南极罗斯海沉积物中可培养菌株的分离及胞外水解酶活性检测          下载免费PDF全文

王飞  丛柏林  张朝晖  杨黄浩 《极地研究》2020,32(1):68-81

研究了南极罗斯海地区沉积物中可培养微生物多样性,并检测了菌株胞外酶活性,为开发利用南极资源奠定基础。采用Zobell2216E培养基、土豆培养基(PDA)及稀释平板划线法分离并获得纯培养的细菌和真菌,分别通过16SrDNA、18S/ITS序列鉴定分析了可培养微生物的多样性和系统发育。从南极罗斯海沉积物样品中获得78株细菌和54株真菌,细菌、真菌的优势菌株分别为嗜冷杆菌属(Psychrobacter)、枝孢属(Cladosporium);78株细菌菌株中有2株与模式菌株的16SrDNA基因序列相似性小于97%,可能是潜在的细菌新物种。细菌API20NE生理生化和真菌产胞外酶活性结果表明,获得的细菌和真菌大多数可检测到胞外水解酶活性。本研究丰富了南极可培养微生物资源,为南极罗斯海地区可培养微生物的多样性研究以及南极微生物资源的应用研究奠定了基础。  相似文献   

A case study on Landscape Component Niche based on Landscape Pattern Indices: Yanchi,Ningxia Province,China     

XiaoNing Zhang  XueLu Liu  Ghanney Philip  XiaoDan Li  QuanXi Wang  YaNan Xu  TingTing Hui 《寒旱区科学》2020,(1):22-33

Yanchi County is located in the agro-pastoral ecotone and belongs to the ecologically fragile area of Northwest China.It is important to study the evolution of landscape pattern to curb its environmental degradation.In order to intuitively show how the landscape pattern of the study area changes over time,Landsat Thematic Mappers(TM)and Landsat Operational Land Imager(OLI)data of 1991,2000,2010 and 2017 were used.This paper attempts to apply niche theories and methods into landscape ecology,and constructs a niche model of landscape components by using"n-dimentional hypervolume niche theory"and landscape pattern indices.By evaluating the spatial and temporal evolution of niche from the perspective of two-dimensional space to reflect the changes of landscape pattern in the study area over the past 26 years,new theories and methods were introduced for the characterization of landscape pattern.The results indicate that:1)The larger the attribute and dominance value of landscape components,the higher the ecological niche and the stronger the control effect on the overall landscape.2)The ecological niche of each landscape component was significantly different,just as its control effect on the overall landscape.3)The dynamic change of the ecological niche of each landscape component was different,with grassland,unused land and arable land always in a high dominant position,although the ecological niche of construction land and water area was always low.In general,the introduction of niche theory into the landscape ecology provided a new method to study the changes in regional landscape pattern.  相似文献   

生物土壤结皮对风沙土和黄绵土膨胀特性的影响     

王国鹏  肖波  李胜龙  姚小萌  孙福海 《中国沙漠》2020,40(1):97-104

作为重要的土壤物理性质，膨胀性在影响土壤导水性、持水性、抗蚀性以及土壤结构的形成和发育等方面发挥着重要作用。为了探讨生物土壤结皮（BSCs）土壤的膨胀特性及其主要影响因素，针对黄土高原风沙土和黄绵土两种典型土壤，利用膨胀仪测定并比较了有、无藓结皮及其在不同因素（初始含水量、干湿循环、冻融循环、温度）下膨胀率的差异，分析了BSCs对土壤膨胀性的影响及其与环境因素和BSCs性质的关系。结果显示：风沙土上藓结皮的膨胀率为1.93%，较无结皮增加了8.65倍；而黄绵土上藓结皮的膨胀率为2.05%，与无结皮相比降低了76.68%。藓结皮的生物量和厚度与其膨胀率在风沙土上均呈线性正相关关系（P < 0.05），在黄绵土上分别呈二次函数（P=0.02）和线性正相关关系（P=0.02）。初始含水量同时影响了土壤最大膨胀率和稳定膨胀时间，影响程度风沙土远大于黄绵土（包括藓结皮和无结皮）；干湿循环次数对无结皮土壤膨胀率的影响程度大于藓结皮土壤，其中风沙土和黄绵土上无结皮的膨胀率分别是50.00%~620.00%和-2.28%~10.81%，而两种土壤上藓结皮的膨胀率分别是-5.70%~10.88%和-10.24%~-21.46%；冻融循环下4种土壤的膨胀率均有不同程度的降低，降幅为0~18.54%。黄绵土无结皮的膨胀率受温度影响程度较大，50℃下黄绵土无结皮的膨胀率分别是25℃和35℃下的1.17倍和1.21倍。BSCs显著地改变了风沙土和黄绵土表层的膨胀性，其影响的程度和方向取决于土壤类型。同时，BSCs的膨胀性受含水量、温度、干湿以及冻融循环等关键因素影响。  相似文献   

Analysis of Spatial–Temporal Evolution of Mining-Induced Fracture Field: A Case Study Using Image Processing in the Shaqu Coal Mine,China     

Cheng  Zhiheng  Liu  Biao  Zou  Quanle  Wang  Xin  Feng  Jicheng  Zhao  Zhiyan  Sun  Fulong 《Natural Resources Research》2020,29(3):1601-1615

Natural Resources Research - Mining-induced fracture plays a key role in gas drainage for gas burst-prone underground coal mines, especially for closely multilayered coal seams. The layout and...  相似文献   

A modified numerical model for moisture-salt transport in unsaturated sandy soil under evaporation     

Wei Wen  YuanMing Lai  ZheMin You 《寒旱区科学》2020,12(3):125-133

Soil salinization, caused by salt migration and accumulation underneath the soil surface, will corrode structures. To analyze the moisture-salt migration and salt precipitation in soil under evaporation conditions, a mathematical model consisting of a series of theoretical equations is briefly presented. The filling effect of precipitated salts on tortuosity factor and evaporation rate are taken into account in relevant equations. Besides, a transition equation to link the solute transport equation before and after salt precipitation is proposed. Meanwhile, a new relative humidity equation deduced from Pitzer ions model is used to modify the vapor transport flux equation. The results show that the calculated values are in good agreement with the published experimental data, especially for the simulation of volume water content and evaporation rate of Toyoura sand, which confirm the reliability and applicability of the proposed model.  相似文献   

情境教学的课堂评价与教学改进研究——以“资源枯竭型城市的发展方向”为例     

马巍  王民 《地理教学》2020,(4):11-13,29

情境教学是培养学生核心素养的重要教学方法,本文提出了情境教学的课堂评价原则:情境具有真实性、情境与教学目标具有关联性、情境应划分水平。同时提出从情境的结构和关系、解决情境中的问题所涉及地理要素的数量及其关联程度两个角度分别对情境水平进行划分,并结合“资源枯竭型城市的发展方向”课例,提出目前情境教学中存在的问题及教学改进建议。  相似文献   

三元插层材料的合成及其在聚丙烯老化中的应用          下载免费PDF全文

郭凡  刘志启  王庭胜  李丽娟  李娜 《盐湖研究》2020,28(3)

以FeCl3?6H2O、NiCl2?6H2O、MgCl2?6H2O为原料，以NaOH为沉淀剂采用水热法合成了镁镍铁水滑石 (MgNiFe-LDH)，通过X射线衍射 (XRD)、傅里叶变换红外光谱 (FTIR) 和扫描电镜 (SEM) 分析了MgNiFe-LDH结构及形貌，探讨了不同陈化时间和水热温度对MgNiFe-LDH合成的影响。将制得的MgNiFe-LDH添加至聚丙烯 (PP) 中，制备MgNiFe-LDH/PP复合材料，通过对材料的加速老化测其力学性能，研究了添加MgNiFe-LDH前后材料力学性能的差异。研究结果表明，当Mg2+:Ni2+:Fe3+=2:1:1，反应温度为140℃、陈化时间为24 h时，合成的MgNiFe-LDH为片状，形貌较为规整，颗粒粒径约为2μm；经加速老化后，填充MgNiFe-LDH 复合材料的抗老化性能优于纯PP，当MgNiFe-LDH的填充量为6 wt% 复合材料拉伸强度不变，可明显提高PP的抗老化性能。  相似文献   

建鲤基因组DNA的RAPD分析     

董在杰  朱健  袁新华  王建新  姜焱 《广东海洋大学学报》2002,22(1):3-6

用 1 5个随机引物对建鲤基因组DNA进行RAPD分析 ,结果显示 ,建鲤群体内的遗传相似系数为 0 91 81± 0 0 73 8,多态位点比例为 0 41 67,平均杂合度为 0 1 884。表明建鲤种质较纯 ,群体内的遗传变异程度较小。建鲤优良性状产生的分子学基础是等位基因的杂合程度较高  相似文献   

LHRH-A和hCG对南方鲶血清促性腺激素水平的影响     

邓思平  王德寿  张耀光  吴天利 《广东海洋大学学报》2003,23(1):13-16

运用放射免疫分析法测定了促黄体释放激素类似物 (LHRH A)和人绒毛膜促性腺激素(hCG)对南方鲶血清促性腺激素 (GTH)水平的影响 ,结果表明 :LHRH A和hCG都能提高南方鲶一龄幼鱼血清GTH水平 ,hCG与LHRH A结合注射后血清GTH水平显著高于单独注射hCG或LHRH A后的血清GTH水平。LHRH A和hCG结合注射可诱导性成熟南方鲶排卵 ,同时排卵过程中伴随着血清GTH水平的急剧上升 ,在排卵后迅速下降 ;注射同样剂量的药物而未排卵的血清GTH水平虽有升高 ,但升高的幅度不及排卵鱼。这种血清GTH水平的急剧增高对诱导南方鲶卵母细胞最后成熟和排卵具有重要作用。  相似文献   

Variability of Soft X—ray Spectral Shape in Blazars Observed by ROSAT     

Lin－PengCheng  Yong－HengZhao 《中国天文和天体物理学报》2002,2(2):117-126

1 INTRODUCTION Blazars, including BL Lac objects, highly polarized and optically violently variable quasars,and flat-spectrum radio quasars (FSRQs), are characterized by highly variable non-thermalemission which dominates their characteristics from radio to y-ray bands. The mechanismbelieved to be responsible for their broadband emission is synchrotron radiation followed by in-verse Compton (IC) scattering at higher energies (e.g. Blandford & Konigl 1979). Relativisticbeaming of a jet…  相似文献