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611.
Leonor Cruzeiro 《Journal of biological physics》2009,35(1):43-55
The current status of the Davydov/Scott model for energy transfer in proteins is reviewed. After a brief introduction to the
theoretical framework and to the basic results, the problems of finite temperature dynamics and of the full quantum and mixed
quantum-classical approximations are described, as well as recent results obtained within each of these approximations. A
short survey of experimental evidence in support of the Davydov/Scott model is made and absorption spectra are calculated
that show the same temperature dependence as that measured in crystalline acetanilide. Future applications of the Davydov/Scott
model to protein folding and function and to misfolding diseases are outlined. 相似文献
612.
Karla Sandoval Leonor Buentello-Malo Rosenda Peñaloza-Espinosa Heriberto Avelino Antonio Salas Francesc Calafell David Comas 《Human genetics》2009,126(4):521-531
Mesoamerica, defined as the broad linguistic and cultural area from middle southern Mexico to Costa Rica, might have played
a pivotal role during the colonization of the American continent. The Mesoamerican isthmus has constituted an important geographic
barrier that has severely restricted gene flow between North and South America in pre-historical times. Although the Native
American component has been already described in admixed Mexican populations, few studies have been carried out in native
Mexican populations. In this study, we present mitochondrial DNA (mtDNA) sequence data for the first hypervariable region
(HVR-I) in 477 unrelated individuals belonging to 11 different native populations from Mexico. Almost all of the Native Mexican
mtDNAs could be classified into the four pan-Amerindian haplogroups (A2, B2, C1, and D1); only two of them could be allocated
to the rare Native American lineage D4h3. Their haplogroup phylogenies are clearly star-like, as expected from relatively
young populations that have experienced diverse episodes of genetic drift (e.g., extensive isolation, genetic drift, and founder
effects) and posterior population expansions. In agreement with this observation, Native Mexican populations show a high degree
of heterogeneity in their patterns of haplogroup frequencies. Haplogroup X2a was absent in our samples, supporting previous
observations where this clade was only detected in the American northernmost areas. The search for identical sequences in
the American continent shows that, although Native Mexican populations seem to show a closer relationship to North American
populations, they cannot be related to a single geographical region within the continent. Finally, we did not find significant
population structure in the maternal lineages when considering the four main and distinct linguistic groups represented in
our Mexican samples (Oto-Manguean, Uto-Aztecan, Tarascan, and Mayan), suggesting that genetic divergence predates linguistic
diversification in Mexico. 相似文献
613.
Mónica Martins Maria Leonor Faleiro Raúl Jorge Barros Ana Raquel Veríssimo Maria Clara Costa 《Biodegradation》2009,20(4):559-567
Biological treatment with dissimilatory sulphate-reducing bacteria has been considered the most promising alternative for
decontamination of sulphate rich effluents. These wastewaters are usually deficient in electron donors and require their external
addition to achieve complete sulphate reduction. The aim of the present study was to investigate the possibility of using
food industry wastes (a waste from the wine industry and cheese whey) as carbon sources for dissimilatory sulphate-reducing
bacteria. The results show that these wastes can be efficiently used by these bacteria provided that calcite tailing is present
as a neutralizing and buffer material. A 95 and 50 % sulphate reduction was achieved within 20 days of experiment by a consortium
of dissimilatory sulphate-reducing bacteria grown on media containing waste from the wine industry or cheese whey respectively.
Identification of the dissimilatory sulphate-reducing bacteria community using the dsr gene revealed the presence of the species Desulfovibrio fructosovorans,
Desulfovibrio aminophilus and Desulfovibrio desulfuricans. The findings of the present study emphasise the potential of using wastes from the wine industry as carbon source for dissimilatory
sulphate-reducing bacteria, combined with calcite tailing, in the development of cost effective and environmentally friendly
bioremediation processes. 相似文献
614.
615.
Lara M. Silva Ana S. Carvalho Patrice Guillon Susana Seixas Maria Azevedo Raquel Almeida Nathalie Ruvoën-Clouet Celso A. Reis Jacques Le Pendu Jorge Rocha Leonor David 《Glycoconjugate journal》2010,27(1):61-68
The secretor (Se)/nonsecretor (se) histo-blood group variation depends on the action of the FUT2 enzyme and has major implications for human susceptibility to infections. To characterize the functionality of FUT2 variants, we assessed the correlation between saliva phenotypes and sequence variation at the FUT2 gene in sixty seven individuals from northern Portugal. While most non-secretor haplotypes were found to carry the 428G > A nonsense mutation in association with a 739G > A missense substitution, we have also identified a recombinant haplotype carrying the 739*A allele together with the efficient 428*G variant in individuals with the Se phenotype. This finding suggested, in contrast to previous results, that the 739*A allele encodes an efficient Se allele. To test this hypothesis we evaluated the in vivo enzyme activity of full coding expression constructs in transient transfection of CHO-K1 cells using FACS (fluorescence-activated cell sorting) analysis and expression of type 2 and type 3 chain H structures as read out. We detected FUT2 activity for the 739*A expression construct, demonstrating that the 739G > A substitution is indeed not inactivating. In accordance with the hypothesis that FUT2 is under long standing balancing selection, we estimated that the time depth of FUT2 global genetic variation is as old as 3 million years. Age estimates of specific variants suggest that the 428G > A mutation occurred at least 1.87 million years ago while the 739G > A substitution is about 816,000 years old. The 385A > T missense mutation underlying the non-secretor phenotype in East Asians appears to be more recent and is likely to have occurred about 256,000 years ago. 相似文献
616.
Lefty antagonism of Squint is essential for normal gastrulation 总被引:1,自引:0,他引:1
Feldman B Concha ML Saúde L Parsons MJ Adams RJ Wilson SW Stemple DL 《Current biology : CB》2002,12(24):2129-2135
617.
618.
619.
Leonor P. Roguin Juan S. Bonifacino Alejandro C. Paladini 《Biochimica et Biophysica Acta (BBA)/General Subjects》1982,715(2):222-229
Human growth hormone binding sites from female rabbit kidney microsomes were solubilized by treatment with the nonionic detergent Triton X-100. The binding of 125I-labelled human growth hormone to the solubilized sites retains many of the properties observed in the particulate fraction, such as saturability, reversibility, high affinity and structural specificity. The association and the dissociation process are time- and temperature-dependent. The association rate constant, k1, is 1.6·107 mol?1·l·min?1 at 25°C, and the dissociation rate constant, k?1, is 2.8·10?4 min?1 at 25°C. Solubilization causes an increase in affinity as well as in binding capacity. Scatchard plots from saturation curves suggest the presence of a single class of binding site with a dissociation equilibrium constant, Kd, of 1.3·10?11 M and a binding capacity of 133 fmol/mg of protein. Similar results were obtained from competition experiments. Specificity studies revealed the lactogenic characteristics of the solubilized sites. The Stokes radii of the free binding sites and of the 125I-labelled human growth hormone-binding site complex, determined on a Sepharose CL-6B column, are 57 and 53 Å, respectively. 相似文献
620.
Salvador Nogués Lurdes Cotxarrera Leonor Alegre Maria Isabel Trillas 《The New phytologist》2002,154(2):461-470