were extracted over a wide frequency range. The total soluble solids (TSS), titratable acidity (TA) and TSS/TA ratio also measured as watermelon quality characters. Stepwise multiple linear regression (SMLR) as well as partial least square regression (PLS) was applied to extracted vibration spectrums to construct prediction models of watermelon quality. The results showed that performance of SMLR models were better than PLS. The determination coefficients (R²) of SMLR validation models were 0.9976, 0.9985 and 0.9542 for TSS, TA and TSS/TA respectively. It is likely that reduction of cell wall materials to soluble solids during ripening process changes viscoelastic properties of watermelon reflected by vibrational response. This study demonstrated the feasibility of mentioned method for predicting the quality of watermelons in an industrial grading system.  相似文献   

矩形区组方“RBS”设计及其在树木育种中的应用Ⅰ.单个“RBS”设计统计分析     

梁一池 《福建林业科技》1997,(1)

本文介绍矩形区组方"RBS"设计的基本方法,单个"RBS"设计方差分析的数学模型,处理平均数效应,期望均方分解,遗传力及其遗传变异系数估值,并举例介绍"RBS"在树木育种中的应用。  相似文献   

湖北省高等院校干道绿化和广场绿化建设的探讨     

胡军  柳长久 《湖北林业科技》2004,(4):55-58

科学进行干道和广场的绿化规划与树种选择 ,对全面提升校园景观质量具有重要的意义。结合当前湖北地区部分高校干道绿化和校园广场绿化建设中存在的一些问题 ,介绍了干道和广场的绿化规划和树种选择原则 ,并详细探讨了适合湖北地区高校种植的干道绿化树种和广场绿化植物。  相似文献   

Customer adapted grading of Scots pine sawn timber using a multivariate method     

Anders Berglund  Olof Broman  Johan Oja  Anders Grönlund 《Scandinavian Journal of Forest Research》2015,30(1):87-97

To define new grading rules, or to customize the ones in use in a rule-based automatic grading (RBAG) system of boards, is a time-consuming job for a sawmill engineer. This has the effect that changes are rarely made. The objective of this study was to continue the development of a method that replaces the calibration of grading rule settings by a holistic-subjective automatic grading, using multivariate models. The objective was also to investigate if this approach can improve sawmill profitability and at the same time have a satisfied customer. For the study, 323 Scots pine (Pinus sylvestris L.) boards were manually graded according to the preferences of an important customer. That is, a customer that regularly purchases significant volumes of sawn timber. This manual grading was seen as reference grading in this work. The same boards were also scanned and graded by a RBAG system, calibrated for the same customer. Multivariate models for prediction of board grade based on aggregated knot variables, obtained from the scanning, were calibrated using partial least squares regression. The results show that prediction of board grades by the multivariate models were more correct, with respect to the manual grading, than the grading by the RBAG system. The prediction of board grades based on multivariate models resulted in 76–87% of the boards graded correctly, according to the manual grading, while the corresponding number was 63% for the RBAG system.  相似文献   

硬岩抗剪强度参数的最优化确定法     

唐杰军  汪亦显 《中南林业科技大学学报(自然科学版)》2007,27(3):95-100

为了减小岩工程分析计算的工作量和节约研究经费,须利用有限的室内实验样本的测定值,通过对有限实验样本数据的回归分析整理,确定岩石抗剪强度参数c、φ,进而估计岩体的抗剪强度c、φ.由于试验方法、试验条件等有一定局限性,因而,岩石力学参数的试验结果具有一定的不确定性.其不确定性包含随机性和模糊性.而用传统的数理统计方法处理岩石样本值,显然是不合适的,只有通过寻求最优的数学回归分析方法,来处理相关试验结果.笔者通过对硬岩变角度剪切实验和常规三轴压缩实验的数据回归分析,得到利用最小二乘法的抛物线回归分析结果和随机-模糊回归分析结果比较符合.因而,为了优化计算结果而又避免繁琐的计算,通常可以采用最小二乘法的抛物线回归分析计算代替随机-模糊回归分析相关结果.  相似文献   

城市广场复层结构绿化比例分析评价——以南京市城市广场为例   总被引：1，自引：0，他引：1  

武文婷  朱云华  田密蜜  吴竹华 《浙江林业科技》2007,27(1):74-78

根据陈自新等专家提出的城市绿地乔、灌、草配植的适宜比例建议方案,将其数值范围按比例扩大化后分为三类评价类型,对南京市19个已经建成的城市广场的复层结构绿化比例进行了单项分析和综合分析评价。根据城市广场的特殊性和三类评价类型的绿化景观丰富度、舒适度和满意度进行实地调查,提出了复层结构绿化的适宜比例、基本适宜比例和不适宜比例,提出了复层结构绿化比例范围扩大化、增加单体灌木色块种植和城市行道树按比例计量的建议。  相似文献   

Height–diameter equations for boreal tree species in Ontario using a mixed-effects modeling approach     

Mahadev Sharma  John Parton 《Forest Ecology and Management》2007

Height–diameter relationships based on stand characteristics (trees/ha, basal area, and dominant stand height) were investigated for balsam fir, balsam poplar, black spruce, jack pine, red pine, trembling aspen, white birch, and white spruce using data from permanent growth study plots in northern Ontario, Canada. Approximately half the data were used to estimate model parameters with the rest used for model evaluation. Multiple Chapman–Richards functions with parameters expressed in terms of various stand characteristics were fit to determine the best models for predicting height.  相似文献   

Determination of moisture content and basic specific gravity of Populus tremuloides (Michx.) and Populus balsamifera (L.) logs using a portable near-infrared spectrometer     

Guillaume Hans  Brigitte Leblon  Paul Cooper  Armand La Rocque  Joseph Nader 《Wood material science & engineering》2015,10(1):3-16

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