后生动物线粒体基因组基因次序重组规律分析     

孔艳    张哲  李岩  刘斌 《干旱区研究》2014,31(2):336-341

后生动物线粒体基因组由于其大小和基因数目的相对稳定,被认为是研究后生动物系统发育关系的一种理想模型。后生动物线粒体基因组大多有37个基因,包括22个tRNA编码基因和13个蛋白编码基因,它们的排列顺序也被认为是研究后生动物线粒体基因组很好的材料。通过对来自NCBI数据库的2 511种后生动物线粒体基因组提取的基因次序,包括对基因的倒置、共有基因簇、基因的缺失和重复、相邻位置的基因交换等重组形式的概述,综述了近年来对动物线粒体基因组基因次序重组的研究状况。  相似文献   

巢湖东半湖沉积物中有机氯农药的残留特征及风险评价     

周婷婷  李学德  张明  花日茂 《农业环境保护》2009,(11):2374-2378

采样测定了巢湖东半湖4个样点的表层沉积物中有机氯农药（OCPs）的含量。结果表明,11种有机氯农药在样品中被检出,总含量为8.26～31.73 ng.g^-1;OCPs在沉积物中的垂直分布从上往下大体呈递减趋势;且OCPs的最高含量都出现在上层沉积物中,说明巢湖东半湖沉积物中有机氯农药主要集中在0-3 cm的表层。根据分析,DDTs来自于早期残留或者施用农药后的长期风化残留。沉积物风险评估表明,巢湖东半湖表层沉积物中的有机氯农药存在一定的生态风险。  相似文献   

“甜叶菊提取物”对肉仔鸡生长和屠宰性能的影响   总被引：1，自引：0，他引：1  

舒邓群  苏州  付党华  吴红翔  谢云  周婷婷 《江西畜牧兽医杂志》2009,(5):29-31

试验选用肉仔鸡120只,随机分成4组,每组30只。Ⅰ、Ⅱ和Ⅲ组分别在基础日粮中添加0.2%、0.3%和0.4%"甜叶菊提取物",Ⅳ组为对照组,饲喂基础日粮,饲养期为8周。研究该物质对肉鸡生产和屠宰性能的影响。结果表明,与对照组(Ⅳ组)相比,Ⅰ、Ⅱ和Ⅲ组日增重分别提高了17.4%、20.2%和9.3%。其中Ⅱ组增重与Ⅳ组的差异达到了显著水平(P<0.05);饲料利用率Ⅰ、Ⅱ和Ⅲ组分别比对照组提高了5.1%、6.27%和0.39%。与对照组相比,鸡屠宰性能没有明显的差异(p>0.05);从以上结果可以看出,在肉鸡日粮中添加0.3%"甜叶菊提取物"可明显改善生产性能,但是对鸡的屠宰性能并没有显著的影响。  相似文献   

Agouti基因及其与动物毛色关系的研究进展          下载免费PDF全文

李英杰  唐家明  张磊  徐桂利  张文香  段玲欣  刘谢荣  刘铮铸  巩元芳 《家畜生态学报》2015,36(9):85-89

动物特别是毛皮动物,毛纤维颜色丰富多彩,其主要由遗传基因调控,在众多的调控基因中,Agouti基因是一个重要的功能基因。论文重点综述了Agouti基因结构及其在人、小鼠、家养普通动物和毛皮动物毛色方面的研究现状,旨在为动物毛色选育提供参考依据。  相似文献   

Safety Assessment of Circular Arches Tunnel Evacuation on Surrounding Geotechnical Environment     

QIAO Shi fan  SUN Xiao  LIU Bao chen 《保鲜与加工》2009,(5):59-64

Based on the stochastic medium theory, influence on the surrounding rock and soil by tunnel excavation was studied. formula for predicting movement and deformation of rock and soil mass caused by tunnelling were deduced. And especially for the tunnel with circular arch section, half analytic solution for this problem was put forward. Furthermore, a program was developed to compute the movement and deformation of the rock and soil mass resulted from excavation. The deformation failure criterion of stochastic medium for estimating the surroundings safety was provided and was applied in an engineering example, which proved that the results of the research were reasonable and significant for the tunnel safety construction.  相似文献   

Performance and Microstructure of Ultra Low Ion Permeability Cementitious Materials     

WANG Xin gang  SONG Gu quan  CHEN Li he  ZHANG Ai ping 《保鲜与加工》2009,(5):138-144

Microstructure and macro performance of Ultra Low Ion Permeability Cementitious Materials (ULIPCM) were investigated by Micro hardness, MIP and SEM EDXA. It was shown that the compressive strength of ULIPCM was more than 80 MPa, flexural strength was more than 11.0 MPa, and elastic modulus was in the range of 38.0 to 42.0 GPa at the age of 28 days; chloride diffusion coefficient was lower than 0.8×10－13m2·s－1, conductive charge for 6 hours was lower than 300 coulombs; sulfate attack resistance was good; shrinkage at the age of 28 days was lower than 400×10－6. Compared with ordinary concrete with which thickness of interfacial transition zone is 60 to 100 μm, the thickness of interfacial transition zone of ULIPCM was lower than 30 μm. Penetration paths of corrosive medium were effectively interrupted in ULIPCM. And pore structure parameters, such as porosity and the most probable pore radius of ULIPCM, were also obviously optimized in ULIPCM. Besides, few CH crystals were in the ULIPCM aggregate and the interfacial transition zone of ULIPCM. And the orientation of CH crystals was poor.  相似文献   

Measurement of dielectric loss based on discrete Fourier transform spectrum correcting algorithms     

DU Lin  GUO Liang feng  LEI Jing  PANG Jun  《保鲜与加工》2009,(3):257-262

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A Hilbert fractal antenna and portable monitoring system for partial discharge detection in gas insulated substations     

ZHANG Xiao xing  LIU Wang ting  YANG Xiao hua  ZUO Fei  HUANG Hu  《保鲜与加工》2009,(3):263-268

We design a third Hilbert fractal antenna for partial discharge (PD) monitoring in gas insulated substations (GIS) based on fractal principles, and analyze the Hilbert antenna impedance characteristics using an equivalent inductance method of parallel transmission lines. The PD experiment of metal protrusion defect is conducted employing fractal and microstrip antennae. The test results show that the characteristic of the Hilbert fractal antenna has good performance and can detect the PD signal for online monitoring in GIS. A portable online monitoring and locating system for GIS is established using the Hilbert fractal antenna and LabVIEW. The locating accuracy of the PD source in the laboratory meets the requirements of the PD site location.  相似文献   

Theory and approach to reactive power flow tracing     

XIE Kai gui  LUO Jing  CAO Kan  《保鲜与加工》2009,(3):247-251

Based on an analysis of the characteristics of reactive power supplies and reactive loads, this paper presents a method for forming a lossless reactive network using an equivalent technique of modeling the branch admittance as a reactive power supply and the branch power loss as a virtual load. A downstream distribution matrix for a power system is constructed based on its reactive lossless network, and the analytical model and its algorithm for tracing reactive power flow (TRPF) is proposed. A method dealing with the abnormal downstream distribution matrix of active power flow also is discussed. The main advantage of the proposed method is that the matrix theory is used to analyze the TRPF model directly and no assumption on the flow distribution is needed. Case studies of the IEEE14 Bus and IEEE30 Bus systems demonstrate the accuracy and the validity of the proposed method.  相似文献   

Dynamic characteristic analysis of an all terrain vehicle body   总被引：1，自引：0，他引：1  

XU Zhong ming   GUO Shi feng  ZHANG Zhi fei  MU Xiao jing  WANG Xian guo 《保鲜与加工》2009,(1):6-10

The body is a key part of all terrain vehicles (ATV). Its dynamic characteristics greatly effect the vibration of the ATV assembly. Simulation and experimental methods are combined to analyze ATV body vibration characteristics. A computer aided design(CAD) model is built using UG4.0. A finite element method(FEM) model of an ATV body and a body with an engine are created using Hypermesh. The FEM model is imported to Msc.Nastran to calculate the free mode. The simulation model is verified by the experimental modal result. The results indicate that after the frame with engine, the first bending mode increases due to the engine increasing the body stiffness, while the first torsion mode decreases due to the engine mass. The effects on the dynamic response of the road and engine excitation are analyzed respectively. Vibration characteristic improvement methods and suggestions regarding the body are provided.  相似文献