采用圆形匹配限制框的指纹特征点匹配算法

介绍了指纹特征点的匹配原理,提出了一种改进的实时指纹特征点匹配算法,并对算法性能进行了实验研究.给出了错误匹配率(FMR)和错误不匹配率(FNMR)随阈值变化的情况及算法的ROC曲线.得到算法的等错误率(EER)为1.8%,最小FMR(zeroFNMR)为6.8%,平均匹配时间为0.1s.算法在指纹库FVC2004上的实验结果表明,算法性能较好,适合于实时指纹识别系统.     

新课程背景下高中生物思想模型的建构探讨

本文结合自身的教学实际,以DNA分子的双螺旋结构模型为例,探讨了生物思想模型的建构过程和方法,论述了生物思想模型的教育价值。     

DNA media storage

In 1994, University of Southern California computer scientist, Dr. Leonard Adleman solved the Hamiltonian path problem using DNA as a computational mechanism. He proved the principle that DNA computing could be used to solve computationally complex problems. Because of the limitations in discovery time, resource requirements, and sequence mismatches, DNA computing has not yet become a commonly accepted practice. However, advancements are continually being discovered that are evolving the field of DNA computing. Practical applications of DNA are not restricted to computation alone. This research presents a novel approach in which DNA could be used as a means of storing files. Through the use of multiple sequence alignment combined with intelligent heu- ristics, the most probabilistic file contents can be determined with minimal errors.     

Gene association study with SVM, MLP and cross validation for diagnosis of diseases

Gene association study is one of the major challenges of biochip technology both for gene diagnosis where only a gene subset is responsible to some diseases, and for treatment of curse of dimensionality which occurs especially in DNA microarray datasets where there are more than thousands of genes and only a few number of experiments (samples). This paper presents a gene selection method by training linear support vector machine (SVM)/nonlinear MLP (multi-layer perceptron) classifiers and testing them with cross validation for finding a gene subset which is optimal/suboptimal for diagnosis of binary/multiple disease types. Genes are selected with linear SVM classifier for the diagnosis of each binary disease types pair and tested by leave-one-out cross validation; then, genes in the gene subset initialized by the union of them are deleted one by one by removing the gene which brings the greatest decrease of the generalization power, for samples, on the gene subset after removal, where generalization is measured by training MLPs with leave-one-out and leave-4-out cross validations. The proposed method was tested with experiments on real DNA microarray MIT data and NCI data. The result shows that it outperforms conventional SNR method in separability of the data with expression levels on selected genes. For real DNA microarray MIT/NCI data, which is composed of 7129/2308 effective genes with only 72/64 labeled samples belonging to 2/4 disease classes, only 11/6 genes are selected to be diagnostic genes. The selected genes are tested by classification of samples on these genes with SVM/MLP with leave-one-out/both leave-one-out and leave-4-out cross validations. The result of no misclassification indicates that the selected genes can be really considered as diagnostic genes for the diagnosis of the corresponding diseases.     

银杏达莫注射液指纹图谱研究

对银杏达莫注射液进行了全面的指纹图谱研究,建立了银杏叶提取物和注射剂的指纹图谱及相关参数。该研究方法的系统性、特征性和重现性良好,保证其标准化,有助于该制剂的质量控制。     

Type II restriction endonucleases: structure and mechanism

Type II restriction endonucleases are components of restriction modification systems that protect bacteria and archaea against invading foreign DNA. Most are homodimeric or tetrameric enzymes that cleave DNA at defined sites of 4–8 bp in length and require Mg²⁺ ions for catalysis. They differ in the details of the recognition process and the mode of cleavage, indicators that these enzymes are more diverse than originally thought. Still, most of them have a similar structural core and seem to share a common mechanism of DNA cleavage, suggesting that they evolved from a common ancestor. Only a few restriction endonucleases discovered thus far do not belong to the PD...D/ExK family of enzymes, but rather have active sites typical of other endonuclease families. The present review deals with new developments in the field of Type II restriction endonucleases. One of the more interesting aspects is the increasing awareness of the diversity of Type II restriction enzymes. Nevertheless, structural studies summarized herein deal with the more common subtypes. A major emphasis of this review will be on target site location and the mechanism of catalysis, two problems currently being addressed in the literature.Received 15 November 2004; accepted 9 December 2004     

几种番茄品种基因组DNA的相似指数初步分析

用４种随机引物（１０ｂｐ）,对普通番茄５个品种的基因组ＤＮＡ进行了ＰＣＲ扩增,并对其ＲＡＰＤ带谱进行了统计处理,发现不同随机引物扩增出来的ＲＡＰＤ标记所表现的相似指数有所不同,综合考虑,普通番茄种内不同品种同ＤＮＡ多态性保持了较高的稳定性。     

菠萝DNA导入黄瓜的初步研究

以菠萝为供体,黄瓜为受体,应用花粉管通道导入外源ＤＮＡ技术,在黄瓜自花授粉后直接导入菠萝ＤＮＡ,导入后代在产量、糖分含量等性状上产生了变异。结果表明：利用花粉管通道直接导入外源ＤＮＡ是改良黄瓜品种的有效技术,这一技术将在作物品种改良及远缘杂交方面起着非常重要的作用。     

用种子醇溶蛋白电泳技术鉴定外源DNA导入春小麦变异后代

采用醇溶蛋白聚丙烯酰胺凝胶电泳技术,对外源DNA导入技术选育的春小麦变异株系的单株及其受体种子的分析结果:小麦各变异后代电泳谱带在15～19条之间变动,受体谱带为16条.多数谱带与受体相似,也出现了受体所没有的新谱带.各后代的谱带着色深度、谱带宽度均存在显著差异,其差异的出现与外源DNA导入有关.同时说明,种子醇溶蛋白电泳技术可用于外源遗传物质导入小麦变异后代的鉴定.