最小群体数在推断基因型中的应用

遗传学上,最小群体数是指杂交后代各性状都能得以充分表现的后代群体最小数目。它是子代性状分离比之和的具体体现,而后者又反映了亲本配子的组合方式。因此,利用最小群体数,可以推测亲本产生配子的种类,进而结合亲本性状,推知其基因型。这种推断基因型的方法,称为最小群体法。 我在运用最小群体法,推断生物基因型的习题教学中,取得了良好的效果。现对其具体使用步骤归纳如下： （１）由亲本性状,写出基因组成。 （２）依据子代性状分离比,求出最小群体数。如果给出的子代是实得个体数,应先约简,再求最小群体数。 （３）利用最…     

杂交育种与杂种优势

目前我国在农业生产上广泛采用杂交育种、诱变育种等手段进行品种培育，尤以杂交育种及杂种优势的利用，在品种选育上取得的成就最为巨大。一、杂交育种的原理杂交育种是利用控制不同性状的基因在杂种个体中重新组合，从而使杂种个体能够集中两个或更多个亲本的优良基因，以显现出兼有亲本各方的优良性状，又由于不同基因具有互补效应及数量效应，这样就使杂交育种中能培育出原有亲本没有的优良性状以及超亲优良性状。二、杂交亲本选配原则由于杂交育种中杂种后代的性状是亲本性状的继承或在亲本性状的基础上加以发展的，因而正确选配亲本是…     

新型四氮杂四乙酸大环配体与铜形成双核配合物的合成及表征

本文在水溶液中合成了新型四氮杂四乙酸大环配体 Ｈ４ Ｌ（５，１２－ 二苯基－ ７，１４－ 二甲基－ １，４，８，１１－ 四氮杂环十四烷－ Ｎ′， Ｎ″， Ｎ， Ｎ ′－ 四乙酸）与铜（Ⅱ）形成的固体配合物，并采用元素分析和红外光谱对其组成（ Ｃｕ２ Ｌ· Ｈ２ Ｏ）进行了表征，对所得结果进行了讨论。     

CH_3OOCCH_2CH_2SnCl(2-OC_6H_4CH=NC_6H_4O-2)·C_6H_6的晶体结构

利用３－三氯锡基丙酸甲酯与Ｎ－（２－羟基苯基）水杨醛亚胺（Ｌ）在苯中反应合成了标题化合物．该化合物的晶体结构分析表明,该晶体属三斜晶系,空间群Ｐ１,ａ＝８．６４８（２）,ｂ＝９．３３２（２）,ｃ＝１４．４１７（４）,α＝９７．４２（３）,β＝１０２．９６（３）,γ＝９７．６８（３）°．化合物具有分子内羰基氧原子和Ｌ的氧、氮、氧原子对锡原子配位的畸变八面体结构     

新型四氮杂大环化合物的合成与表征

合成了新型四氮杂大环化合物：５,１２－二苯基－７,１４－二甲基－１,４,８,１１－四氮杂环十四烷－Ｎ,Ｎ″－二乙酸－二硝酸的水合物（Ｈ２Ｌ·２ＨＮＯ３·３５Ｈ２Ｏ）．用元素分析和红外光谱对其组成进行了确定,并对结果进行了讨论     

现代生物育种的知识复习策略

现代生物育种是生物的变异和现代生物技术在生产实践中的应用，为高考考查的重点之一．1．杂交育种（如：抗倒伏锈病小麦的培育）原理：基因重组．通过杂交将分散在不同品种中的优良性状基因集中到新品种中．方法：去雄（两性花）、人工授粉．为了增加授粉机会，大田试验通常采用间行种植两种亲本方法．     

关于格拟环的凸子格拟环格

主要讨论了格拟环的基本性质与凸子格拟环格,给出并证明了：Ａ）若Ｌ是一个格拟环,Ｍ是Ｌ的一个子拟环,则以下条件等价：１）Ｍ是凸子格拟环;２）Ｍ是凸的与定向的;３）Ｍ的右陪集Ｒ（Ｍ）是一个分配格,且Ａｍ１,ｍ２∈Ｌ,（Ｍ＋ｍ１）∨（Ｍ＋ｍ２）＝Ｍ＋ｍ１∨ｍ２,（Ｍ＋ｍ１）∧（Ｍ＋ｍ２）＝Ｍ＋ｍ１∧ｍ２．Ｂ）若Ｌ是一个格拟环,则Ｃ（Ｌ）＝｛Ｍ│Ｍ是Ｌ的一个凸子格拟环｝是一个Ｂｒｏｕｗｅｒｉａｎ格,并且它     

关于子空间交的基和维数

关于子空间交的基和维数王伟贤通常求Ｆｎ上两个子空间Ｌ１（ａ１，ａ２…ａ２）与Ｌ２（Ｂ１，Ｂ２…Ｂ２）的交Ｌ１∩Ｌ２的基和维数是比较麻烦的，一般教科书上都是取其维数为１的例子加以说明。本文给出一种方法，可以与求Ｌ１＋＋Ｌ２的基和维数的过程一气呵成，而且...     

几个有趣的化学演示实验

几个有趣的化学演示实验刘耀华一、沉淀多次转化的试验药品０．５ｍｏｌ／Ｌ的Ｐｂ（ＮＯ３）２、Ｎａ２ＳＯ４、Ｎａ２ＣＯ３溶液,０．１ｍｏｌ／Ｌ的ＫＩ溶液,０．２ｍｏｌ／Ｌ的Ｎａ２Ｓ溶液。操作在试管中加入Ｐｂ（ＮＯ３）２溶液,再依次加入Ｎａ２ＳＯ４、ＫＩ、...     

L^2（R）的分解及其函数逼近

本文利用多分辨力逼近理论讨论了任意不同子空间对Ｌ＾２（Ｒ）中函数的逼近误差，给出了比（１）中对Ｌ＾２（Ｒ）的分解更一般的形式。     

Word-meaning inference in L2 Chinese: an interactive effect of learners’ linguistic knowledge and words’ semantic transparency

Reading and Writing - Recent second language (L2) reading studies have examined how characteristics of an individual learner and word-specific linguistic properties jointly predict successful L2...     

“多肽保”防控烟草病害的有效技术探究

为了在烟叶生产上有效利用植物有机诱导抗病剂＂多肽保＂,降低使用成本实现效益最大化.2011年,以不防病为空白对照,设置＂多肽保＂不同施用量和施用方式的11个处理,与当前生产上采取的化学防治措施的防效相比较.结果表明：1）＂多肽保＂仅苗期施用量0.1～0.2 g/株,有利于烟株的生长发育和获得较好的经济效益,增产、增值幅度分别达到25.0%和35.5%;苗期施用量达到或超过0.4 g/株对烟株生长及丰产会造成不利影响,在苗期及大田期同时施用并不能改变这一结果.2）＂多肽保＂仅苗期施用量0.1～0.6 g/株,对烟草黑胫病的平均防效为60.12%,而常规对照防效为53.37%,若在苗期及大田期同时施用也几乎不能改变这一结果;苗期施用量达到或超过0.8 g/株会严重影响到防治效果.3）＂多肽保＂对烟草花叶病的防效,在苗期和大田期同时施用表现为叠加效应,其防效可达到93.44%,而常规对照的防效仅为61.7%;苗期施用量达到或超过0.2 g/株,在移栽时不施的情况下也能表现出良好的防效.     

烟草中NAC转录因子NtNAC8的克隆与序列分析

利用数据库资源和RT-PCR技术从烟草中克隆出一个NAC转录因子新成员--NtNAC8,并进一步对NtNAC8转录因子的序列进行分析;同时对该基因编码蛋白质的理化性质、蛋白质结构及其生物学功能等进行预测.结果表明,NtNAC8编码一个由301个氨基酸残基组成的相对分子质量为34.98 kD的NAC转录因子,并推测其可能...     

Lexical inference in L2: predictive roles of vocabulary knowledge and reading skill beyond reading comprehension

The current study examined the predictive roles of L2 vocabulary knowledge and L2 word reading skills in explaining individual differences in lexical inferencing in the L2. Participants were 53 Israeli high school students who emigrated from the former Soviet Union, and spoke Russian as an L1 and Hebrew as an L2. L2 vocabulary knowledge and decoding accuracy predicted L2 reading comprehension, which in turn was strongly related to lexical inferencing abilities in the L2. In addition, decoding accuracy predicted additional variance in lexical inferencing, beyond the role of reading comprehension. These findings support the idea that beginning L2 readers with more precise and efficient lexical representations demonstrate better lexical inferencing abilities, most likely due to the increased automatization of word reading, which frees up resources for higher level processing. These results suggest that lexical inferencing from text in the L2 might be limited not only by vocabulary knowledge and higher order comprehension processes, but also by basic decoding skills.     

凤鲚瓯江种群的生物学特性

2006年5—8月对浙南瓯江凤鲚的繁殖期生物学特性进行了调查和研究．结果表明,凤鲚瓯江种群汛期雌雄个体体重（W）与体长（L）的关系分别为Wf=0．021 Lf^2.52（R^2=0．77）和Wm=0．0127 Lm^2.605（R^2=0．72）．个体绝对繁殖力在2836—62901粒之间,平均为（21112±8919）粒;绝对繁殖力（r）与体长（L）、体重（W）和纯重（NW）均呈线性正相关．相对繁殖力（r／L）与体长、体重呈线性正相关,平均个体相对繁殖力（r／L）为（1146±398）粒／cm;相对繁殖力（HW）与体长、体重无关,平均个体相对繁殖力（HW）为（657±186）粒/g．     

Individual differences in late bilinguals' L2 phonological processes: From acoustic-phonetic analysis to lexical access

The extent to which the phonetic system of a second language is mastered varies across individuals. The present study evaluates the pattern of individual differences in late bilinguals across different phonological processes. Fifty-five late Dutch-English bilinguals were tested on their ability to perceive a difficult L2 speech contrast (the English /æ/-/ε/ contrast) in three different tasks: A categorization task, a word identification task and a lexical decision task. As a group, L2 listeners were less accurate than native listeners. However, at the individual level, almost half of the L2 listeners scored within the native range in the categorization task whereas a small percentage scored within the native range in the identification and lexical decision tasks. These results show that L2 listeners' performance crucially depends on the nature of the task, with higher L2 listener accuracy on an acoustic-phonetic analysis task than on tasks involving lexical processes. These findings parallel previous results for early bilinguals, where the pattern of performance was consistent with the processing hierarchy proposed by different models of speech perception. The results indicate that the analysis of patterns of non-native performance can provide important insights concerning the architecture of the speech perception system and the issue of language learnability.     

The impact of resilience on L2 learners’ motivated behaviour and proficiency in L2 learning

This exploratory study focused on the factors that constitute second language (L2) learners’ resilience, and how these factors are related to L2 learning by investigating what relation resilience may have to motivated behaviour and proficiency in English learning. A total of 1620 secondary school learners of English participated in a questionnaire survey. By analysing the quantitative data, five resilience factors were extracted: perceived happiness, empathy, sociability, persistence, and self-regulation. Confirmative factor analysis using AMOS proved that these five factors are distinctive constructs. Among the factors, persistence was identified to play the most influential role in L2 learning. Persistence showed the highest correlations with, and the strongest explanatory power for, motivated behaviour and English proficiency. It is suggested that resilience can be further explored as an individual differences factor in L2 learning, which is involved in L2 learning process and outcomes.     

Comprehensive screening and selection of okra (Abelmoschus esculentus) germplasm for salinity tolerance at the seedling stage and during plant ontogeny

The okra germplasm was screened for salinity tolerance at the seedling stage and during plant ontogeny. Substantial variation existed in okra for salinity tolerance at the seedling stage. An 80 mmol/L NaCl concentration was suitable for discriminating tolerant and non-tolerant okra genotypes. The pooled ranking of the genotypes, based on individual rankings for each trait (root and shoot length, germination percentage, and relative Na⁺ and K⁺) in individual NaCl concentrations, was effective for selecting tolerant genotypes. Genotypes selected at the seedling stage maintained their tolerance to NaCl during plant ontogeny, suggesting that screening of the germplasm entries and advanced breeding materials for salt tolerance at the seedling stage is effective. Among 39 okra genotypes, five were identified as the most tolerant genotypes and showed potential for use in breeding programs that focus on the development of salt-tolerant, high-yield okra cultivars.     

盘龙参组织培养的初步研究

以盘龙参（Spiranthes sinensis）的花梗为外植体,探讨了不同前灭菌处理及植物生长调节剂对盘龙参花梗组织培养的影响。结果表明：75%的酒精浸30s的前灭菌处理效果较好;植物生长调节剂组合6-BA0.1（mg/L）＋NAA1（mg/L）组合和6-BA1.5（mg/L）＋NAA1（mg/L）组合的效果较好,其生存率分别达到了60%和66%。     

NaCl胁迫对水稻（Oryza sativa）种子萌发和幼苗生长的影响

采用水培法,研究不同浓度（0、50、100、150、200、250、300、350、400、450、500mmol／L）的NaCl胁迫对水稻种子萌发,胚根、胚芽和幼苗生长的影响。结果表明：种子的发芽势、发芽率、都随着NaCl胁迫浓度的升高而降低,300mmol／L以上种子发芽率为0;胚根长,胚芽长也随着NaCl胁迫浓度的升高而降低,浓度大于100mmol／L时有显著（p〈0．05）影响。水稻幼苗的根长、株高、株鲜重、根干重以及茎干重也随NaCl胁迫浓度的升高呈逐渐降低的趋势,当浓度大于250mmol／L时影响尤为显著,大于300mmol／L时,植株严重失水,萎蔫,枯黄,死亡。研究结果说明NaCl胁迫对水稻种子的萌发和幼苗的生长有严重的抑制作用。