基于深度学习算法的京津冀地区综合干旱评估模型构建

及时准确的干旱评估对社会经济发展和农业生产具有重要的指导意义,当前的干旱评估指标通常仅考虑植被或降水等单方面影响因素,在实际干旱评估中存在一定的局限性。本研究综合考虑降水、温度、地形等多个干旱致灾因子,以主要产粮基地京津冀地区为例,基于2007-2017年地表温度（Land Surface Temperature,LST）、归一化植被指数（Normalized Difference Vegetation Index,NDVI）以及降水等多源数据,利用深度学习框架Tensorflow构建以标准化降水蒸散发指数（Standardized Precipitation Evapotranspiration Index,SPEI）为目标值的综合干旱评估模型。利用决定系数（R2）和均方根误差（RMSE）对模型进行测试;利用站点标准化降水指数（Standardized Precipitation Index,SPI）、土壤相对湿度数据以及2016年京津冀地区的气象灾害数据,从时间和空间上对模型的可靠性进行验证。结果表明：模型的训练集和测试集在不同月份上均表现较好（R2均大于0.5而RMSE均小于0.55）。模型输出的综合干旱指数（Comprehensive Drought Index,CDI）在密云站上与SPI和SPEI接近,变化趋势基本一致,并且与站点SPI和土壤相对湿度的相关系数分别大于0.7和0.4,均通过了0.01水平的显著性检验。空间上,相较于SPEI,CDI计算的2016年3-7月京津冀地区干旱事件结果与实际情况符合度更高,表明该模型适用于京津冀地区干旱评估。     

Short term soil priming effects and the mineralisation of biochar following its incorporation to soils of different pH

The aim of this work was to determine the magnitude of the priming effect, i.e. short-term changes in the rate (negative or positive) of mineralisation of native soil organic carbon (C), following addition of biochars. The biochars were made from Miscanthus giganteus, a C4 plant, naturally enriched with ¹³C. The biochars were produced at 350 °C (biochar350) and 700 °C (biochar700) and applied with and without ryegrass as a substrate to a clay-loam soil at pH 3.7 and 7.6. A secondary aim was to determine the effect of ryegrass addition on the mineralisation of the two biochars.After 87 days, biochar350 addition caused priming effects equivalent to 250 and 319 μg CO₂-C g⁻¹ soil, in the low and high pH soil, respectively. The largest priming effects occurred at the start of the incubations. The size of the priming effect was decreased at higher biochar pyrolysis temperatures, which may be a way of controlling priming effects following biochar incorporation to soil, if desired. The priming effect was probably induced by the water soluble components of the biochar. At 87 days of incubation, 0.14% and 0.18% of biochar700 and 0.61% and 0.84% of biochar350 were mineralized in the low and high pH soil, respectively. Ryegrass addition gave an increased biochar350 mineralisation of 33% and 40%, and increased biochar700 at 137% and 70%, in the low and high pH soils, respectively. Certainly, on the basis of our results, if biochar is used to sequester carbon a priming effect may occur, increasing CO₂-C evolved from soil and decreasing soil organic C. However, this will be more than compensated for by the increased soil C caused by biochar incorporation. A similar conclusion holds for accelerated mineralisation of biochar due to incorporation of fresh labile substrates. We consider that our results are the first to unequivocally demonstrate the initiation, progress and termination of a true positive priming effect by biochar on native soil organic C.     

乡村景观格局热效应研究

利用Quickbird和ETM影像对浙江省绍兴县北部平原220 km2区域内50个村庄景观格局热效应进行了研究。通过环境亮温与建筑、水体、草地、林地、绿地(草地＋林地)5种地类斑块共45个景观指数间的数量关系分析,结果表明:各景观指数与环境亮温间具有良好的线性关系;众多景观指数可分为密度类指数、覆盖率类指数、形状指数、核心区规模指数、100 m缓冲区相关指数、其它指数6类,其中优势斑块和景观总体的密度类指数、覆盖率类指数是环境亮温的主要作用因子;有关建筑斑块及核心区景观总体规模的指数(建筑的覆盖率、块均面积、聚合度,核心区的总面积、总周长、总块均面积)与环境亮温为正相关关系,其它多为负相关,因此建成区规模较小、各地类以众多小斑块均匀分布、建筑覆盖率低且形状狭长的村庄更有助于环境降温。建立了4个亮温预测模型(Ra2>0.9),筛选出相应的亮温预测及调控因子组;在核心区,环境亮温的单因子拟合效果欠佳,景观格局结构指数的作用不能忽略,结构指数对亮温的作用贡献约占总量的25%。     

冀北山地杨桦次生林林分空间结构研究

在木兰林管局桃山林场选取面积为100 m×100 m的杨桦次生林样地,以每株林木树高、胸径和坐标为基础数据,运用混交度、大小比数和角尺度等林分空间结构参数分析了杨桦次生林的空间结构特征。结果表明:(1)该林分中山杨Populus davidiana和白桦Betula platyphylla在株数和断面积比例上占优势,为林分内优势树种;(2)林分各混交类型的比例相差不大,林分整体呈中度混交状态;(3)林分优势木和亚优势木相对较多,基于胸径、树高得到的平均大小比数结果基本一致,均能客观反映林分的分化规律;(4)林分平均角尺度为0.504,属于随机分布,林下伴生树种以集聚分布为主,但优势树种的随机分布趋势起决定作用。     

Assessment of the IgG index in dogs by indirect immunoenzimatic assays as diagnostic tool for inflammatory diseases of central nervous system

The IgG index measures the intrathecal immunoglobulin production and it is a useful tool for diagnosis of inflammatory diseases involving the central nervous system. This index is based on the precise quantification of albumin and IgG in canine cerebrospinal fluid and serum. Here, we report the development of an indirect competitive ELISAs for the detection of both antigens. Thirty-two dogs were included in this study, divided into three experimental groups. Group A was composed of 22 healthy animals, as determined by standard clinical examination. In group B, six animals, presented neurological pathologies associated with endogenous IgG production and, in group C four animals presented neurological diseases or symptoms not associated with intrathecal IgG production. Cerebrospinal fluid and serum samples were obtained from these animals. As expected, by using the indirect ELISAs proposed here, the IgG indexes obtained in healthy animals (A) were 0.371+/-0.252 (SD). In B and C, the values (3.002+/-1.897; 0.36+/-0.306, respectively), were in agreement with the pathologic conditions of the individuals in each group. Thus, the immunometric competition ELISA methods proposed here allow the discrimination of abnormal intrathecal IgG production, in a variety of inflammatory pathologic conditions of the central nervous system.     

低能N+注入紫花苜蓿生物学效应初步研究

对N 注入紫花苜蓿Medicago sativa所引起生物学效应从生理生化层面进行了较系统的研究,结果显示:在低剂量范围内(0~2.08×1016N /cm2),N 注入对紫花苜蓿种子存在当代刺激效应,所研究的几种生理生化指标相对CK都有所提高。剂量为6.24×1016~8.32×1016N /cm2的N 注入对紫花苜蓿种子存在反常辐照损伤效应。即随着N 注入剂量增加,各生理生化指标先降,后升,再降。N 注入使紫花苜蓿过氧化物酶同工酶酶谱发生变异。处理组与对照组扩增出的相同谱带亦存在谱带荧光强度有差异的现象。另外,对N 注入束介导大豆基因组DNA转入紫花苜蓿做了初步研究,结果M2总性状突变率达到19.8%,并得到3株叶片粗蛋白含量较高的突变株(粗蛋白含量比对照高约0.5%)、1株高叶绿素含量的突变株(叶绿素含量比对照高33.3%)。     

湟中马血清酯酶多态性的研究

采用聚丙烯酰胺凝胶电泳法对青海省湟中县９１匹马血清酯酶的多态性进行了研究。结果发现：①湟中马的血清酯酶受ＥＳ＾Ｆ，ＥＳ＾Ｉ，ＥＳ＾Ｓ和ＥＳ＾Ｏ４个等位基因的控制，其基因频率分别为０．４４５０，０．５３３０，０．０１１０和０．０１１０；②在被检湟中马的ＥＳ位点上共发现ＥＳ Ｆ，ＥＳ ＦＩ，ＥＳ Ｉ，ＥＳ ＩＳ和ＥＳ Ｏ五种表型，以ＥＳ ＦＩ为优势表型（４７．２５％）；③ＥＳ等位基因频率无性别差异；④     

干旱胁迫条件下不同饲用燕麦品种种子萌发指标比较与评价

本研究采用PEG-6000溶液模拟干旱胁迫条件,比较研究了26份饲草型燕麦(Avena sativa L.)种子的萌发特征,利用主成分分析法和隶属函数法进行了综合评价,为抗旱燕麦品种选育提供实验参考。结果表明,与CK相比,15% PEG浓度下,所有材料的发芽率、发芽势、芽长、根长、种子活力指数等指标均显著下降,不同品种之间差异显著。经主成分分析法筛选,发芽势、发芽指数、活力指数为燕麦种质耐旱性评价的主效指标。通过综合评价,'荟峰’、'三星’、'喜韵’为强抗旱品种;'梦龙’、'大富翁’为中等抗旱品种;'甜燕2号’、'挑战者’、'白燕7号’、'甜燕麦青海’、'甜燕70’、'牧乐思’、'进口甜燕’、'禾王’、'当地燕麦’、'莫尼卡’、'巴燕3号’、'燕麦克劳沃’、'甜燕麦’、'摄政王’、'青海444’为弱抗旱品种;'青牧’、'福燕1号’、'喜越’、'青甜1号’、'甜燕1号’、'shooter’为不抗旱品种。     

复合双歧杆菌制剂对肉羊生长性能、养分表观消化率及血液生化指标的影响

为研究复合双歧杆菌制剂对肉羊生长性能、养分表观消化率及血液生化指标的影响,试验选择健康、体重相近的杜寒杂交肉羊60只随机分成4组,每组15个重复,每个重复1只,1组为对照组饲喂基础日粮,试验2、3、4组分别在基础日粮中添加2.5％、5.0％、10％的复合双歧杆菌制剂,预试验7 d,试验期56 d.结果表明:(1)试验3...     

氨基糖苷类药物抗生素后效应的研究进展

对氨基糖苷类药物抗生素后效应的产生机制、体内外的研究方法、影响因素及常用氨基糖苷类药物抗生素后效应的研究现状进行概述,为评价氨基糖苷类药物的药效学指标和在兽医临床的合理应用提供理论基础。