环境因子对蛋鸡生产性能的影响

本文研究了春季蛋鸡舍空气环境因素对伊莎蛋鸡生产性能的影响。结果表明 ,各层笼温差较大 ,下层比中、上层低 1 .5～ 3.0℃ ;上、中层与下层的产蛋率存在极显著差异 (P<0 .0 1 )。而中、上层间差异不显著 (P>0 .0 5)。 1～ 3层昼夜光照强度差异大 ;白天光照强烈 ,且不均匀 ,南北两列差异极显著 (P<0 .0 1 )。南列平均值为 2 0 4 .8L x,北列仅为 2 1 .1 Lx,是南列出现啄癖多、死淘率高的一个重要原因。相对湿度平均 66.7% ,在适宜范围之内。舍内平均风速小 ,仅 0 .0 4 8± 0 .0 1 9m/s;NH3为 2 7.9ppm、CO2 0 .1 8%超过卫生学标准。经相关回归分析 ,此浓度的氨对产蛋率已产生明显的负效应 (P<0 .0 1 )。     

Several Influencing Factors on Fluorescent in situ Hybridization Experimental System Applied to Dendranthema spp.

Fluorescent in situ hybridization (FISH) was applied to investigate the phylogenetic relationship among Dendranthema spp. Genomic DNA of wild species which was used as probe did not give specific signals, while 18S-26S rDNA from Arabidopsis, which was used as control probe, showed the loci on the target chromosomes clearly. Satisfied results of FISH were gotten when denaturing digoxingenen-labeled probe and chromosome together in oven at 80℃ for 10-15min. There is little influence on the result by the stringency of washing when rDNA was used as probe. The result also indicates the limitation of genomic in situ hybridization (GISH) when used as an approach to analyze the phylogenetic relationship among Dendranthema spp. and the origin of cultivated chrysanthemum.     

GDNF对海仁酸损伤体外培养新生大鼠背根神经节神经元的影响

N1无血清培养基原代分离培养新生大鼠背根神经节（dorsal root ganglion DRG)神经元，用兴奋性毒素海仁酸（kainic acidKA)损伤体外培养细胞后，加入胶质源性神经营养因子（glial-derived neurotrophic factor,GDNF)作用。最后通过MTT法检测，细胞总蛋白测定，胎盘兰染色计数，形态学观察等方法研究分析GDNF对兴奋性毒素海仁酸损伤后大鼠DRG神经元的活性，存活及突起生长的影响，结果表明：GDNF对体外正常生长的DRG神经元的存活，活性及突起生长没有明显的促进作用。而在海仁酸损伤后，GDNF对其存活和活性有明显的促进作用。但对突起生长没有明显的影响。     

保护性耕作推广中的制约因素及其对策

在保护性耕作的推广过程中存在技术、经济、文化三个方面的制约因素,它们降低了保护性耕作的发展速度。这三个方面因素有着内在联系,他们的影响通过机具数量不足的形式表现出来。本文分析了这些因素的影响,提出了相应的解决措施。     

基于不同立地因子的杉木与马尾松地位指数相关模型

偏差较大、精度不够高是地位指数相关模型应用的关键问题.通过科学地划分雪峰山地区的立地因子,有效地选择立地因子,采用SPSS对雪峰山地区324块同时具有杉木和马尾松地位指数值数据的样地进行11种方程的模拟分析,建立了基于立地因子的雪峰山杉木与马尾松地位指数相关模型,模拟效果较好;预测误差绝对差值分布在0~0.7 m之间,95%以上分布在0.3 m左右.解决了地位指数代换偏差较大、精度不够高的问题,提高了模型的实用性能.     

小麦品种产量改良的限制因素分析

通过对关中地区 5 0年来不同时期小麦品种在目前栽培条件下产量性状变化与当前推广品种源库关系的研究 ,初步探明 :①在以往品种改良中 ,收获指数的提高起了重要作用 ;②当前种植的品种中 ,源是产量进一步提高的制约因素 ;③引入新的种质 ,以改善源的功效为基础提高生物学产量 ,且不降低收获指数 ,是超高产育种的根本方法。     

中德合作滇渝造林管理系统的研究与应用

探讨及介绍了中德合作滇渝造林管理系统软件研制情况、系统功能、特点及应用前景。应用现代信息技术改进传统造林管理，提高生产效率和管理水平。     

Detection of Escherichia coli strains producing cytotoxic necrotizing factor type two (CNF2) by enzyme-linked immunosorbent assay

Sheep and rabbit antisera were produced against lysates of E. coli strain 711 (pVir). This K-12 strain carries the Vir plasmid which codes for Cytotoxic Necrotizing Factor type 2 (CNF2). Immunoglobulin G (IgG) fractions of both immune sera were subsequently purified by a two-step precipitation method. To increase the specificity for CNF2, the sheep IgG preparation was extensively adsorbed against both a sonicated extract of isogenic K-12 strain 711 and intact phenol-treated cells of vaccine strain 711 (pVir). An enzyme-linked immunosorbent assay (ELISA) was developed to detect clinical isolates of E. coli producing CNF2, using the final preparations of rabbit and sheep IgG in a double sandwich technique. The results obtained with this CNF2-ELISA were compared to those obtained with the conventional HeLa cell cytotoxicity assay. The testing of 133 E. coli strains (49 CNF2 positive strains and 84 negative strains) resulted in no false-negative and no false-positive. Therefore, the CNF2-ELISA offers a good alternative to the HeLa cell culture assay for the detection of CNF2-producing strains where facilities for and experience with cell cultures is lacking.     

小麦籽粒饱满度与环境条件的关系及其遗传分析

小麦籽粒表面皱缩的遗传力很低,仅为18.67％,易随栽培条件而发生变化,宜改善栽培条件增加其充实程度。腹沟比率的遗传力较高,品种(系)为56.15％,杂种为59.88％。说明腹沟比率的遗传性较稳定,不易受环境条件的影响。可选用腹沟丰满的亲本组配、选育成籽粒饱满的品种。     

桉树容器快速育苗试验

桉树采用营养土容器育苗,能缩短苗期管理时间,减少苗期地下病虫危害,自播种后60～70d即可造林,并能提高造林成活率。