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1.
本文主要介绍了在求平面向量数量积时的两种常用的方法:基底法和坐标法,对这两种方法的使用条件做了适当的阐述,并通过对比对这两种方法之间的差异和联系进行了适当的分析.  相似文献   

2.
几何法和坐标法是向量的两种表示方法,表示方法不同,对应的运算方式也不同．两个向量的加法、减法、数量积,以及实数与向量的数乘等运算的两种表示列表如下：  相似文献   

3.
应用组织块法和酶消化法进行原代大鼠颌下腺细胞(rat submandibular gland cells,RSGCs)分离培养,通过免疫细胞化学法检测细胞角蛋白-8的表达,经DAB染色均呈阳性,提示培养细胞为上皮细胞来源。在倒置显微镜下观察细胞数量、生长情况和生长周期,两种方法所培养的原代大鼠颌下腺细胞均生长良好,相互聚集形成腺泡、腺管样结构或呈铺路石状。其中酶消化法所培养细胞贴壁较好,生长周期短,细胞数量更多。提示酶消化法分离培养较组织块法更易获得大量RSGCs,为以颌下腺细胞作为实验载体的涎腺非肿瘤性疾病的研究奠定了实验基础。  相似文献   

4.
根据烟尘检测的原理和方式不同可将探测方法分为取样法与非取样法两种,文章针对各自范畴的不同,分别介绍了几种常见方法。对光学法的优势作了详细的阐述,对散射法进行了模拟,并对几种方法进行了横向、纵向的对比分析。  相似文献   

5.
简述了声透法检测的研究现状和基本原理,阐明了桩身完整性的3种质量判据:声速值、波幅和PSD值.结合邢清干渠调压塔工程实际,提出了声透法的检测条件,确定了检测数量和方法.选取典型桩,合理设定了仪器参数,依据波形数据,对各检测剖面的声学参数进行了分析和评价.检测结果表明,桩身完整性满足工程设计需要.  相似文献   

6.
近20年是统计遗传学应用于植物数量性状的研究发展最快的时期，随着计算技术的迅猛发展和分子标记的普遍应用，对数量性状的遗传剖析能力也在逐渐加强，认识也在逐步深入。本文综述了近20多年来关于植物数量性状的研究方法，特别介绍多维性状的遗传检测方法。  相似文献   

7.
一、引言在中小学教室里，课堂座位编排有以下几种：秧田式排列法（按行列式排列）、圆形式排列法、会议式排列法、小组式排列法和U形排列法等，其中，最常见的、最普遍的课堂座位编排方式是秧田式排列法。  相似文献   

8.
目前国内混凝土强度检测主要采用回弹法和混凝土试块检测方法,在此介绍两种检测方法原理及优缺点。  相似文献   

9.
探讨了两种避雷针保护范围的计算方法,即折线法和滚球法。通过比较两种方法得到保护范围差别,且分析了两种方法对防雷设计的影响。  相似文献   

10.
介绍了用气相色谱法测定白酒中己酸乙酯的两种定量方法:内标法和外标法,并分别对三个白酒样品进行测定。测定结果的RSD值依次为0.43%~0.86%和0.46%~1.40%,说明两种定量方法在检测白酒中己酸乙酯时结果无显著性差异,可将外标法推广到日常的白酒检测工作中。  相似文献   

11.
Quantitative trait loci (QTL) analysis was conducted in bread wheat for 14 important traits utilizing data from four different mapping populations involving different approaches of QTL analysis. Analysis for grain protein content (GPC) sug- gested that the major part of genetic variation for this trait is due to environmental interactions. In contrast, pre-harvest sprouting tolerance (PHST) was controlled mainly by main effect QTL (M-QTL) with very little genetic variation due to environmental interactions; a major QTL for PHST was detected on chromosome arm 3AL. For grain weight, one QTL each was detected on chromosome arms 1AS, 2BS and 7AS. QTL for 4 growth related traits taken together detected by different methods ranged from 37 to 40; nine QTL that were detected by single-locus as well as two-locus analyses were all M-QTL. Similarly, single-locus and two-locus QTL analyses for seven yield and yield contributing traits in two populations respectively allowed detection of 25 and 50 QTL by composite interval mapping (CIM), 16 and 25 QTL by multiple-trait composite interval mapping (MCIM) and 38 and 37 QTL by two-locus analyses. These studies should prove useful in QTL cloning and wheat improvement through marker aided selection.  相似文献   

12.
INTRODUCTIONKilo-grainweight,characteristicallyacom-plextrait,isanimportantcomponentofyieldinrice.QTLmappingforkilo-grainweightofricewascon-ductedusingpopulationsofF2(Linetal.,1996),doubledhaploidlines(Luetal.,1997),recombi-nantinbredlines(Xiaoetal.,1996),backcrosstestcross(Xiaoetal.,1995;Lietal.,1997)andratoonedF2(Lietal.,2000).Consideringthesen-sitivityofkilo-grainweighttoenvironments,Luetal.(1997)andZhuangetal.(1997)comparedthedifferentialdetectionofQTLacrossenvironmentstodetermin…  相似文献   

13.
Immortalized F2 population of rice (Oryza sativa L.) was developed by randomly mating F1 among recombinant inbred (RI) lines derived from (Zhenshan 97B ( Minghui 63), which allowed replications within and across environments. QTL (quantitative trait loci) mapping analysis on kilo-grain weight of immortalized F2 population was performed by using newly developed software for QTL mapping, QTLMapper 2.0. Eleven distinctly digenic epistatic loci included a total of 15 QTL were located on eight chromosomes. QTL main effects of additive, dominance, and additive ( additive, additive ( dominance, and dominance ( dominance interactions were estimated. Interaction effects between QTL main effects and environments (QE) were predicted. Less than 40% of single effects, most of which were additive effects, for identified QTL were significant at 5% level. The directional difference for QTL main effects suggested that these QTL were distributed in parents in the repulsion phase. This should make it feasible to improve kilo-grain weight of both parents by selecting appropriate new recombinants. Only few of the QE interaction effects were significant. Application prospect for QTL mapping achievements in genetic breeding was discussed.  相似文献   

14.
Immortalized F2 population of rice (Oryza sativa L.) was developed by randomly mating F1 among recombinant inbred (RI) lines derived from (Zhenshan 97B × Minghui 63), which allowed replications within and across environments. OTL (quantitative trait loci) mapping analysis on kilo-grain weight of immortalized F2 population was performed by using newly developed software for QTL mapping, QTLMapper 2.0. Eleven distinctly digenic epistatic loci included a total of 15 QTL were located on eight chromosome. QTL main effects of additive, domainance, and additive × additive, additive × domainance, and dominance × dominance interactions were estimated. Interaction effects between QTL main effects and environments (QE) were predicted. Less than 40% of single effects, most of which were additive effects, for identified QTL were significant at 5% level. The directional difference for QTL main effects suggested that these QTL were distributed in parents in the repulsion phase. This should make it feasible to improve kilo-grain weight of both parents by selecting apprents in the repulsion phase. This should make it feasible to improve kilo-grain weight of both parents by selecting appropriate new recombinants. Only few of theQE interaction effects were significant. Application prospect for QTL mapping achievements in genetic breeding was discussed. Project (No. 39893354) supported by the National Natural Science Foundation of China  相似文献   

15.
通过对第二语言写作教学的三个教学流派:成果教学法、过程教学法和体裁教学法的分析,本文提出大学英语的写作教学有其自身的特点,写作教学应该兼收并蓄,以调动学生的积极性为主,教师要了解以上三个教学流派的优点及其缺点,在教学中使用最新的科研成果--写长法,以达到更好的教学效果.  相似文献   

16.
Quantitative trait loci (QTL) and their additive, dominance and epistatic effects play a critical role in complex trait variation. It is often infeasible to detect multiple interacting QTL due to main effects often being confounded by interaction effects. Positioning interacting QTL within a small region is even more difficult. We present a variance component approach nested in an empirical Bayesian method, which simultaneously takes into account additive, dominance and epistatic effects due to multiple interacting QTL. The covariance structure used in the variance component approach is based on combined linkage disequilibrium and linkage (LDL) information. In a simulation study where there are complex epistatic interactions between QTL, it is possible to simultaneously fine map interacting QTL using the proposed approach. The present method combined with LDL information can efficiently detect QTL and their dominance and epistatic effects, making it possible to simultaneously fine map main and epistatic QTL.  相似文献   

17.
英语语言象其它语言一样,既是社会发展的产物,也是反映社会的一面镜子.英语语言中一些词法、词义和句法现象在一定程度上反映了西方社会存在的性别歧视现象. 语言学家、人类学家、社会学家甚至心理学家们都看到了英语日常交际中存在的性别差异,并积极地从各个角度寻找成因.在众多关于性别差异成因的解释中,"优势说 "和"差异说"被广为关注."优势说"将女性日常交际中的语言特点归因于女性附属性的社会地位;"差异说"则否定了"优势说",从男女不同的成长亚文化背景中寻找性别差异形成的原因.两种解释分别都有可取之处,因此,有必要将二者结合起来,形成一种更加完整和完善的解释.  相似文献   

18.
本文回答管春林（2008）对刘颂浩（2006a）的批评。文章首先澄清几处事实,然后就字本位教学法和词本位教学法的关系阐述了自己的看法：二者是可以在一定程度上兼顾的。  相似文献   

19.
The phosphorus uptake （PU） in above-ground parts of plant, root characteristics and root exudations as well as the quantitative trait loci （QTLs） associated with these characteristics were determined for a F2：3 population derived from the cross of two contrasting maize （Zea mays L.） genotypes, 082 and Yel07. A total of 241 F2：3 families were evaluated in replicated trials under deficient phosphorus conditions in 2007 at two sites （Kaixian County and Southwest University, Chongqing, P. R. China）. The results show pleiotropy and close linkage among QTLs. Four common regions in different environments were in bnlg100- bnlg1268b （bins 1.02） for QTL of H＋, bnlg1268a-umc1290a （bins 1.09） for QTL of AP （acid phospbatase activity）, dupssrl5- P 1MT/a （bins 6.06） for QTLs of PU （phosphorus uptake） and RW （root weight）, and P IM3/d-P1M3/g （bins9.04） for QTLs of PU and AP. These QTLs are non-environment or minor QTLs x environment. By epistatic analysis, three main QTLs and eighteen QTLs x QTLs interactions were detected for the seven measured characteristics. These QTLs may affect trait expression by epistatic interaction with the other loci, and make a substantial contribution to phosphorus utilization efficiency, which should be considered when breeding maize varieties with high P efficiency. Two regions were detected in dupssrl 5- P1MT/a （bins 6.06） for QTL of RW and P1M3/d- P 1M3/g （bins 9.04） for QTL of PU and AP. They were detected in two different environments and by two methods of QTL analysis, which were useful for marker-assisted selection.  相似文献   

20.
A method was proposed for the detection of outliers and influential observations in the framework of a mixed linear model, prior to the quantitative trait locus (QTL) mapping analysis. We investigated the impact of outliers on QTL mapping for complex traits in a mouse BXD population, and observed that the dropping of outliers could provide the evidence of additional QTL and epistatic loci affecting the 1 stBrain-OB and the 2ndBrain-OB in a cross of the abovementioned population. The results could also reveal a remarkable increase in estimating heritabilities of QTL in the absence of outliers. In addition, simulations were conducted to investigate the detection powers and false discovery rates (FDRs) of QTLs in the presence and absence of outliers. The results suggested that the presence of a small proportion of outliers could increase the FDR and hence decrease the detection power of QTLs. A drastic increase could be obtained in the estimates of standard errors for position, additive and additivex environment interaction effects of QTLs in the presence of outliers.  相似文献   

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