全文获取类型
收费全文 | 159篇 |
免费 | 7篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 10篇 |
2013年 | 7篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 7篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 11篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 5篇 |
1973年 | 2篇 |
1972年 | 5篇 |
1971年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有166条查询结果,搜索用时 15 毫秒
1.
2.
Excess amino acid polymorphism in mitochondrial DNA: contrasts among genes from Drosophila, mice, and humans 总被引:13,自引:3,他引:10
Recent studies of mitochondrial DNA (mtDNA) variation in mammals and
Drosophila have shown an excess of amino acid variation within species
(replacement polymorphism) relative to the number of silent and replacement
differences fixed between species. To examine further this pattern of
nonneutral mtDNA evolution, we present sequence data for the ND3 and ND5
genes from 59 lines of Drosophila melanogaster and 29 lines of D. simulans.
Of interest are the frequency spectra of silent and replacement
polymorphisms, and potential variation among genes and taxa in the
departures from neutral expectations. The Drosophila ND3 and ND5 data show
no significant excess of replacement polymorphism using the
McDonald-Kreitman test. These data are in contrast to significant
departures from neutrality for the ND3 gene in mammals and other genes in
Drosophila mtDNA (cytochrome b and ATPase 6). Pooled across genes, however,
both Drosophila and human mtDNA show very significant excesses of amino
acid polymorphism. Silent polymorphisms at ND5 show a significantly higher
variance in frequency than replacement polymorphisms, and the latter show a
significant skew toward low frequencies (Tajima's D = -1.954). These
patterns are interpreted in light of the nearly neutral theory where mildly
deleterious amino acid haplotypes are observed as ephemeral variants within
species but do not contribute to divergence. The patterns of polymorphism
and divergence at charge-altering amino acid sites are presented for the
Drosophila ND5 gene to examine the evolution of functionally distinct
mutations. Excess charge-altering polymorphism is observed at the carboxyl
terminal and excess charge-altering divergence is detected at the amino
terminal. While the mildly deleterious model fits as a net effect in the
evolution of nonrecombining mitochondrial genomes, these data suggest that
opposing evolutionary pressures may act on different regions of
mitochondrial genes and genomes.
相似文献
3.
4.
5.
Sara Santarossa Alexandra R. Sitarik Christine Cole Johnson Jia Li Susan V. Lynch Dennis R. Ownby Alex Ramirez Germaine LM. Yong Andrea E. Cassidy-Bushrow 《Journal of Exercise Nutrition & Biochemistry》2021,25(4):24
[Purpose] To determine whether physical activity (PA), primarily the recommended 60 minutes of moderate-to-vigorous PA, is associated with gut bacterial microbiota in 10-year-old children.[Methods] The Block Physical Activity Screener, which provides minutes/day PA variables, was used to determine whether the child met the PA recommendations. 16S rRNA sequencing was performed on stool samples from the children to profile the composition of their gut bacterial microbiota. Differences in alpha diversity metrics (richness, Pielou’s evenness, and Faith’s phylogenetic diversity) by PA were determined using linear regression, whereas beta diversity (unweighted and weighted UniFrac) relationships were assessed using PERMANOVA. Taxon relative abundance differentials were determined using DESeq2.[Results] The analytic sample included 321 children with both PA and 16S rRNA sequencing data (mean age [SD] =10.2 [0.8] years; 54.2% male; 62.9% African American), where 189 (58.9%) met the PA recommendations. After adjusting for covariates, meeting the PA recommendations as well as minutes/day PA variables were not significantly associated with gut richness, evenness, or diversity (p ≥ 0.19). However, meeting the PA recommendations (weighted UniFrac R2 = 0.014, p = 0.001) was significantly associated with distinct gut bacterial composition. These compositional differences were partly characterized by increased abundance of Megamonas and Anaerovorax as well as specific Christensenellaceae_R-7_group taxa in children with higher PA.[Conclusion] Children who met the recommendations of PA had altered gut microbiota compositions. Whether this translates to a reduced risk of obesity or associated metabolic diseases is still unclear. 相似文献
6.
Krupnik OV Fadeeva NV Kvitko N Shepelev VA Nielsen PE Lazurkin YS 《Journal of biomolecular structure & dynamics》2004,21(4):503-512
Structurally isomeric complexes formed between homopyrimidine bis-PNAs (T(2)JT(2)JT(4)-linker-T(4)CT(2)CT(2)) and single- and double-stranded DNA targets were investigated. These complexes are triplexes designated S1, S2 and S3 in order of increased mobility by polyacrylamide gel electrophoresis. It is shown that the S3 isomer is formed only on double-stranded DNA and possesses highest stability. Isomers S2 and S1 are formed upon binding of bis-PNA to double-stranded as well as to single-stranded DNA. It was found that the stability of the isomer S1 increases dramatically in the presence of excess single-stranded oligonucleotide complementary to the bis-PNA. The structure of the stabilized S1 isomer is proposed to consist of two bis-PNA/DNA triplexes. The relationship between the yield of the isomer S1 formed on single-stranded DNA and the bis-PNA concentration was investigated and a kinetic model of the formation of S1 is presented. 相似文献
7.
Fadeeva MS Yakovtseva EA Belevich GA Bertsova YV Bogachev AV 《Archives of microbiology》2007,188(4):341-348
The expression of genes encoding sodium-translocating NADH:quinone oxidoreductase (Na+-NQR) was studied in the marine bacterium Vibrio harveyi and in the enterobacterium Klebsiella pneumoniae. It has been shown that such parameters as NaCl concentration, pH value, and presence of an uncoupler in the growth media
do not influence significantly the level of nqr expression. However, nqr expression depends on the growth substrates used by these bacteria. Na+-NQR is highly repressed in V. harveyi during anaerobic growth, and nqr expression is modulated by electron acceptors and values of their redox potentials. The latter effect was shown to be independent
of the ArcAB regulatory system.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Accession
number: EF394942 (Vibrio harveyi
arcB gene, partial cds). 相似文献
8.
Zvyagina A. I. Dal A. I. Minaychev V. V. Krasnova O. A. Akatov V. S. Fadeeva I. S. 《Biophysics》2022,67(1):134-140
Biophysics - Abstract—The mechanism of passive (independent of recipient cells) aseptic calcification of pericardial materials fixed with gluteraldehyde, which are used for the manufacture of... 相似文献
9.
Bathylaimus anatolii sp. n. is described and illustrated. The new species resembles B. capacosus Hopper, 1962 but differs from the latter by shorter setae, body and by the c-index and has three onchs in the buccal cavity.
The seasonal dynamics of abundance, proportion of adults and larvae, as well as the gravid and nongravid females and males
were studied. An elongated breeding season from April to November and a long spring-summer peak of population density with
a winter minimum at low temperatures for B. anatolii are characteristic in Peter the Great Bay. 相似文献
10.
Nefedova VV Korenberg EI Andreĭchuk IuV Gorelova NB Markov AV Fadeeva IA Evstaf'ev IL 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》2005,(4):23-27
Borrelia Ir-5215, isolated from ticks Ixodes ricinus in Ukraine (the Crimean autonomous region), was identified by the method of the polymorphism of the fragment length of the restriction amplicon of rRNA spacer region 5S-23S. Its Msel-restriction profile was relatively similar to that of B. afzelii. The sequencing of spacer region rrf (5S)-rrl (23S) and 16S rRNA gene, as well as the analysis of the similarity of nucleotide sequences, obtained in the course of these study, revealed the differences between Borrelia sp, lr-5215 and six European species of Borrelia burgdorferi sensu lato and a high level of similarity (more than 95.1% for 5S-23S rRNA and 99.4% for 16S rRNA gene) to three known representatives of genome group A14S (Borrelia spp. A14S, I-77 and PC-Rq17). This suggests that isolated Borrelia lr-5215 is a new representative of pathogenic B. burgdorferi sensu lato genome group A14S, which is spread, together with Central Europe, also in southern Ukraine. 相似文献