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信号的突变点和不规则的结构经常带有大量重要的信息.有平滑边缘的突变点的3个参数分别是边缘的李氏指数α、平滑因子σ和幅度κ.采用高斯函数的一个阶导数作为小波函数,推导出κ,σ,α满足的方程和σ满足的方程,给出了求突变点3个参数的算法. 相似文献
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变性高效液相色谱(denaturing high-performance liquid chromatography,DHPLC)是新发展起来的检测基因组单核苷酸多态(single nucleotide polymorphism,SNP)的技术,在部分变性的条件下,根据发生错配的异源双链DNA和完全匹配的同源双链DNA分子的特点进行SNP检测.DHPLC具有自动化程度高、准确灵敏、快速、经济等特点,已成为分子生物学和基因组学研究中的重要方法. 相似文献
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理想绳是中学阶段常见的力学模型之一,理想绳上的力可以突变,理想绳可以使物体的速度发生突变,也可以使物体的动能发生突变,突变问题是绳类问题中的难点、易错点,掌握了突变规律,也就掌握了绳类问题.1弹力发生突变例1.如图1所示,将完全相同的两个小球A、B,用长L=0.8m的细绳悬于以速度v= 相似文献
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林良斌 《湘潭师范学院学报(社会科学版)》1991,(3)
突变产生和修复的机制是遗传学中 个最其本的问题,许多学者正在为之而奋斗.如果这个问题弄清楚了,那将对诱变育种和人类遗传病的治疗起到理论上和实践上的指导作用.突变的修复和突变的产生是相互矛盾的.但SOS修复是一种特殊的修复,在修复过程中产生大量的突变.本文着重谈谈这个问题.1 SOS修复 1.1 SOS修复的发现 SOS修复现象是四十年代发现的,但对它的机制以及功能的研究在七十年代中期才兴起.Witkin是研究SOS修复最有贡献的人之一. 相似文献
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目的:建立检测MBL基因54位密码子点突变的方法,初步调查健康汉族人MBL基因54位密码子点突变的情况,检测其血浆MBL含量,找出二者的相关性.方法:根据MBL基因序列设计引物建立MBL基因点突变检测方法即PCR-RFLP;用MBL Oligomer ELISA试剂盒测定出血浆MBL的浓度.结果:建立了特异敏感的检测MBL基因54位密码子点突变的方法,测得健康汉族人基因突变频率为0.2321;健康汉族人血浆MBL含量的平均值为1999μg/L,标准差为1505;健康汉族人血浆MBL含量与其编码基因Exon 1 54位密码子的点突变频率呈负相关,X2=48.107,P＜0.001;r=-0.62.结论:所建立的MBL的PCRRFLP测定点突变的方法,特异性高,重复性好,较为灵敏(最低检出量为160pgDNA);初步测定了健康汉族人的基因突变频率及其血浆MBL含量,二者呈负相关. 相似文献
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目的:建立检测MBL基因54位密码子点突变的方法,初步调查健康汉族人MBL基因54位密码子点突变的情况,检测其血浆MBL含量,找出二者的相关性.方法:根据MBL基因序列设计引物建立MBL基因点突变检测方法即PCR-RFLP;用MBL Oligomer ELISA试剂盒测定出血浆MBL的浓度.结果:建立了特异敏感的检测MBL基因54位密码子点突变的方法,测得健康汉族人基因突变频率为0.2321;健康汉族人血浆MBL含量的平均值为1999μg/L,标准差为1505;健康汉族人血浆MBL含量与其编码基因Exon 1 54位密码子的点突变频率呈负相关,χ2=48.107,P＜0.001;r=-0.62.结论:所建立的MBL的PCR-RFLP测定点突变的方法,特异性高,重复性好,较为灵敏(最低检出量为160pgDNA);初步测定了健康汉族人的基因突变频率及其血浆MBL含量,二者呈负相关. 相似文献
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在物体的运动状态发生变化,并达到一个特定状态时,有关的物理量就会发生突变.这个特定状态即为临界状态,相应物理量的值为临界值.当物体受力或运动发生变化时,摩擦力常常发生突变.摩擦力的突变,又会导致物体的受力情况和运动状态的改变,其突变点(时刻或位置)往往具有很深的隐蔽性.解决摩擦力发生突变时的临界问题的关键在于分析突变情况,找出摩擦力发生突变的时刻或位置.一、静摩擦力发生突变静摩擦力是被动力,其存在的大小、方向取决于物体间相对运动的趋势,而且静摩擦力存在最大值.静摩擦力为零的状态,是方向变化的临界状态;静摩擦力到达… 相似文献
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分析物理过程 ,构建物理情景是解决物理问题的必经之路 ,物理习题难解 ,则往往难在对一个具体的问题不能分析其物理过程 ,建立清晰的物理情景 .本文就分析物理过程应注意的几个问题谈一谈粗浅的体会 .1 物理量突变在有些习题中 ,物理量在变化过程中受物理规律或约束条件的限制而发生突变 ,学生在解这类问题时 ,容易忽视突变的存在而当作连续变化的问题来处理 ,造成失误 .这就要求教师引导学生分析物理过程 ,提示突变点的存在 ,分析突变前后的运动情况 .图 1[例 1]如图 1所示 ,长为ｌ的细绳一端固定于Ｏ点 ,一端悬质量为ｍ的小球 ,把小球拉… 相似文献
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黑斑蛙Sox基因的PCR-SSCP分析 总被引：1，自引：0，他引：1
Sox基因家族是一类高度保守的基因家族,具有一个保守基序HMG-box,可以与DNA序列特异性结合,促进基因的特异转录,从而在胚胎发育及性别分化中起着重要作用。本文采用简并PCR方法,扩增并克隆了黑斑蛙的Sox基因保守区,获得长约220bp的片段;结合SSCP分析技术,在阳性克隆中筛选出六个不同的Sox基因。本研究为Sox家族成员的分类及分子进化的研究提供了资料。 相似文献
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A great obstacle for wider use of structural equation modeling (SEM) has been the difficulty in handling categorical variables. Two data sets with known structure between 2 related binary outcomes and 4 independent binary variables were generated. Four SEM strategies and resulting apparent validity were tested: robust maximum likelihood (ML), tetrachoric correlation matrix input followed by SEM ML analysis, SEM ML estimation for the sum of squares and cross-products (SSCP) matrix input obtained by the log-linear model that treated all variables as dependent, and asymptotic distribution-free (ADF) SEM estimation. SEM based on the SSCP matrix obtained by the log-linear model and SEM using robust ML estimation correctly identified the structural relation between the variables. SEM using ADF added an extra parameter. SEM based on tetrachoric correlation input did not specify the data generating process correctly. Apparent validity was similar for all models presented. Data transformation used in log-linear modeling can serve as an input for SEM. 相似文献
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Effect of enalapril on plasma homocysteine levels in patients with essential hypertension 总被引：1，自引：0，他引：1
Fang-fang Fan Yong Huo Xu Wang Xin Xu Bin-yan Wang Xi-ping Xu Jian-ping Li 《Journal of Zhejiang University. Science. B》2010,11(8):583-591
Objective:To investigate the effect of enalapril on plasma homocysteine(Hcy) levels and the association of methylenetetrahydrofolate reductase(MTHFR) C677T polymorphism with the changes of Hcy levels in response to enalapril among patients with essential hypertension.Methods:A total of 130 patients with mild-to-moderate essential hypertension were enrolled and enalapril was orally administered at a dose of 10 mg/d for eight weeks.Plasma Hcy levels were measured by denaturing high-performance liquid chromatography(DHPLC) at baseline and after eight weeks of treatment.Genotyping of MTHFR C677T polymorphism was performed by TaqMan probe technique.Results:Compared with baseline,plasma Hcy levels did not change significantly after eight weeks(P=0.81).Stratified by baseline Hcy levels,a significant increase in plasma Hcy levels(P=0.02) among those with Hcy 10 μmol/L was observed,in contrast to no significant changes in plasma Hcy levels(P=0.54) among those with Hcy ≥10 μmol/L.No significant association was observed between MTHFR C677T polymorphism and changes in Hcy levels in response to enalapril.Conclusions:Enalapril may cause an increase in plasma Hcy levels among the hypertensives with low baseline Hcy levels.There was no significant association between MTHFR C677T genotypes and changes in Hcy levels in response to enalapril among subjects with essential hypertension. 相似文献
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Shang YP Xie XD Wang XX Chen JZ Zhu JH Tao QM Zheng LR 《Journal of Zhejiang University. Science. B》2005,6(7):626-630
Congenital long QT syndrome (LQTS) is a genetically heterogeneous disease in which six ion-channel genes have been identified. The phenotype-genotype relationships of the HERG (human ether-a-go-go-related gene) mutations are not fully understood. The objective of this study is to identify the underlying genetic basis of a Chinese family with LQTS and to characterize the clinical manifestations properties of the mutation. Single strand conformation polymorphism (SSCP) analyses were conducted on DNA fragments amplified by polymerase chain reaction from five LQT-related genes. Aberrant conformers were analyzed by DNA sequencing. A novel splice mutation in C-terminus of HERG was identified in this Chinese LQTS family, leading to the deletion of 11-bp at the acceptor splice site of Exon9 [Exon9 IVS del (-12→-2)]. The mutation might affect, through deficient splicing, the putative cyclic nucleotide binding domain (CNBD) of the HERG K channel. This mutation resulted in a mildly affected phenotype. Only the proband had a history of syncopes, while the other three individuals with long QT interval had no symptoms. Two other mutation carriers displayed normal phenotype. No sudden death occurred in the family. The 4 affected individuals and the two silent mutation carriers were all heterozygous for the mutation. It is the first splice mutation of HERG reported in Chinese LQTS families. Clinical data suggest that the CNBD mutation may be less malignant than mutations occurring in the pore region and be partially dominant over wild-type function. 相似文献
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In this paper, we report the clinical and molecular features of the distinct TGFBI (human transforming growth factor β-induced, OMIM No. 601692) gene-linked corneal dystrophy. Altogether, five pedigrees and
ten unrelated individuals diagnosed as corneal dystrophy were recruited. Peripheral venous DNA was extracted, and then amplified
by polymerase chain reaction (PCR) and scanned for mutation by single-stranded conformation polymorphism (SSCP). Direct DNA
sequencing was used to analyze the mutations of the TGFBI gene. In our study, thirty patients from five pedigrees and ten sporadic patients were diagnosed as four TGFBI gene-linked corneal dystrophies of granular corneal dystrophy type I (GGCD I), Avellino corneal dystrophy (ACD), lattice
corneal dystrophy type I (LCD I), and lattice corneal dystrophy type IIIA (LCD IIIA), and in total, seven disease-causing
mutations, namely R555W, A546D, A546T, and T538P mutations in exon 12, R124H and R124C mutations in exon 4, and P501T mutation
in exon 11, were identified, while four polymorphisms of V327V, L472L, F540F, and 1665-1666insC were screened in exons 8,11,
and 12. The study ascertained the tight genotype-phenotype relationship and confirmed the clinical and genetic features of
four TGFBI gene-linked corneal dystrophies. 相似文献
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王芝华 《湖南师范大学社会科学学报》2011,40(5):83-86
宗教是一种长期的、复杂的社会历史现象。科学认识宗教,正确处理宗教问题,切实做好宗教工作,关系到党和国家工作的全局,关系到社会和谐稳定,关系到全面建设小康社会进程,关系到中国特色社会主义事业发展,最终关系到党的执政安全。在我国社会主义条件下,我们必须科学把握宗教的长期性、群众性和特殊复杂性,从而维护好党的执政安全。 相似文献
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王文东 《常熟理工学院学报》2011,25(7):17-20
从本质上看,共识是近代社会利益分化和文化多元化的结果,也就是说,没有分化也就没有共识可言。在古代社会,尽管没有社会多元化、差异化基础上的共识,没有自由、自觉、主动的交往共识,但仍存在着自上而下的意识形态高度统一和整合的共识,共识以一种逼迫的路径嵌入在社会的秩序建制中。共识机制体现为权威建制和意识形态霸权。 相似文献
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曲文军 《临沂师范学院学报》2005,27(4):28-32
释义是词典编纂的一个最重要的环节。《汉语大词典》是现存大型汉语词典中质量较高的一部,但它并非完美无缺,部分词目在释义方面还存在着牵强附会的问题,具体表现为轻言通假或借音、轻言引申或比喻意义、用语素意义拼凑词目意义、生硬地关联形近义异的词目等四个方面。这些问题的存在,在很大程度上影响了它成为一部精致的大词典。 相似文献
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以“八景”为题进行诗歌创作，是中国历史上特有的文化现象。《八景诗》创作需要有较长的心理准备和较长的酝酿时间，是有目的、有思考的创作活动；其创作有极强的针对性，特定的场所，特定的关系，为命题之作；题目为预先设定，景点名称，所在区域，何种季节适宜，何种时间段最佳，何种气候条件理想等等，种种旅行要素均有所体现。《八景诗》是士人对出生地或寄居地心理认同基础上的宣传和推介，有浓郁的乡土意识和极强的功利性，为游历提供旅游线索和游览路线，对地域旅游的文化资源建设有重要意义。 相似文献