排序方式： 共有39条查询结果，搜索用时 375 毫秒
31.
在应用ＥＩＪＳＡ鉴定７株抗奶牛ＩｇＭ、ＩｇＡ、ＩｇＧ＿１、ＩｇＧ＿２和Ｉｇ一轻链的单克隆抗体（ｍＡｂ）反应性中发现,这些ｍＡＢ均是特异地与相应ｌｇ分子中的轻链或重链的抗原决定簇结合,用夹心法和抑制法均证明了这点。还发现,在奶牛ＩｇＡ的ａ一链和ＩｇＭ的μ一链上有相同的结合位点。与其他动物血清和经盐析Ｉｇ的反应结果表明,其中有一株抗Ｉｇ一Ｌ（轻链）的ｍＡｂ能与狗和海狗Ｉｇ较好地结合,与马和骆驼的ｌｇ亲和力轻小,但不能与猫、豚鼠、大白鼠、猪和家兔的Ｉｇ结合。这表明,不同种的动物Ｉｇ存在着共同抗原决定簇。 相似文献
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配子体自交不亲和由具有多基因的单一位点S位点控制,该位点包括紧密连锁的雌性(雌蕊)和雄性(花粉)S决定因子。本文综述了近年来金鱼草、矮牵牛、李亚科植物花粉特异性F-box基因的鉴别及雄性S决定因子的鉴定,论述了雄性决定因子在自交不亲和反应中的功能研究进展。当前对雄性决定因子的功能研究认为,在亲和反应中它非特异地与S-RNases作用,通过形成一个功能的SCF复合体仅使非自身S-RNase被泛素介导的26S蛋白酶体降解,花粉管得以继续生长至胚囊完成双受精;而自身S-RNase的活性被特异保留,作为细胞毒素降解花粉管RNA,从而抑制自身花粉管的生长。图3参43。 相似文献
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林业标准化经营是促进林业产业转型升级的"推进器",同时又是加快林业科技成果转化的重要措施。基于浙江省安吉、临海2个县(市)的实地调查数据,采用Binary Logistic回归模型对农户参与林业标准化项目经营意愿及影响因素进行了实证分析。结果表明:农户家庭林地细碎化程度、家庭是否有充足的资金、家庭有无人员接受过林业生产技术培训、所在乡镇有无林产品合作社以及对林业标准化项目未来前景预期等是影响农户参与林业标准化项目经营意愿的主要因素。并以此为基础,提出了相应的政策建议:加大林业标准化宣传力度,提高农户对标准化经营的认知;加大林业标准化配套资金扶持力度,提高农户参与标准化经营意愿;加强林业生产技术培训,提高农户参与标准化经营积极性;完善林产品合作社建设,提高林产品服务制度保障。 相似文献
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为了探究梨形环棱螺各形态性状与体质量的相关性及影响体质量的因素组成,随机选取太湖野生群体、阳澄湖野生群体、江阴养殖群体共698个个体,测量梨形环棱螺壳高(SH)、壳宽(SW)、壳口高(AH)、壳口宽(AW)、体螺层高(BWH)、体质量(BW),并鉴定其性别,采用相关与通径分析方法进行分析,为梨形环棱螺人工繁育和品系选育提供理论依据和测度指标。结果表明:不同群体的壳高、壳宽、壳口高、壳口宽、体螺层高、体质量及性别比均存在显著性差异。决定系数分析表明不同群体梨形环棱螺影响体质量的主要形态性状并不相同,但不同群体中壳高对体质量的相关系数和直接作用均最大,是影响体质量的主要因素。 相似文献
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甘肃省小杂粮产业竞争优势度及影响因素分析 总被引：4，自引：0，他引：4
以资源禀赋系数、成本收益、综合比较优势指数3个指标为基础,比较分析了甘肃小杂粮产业竞争优势度;通过对消费者和农户的深入调查,并建立计量经济模型对影响甘肃小杂粮产业竞争优势的主要因素进行了实证分析.结果表明,甘肃谷子、糜子、荞麦、蚕豆的资源禀赋系数分别为1.53、6.64、8.72、3.9,比较优势指数分别为1.23、2.57、2.95、1.97,小杂粮从资源的丰富程度、成本收益、种植规模、产出水平等方面具有竞争潜力;消费者收入水平、认知程度、年龄、受教育程度对甘肃小杂粮的市场竞争力有显著影响;家庭耕地面积、小杂粮收入占家庭收入比例对农户扩大生产规模的意愿有显著影响. 相似文献
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Siti Isrina Oktavia Salasia Syarifudin Tato Ngalijan Sugiyono Dwi Ariyanti Feny Prabawati 《Journal of veterinary science (Suw?n-si, Korea)》2011,12(4):353-361
The present study determined the genetic relationships between 41 Staphyloccocus (S.) aureus isolates from bovines, humans, and food using a single enzyme amplified fragment length polymorphism (AFLP) technique. We evaluated the prevalence of staphylococcal enterotoxin (SE) genes and other virulence gene determinants by PCR. The identification of S. aureus was based on culturing and biochemical tests, and by amplifying a specific section of the 23S rRNA gene. PCR amplification of the SE genes (sea, seb, sec, see, seg, seh, and sei) singly or in combination was observed. Most isolates of bovine origin harbored hla (84%) and cap5 (74%), while most isolates from humans harbored hla (73%), cap8 (91%), and fnbA (100%). Strains from food sources were positive for hla (100%), cap5 (100%), and cap8 (64%) unlike isolates from humans or bovines. A single enzyme AFLP analysis revealed a correlation between AFLP clusters of some strains and the source of the isolates The genotypic results of the present study might help to better understand the distribution of prevalent S. aureus clones among humans, bovines, and food and will help control S. aureus infections in Indonesia. 相似文献
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杨丽娟 《吉林农业科技学院学报》2007,(3)
线性代数中有许多难度较高的问题,若从代数学内部系统出发处理起来,相当繁冗,但是从另一角度出发,运用摄动方法和数学分析的一些概念去处理这些代数问题,可能有事半功倍之效。为此,本文运用摄动方法和数学分析的一些概念证明线性代数的某些问题,供读者在教与学时参考。 相似文献
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There exist some controversies over the larger zoogeographic divisions of the arid areas of Central Asia, whose characteristics include complex ecological environments, complex fauna origins and unique patterns of animal distribution. The aim of this study was to determine, using quantitative analysis, the distribution patterns of amphibians and reptiles in the arid areas of Central Asia, whose various physiographical regions were divided into 17 Operative Geographical Units(OGUs). Based on the presence or absence of 52 amphibian and reptile genera in the 17 OGUs, and by making use of the Czekanowski Similarity Index, the Baroni-Urbani and Buser's Similarity Index, and the strong and weak boundary test, we studied the biotic boundaries within these contested regions. In accordance with our results, the classification dendrogram was divided into two main branches. One branch is composed of the northern OGUs of the Altai Mountains which are a part of the Euro-Siberian Subrealm. The other branch includes all of the OGUs south of the Altai Mountains, which belong to the Central Asia Subrealm. There is a significantly weak biotic boundary(DW>0, GW>GS, P<0.01) between the Euro-Siberian Subrealm and the Central Asia Subrealm that corresponded to the transitional zones. The boundary between the two subrealms runs along the Altai Mountains, the Sayan Mountains, the Hangai Mountains and the Mongolian Dagurr Mountains. The boundaries between the main branches in the Central Asia Subrealm are weak, reflecting the widespread existence of transitional zones in the arid areas of Central Asia. The Tianshan Mountains should be elevated to form its own separate region, "the Middle Asian Mountain Region", which, due to its special fauna and environment, would be classified at the same level as the Mongolia-Xinjiang Region. With the approach of creating a cluster analysis dendogram based upon the genera of amphibians and reptiles, the relationship of these higher level zoogeographical divisions was successfully resolved and the error of long-branch attraction was also avoided. With our clustering dendrogram as the foundation, the independence test was applied to strong and weak boundaries, and this resolved the problem of where to attribute the transition areas and revealed as well the barrier effect that physical, geographic boundaries have upon amphibians and reptiles. The approach of combining genera clustering analysis with a statistical boundary test should be applicable not only to the distribution patterns of other animal groups, but also to delineating large-scale zoogeographical divisions. 相似文献