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排序方式: 共有430条查询结果,搜索用时 15 毫秒
91.
Rousso Benny Zuse Bertone Edoardo Stewart Rodney A. Hughes Sara P. Hobson Peter Hamilton David P. 《Hydrobiologia》2022,849(6):1453-1469
Hydrobiologia - The objective of this study was to identify correlations between environmental variables and cyanobacterial diversity, succession and dominance in three Australian water supply... 相似文献
92.
In a previous paper we have introduced a phenomenological model of cell metabolism and of the cell cycle to simulate the behavior of large tumor cell populations (Chignola and Milotti 2005 Phys. Biol. 2 8). Here we describe a refined and extended version of the model that includes some of the complex interactions between cells and their surrounding environment. The present version takes into consideration several additional energy-consuming biochemical pathways such as protein and DNA synthesis, the tuning of extracellular pH and of the cell membrane potential. The control of the cell cycle, which was previously modeled by means of ad hoc thresholds, has been directly addressed here by considering checkpoints from proteins that act as targets for phosphorylation on multiple sites. As simulated cells grow, they can now modify the chemical composition of the surrounding environment which in turn acts as a feedback mechanism to tune cell metabolism and hence cell proliferation: in this way we obtain growth curves that match quite well those observed in vitro with human leukemia cell lines. The model is strongly constrained and returns results that can be directly compared with actual experiments, because it uses parameter values in narrow ranges estimated from experimental data, and in perspective we hope to utilize it to develop in silico studies of the growth of very large tumor cell populations (10(6) cells or more) and to support experimental research. In particular, the program is used here to make predictions on the behavior of cells grown in a glucose-poor medium: these predictions are confirmed by experimental observation. 相似文献
93.
Ihssane Bouybayoune Susanna Mantovani Federico Del Gallo Ilaria Bertani Elena Restelli Liliana Comerio Laura Tapella Francesca Baracchi Natalia Fernández-Borges Michela Mangieri Cinzia Bisighini Galina V. Beznoussenko Alessandra Paladini Claudia Balducci Edoardo Micotti Gianluigi Forloni Joaquín Castilla Fabio Fiordaliso Fabrizio Tagliavini Luca Imeri Roberto Chiesa 《PLoS pathogens》2015,11(4)
Fatal familial insomnia (FFI) and a genetic form of Creutzfeldt-Jakob disease (CJD178) are clinically different prion disorders linked to the D178N prion protein (PrP) mutation. The disease phenotype is determined by the 129 M/V polymorphism on the mutant allele, which is thought to influence D178N PrP misfolding, leading to the formation of distinctive prion strains with specific neurotoxic properties. However, the mechanism by which misfolded variants of mutant PrP cause different diseases is not known. We generated transgenic (Tg) mice expressing the mouse PrP homolog of the FFI mutation. These mice synthesize a misfolded form of mutant PrP in their brains and develop a neurological illness with severe sleep disruption, highly reminiscent of FFI and different from that of analogously generated Tg(CJD) mice modeling CJD178. No prion infectivity was detectable in Tg(FFI) and Tg(CJD) brains by bioassay or protein misfolding cyclic amplification, indicating that mutant PrP has disease-encoding properties that do not depend on its ability to propagate its misfolded conformation. Tg(FFI) and Tg(CJD) neurons have different patterns of intracellular PrP accumulation associated with distinct morphological abnormalities of the endoplasmic reticulum and Golgi, suggesting that mutation-specific alterations of secretory transport may contribute to the disease phenotype. 相似文献
94.
4‐Cyano‐α‐methyl‐l‐phenylalanine as a Spectroscopic Marker for the Investigation of PeptaibioticMembrane Interactions
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Marta De Zotti Sara Bobone Annalisa Bortolotti Edoardo Longo Barbara Biondi Cristina Peggion Fernando Formaggio Claudio Toniolo Andrea Dalla Bona Bernard Kaptein Lorenzo Stella 《化学与生物多样性》2015,12(4):513-527
Two analogs of the ten‐amino acid residue, membrane‐active lipopeptaibiotic trichogin GA IV, mono‐labeled with 4‐cyano‐α‐methyl‐L ‐phenylalanine, a potentially useful fluorescence and IR absorption probe of the local microenvironment, were synthesized by the solid‐phase methodology and conformationally characterized. The single modification was incorporated either at the N‐terminus (position 1) or near the C‐terminus (position 8) of the peptide main chain. In both cases, the replaced amino acid was the equally helicogenic α‐aminoisobutyric acid (Aib) residue. We performed a solution conformational analysis by use of FT‐IR absorption, CD, and 2D‐NMR spectroscopies. The results indicate that both labeled analogs essentially maintain the overall helical propensity of the naturally occurring lipopeptaibiotic. Peptide? membrane interactions were assessed by fluorescence and ATR‐IR absorption techniques. Analogies and differences between the two peptides were highlighted. Taken together, our data confirm literature results that some of the spectroscopic parameters of the 4‐cyanobenzyl chromophore are sensitive markers of the local microenvironment. 相似文献
95.
Ornella Piazza Simona Cotena Edoardo De Robertis Ferdinando Caranci Rosalba Tufano 《Neurochemical research》2009,34(7):1289-1292
The pathogenesis of sepsis associated encephalopathy (SAE) is not yet clear: the blood–brain barrier (BBB) disruption has
been indicated among the possible causative mechanisms. S100B, a calcium binding protein, originates in the central nervous
system but it can be also produced by extra-cerebral sources; it is passively released from damaged glial cells and neurons;
it has limited passage through the BBB. We aimed to demonstrate BBB damage as part of the pathogenesis of SAE by cerebral
spinal fluid (CSF) and serum S100B measurements and by magnetic resonance imaging (MRI). This paper describes four septic
patients in whom SAE was clinically evident, who underwent MRI and S100B measurement. We have not found any evidence of CSF-S100B
increase. Serum S100B increase was found in three out of four patients. MRI did not identify images attributable to BBB disruption
but vasogenic edema, probably caused by an alteration of autoregulation, was diagnosed. S100B does not increase in CSF of
septic patients; S100B increase in serum may be due to extracerebral sources and does not prove any injury of BBB. MRI can
exclude other cerebral pathologies causing brain dysfunction but is not specific of SAE. BBB damage may be numbered among
the contributors of SAE, which aetiology is certainly multifactorial: an interplay between the toxic mediators involved in
sepsis and the indirect effects of hyperthermia, hypossia and hypoperfusion. 相似文献
96.
Edoardo Daly Sari Palmroth Paul Stoy Mario Siqueira A. Christopher Oishi Jehn-Yih Juang Ram Oren Amilcare Porporato Gabriel G. Katul 《Biogeochemistry》2009,94(3):271-287
Profiles of subsurface soil CO2 concentration, soil temperature, and soil moisture, and throughfall were measured continuously during the years 2005 and
2006 in 16 locations at the free air CO2 enrichment facility situated within a temperate loblolly pine (Pinus taeda L.) stand. Sampling at these locations followed a 4 by 4 replicated experimental design comprised of two atmospheric CO2 concentration levels (ambient [CO2]a, ambient + 200 ppmv, [CO2]e) and two soil nitrogen (N) deposition levels (ambient, ambient + fertilization at 11.2 gN m−2 year−1). The combination of these measurements permitted indirect estimation of belowground CO2 production and flux profiles in the mineral soil. Adjacent to the soil CO2 profiles, direct (chamber-based) measurements of CO2 fluxes from the soil–litter complex were simultaneously conducted using the automated carbon efflux system. Based on the
measured soil CO2 profiles, neither [CO2]e nor N fertilization had a statistically significant effect on seasonal soil CO2, CO2 production, and effluxes from the mineral soil over the study period. Soil moisture and temperature had different effects
on CO2 concentration depending on the depth. Variations in CO2 were mostly explained by soil temperature at deeper soil layers, while water content was an important driver at the surface
(within the first 10 cm), where CO2 pulses were induced by rainfall events. The soil effluxes were equal to the CO2 production for most of the time, suggesting that the site reached near steady-state conditions. The fluxes estimated from
the CO2 profiles were highly correlated to the direct measurements when the soil was neither very dry nor very wet. This suggests
that a better parameterization of the soil CO2 diffusivity is required for these soil moisture extremes. 相似文献
97.
98.
Elena Cassani Edoardo Bertolini Francesco Cerino Badone Michela Landoni Dario Gavina Alberto Sirizzotti Roberto Pilu 《Molecular breeding : new strategies in plant improvement》2009,24(4):375-385
The “green revolution” involving mainly wheat and rice was based on the use by breeders of semidominant mutations involved
in the signal transduction pathway of Gibberellin (GA). In particular, mutations in the Reduced height (Rht) gene of wheat have been used to reduce plant height and consequently to avoid storm damage and lodging. These genes have
been cloned and they encode for DELLA proteins which contain an N-terminal DELLA and a VHYNP domain essential for GA-dependent
degradation of these proteins. In maize several mutations have been isolated which affect gibberellin biosynthesis and perception
and in particular, mutations in Dwarf8 (D8) gene cause a severe dwarfing phenotype. D8 gene has been identified as an orthologue of Rht (Reduced height), Slr1(Slender rice 1) and Gibberellic Acid Insensitive (GAI) genes, this latter is a negative regulator of GA response in Arabidopsis. In this work, for the first time, we isolated and characterized a single amino acid insertion in the VHYNP domain of D8 maize gene causing the appearance of a dominant dwarf mutation. This spontaneous mutation, named D8-1023, showed a phenotype which is less severe in comparison with the other D8 mutants previously isolated which have modifications
in the DELLA domain. This mutant appears to be an useful tool either to study the mechanism of GA-modulated growth in plants
or to lower the height of maize tropical germplasm for breeding purposes. 相似文献
99.
The Novel PMCA2 Pump Mutation Tommy Impairs Cytosolic Calcium Clearance in Hair Cells and Links to Deafness in Mice 总被引:1,自引:0,他引:1
Mario Bortolozzi Marisa Brini Nick Parkinson Giulia Crispino Pietro Scimemi Romolo Daniele De Siati Francesca Di Leva Andrew Parker Saida Ortolano Edoardo Arslan Steve D. Brown Ernesto Carafoli Fabio Mammano 《The Journal of biological chemistry》2010,285(48):37693-37703
The mechanotransduction process in hair cells in the inner ear is associated with the influx of calcium from the endolymph. Calcium is exported back to the endolymph via the splice variant w/a of the PMCA2 of the stereocilia membrane. To further investigate the role of the pump, we have identified and characterized a novel ENU-induced mouse mutation, Tommy, in the PMCA2 gene. The mutation causes a non-conservative E629K change in the second intracellular loop of the pump that harbors the active site. Tommy mice show profound hearing impairment from P18, with significant differences in hearing thresholds between wild type and heterozygotes. Expression of mutant PMCA2 in CHO cells shows calcium extrusion impairment; specifically, the long term, non-stimulated calcium extrusion activity of the pump is inhibited. Calcium extrusion was investigated directly in neonatal organotypic cultures of the utricle sensory epithelium in Tommy mice. Confocal imaging combined with flash photolysis of caged calcium showed impairment of calcium export in both Tommy heterozygotes and homozygotes. Immunofluorescence studies of the organ of Corti in homozygous Tommy mice showed a progressive base to apex degeneration of hair cells after P40. Our results on the Tommy mutation along with previously observed interactions between cadherin-23 and PMCA2 mutations in mouse and humans underline the importance of maintaining the appropriate calcium concentrations in the endolymph to control the rigidity of cadherin and ensure the function of interstereocilia links, including tip links, of the stereocilia bundle. 相似文献
100.