饲料中不同维生素C含量对长吻的影响

用维生素C含量为38、364和630mg/kg的三种饲料饲喂初体重为(23.19±0.58)g的长吻8个月,实验结果表明,38mg/kgVC饲料组饲喂的长吻表现出了典型的VC缺乏症状:体色发黑,脊椎侧弯,鳍边由开始的萎缩直到腐烂、贫血、特定生长率显著降低(p<0.05)。并且38mg/kgVC饲料组长吻的生理指标也受到影响:血清溶菌酶活性显著下降(p<0.05),肝脏的SOD活性及MDA含量均显著升高(p<0.05),血清皮质醇没有显著差异(p>0.05),但各处理组长吻肝脏中均未检测到诱导型HS

低C/N对湿地中硝化反硝化作用的影响

通过监测几种形态氮的变化,研究了人工湿地小试系统在不同浓度和低C/N条件下的除氮效果和反硝化途径.结果发现,湿地对浓度为5.5～50.5mg/L的NH4+-N有很好的去除效果,去除率可达95%以上.在此浓度范围内,NH4+-N的进、出水浓度呈线性关系,R2值为0.9971.当进水含氮量低于16.4mg/L时,湿地的除氮效率随进水浓度的增加而明显增加.进水含氮量为16.4～51.4mg/L时,湿地的除氮效率为85%以上,且浓度对去除率无显著影响.当C/N<1时,湿地系统对总氮的去除率为86.3%,而碳源充足

3D modeling of high-T c superconductors by finite element software

A three-dimensional (3D) numerical model is proposed to solve the electromagnetic problems involving transport current and background field of a high-T c superconducting (HTS) system. The model is characterized by the E-J power law and H-formulation, and is successfully implemented using finite element software. We first discuss the model in detail, including the mesh methods, boundary conditions and computing time. To validate the 3D model, we calculate the ac loss and trapped field solution for a bulk material and compare the results with the previously verified 2D solutions and an analytical solution. We then apply our model to test some typical problems such as superconducting bulk array and twisted conductors, which cannot be tackled by the 2D models. The new 3D model could be a powerful tool for researchers and engineers to investigate problems with a greater level of complicity.

On the photoluminescence of a-C:H films

a-C:H films deposited from methane and helium mixture in a capacitively coupled rf plasma were found to show photoluminescence (PL) with peak intensities at energies far above the Taue gap of these films. Apart from the PL the films were investigated with respect to their IR and UV/VIS absorption properties as well as their Raman spectra were examined. The ultraviolet (UV) and blue luminescence from hard a-C:H thin films are explained by incorporation of polycyclic hydrocarbons from gas-phase reactions in the methane helium plasma into the film.

鲤科鱼类的c-myc CDS及其系统发育关系

鲤科鱼类在东亚的物种多样,分布广泛,物种特征尺寸差异明显,弄清其功能基因的系统演变,对于理解物种分化和功能进化具有重要意义.以具有重要生长调控作用的c-myc基因为标记,通过PCR扩增、克隆和测序,共获得41种鲤科鱼类和外类群c-myc基因全序列,发现并分析了c-myc编码区的两个高变异区.基于c-myc CDS序列,分别采用最大简约法(MP)、最大似然法(ML)和Bayesian法重建了鲤科鱼类的系统发育关系.3种方法所得系统发育关系较为相似.当以亚口鱼科的胭脂鱼(Myxocyprinus asiati

牙鲆淋巴囊肿病毒中国株(LCDV-C)羟类固醇脱氢酶基因的特征分析

属于虹彩病毒科的淋巴囊肿病毒(Lymphoeystisdiseasevirus,LCDV)是一类能引起全球各地上百种淡、海水鱼产生囊肿的病原。在新分离到淋巴囊肿病毒中国株(LymphocystisdiseasevirusisolatefromChina,LCDV—C)并完成序列测定的基础上,用计算机辅助分析了LCDV—C羟类固醇脱氢酶(hydroxysteroiddehydrogenase,HSD)基因结构特征,LCDV—CHSD读码框为1023bp,推导其编码含340个氨基酸、分子量约为39.3kD的蛋

~(14)C标记1,2,7,8-TCDD在鲤体内分布及代谢的初步研究

利用14C标记1,2,7,8-四氯代二苯并二噁英(1,2,7,8Tetrachloro[U—14C]dibenzodioxin,14C1,2,7,8TCDD)初步研究了其在鲤体内的分布和代谢规律。14C1,2,7,8-TCDD溶解于丙酮/植物油中,腹腔暴露。暴露1、2、4、8、12d后取样,肝脏、胆汁、腹腔脂肪等消化制样后用液闪仪测量放射性活度。肝脏和胆汁内的放射性活度同步变化,都是第8d达到峰值后下降。腹腔脂肪内1—2d放射性明显高于随后取样的样品。肝和腹腔脂肪的分布量之比呈现“S”型变化趋势。暴露4d