Estimation of sensitivity and specificity of diagnostic tests and disease prevalence when the true disease state is unknown   总被引：1，自引：0，他引：1  

Enøe C  Georgiadis MP  Johnson WO 《Preventive veterinary medicine》2000,45(1-2):61-81

The performance of a new diagnostic test is frequently evaluated by comparison to a perfect reference test (i.e. a gold standard). In many instances, however, a reference test is less than perfect. In this paper, we review methods for estimation of the accuracy of a diagnostic test when an imperfect reference test with known classification errors is available. Furthermore, we focus our presentation on available methods of estimation of test characteristics when the sensitivity and specificity of both tests are unknown. We present some of the available statistical methods for estimation of the accuracy of diagnostic tests when a reference test does not exist (including maximum likelihood estimation and Bayesian inference). We illustrate the application of the described methods using data from an evaluation of a nested polymerase chain reaction and microscopic examination of kidney imprints for detection of Nucleospora salmonis in rainbow trout.  相似文献   

国外土地整理实践对我国土地整理的启示   总被引：1，自引：0，他引：1  

丁恩俊周维禄  谢德体 《四川畜牧兽医学院学报》2006,4(2):11-15

土地整理在我国起步较晚，很多理论还不成熟。采用文献参阅法，从土地整理的发展阶段、内容和特点等方面介绍了德国、俄国和荷兰等国外土地整理的基本情况，并由此得出其对我国土地整理的启示：建立健全土地整理法律政策，重视土地整理的权属调整，拓宽土地整理融资渠道，重视土地整理中的生态环境保护，积极推动土地整理公众参与和高度重视土地整理规划等。  相似文献   

Isolation and Identification of Enterococcus faecalis from Fur-bearing Animals     

CI Yang  SHI Xiaojie  SONG Peng  DING Qi  LI Wenli 《中国畜牧兽医》2007,47(9):2997-3005

In order to obtain Enterococcus faecalis from fur animals and evaluate its prebiotic properties,in this study,Enterococcus faecalis was isolated from the feces of healthy adult fur-bearing animals (mink,fox,raccoon dog),identified by morphological observation,biochemical test and 16S rRNA sequence analysis.The growth curve,acid production capacity and antibiotic sensitivity of the Enterococcus faecalis isolates were measured to evaluate their probiotic properties.Some strains were selected to determine their tolerance to temperature,artificial gastric juice and artificial bile salt.The results showed that five strains were Gram-positive,and their biochemical characteristics were basically consistent with the standard strains of Enterococcus faecalis,and they were identified as Enterococcus faecalis by 16S rRNA sequence analysis.The five strains all entered the logarithmic phase at 2 h after culture,and entered the stable phase at 8-10 h,and had weak acid production capacity.The resistance rate of the isolates to tetracycline and levofloxacin was 100%,followed by penicillin (80%),erythromycin (80%),gentamicin (80%) and chloramphenicol (40%).All the isolates were sensitive to ampicillin and vancomycin.Enterococcus faecalis from mink,fox and raccoon dog had strong tolerance to temperature below 60 ℃,artificial gastric juice with pH>3.0 and 0.3%-0.5% concentration of bile salt,but poor tolerance to temperature above 70 ℃,and artificial gastric juice with pH<3.0.In conclusion,five strains of Enterococcus faecalis from fur animals (mink,fox,raccoon dog) were obtained in this study.The isolated strains propagated rapidly,which were suitable for colonization and played a prebiotic role in fur animals' intestines,and had good prebiotic characteristics and stress resistance.They could be used as candidate strains for animal microbiological agents for further study.  相似文献   

放牧因子与VA菌根的相互作用对鸭茅养分吸收和生长发育的影响   总被引：1，自引：0，他引：1  

乌恩  菅原和夫  云锦凤 《干旱区资源与环境》2007,21(11):136-140

探讨了放牧因子与VA菌根的相互作用对鸭茅(Dactylis glomerataL.)养分吸收和生长发育的影响。菌根效应表现在不施磷肥条件下的鸭茅地上部生育与地上、地下部的磷素营养上,但对地上部生育的效应因刈割次数的增加而降低,对地上、地下部磷素营养的效应因土壤镇压而降低。菌根对鸭茅钙素营养的效应只见于不施磷肥条件下的土壤镇压处理,而在相同条件下菌根却降低了鸭茅的镁含量。说明VA菌根对鸭茅磷素营养和生长发育的效应与土壤磷营养有关,而且因地上部的过度采食和土壤镇压而降低。  相似文献   

西藏波密县天麻产业发展问题研究   总被引：1，自引：0，他引：1  

次仁卓嘎  沈娟 《现代农业科学》2009,(5):269-270

由于西藏波密县农业生产具有地质史独特,地形地貌复杂,气候异常,土壤种类繁多,野生植被多样的特点,给天麻生产带来机遇的同时,又带来了严峻的挑战。笔者主要从西藏波密县天麻生产的现状入手,科学地分析了西藏波密县天麻生产中存在的问题,提出了天麻生产发展的对策。  相似文献   

四翅滨藜在固阳县的引种试验研究     

段霞  鲁海  次国鑫 《内蒙古林业调查设计》2009,32(1):44-45

包头固阳地区自然气候条件恶劣,可供造林的树种贫乏,四翅滨藜耐干旱、瘠薄、耐盐碱,适应性强,既是林又是草,是林草兼用的饲料植物,对牲畜有较好的适口性。四翅滨藜可采用播种子和扦插繁育,但用半木质化的嫩枝扦插繁殖成苗率高,生产成本低,技术简单。是包头固阳地区造林、盐碱地改造、荒山营建灌木林的较理想的树种之一。  相似文献   

ULMUS ANTI- INSECT FAST- GROWING NEW VARIETY LAYER CUTTING REPRODUCTION TECHNOLOGY     

Du ran  LAN Zai-ping  MA Ke  CI Zhong-ling 《内蒙古农业大学学报(自然科学版)》2008,29(4)

  相似文献   

施氮水平对杂交狼尾草产量、品质和氮素吸收利用的影响   总被引：4，自引：0，他引：4  

黄勤楼  陈恩  黄秀声  陈钟佃  钟珍梅 《热带作物学报》2009,30(1):26-30

在大田种植情况下.研究4种施氮水平对杂交狼尾草产量、粗蛋白含量和氮素生产效率的影响,以及牧草产量、粗蛋白含量与施氮量和各种农艺性状的相关性.结果表明,施氮肥能显著提高杂交狼尾草的分蘖数、株高、产量和粗蛋白含量,N2、N4处理间分蘖数差异不显著,N3、N4处理间株高、干草产量和粗蛋白含量差异不显著.杂交狼尾草鲜草产量、干草产量、粗蛋白含量、分蘖数、株高和施氮量相互间都呈正相关,其中鲜草产量与施氮量、分蘖数和粗蛋白含量呈显著相关,与株高和干草产量呈极显著相关;干草产量与施氮量和分蘖数呈显著相关.与株高呈极显著相关:粗蛋白含量与施氮量也呈显著相关.杂交狼尾草在一定的施氮量范围内,随着施氮量增加.牧草的干物质积累总量、粗蛋白质产量和氮素积累总量也越多,而牧草的氮素干物质生产效率、干物质生产效率、粗蛋白质生产效率、氮素农艺效率和氮素表观回收率都逐渐降低.在施纯氮量为350～1 050 kg/hm2时,杂交狼尾草的氮素表观回收率为25.73%～45.12%,氮素回收率只有16.68%～20.35%.  相似文献   

滇东南岩溶山区4个树种的造林试验结果分析     

常恩福  李品荣  陈强  周洪昌  王锡全  李红兵  李玉文  刘永国  徐珑峰 《西部林业科学》2001,(2):7-12

通过在砚山县铳卡农场对圣诞树、滇合欢、新银合欢、刺槐4个树种不同造林密度、施肥措施、苗根处理方式及苗期喷云大-120等5个因素的对比试验,幼树期的结果表明树种对林木生长量及生物量的影响最大,施肥措施和苗根处理方式对林木的生长发育也具有一定的作用,而苗期喷云大-120对定植后林木的生长发育作用不明显,密度效应除圣诞树外其他3个树种还不显著。参试的4个树种中,圣诞树3年生时已经郁闭,其最佳技术组合A1B1C1D1E1的树高、地径、冠幅和单株生物量分别为5.05m、4.72cm、1.79m和7.05kg,每公顷可提供薪材22678kg、绿肥和饲料24345.5kg,产值3485.08元;滇合欢的最佳技术组合A2B1C2D2E1的树高、地径、冠幅和单株生物量分别为1.84m、4.33cm、1.23m和1.26kg,每公顷可产薪材6936.8kg、绿肥和饲料1467.4kg,产值767.05元;新银合欢则不太适应试区的气候,每年都受霜冻的危害。预计在滇东南岩溶山区选择多用途的圣诞树和滇合欢,采用最佳的技术措施组合造林,能取得良好的生态效益和经济效益。  相似文献   

江苏仪征低丘岗地营林开发模式优化选择研究   总被引：4，自引：3，他引：4  

李晓储  王伟  董志良  刘贵阳  黄利斌  张辉  刘广科  丁翠柏  徐恩云 《江苏林业科技》2001,28(2):1-5

总结江苏省仪征低丘岗地开发的经济林、用材林等7种营林模式和5种纯板栗与农作物间作模式，评估其生产和经济效益，优化选择出了板栗与茶复合林模式、纯梨园、纯茶园、纯桃园等4种开发营林模式；板栗与山芋 雪菜、板栗与芝麻 胡罗卜、板栗与花生 苕子等3种板栗与农作物间模式。其中板栗与茶，并期板栗与山芋 雪菜等间作模式，可形成高效复合经营开发模式。文内还提出了该市低丘岗地综合治理与开发试点试区的建设原则，发展模式及应实施的集约组装技术。  相似文献