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991.
Natalia DionisioCarmen Galán Isaac JardínGinés M. Salido Juan. A. Rosado 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2011,1813(3):431-437
STIM1 is a transmembrane protein essential for the activation of store-operated Ca2+ entry (SOCE), a major Ca2+ influx mechanism. STIM1 is either located in the endoplasmic reticulum, communicating the Ca2+ concentration in the stores to plasma membrane channels or in the plasma membrane, where it might sense the extracellular Ca2+ concentration. Plasma membrane-located STIM1 has been reported to mediate the SOCE sensitivity to extracellular Ca2+ through its interaction with Orai1. Here we show that plasma membrane lipid raft domains are essential for the regulation of SOCE by extracellular Ca2+. Treatment of platelets with the SERCA inhibitor thapsigargin (TG) induced Mn2+ entry, which was inhibited by increasing concentrations of extracellular Ca2+. Platelet treatment with methyl-β-cyclodextrin, which removes cholesterol and disrupts the lipid raft domains, impaired the inactivation of Ca2+ entry induced by extracellular Ca2+. Methyl-β-cyclodextrin also abolished translocation of STIM1 to the plasma membrane stimulated by treatment with TG and prevented TG-evoked co-immunoprecipitation between plasma membrane-located STIM1 and the Ca2+ permeable channel Orai1. These findings suggest that lipid raft domains are essential for the inactivation of SOCE by extracellular Ca2+ mediated by the interaction between plasma membrane-located STIM1 and Orai1. 相似文献
992.
Solomon IH Khatri N Biasini E Massignan T Huettner JE Harris DA 《The Journal of biological chemistry》2011,286(16):14724-14736
There is evidence that alterations in the normal physiological activity of PrP(C) contribute to prion-induced neurotoxicity. This mechanism has been difficult to investigate, however, because the normal function of PrP(C) has remained obscure, and there are no assays available to measure it. We recently reported that cells expressing PrP deleted for residues 105-125 exhibit spontaneous ionic currents and hypersensitivity to certain classes of cationic drugs. Here, we utilize cell culture assays based on these two phenomena to test how changes in PrP sequence and/or cellular localization affect the functional activity of the protein. We report that the toxic activity of Δ105-125 PrP requires localization to the plasma membrane and depends on the presence of a polybasic amino acid segment at the N terminus of PrP. Several different deletions spanning the central region as well as three disease-associated point mutations also confer toxic activity on PrP. The sequence domains identified in our study are also critical for PrP(Sc) formation, suggesting that common structural features may govern both the functional activity of PrP(C) and its conversion to PrP(Sc). 相似文献
993.
Díaz-Prado S Muiños-López E Hermida-Gómez T Cicione C Rendal-Vázquez ME Fuentes-Boquete I de Toro FJ Blanco FJ 《Differentiation; research in biological diversity》2011,81(3):162-171
The human amniotic membrane (HAM) is a highly abundant and readily available tissue. This amniotic tissue has considerable advantageous characteristics to be considered as an attractive material in the field of regenerative medicine. It has low immunogenicity, anti-inflammatory properties and their cells can be isolated without the sacrifice of human embryos. Since it is discarded post-partum it may be useful for regenerative medicine and cell therapy. Amniotic membranes have already been used extensively as biologic dressings in ophthalmic, abdominal and plastic surgery. HAM contains two cell types, from different embryological origins, which display some characteristic properties of stem cells. Human amnion epithelial cells (hAECs) are derived from the embryonic ectoderm, while human amnion mesenchymal stromal cells (hAMSCs) are derived from the embryonic mesoderm. Both populations have similar immunophenotype and multipotential for in vitro differentiation into the major mesodermal lineages, however they differ in cell yield. Therefore, HAM has been proposed as a good candidate to be used in cell therapy or regenerative medicine to treat damaged or diseased tissues. 相似文献
994.
To probe structural changes that occur when a membrane protein is transferred from lipid bilayers to SDS micelles, a fragment of bacteriorhodopsin containing transmembrane helical segments A and B was studied by fluorescence spectroscopy, molecular dynamics (MD) simulation, and stopped flow kinetics. In lipid bilayers, F?rster resonance energy transfer (FRET) was observed between tyrosine 57 on helix B and tryptophans 10 and 12 on helix A. FRET efficiency decreased substantially when the peptide was transferred to SDS. MD simulation showed no evidence for significant disruption of helix-helix interactions in SDS micelles. However, a cluster of water molecules was observed to form a hydrogen-bonded network with the phenolic hydroxyl group of tyrosine 57, which probably causes the disappearance of tyrosine-to-tryptophan FRET in SDS. The tryptophan quantum yield decreased in SDS, and the change occurred at nearly the same rate as membrane solubilization. The results provide a clear example of the importance of corroborating distance changes inferred from FRET by using complementary methods. 相似文献
995.
Collen B Turvey ST Waterman C Meredith HM Kuhn TS Baillie JE Isaac NJ 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2011,366(1578):2611-2622
Under the impact of human activity, global extinction rates have risen a thousand times higher than shown in the fossil record. The resources available for conservation are insufficient to prevent the loss of much of the world's threatened biodiversity during this crisis. Conservation planners have been forced to prioritize their protective activities, in the context of great uncertainty. This has become known as 'the agony of choice'. A range of methods have been proposed for prioritizing species for conservation attention; one of the most strongly supported is prioritizing those species that maximize phylogenetic distinctiveness (PD). We evaluate how a composite measure of extinction risk and phylogenetic isolation (EDGE) has been used to prioritize species according to their degree of unique evolutionary history (evolutionary distinctiveness, ED) weighted by conservation urgency (global endangerment, GE). We review PD-based approaches and provide an updated list of EDGE mammals using the 2010 IUCN Red List. We evaluate how robust this method is to changes in phylogenetic uncertainty, knowledge of taxonomy and extinction risk, and examine how mammalian species that rank highly in EDGE score are representative of the collective from which they are drawn. 相似文献
996.
997.
Uchima CA Tokuda G Watanabe H Kitamoto K Arioka M 《Applied microbiology and biotechnology》2011,89(6):1761-1771
Neotermes koshunensis is a lower termite that secretes endogenous β-glucosidase in the salivary glands. This β-glucosidase (G1NkBG) was successfully
expressed in Aspergillus oryzae. G1NkBG was purified to homogeneity from the culture supernatant through ammonium sulfate precipitation and anion exchange,
hydrophobic, and gel filtration chromatographies with a 48-fold increase in purity. The molecular mass of the native enzyme
appeared as a single band at 60 kDa after gel filtration analysis, indicating that G1NkBG is a monomeric protein. Maximum
activity was observed at 50 °C with an optimum pH at 5.0. G1NkBG retained 80% of its maximum activity at temperatures up to
45 °C and lost its activity at temperatures above 55 °C. The enzyme was stable from pH 5.0 to 9.0. G1NkBG was most active
towards laminaribiose and p-nitrophenyl-β-d-fucopyranoside. Cellobiose, as well as cello-oligosaccharides, was also well hydrolyzed. The enzyme activity was slightly
stimulated by Mn2+ and glycerol. The K
m and V
max values were 0.77 mM and 16 U/mg, respectively, against p-nitrophenyl-β-d-glucopyranoside. An unusual finding was that G1NkBG was stimulated by 1.3-fold when glucose was present in the reaction mixture
at a concentration of 200 mM. These characteristics, particularly the stimulation of enzyme activity by glucose, make G1NkBG
of great interest for biotechnological applications, especially for bioethanol production. 相似文献
998.
Comparison of the biochemical and molecular properties of myoglobins from three Biomphalaria species
Kádima N. Teixeira Jamil S. Oliveira Karyne N. Souza Juliana de Moura Cristiane A. Brito Teofânia H.D.A. Vidigal Alexandre M.C. Santos Marcelo M. Santoro 《Biochemical Systematics and Ecology》2011,39(4-6):581-586
Myoglobin is a globin with heme as prosthetic group whose main known biological role is to bind to O2 reversibly. On account of their large diversity, globins from mollusks have contributed to the study of this protein class. The cDNA of the myoglobins from Biomphalaria straminea and Biomphalaria tenagophila, which have a glutamine as distal residue (E7), were constructed and analyzed by bioinformatic tools. Native (not recombinant) myoglobins of these two Biomphalaria species were purified and their experimental molecular mass (about 16 kDa) and pI (about (8.0) were provided. Data analysis showed that these proteins are monomers with the signature for the classic myoglobin fold and they are blocked in amino terminus probably by an acetyl group. Values of the autoxidation rates showed that these myoglobins oxidized slowly. About the primary sequences of the myoglobins, they turned out to be satisfactory to group mollusks in phylogenetic class. 相似文献
999.
de Oliveira Silva F das Neves Santos P de Melo CM Teixeira EH de Sousa Cavada B Arruda FV Cajazeiras JB Almeida AC Pereira VA Porto AL 《Cell and tissue research》2011,346(2):237-244
Lectins constitute a class of glycoproteins, which are capable of selectively and reversibly binding to carbohydrates, distinguishing
small structural differences in complex oligosaccharides. Studies have shown that the binding of lectins to cell-surface carbohydrates
can lead to various effects such as cellular proliferation, histamine release and cytokine production. Canavalia brasiliensis lectin (ConBr) is a (D-mannose) D-glucose lectin. In this study, murine splenocytes were cultured to determine the effect
of ConBr on cell proliferation, nitric oxide (NO) release and cytokine secretion. In addition, cellular viability assays were
performed to evaluate any mitogenic activity induced by this lectin. ConBr significantly increased cell proliferation with
minimal cell damage. This lectin was able to induce an increased production of cytokines such as IL-2, IL-6 and IFN-γ and
a decreased production of IL- 10. The release of NO was also observed. The results of this study indicate that ConBr could
potentially be used as an immunomodulator. 相似文献
1000.
Cristiane Aparecida Pereira Anna Carolina Borges Pereira da Costa Ana Karina Silva Machado Miltom Beltrame Júnior Maria Stella Amorin Costa Zöllner Juliana Campos Junqueira Antonio Olavo Cardoso Jorge 《Mycopathologia》2011,171(2):103-109
Candida strains can cause oral candidosis, as well as nipples candidosis and lead to premature weaning or yeast transmission. The
aim of this study was to evaluate 51 Candida isolates obtained from the oral cavities of infants during breastfeeding and mothers’ oral cavities and nipples, their enzymatic
activity and their sensitivity to amphotericin B, fluconazole and Baccharis dracunculifolia essential oil. Among the studied strains, 96.1% produced phospholipase and 78.4% produced proteinase. The antifungal resistance
was only observed among isolates of C. albicans, for which three strains showed a resistant activity to fluconazole and one showed a resistant activity to amphotericin B.
All strains were sensitive to B. dracunculifolia essential oil with MIC between 0.2 and 6.25 mg/ml. It was concluded that most of the strains showed significant enzymatic
activity and were sensitive to amphotericin B and fluconazole. B. dracunculifolia essential oil inhibited the growth of all strains, including the ones resistant to commercial antifungal agents. 相似文献