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51.
Vincenzo Pavone Angelina Lombardi Michele Saviano Benedetto Di Blasio Flavia Nastri Roberto Fattorusso Ornella Maglio Carla Isernia 《Biopolymers》1994,34(11):1505-1515
In the present paper we describe the synthesis, purification, single crystal x-ray analysis, and solution structural characterization by nmr spectroscopy, combined with restrained molecular dynamic simulations, of the cyclic hexapeptide cyclo-(Pro-Phe-β-Ala-Phe-Phe-β-Ala). The peptide was synthesized by classical solution methods and the cyclization of the free hexapeptide was accomplished in good yields in diluted methylenechloride solution using N, N-dicyclohexyl-carbodiimide. The compound crystallizes in the monoclinic space group P21 from methanol/ethyl acetate. The molecule adopts in the solid state a conformation characterized by cis β-Ala6-Pro1 peptide bond. The α-amino acid residues are at the corner positions of turned structures. The Pro1-Phe2 segment is incorporated in a pseudo type I β-turn, while Phe4-Phe5 is in a typical type I β-turn. Assignment of all 1H and 13C resonances was achieved by homo- and heteronuclear two-dimensional techniques in dimethylsulfoxide (DMSO) solutions. The conformational analysis was based on inter-proton distances derived from rotating frame nuclear Overhauser effect spectroscopy spectra and homonuclear coupling constants. Restrained molecular dynamic simulation in vacuo was also performed to built refined molecular models. The molecule is present in DMSO solution as two slowly interconverting conformers, characterized by a cis-tran isomerism around the β-Ala6-Pro1 peptide bond. This work confirms our expectations on the low propensity of β-alanyl residues to be positioned at the corners of turned structure. © 1994 John Wiley & Sons, Inc. 相似文献
52.
53.
Ontañon Ornella M. Ghio Silvina Marrero Díaz de Villegas Rubén Piccinni Florencia E. Talia Paola M. Cerutti María L. Campos Eleonora 《Applied microbiology and biotechnology》2018,102(16):6959-6971
Applied Microbiology and Biotechnology - Biomass hydrolysis constitutes a bottleneck for the biotransformation of lignocellulosic residues into bioethanol and high-value products. The efficient... 相似文献
54.
M Marelli D J Dilworth R W Wozniak J D Aitchison 《Biochimie et biologie cellulaire》2001,79(5):603-612
The regulated exchange of proteins and nucleic acids between the nucleus and cytoplasm demands a complex interplay between nuclear pore complexes (NPCs), which provide conduits in the nuclear envelope, and mobile transport receptors (or karyopherins, also known as importins/exportins) that bind and mediate the translocation of cargoes through the NPCs. Biochemical characterization of individual karyopherins has led to the identification of many of their cargoes and to the elucidation of the mechanisms by which they mediate transport. Likewise, the characterization of numerous NPC-associated components, in combination with structural studies of NPCs, have begun to address the possible mechanisms that drive nucleocytoplasmic transport, and the role that different nucleoporins play in the transport process. Some recent studies indicate that several NPC-associated factors, previously thought to be stable components of the NPC, dynamically interact with both nuclear and cytoplasmic aspects of the NPC. The mobility of these components challenges our conventional view of the NPC as the stationary phase of transport. These components and their potiential roles in nucleo-cytoplasmic transport are discussed. 相似文献
55.
Giovanni Battista Conselvan Diego Pizzeghello Ornella Francioso Michele Di Foggia Serenella Nardi Paolo Carletti 《Plant and Soil》2017,420(1-2):119-134
Background and aims
Biostimulants are natural compounds that enhance plant growth and plant nutrient use efficiency. In this study, biostimulant effects of humic substances (HS) extracted from leonardites were analysed on the metabolism of maize plants grown in hydroponic conditions.Methods
HS extracted from four leonardites were tested for their auxin-like and gibberellin-like activities. Then, 11 day old maize seedlings were treated for 48 h with five concentrations (0, 0.1, 0.5, 1, and 10 mg C L?1) of HS. After sampling, root growth and morphology, glutamine synthetase (GS) activity, glutamate synthase (GOGAT) activity, total protein content, soluble sugars content, phenylalanine ammonia-lyase (PAL) activity, soluble phenols, and free phenolic acids were analysed.Results
HS from leonardites had similar spectroscopic pattern, with small differences. The HS from the South Dakota lignite (HS_USA) had more carboxylic groups, whereas the three from Turkish mines had more aromatic and aliphatic structures. HS_USA best enhanced total root growth, root surface area, and proliferation of secondary roots. Plant nutrient use efficiency was enhanced by HS_4, HS_USA and HS_B, with increment of GS and GOGAT enzymes activity and total protein production. HS stimulated also PAL enzyme activity, followed by a higher production of total soluble phenols, p-hydroxybenzoic acid, p-coumarilic acid, and chlorogenic acid.Conclusion
This study found that, although the activity of the HS depended on the origin of the leonardite, these compounds can be attributed to the biostimulant products, eliciting plant growth, nitrogen metabolism, and accumulation of phenolic substances.56.
Ornella Rossetto Laura Morbiato Paola Caccin Michela Rigoni Luca Carli Marco Paoli Mariana Cintra-Francischelli Cesare Montecucco 《Rendiconti Lincei》2008,19(2):173-188
Tetanus and botulinum neurotoxins, produced by anaerobic bacteria of the genus Clostridium, are the most toxic proteins known
and are solely responsible for the pathogenesis of tetanus and botulism. They are metallo-proteases that enter nerve terminals
and cleave proteins of the neuroexocytosis apparatus causing a persistent, but reversible, inhibition of neurotransmitter
release. Botulinum neurotoxins are used in the therapy of many human syndromes caused by hyperactive nerve terminals. Snake
presynaptic PLA2 neurotoxins block nerve terminals by binding to the nerve membrane and catalyzing phospholipid hydrolysis
with production of lysophospholipids and fatty acids. These compounds change the membrane conformation causing enhanced fusion
of synaptic vesicle via hemifusion intermediate with release of neurotransmitter and, at the same time, inhibition of vesicle
fission and recycling. It is possible to envisage clinical applications of the lysophospholipid/fatty acid mixture to inhibit
hyperactive superficial nerve terminals.
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57.
Structural and mechanical properties of UV-photo-cross-linked poly(N-vinyl-2-pyrrolidone) hydrogels 总被引:1,自引:0,他引:1
D'Errico G De Lellis M Mangiapia G Tedeschi A Ortona O Fusco S Borzacchiello A Ambrosio L 《Biomacromolecules》2008,9(1):231-240
Biocompatible poly( N-vinyl-2-pyrrolidone) (PVP) hydrogels have been produced by UV irradiation of aqueous polymer mixtures, using a high-pressure mercury lamp. The resulting materials have been characterized by a combination of experimental techniques, including rheology, small-angle neutron scattering (SANS), electron paramagnetic resonance (EPR), and pulsed gradient spin-echo nuclear magnetic resonance (PGSE-NMR), to put in evidence the relationship between the microstructural properties and the macrofunctional behavior of the gels. Viscoelastic measurements showed that UV photo-cross-linked PVP hydrogels present a strong gel mechanical behavior and viscoelastic moduli values similar to those of biological gels. The average distance between the cross-linking points of the polymer network was estimated from the hydrogels elastic modulus. However, SANS measurements showed that the network microstructure is highly inhomogeneous, presenting polymer-rich regions more densely cross-linked, surrounded by a water-rich environment. EPR and PGSE-NMR data further support the existence of these water-rich domains. Inclusion of a third component, such as glycerol, in the PVP aqueous mixture to be irradiated has been also investigated. A small amount of glycerol (<3% w/w) can be added keeping satisfactory properties of the hydrogel, while higher amounts significantly affect the cross-linking process. 相似文献
58.
Ornella Spadoni Alessio Crestini Paola Piscopo Lorenzo Malvezzi-Campeggi Irene Carunchio Massimo Pieri Cristina Zona Annamaria Confaloni 《Cellular and molecular neurobiology》2009,29(5):635-641
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease defined by motor neuron loss. Transgenic mouse
model (Tg SOD1G93A) shows pathological features that closely mimic those seen in ALS patients. An hypothetic link between
AD and ALS was suggested by finding an higher amount of amyloid precursor protein (APP) in the spinal cord anterior horn neurons,
and of Aβ peptides in ALS patients skin. In this work, we have investigated the expression of some genes involved in Alzheimer’s
disease, as APP, β- and γ-secretase, in an animal model of ALS, to understand some possible common molecular mechanisms between
these two pathologies. For gene expression analysis, we carried out a quantitative RT-PCR in ALS mice and in transgenic mice
over-expressing human wild-type SOD1 (Tg hSOD1). We found that APP and BACE1 mRNA levels were increased 1.5-fold in cortical
cells of Tg SOD1G93A mice respect to Tg hSOD1, whereas the expression of γ-secretase genes, as PSEN1, PSEN2, Nicastrin, and
APH1a, showed no statistical differences between wild-type and ALS mice. Biochemical analysis carried out by immunostaining
and western blotting, did not show any significant modulation of the protein expression compared to the genes, suggesting
the existence of post-translational mechanisms that modify protein levels. 相似文献
59.
Jean-Philippe Marelli Siela N. Maximova Karina P. Gramacho Seogchan Kang Mark John Guiltinan 《Tropical plant biology》2009,2(3-4):149-160
The C-biotype of Moniliophthora perniciosa is the causal agent of witches’ broom disease of Theobroma cacao L. While this disease is of major economic importance, the pathogenicity mechanisms and plant responses underlying the disease are difficult to study given the cacao tree’s long life cycle and the limited availability of genetic and genomic resources for this system. The S-biotype of M. perniciosa infects solanaceous hosts, particularly pepper (Capsicum annuum) and tomato (Solanum lycopersicum). These species are much more amenable for performing studies of mechanisms underpinning host-pathogen interactions as compared to cacao. A phylogenetic analysis performed in this study demonstrated that S-biotype strains clustered with C-biotype strains, indicating that these biotypes are not genetically distinct. A comparative analysis demonstrated that disease progression in tomato infected with the S- biotype is similar to that described for cacao infected with the C- biotype. The major symptoms observed in both systems are swelling of the infected shoots and activation and proliferation of axillary meristems. Cellular changes observed in infected tissues correspond to an increase in cell size and numbers of xylem vessels and phloem parenchyma along the infected stem. Observations revealed that fungal colonization is biotrophic during the first phase of infection, with appearance of calcium oxalate crystals in close association with hyphal growth. In summary, despite different host specificity, both biotypes of M. perniciosa exhibit similar disease-related characteristics, indicating a degree of conservation of pathogenicity mechanisms between the two biotypes. 相似文献
60.
Giacomucci L Bertoncello R Salvadori O Martini I Favaro M Villa F Sorlini C Cappitelli F 《Microbial ecology》2011,62(2):287-298
The Grande Albergo Ausonia &; Hungaria (Venice Lido, Italy) has an Art Nouveau polychrome ceramic coating on its façade, which was restored in 2007. Soon after the conservation treatment, many tiles of the façade decoration showed coloured alterations putatively attributed to the presence of microbial communities. To confirm the presence of the biological deposit and the stratigraphy of the Hungaria tiles, stereomicroscope, optical and environmental scanning electron microscope observations were made. The characterisation of the microbial community was performed using a PCR–DGGE approach. This study reported the first use of a culture-independent approach to identify the total community present in biodeteriorated artistic tiles. The case study examined here reveals that the coloured alterations on the tiles were mainly due to the presence of cryptoendolithic cyanobacteria. In addition, we proved that the microflora present on the tiles was generally greatly influenced by the environment of the Hungaria hotel. We found several microorganisms related to the alkaline environment, which is in the range of the tile pH, and related to the aquatic environment, the presence of the acrylic resin Paraloid B72® used during the 2007 treatment and the pollutants of the Venice lagoon. 相似文献