石羊河流域近50a来气候变化与人类活动对水资源的影响   总被引：7，自引：3，他引：4  

李金标  王刚  李相虎  马金珠 《干旱区资源与环境》2008,22(2):75-80

用主成分回归法对石羊河流域径流及进入红崖山水库水量的各影响因素进行耦合关系分析,得到三个主成分,其方差贡献率达92.79%。根据各自对应的特征向量特点,以人为因子、温度因子和降水因子代替原自变量进行回归分析,方程相关系数为0.865,对各系数进行t检验,结果都已通过,影响作用显著,回归方程有显著意义。根据回归方程,近50a来人为因子在水资源变化过程中起主导负作用,其影响力占总影响力的-58.46%,大大超过了降水因子22.35%的正作用,而温度因子虽其影响力不是很大,只占总影响力的-19.19%,但却使水资源减少的趋势进一步加剧。  相似文献   

大肠杆菌多重耐药调节基区AcrR和MarR突变     

佟海山李乾学  邓彦宏孙智勇　邓旭明 《中国兽医杂志》2007,43(7):10-12

研究大肠杆菌多重耐药外输泵抑制基因AcrR和MarR突变对大肠杆菌多重耐药的调节机制。采用琼脂平板二倍稀释法测定环丙沙星、诺氟沙星、氯霉素、四环素、利福平、庆大霉素、大观霉素、阿米卡星、链霉素、阿莫西林等10种药物对临床分离的33株大肠杆菌和大肠埃希氏菌的标准菌株ATCC25922的最小抑菌浓度（MIC），从中筛选出7株多重耐药菌和2株相对敏感菌，并对这9株菌及标准菌ATCC25922的AcrR和MarR基因进行聚合酶链式反应（PCR）扩增并克隆后测序，分析DNA序列及氨基酸序列的突变情况。耐药菌和敏感菌均发现有部分菌株发生了不同程度的点突变。AcrR和MarR同时突变将更大限度的提高细菌的耐药性。  相似文献   

鸡致病性大肠杆菌对头孢喹肟等的体外敏感性     

杜向党  莫娟  张素梅  刘建华  李新生 《中国畜牧兽医》2007,34(8):83-84

从2006年1月~6月河南省中北部8个地级市鸡场的发病或死亡鸡分离细菌，选取经生化和动物试验结果证明的鸡致病性大肠杆菌共63株，采用肉汤稀释法测定其对头孢喹肟、头孢噻呋、氟苯尼考和沙拉沙星的敏感性。结果显示，试验菌对以上药物的耐药率分别为33.3%、46.0%、63.5%和98.4%。鸡致病性大肠杆菌对几种较新的动物专用抗生素耐药性状况不容忽视。  相似文献   

易与猪大肠杆菌病混淆的腹泻类疾病鉴别诊断     

杨天宁  李莎  熊喜华  魏国春  郗文源 《猪业科学》2021,38(3):50-52

新生仔猪腹泻是猪场常见的疾病。因为新生仔猪免疫系统、消化系统发育不完全,抵抗力低下,一旦感染相关病原,发生腹泻,死亡率较高,对猪场造成巨大的经济损失。能导致仔猪发生腹泻的病原很多,虽然临床症状都为腹泻,但是表现出的具体症状有所区别。文章对不同病原引起的临床症状进行总结,为猪场的相关人员进行诊断提供依据。  相似文献   

东南沿海地区水禽源大肠杆菌耐药表型及耐药基因型的调查     

刘凯迪  罗华东  王琳琳  王长珍  王民歌  廖晓萍 《中国畜牧兽医》2021,48(12):4690-4701

为研究水禽中大肠杆菌的耐药表型及耐药基因型,本研究从中国广东、福建、浙江、江苏和山东5个省市的水禽养殖场及周边环境中采集鸭粪便样品、水样以及土样1 505份,采用选择性培养基和基质辅助激光解吸电离飞行时间(MALDI-TOF-MS)质谱分离鉴定大肠杆菌,采用微量肉汤稀释法检测耐药表型,采用PCR方法筛选大肠杆菌中的25种耐药基因。结果显示,1 505份样品中共分离鉴定出449株大肠杆菌,分离率为29.8%,其中335份来源于粪便,52份来源于土壤,62份来源于水,这些样品中浙江(43.3%)和广东(43.2%)的分离率最高,其次是福建(28.1%)和江苏(23.8%),山东(18.3%)的分离率最低。449株大肠杆菌具有多重耐药性,对氨苄西林、环丙沙星、金霉素、氟苯尼考和磺胺类药物的耐药率分别为90.2%、50.3%、96.7%、87.3%和90.6%,而对替加环素和美罗培南则比较敏感,来源不同省份的大肠杆菌对不同抗菌药呈现出不同的耐药率。PCR检测结果发现,449株大肠杆菌中耐药基因tet(A)检出率最高(88.2%),随后是floR(58.13%)、sul2(57.02%)、tet(B)(53.9%)、cmlA(39.2%)和sul1(36.75%),未检测到qnrA、tet(M)和tet(X)耐药基因的大肠杆菌。在这5个省份中,上述耐药基因在山东省样品中分布均较高,而在浙江省和江苏省样品中分布较低。综上所述,本研究调查了中国东南沿海五省水禽及环境中大肠杆菌的耐药现状,为养殖业抗生素的规范使用提供理论依据。  相似文献   

劳伦斯作品中人与自然和谐关系的探析     

张敬 《信阳农业高等专科学校学报》2014,(2):73-75

面对第一次世界大战与工业文明给人类所带来的困境,劳伦斯提出通过建立人与自然的和谐关系,帮助人类找寻出路。本文从劳伦斯的三部主要作品《虹》、《恋爱中的女人》和《查泰来夫人的情人》中分析其倡导人与自然和谐的思想。  相似文献   

Land cover change and eco-environmental quality response of different geomorphic units on the Chinese Loess Plateau     

SONG Yongyong  XUE Dongqian  DAI Lanhai  WANG Pengtao  HUANG Xiaogang  XIA Siyou 《干旱区科学》2020,12(1):29-43

Land cover in the Chinese Loess Plateau has undergone dramatic changes since the late 1980s.Revealing the trend in land cover change and eco-environmental quality response of different geomorphic units in this stage is a realistic requirement for promoting sustainable development of the Chinese Loess Plateau.Based on the data of geomorphic units and land cover in 1990,2000,2010 and 2018 of the Chinese Loess Plateau,we studied the trend of land cover change and eco-environmental quality response of different geomorphic units by using a significance index of land cover change,a proportion index of land cover change and an eco-environmental response model.The results indicated that from 1990 to 2018,the areas of forestland and construction land substantially increased,whereas those of cropland,grassland,wetland and unused land considerably decreased.Land cover change exhibited large geomorphic differences,and the main conversion of land cover was from cropland into other land types.Unstable trend of land cover change in the loess tablelands and sandy loess hills declined,whereas the unstable trends in the other geomorphic units enhanced.Eco-environmental quality varied among different geomorphic units.The expansion of construction land and degradation of forestland,grassland and wetland resulted in the deterioration of eco-environmental quality.The conversion of cropland and unused land into forestland and grassland,and the conversion of grassland into forestland were the main factors that drove the improvement of eco-environmental quality.The findings of this study may provide theoretical reference and support decision making for the optimization of land use structure and the improvement of eco-environmental quality on the Chinese Loess Plateau.  相似文献   

Identification of tumor antigen epitopes by MHC-I/peptide binding prediction and immunological experiments     

LI Qing-yang  HU Wei  SONG Chan-chan  LI Liang-ping 《园艺学报》2019,35(4):584-591

AIM:To establish the methods to identify immune epitopes of tumor antigens restricted by human leukocyte antigen (HLA) alleles frequent in the Chinese population for the isolation and identification of tumor-specific T cells and the cloning of tumor antigen-specific T-cell receptor gene. METHODS:Three cancer/testis antigens NY-ESO,MAGE-A1 and KK-LC-1 were selected as the model antigens to predict the MHC-I binding peptides by major histocompatibility complex (MHC)-peptide binding prediction software. The HLA alleles of healthy volunteers were determined by PCR. The predicted epitopes restricted by HLA-A*11:01 and HLA-B*46:01 of the volunteers were selected for the long peptide design. ELISPOT and flow cytometry were used to analyze the interferon-γ (IFN-γ) spots of the activated T-cells and the up-regulation of CD137 to verify the effectiveness of peptides for T-cell-specific stimulation. We selected long peptides with the best response to verify short peptides. RESULTS:Three cancer/testis antigens containing many strong binding epitopes restricted by 35 HLA alleles common in Chinese population were found. It was found that the predicted epitopes were not equally distributed in the protein sequences. KK-LC-1 antigen was selected for further study. The 2 long peptides stimulated T-cell activation:the release of IFN-γ and up-regulation of CD137 molecules by T cells of the volunteers with the matched HLA alleles. The short peptides worked better than the long peptides.CONCLUSION:Tumor antigen epitopes are quickly identified by MHC/peptide binding prediction and T-cell stimulation analysis. According to the reaction of the long peptide, the short peptide is synthesized to verify the precise epitope. This study provides a new way to determine tumor antigen epitopes quickly.  相似文献   

河北省犊牛腹泻大肠杆菌致病性及耐药性分析   总被引：1，自引：0，他引：1  

刘勃兴  赵安奇  柳翠翠  刘畅  李浩  高桂生  吴同垒  史秋梅  张志强 《中国预防兽医学报》2020,(2):133-138

为确定河北省犊牛腹泻大肠杆菌的致病性与耐药性,本研究对2018年1月至2019年6月期间从河北省石家庄、保定、承德、唐山、廊坊的部分肉牛场腹泻犊牛样品中分离到的50株大肠杆菌进行了致病性试验、药物敏感性试验、毒力基因和耐药基因检测。结果显示:50株分离菌均对小鼠具有致病性,致病菌占比100%(50/50)。毒力基因fyuA、irp2、eaeA、ler检出率分别为68.0%、66.0%、34.0%、34.0%。50株分离菌均对15种抗生素中的2种及以上表现为耐药,对10种及以上抗生素耐药的菌株占比达34%(17/50);分离菌对土霉素、磺胺对甲氧嘧啶、磺胺间甲氧嘧啶、替米考星4种药物表现为高度耐药,耐药率分别为90%、90%、94%、100%。除四环素类tetD基因检出率为0外,其它耐药基因均有检出,其中四环素类tetC、氨基糖苷类aadA1、喹诺酮类gyrA、gyrB基因检测率高达100%。试验的50株大肠杆菌均具有较强的毒力和多重耐药性。本研究为河北省大肠杆菌所致犊牛腹泻病的防治提供了实验依据。  相似文献   

母乳低聚糖及其在婴幼儿配方乳粉中的替代品研究进展     

王艳菲  公丕民  张兰威 《乳业科学与技术》2020,43(1):25-32

母乳低聚糖（human milk oligosaccharides，HMOs）是母乳的重要成分，研究非母乳低聚糖与HMOs之间的差异是实现婴儿配方乳粉母乳化、提升婴儿配方乳粉营养功能、满足婴儿营养健康的基础性工作。本文综述近几年关于HMOs种类、结构特征、HMOs对肠道微生物的调节、肠道健康及免疫系统发育影响的研究成果，同时比较常见动物乳中低聚糖的构成与HMOs的差异，阐述目前婴儿配方乳粉中常用低聚糖的特点及其功能，提出低聚糖在婴幼儿配方乳粉中应用存在的问题与展望，为开发新型婴儿配方乳粉提供理论指导。  相似文献