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1.
PAML 4: phylogenetic analysis by maximum likelihood   总被引:40,自引:1,他引:39  
PAML, currently in version 4, is a package of programs for phylogeneticanalyses of DNA and protein sequences using maximum likelihood(ML). The programs may be used to compare and test phylogenetictrees, but their main strengths lie in the rich repertoire ofevolutionary models implemented, which can be used to estimateparameters in models of sequence evolution and to test interestingbiological hypotheses. Uses of the programs include estimationof synonymous and nonsynonymous rates (dN and dS) between twoprotein-coding DNA sequences, inference of positive Darwinianselection through phylogenetic comparison of protein-codinggenes, reconstruction of ancestral genes and proteins for molecularrestoration studies of extinct life forms, combined analysisof heterogeneous data sets from multiple gene loci, and estimationof species divergence times incorporating uncertainties in fossilcalibrations. This note discusses some of the major applicationsof the package, which includes example data sets to demonstratetheir use. The package is written in ANSI C, and runs underWindows, Mac OSX, and UNIX systems. It is available at http://abacus.gene.ucl.ac.uk/software/paml.html.  相似文献
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用SSR分子标记研究大豆属种间亲缘进化关系   总被引:39,自引:2,他引:37  
利用SSR标记技术对大豆属11个种37份材料的遗传多样性进行分析,不同位点在种间的等位基因数为6-29,平均生个位点15.9个等位基因,Soja亚属的等位基因数是Glycine亚属的71.5%,并且Glycine亚属种间指纹 谱的差异大于Soja亚属种间的指纹图谱,SSR等位基因的主成分分析结果表明,大豆属中的Glycine亚属和Soja亚属的分类界限是比较明确的,利用第一主成分和第二主成分可较明显地区分开Glycine 亚属的分类界限是比较明显的,利用第一主成分和第二主成分可较明显地区分开Glycine亚属和Soja亚属,通过UPGMA方法构建了大豆属11个种的遗传进化关系,Soja亚属中G.max,G.soja和G.gracilis3个种在系统分化树上界限是比较明显的,由此看来这3个种是独立存在的。  相似文献
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A Novel Family of Ubiquitous Heavy Metal Ion Transport Proteins   总被引:32,自引:0,他引:32  
We describe a novel diverse family of metal ion transporter (CDF) proteins (the cation diffusion facilitator (CDF) family) with members occurring in both prokaryotes and eukaryotes. Thirteen sequenced protein members of the CDF family have been identified, several of which have been shown to transport cobalt, cadmium and/or zinc. All members of the CDF family possess six putative transmembrane spanners with strongest conservation in the four N-terminal spanners, and on the basis of the analyses, we present a unified structural model. Members of the family are shown to exhibit an unusual degree of size variation, sequence divergence, and differences in cell localization and polarity. The phylogenetic tree for the CDF family reveals that prokaryotic and eukaryotic proteins cluster separately. It allows functional predictions for some uncharacterized members of this family. A signature sequence specific for the CDF family is derived. Received: 15 July 1996/Revised: 21 October 1996  相似文献
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一株牙鲆皮肤溃烂症病原菌的鉴定   总被引:30,自引:0,他引:30       下载免费PDF全文
从山东荣成养鱼场发病牙鲆分离到一株病原菌M3,革兰氏阴性,杆状,能运动,菌落半透明,用BIOLOG细菌鉴定系统不能鉴定。通过16S rDNA序列分析和同源性检索发现M3菌株与弧菌属的同源性较高,为94%~98%。系统发育学分析表明菌株M3与鳗弧菌关系最近,相似性为996%,其生化性状也和鳗弧菌的特征相似,故可把M3定为鳗弧菌(Vibrio anguillarum)。  相似文献
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Summary A new method of analyzing phylogenetic relations among members of the sequence family is presented and applied to human Alu sequences upon which work has been published. This method, based upon a correspondence analysis, works with large samples and yields easily interpretable graphical representations. Results obtained argue in favor of a new evolutionary scheme for Alu sequences, implying successives waves of amplification/fixation closely connected to primate lineage history.  相似文献
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Summary NTP-motif, a consensus sequence previously shown to be characteristic of numerous NTP-utilizing enzymes, was identified in nonstructural proteins of several groups of positive-strand RNA viruses. These groups include picorna-, alpha-, and coronaviruses infecting animals and como-, poty-, tobamo-, tricorna-, hordei-, and furoviruses of plants, totalling 21 viruses. It has been demonstrated that the viral NTP-motif-containing proteins constitute three distinct families, the sequences within each family being similar to each other at a statistically highly significant level. A lower, but still valid similarity has also been revealed between the families. An overall alignment has been generated, which includes several highly conserved sequence stretches. The two most prominent of the latter contain the socalled A and B sites of the NTP-motif, with four of the five invariant amino acid residues observed within these sequences. These observations, taken together with the results of comparative analysis of the positions occupied by respective proteins (domains) in viral multidomain proteins, suggest that all the NTP-motif-containing proteins of positive-strand RNA viruses are homologous, constituting a highly diverged monophyletic group. In this group the A and B sites of the NTP-motif are the most conserved sequences and, by inference, should play the principal role in the functioning of the proteins. A hypothesis is proposed that all these proteins posses NTP-binding capacity and possibly NTPase activity, performing some NTP-dependent function in viral RNA replication. The importance of phylogenetic analysis for the assessment of the significance of the occurrence of the NTP-motif (and of sequence motifs of this sort in general) in proteins is emphasized.  相似文献
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The human gut microbiota from three healthy subjects were compared by the use of a sequence analysis of 16S rDNA libraries and a culture-based method. Direct counts ranged from 1.9 X 10" to 4.0 X 10" cells/g (wet weight), and plate counts totaled 6.6 X 10(10) to 1.2 X 10(11) CFU/g (wet weight). Sixty to seventy percent of the bacteria in the human intestinal tract cannot be cultured with currently available methods. The 16S rDNA libraries from three subjects were generated from total community DNA in the intestinal tract with universal primer sets. Randomly selected clones were partially sequenced. All purified colonies detected from the surface of the agar plate were used for a partial sequencing of 16S rDNA. On the basis of sequence similarities, the clones and colonies were classified into several clusters corresponding to the major phylum of the domain Bacteria. Among a total of 744 clones obtained, approximately 25% of them belonged to 31 known species. About 75% of the remaining clones were novel "phylotypes" (at least 98% similarity of clone sequence). The predominant intestinal microbial community consisted of 130 species or phylotypes according to the sequence data in this study. The 16S rDNA libraries and colonies included the Bacteroides group, Streptococcus group, Bifidobacterium group, and Clostridium rRNA clusters IV, IX, XIVa, and XVIII. Moreover, several previously uncharacterized and uncultured microorganisms were recognized in clone libraries and colonies. Our results also showed marked individual differences in the composition of intestinal microbiota.  相似文献
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