不同类型土壤的光谱特征及其有机质含量预测

 【目的】构建适合土壤有机质含量估测的高光谱参数及定量反演模型。【方法】系统分析中国中、东部地区5种不同类型土壤风干样本有机质含量与350～2 500 nm波段范围高光谱反射率之间的关系,利用特征光谱参数和BP神经网络建立土壤有机质的定量估测模型。【结果】光谱一阶导数构成的两波段光谱参数与土壤有机质含量的相关性明显优于原始光谱,尤其采用Norris平滑滤波后导数光谱效果更好。光谱参数构成形式以差值指数最好,其次为比值和归一化指数。与土壤有机质含量相关程度最高的光谱参数是由可见光区554 nm和近红外区1 398 nm两个波段的一阶导数组合而成的差值指数DI(D554,D1398),两者呈显著指数曲线关系,拟合方程为y= 184.2 ×exp[-1297×DI(D554,D1398)],决定系数为0.90。经不同类型土壤的观测资料检验,模型预测决定系数为0.84,均方根误差RMSE为3.64,相对分析误差RPD为2.98,显示估测模型具有较好的预测精度。另外,利用BP神经网络结合偏最小二乘法(PLS)对导数光谱进行分析,提取贡献率达到99.56 %的前6个主成分建立了三层BP 神经网络模型,模型决定系数为0.98,经不同类型土壤的观测资料检验,模型预测决定系数为0.96,RMSE为2.24,相对偏差RPD为4.83。比较利用DI(D554,D1398)和BP网络进行土壤有机质含量的预测结果,前者精度低于后者,但可以满足土壤有机质监测的需要。【结论】利用差值光谱指数DI(D554,D1398)和BP神经网络模型均可实现对土壤有机质的精确估测。     

有机锌对哺乳动物先天性免疫的调控机制研究进展

锌作为动物机体一种不可缺少的微量元素,在加强机体免疫方面起着重要作用。基于微量元素锌对动物机体免疫功能的调节作用机理研究的日益深入,文中通过阐述有机锌作用、功效以及在哺乳动物生产中的应用,探究有机锌单独添加对哺乳动物先天性免疫的影响,旨在探究锌对动物机体先天性免疫的调控机制。     

MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF THE FOOT IN HORSES WITH PALMAR FOOT PAIN AND CONTROL HORSES

Palmar foot pain is a common cause of lameness. Magnetic resonance imaging (MRI) has the potential to detect damage in all tissues of the equine foot, but an understanding of the differences in magnetic resonance (MR) images between feet from horses with and without palmar foot pain is required. This study aimed to describe MR findings in feet from horses with no history of foot-related lameness, and to compare these with MR findings in horses with lameness improved by palmar digital local analgesia. Thirty-four limbs from horses euthanized with a clinical diagnosis of navicular syndrome (ameness >2 months duration, positive response to palmar digital nerve blocks and absence of other forelimb problems) (Group L), and 25 feet from age-matched horses with no history of foot pain (Group N) were examined. For each anatomic structure, MR signal intensity and homogeneity, size, definition of margins, and relationships with other structures were described. Alterations in MR signal intensity and homogeneity were graded as mild, moderate, or severe and compared between Groups L and N. Results revealed that there were significant differences in MR images between Groups N and L. Multiple moderate-severe MR signal changes were present in 91% of limbs from Group L and moderate (none were graded severe) in 27% of limbs from Group N. In most Group L limbs, more than three structures and frequently six to eight structures were abnormal. Concomitant abnormalities involved most frequently the deep digital flexor tendon, distal sesamoidean impar ligament, navicular bone, collateral sesamoidean ligament, and navicular bursa (with significant associations in severity grade between these structures), sometimes with involvement of the distal interphalangeal joint and/or its collateral ligaments. It was concluded that findings on MR images were different between horses with and without foot pain, and that pain localized to the foot was associated with MR changes in a variety of structures, indicating that damage to several structures may occur concurrently and that MR imaging was useful for evaluation of foot pain.     

一种核桃专用肥的生产及应用试验

针对云南省临沧市核桃种植区土壤特点,以及核桃生长发育的需肥规律,配制出专用核桃生物有机肥,将该核桃专用生物有机肥分别应用于投产区核桃园和初投产核桃园,取得很好的应用效果,以对照相对,施用该有机肥的核桃表现出植株健壮、树势强,树高、冠幅生长加快,并对核桃有较好的增产效果。     

追施氮肥对苏丹草碳氮代谢及种子产量的影响

以新苏2号苏丹草(Sorghum sudanense ‘Xinsu No.2')为材料,采用单因素完全随机区组设计,在拔节、孕穗和灌浆期以固定比例追施尿素(0, 150, 300, 450, 600, 750 kg·hm^-2),揭示不同氮(N)处理苏丹草碳氮代谢及种子产量性状变化规律.结果表明:追施氮肥有效提高了碳氮代谢水平,随氮肥追施量增加,苏丹草叶片与茎秆中碳氮含量显著增高,施氮量大于600 kg·hm^-2后,总糖和全氮含量均不同程度下降.整个生长期随施氮量增加,苏丹草茎叶碳氮比(C/N)呈逐渐减小趋势,且不追肥、施氮肥150 kg·hm^-2与其它处理间存在显著差异(P < 0.05).氮肥可有效增加种子千粒重、穗粒数,从而使苏丹草种子产量明显增加.然而,随施氮量增加产量增加幅度明显减小,施氮150与300 kg·hm^-2产量增幅分别达23.7%和32.2%,而施氮750 kg·hm^-2产量增幅仅为3.9%,追施氮肥600 kg·hm^-2可获最大种子产量3815 kg·hm^-2.综合碳氮积累、C/N及种子产量表现,试验条件下以追施氮肥600 kg·hm^-2为最佳.     

C18-磁性纳米颗粒萃取虾肉中氯霉素残留

建立了一种用C18键合磁珠固相萃取虾肉中氯霉素残留的方法。在Fe3O4超顺磁性纳米颗粒的表面键合C18基团,制备双功能反相萃取颗粒。用该颗粒对样品中的氯霉素残留进行固相萃取,对结合时间、温度、磁珠用量等因素进行了优化,建立磁珠法兽药残留固相萃取方法。用标准方法(SN/T 1864-2007)对萃取所得产物进行检测。经过优化,C18键合磁珠的最佳萃取条件为50℃结合5 min,用1 mL甲醇洗脱3次。检测结果显示该方法具有良好的精密度和回收率。在0.1～10μg/kg之间具有良好的线性关系,相关系数为0.9941,检出限为0.1μg/kg。该方法灵敏度高、重现性好、准确度高,可满足虾肉中氯霉素残留检测的需要。     

氮添加对内蒙古不同草原生物量及土壤碳氮变化特征的影响

以内蒙古草甸草原、典型草原、荒漠草原3种草原实验区草地植物群落为研究对象, 设置7种氮添加梯度, 分别为CK（0 g N·m^-2·a^-1）、N₁（5 g N·m^-2·a^-1）、N₂（10 g N·m^-2·a^-1）、N₃（15 g N·m^-2·a^-1）、N₄（20 g N·m^-2·a^-1）、N₅（25 g N·m^-2·a^-1）、N₆（30 g N·m^-2·a^-1）,应用单因素方差分析（One-way ANOVA）方法研究不同浓度梯度氮添加下不同草原类型区植被生物量、土壤碳氮差异及其影响因素。结果表明：1）氮添加并未对3种草原类型地下生物量产生显著影响（P>0.05）,但显著提高了草甸草原和荒漠草原地上生物量（P<0.05）,且本研究初步判断在N₃添加时接近饱和阈值, 整体上氮添加使内蒙古草原总生物量平均增加了29.66%,较干旱的荒漠草原对氮添加的响应较为明显。施氮肥使草甸草原的根冠比显著降低（P<0.05）,典型草原根冠比在N₃处理下显著增加（P<0.05）,但对荒漠草原影响不显著（P>0.05）。2）选择不同土层（0~10 cm、10~30 cm）分析氮添加对3种草地类型土壤有机碳、全氮含量的影响, 结果显示氮添加对草甸草原土壤碳氮含量没有显著影响（P>0.05）,对典型草原和荒漠草原土壤碳氮含量存在显著影响（P<0.05）,且0~10 cm土层对施氮的响应更明显。3）施氮条件下地上生物量与土壤C/N、年均降水显著相关（P<0.01）,地下生物量、总生物量均与土壤全氮含量、有机碳含量、土壤C/N、年均温、年均降水显著相关（P<0.01）。总的来说,不同类型的草地生态系统生物量及土壤碳氮含量对施肥的响应存在差异,这意味着草地恢复与管理过程中需要对养分的添加作用进行考虑。     

有机化合物构性相关分析的解析程序

根据有机化合物的构性相关规则 ,用演绎推理的方法建立了有机化合物构性相关分析的解析程序。这一解析程序把有机化合物的构性相关分析归纳成 5个步骤 ,即写出靶结构式 ,找出官能团 ,分析官能团和烃基中所含的每 1根化学键 ,考察分子中各结构单元之间产生的相互影响 ,最后分类总结出有机化合物的全部性能。     

施肥对黔中地区混播草地牧草生长性能的影响

本文研究了氮磷钾不同配比施肥量对黑麦草和紫花苜蓿混播草地牧草生长的影响,结果表明:氮肥促进禾本科牧草叶的生长(P<0.05),增施钾肥对禾草的生长有利;磷能促进豆科牧草根的生长(P<0.05)且豆科牧草株高随着施磷量的增加各处理间差异显著(P<0.05),高氮抑制豆科牧草的生长;最高产量的施肥方式:N:P_2O_5:K_2O为20:30:20,比对照处理的草地产量增加63.92％。     

IMAGING DIAGNOSIS: MAGNETIC RESONANCE IMAGING OF A CERVICAL WOODEN FOREIGN BODY IN A DOG

This article describes the discovery of a chronic cervical wooden foreign body ventral to the left transverse processes of the cranial cervical spine using magnetic resonance imaging (MRI) in a dog that presented with chronic neck pain and lameness. The dog did not exhibit dysphagia or chronic draining tracts, the most common signs of the presumed cause, that of a penetrating oropharyngeal foreign body. The foreign body itself was represented on MR images as an oval straight-edged core within an inflammatory tissue reaction. The wood was slightly hyperintense on T2- and isointense on T1-weighted images relative to muscle. Surrounding this was a more conspicuous contrast-enhancing reactive tissue rim that was hyperintense on all pulse sequences. Adjacent musculature also exhibited diffuse edema and contrast enhancement that extended around the left cervical vertebral transverse processes and local intervertebral nerve roots. The foreign body was found to be a wooden stick upon surgical removal. MRI is an excellent method for visualizing the inflammatory tissue reactions associated with soft-tissue foreign bodies because of its contrast resolution and depiction of anatomy in multiple imaging planes.