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171.
Dityatev A Brückner G Dityateva G Grosche J Kleene R Schachner M 《Developmental neurobiology》2007,67(5):570-588
Extracellular matrix molecules--including chondroitin sulfate proteoglycans, hyaluronan, and tenascin-R--are enriched in perineuronal nets (PNs) associated with subsets of neurons in the brain and spinal cord. In the present study, we show that similar cell type-dependent extracellular matrix aggregates are formed in dissociated cell cultures prepared from early postnatal mouse hippocampus. Starting from the 5th day in culture, accumulations of lattice-like extracellular structures labeled with Wisteria floribunda agglutinin were detected at the cell surface of parvalbumin-expressing interneurons, which developed after 2-3 weeks into conspicuous PNs localized around synaptic contacts at somata and proximal dendrites, as well as around axon initial segments. Physiological recording and intracellular labeling of PN-expressing neurons revealed that these are large fast-spiking interneurons with morphological characteristics of basket cells. To study mechanisms of activity-dependent formation of PNs, we performed pharmacological analysis and found that blockade of action potentials, transmitter release, Ca2+ permeable AMPA subtype of glutamate receptors or L-type Ca2+ voltage-gated channels strongly decreased the extracellular accumulation of PN components in cultured neurons. Thus, we suggest that Ca2+ influx via AMPA receptors and L-type channels is necessary for activity-dependent formation of PNs. To study functions of chondroitin sulfate-rich PNs, we treated cultures with chondroitinase ABC that resulted in a prominent reduction of several major PN components. Removal of PNs did not affect the number and distribution of perisomatic GABAergic contacts but increased the excitability of interneurons in cultures, implicating the extracellular matrix of PNs in regulation of interneuronal activity. 相似文献
172.
The Sandfish's Skin: Morphology, Chemistry and Reconstruction 总被引:1,自引:0,他引:1
Werner Baumgartner Friederike Saxe Agnes Weth David Hajas Darwin Sigumonrong Jens Emmerlich Martin Singheiser Wolfgang Boehme Jochen M. Schneider 《仿生工程学报(英文版)》2007,4(1):1-9
The sandfish is a lizard having the remarkable ability to move in desert sand in a swimming-like fashion. The most outstanding adaptations to this mode of life are the low friction behaviour and the extensive abrasion resistance of the sandfish skin against sand, outperforming even steel. We investigated the topography, the composition and the mechanical properties of sandfish scales. These consist of glycosylated keratins with high amount of sulphur but no hard inorganic material, such as silicates or lime. Remarkably, atomic force microscopy shows an almost complete absence of attractive forces between the scale surface and a silicon tip, suggesting that this is responsible for the unusual tribological properties. The unusual glycosylation of the keratins was found to be absolutely necessary for the described phenomenon. The scales were dissolved and reconstituted on a polymer surface resulting in properties similar to the original scale. Thus, we provide a pathway towards exploitation of the reconstituted scale material for future engineering applications. 相似文献
173.
Background
Immunity against the bovine protozoan parasite Theileria parva has previously been shown to be mediated through lysis of parasite-infected cells by MHC class I restricted CD8+ cytotoxic T lymphocytes. It is hypothesized that identification of CTL target schizont antigens will aid the development of a sub-unit vaccine. We exploited the availability of the complete genome sequence data and bioinformatics tools to identify genes encoding secreted or membrane anchored proteins that may be processed and presented by the MHC class I molecules of infected cells to CTL.Results
Of the 986 predicted open reading frames (ORFs) encoded by chromosome 1 of the T. parva genome, 55 were selected based on the presence of a signal peptide and/or a transmembrane helix domain. Thirty six selected ORFs were successfully cloned into a eukaryotic expression vector, transiently transfected into immortalized bovine skin fibroblasts and screened in vitro using T. parva-specific CTL. Recognition of gene products by CTL was assessed using an IFN-γ ELISpot assay. A 525 base pair ORF encoding a 174 amino acid protein, designated Tp2, was identified by T. parva-specific CTL from 4 animals. These CTL recognized and lysed Tp2 transfected skin fibroblasts and recognized 4 distinct epitopes. Significantly, Tp2 specific CD8+ T cell responses were observed during the protective immune response against sporozoite challenge.Conclusion
The identification of an antigen containing multiple CTL epitopes and its apparent immunodominance during a protective anti-parasite response makes Tp2 an attractive candidate for evaluation of its vaccine potential. 相似文献174.
High Performance Proteomics: 7th HUPO Brain Proteome Project Workshop March 7-9, 2007 Wellcome Trust Conference Centre, Hinxton, UK 总被引:1,自引:0,他引:1
Hamacher M Stephan C Eisenacher M Lewczuk P Wiltfang J Martens L Vizcaíno JA Kwon KH Yoo JS Park YM Beckers J Horsch M de Angelis MH Cho ZH Apweiler R Meyer HE 《Proteomics》2007,7(15):2490-2496
The Wellcome Trust Conference Centre at Hinxton, UK, was the meeting place of the 7th HUPO Brain Proteome Project Workshop entitled "High Performance Proteomics". It started on Wednesday, March 7, 2007 with a steering committee meeting followed by a two days series of talks dealing with the standardization and handling of tissues, body fluids as well as of proteomics data. The presentation and accompanying vivid discussions created a picture of actual strategies and standards in recent proteomics. 相似文献
175.
Comparative quantitative proteomics to investigate the remodeling of bioenergetic pathways under iron deficiency in Chlamydomonas reinhardtii 总被引:2,自引:0,他引:2
Naumann B Busch A Allmer J Ostendorf E Zeller M Kirchhoff H Hippler M 《Proteomics》2007,7(21):3964-3979
The basic question addressed in this study is how energy metabolism is adjusted to cope with iron deficiency in Chlamydomonas reinhardtii. To investigate the impact of iron deficiency on bioenergetic pathways, comparative proteomics was combined with spectroscopic as well as voltametric oxygen measurements to assess protein dynamics linked to functional properties of respiratory and photosynthetic machineries. Although photosynthetic electron transfer is largely compromised under iron deficiency, our quantitative and spectroscopic data revealed that the functional antenna size of photosystem II (PSII) significantly increased. Concomitantly, stress-related chloroplast polypeptides, like 2-cys peroxiredoxin and a stress-inducible light-harvesting protein, LhcSR3, as well as a novel light-harvesting protein and several proteins of unknown function were induced under iron-deprivation. Respiratory oxygen consumption did not decrease and accordingly, polypeptides of respiratory complexes, harboring numerous iron-sulfur clusters, were only slightly diminished or even increased under low iron. Consequently, iron-deprivation induces a transition from photoheterotrophic to primarily heterotrophic metabolism, indicating that a hierarchy for iron allocations within organelles of a single cell exists that is closely linked with the metabolic state of the cell. 相似文献
176.
Hoppen J Dietz M Warsow G Rohde R Schüller HJ 《Molecular genetics and genomics : MGG》2007,278(3):317-330
177.
Thorsten Hugel Jens Michaelis Craig L Hetherington Paul J Jardine Shelley Grimes Jessica M Walter Wayne Falk Dwight L Anderson Carlos Bustamante 《PLoS biology》2007,5(3)
The bacteriophage ϕ29 generates large forces to compact its double-stranded DNA genome into a protein capsid by means of a portal motor complex. Several mechanical models for the generation of these high forces by the motor complex predict coupling of DNA translocation to rotation of the head-tail connector dodecamer. Putative connector rotation is investigated here by combining the methods of single-molecule force spectroscopy with polarization-sensitive single-molecule fluorescence. In our experiment, we observe motor function in several packaging complexes in parallel using video microscopy of bead position in a magnetic trap. At the same time, we follow the orientation of single fluorophores attached to the portal motor connector. From our data, we can exclude connector rotation with greater than 99% probability and therefore answer a long-standing mechanistic question. 相似文献
178.
Roman M Baevsky Victor M Baranov Irina I Funtova André Diedrich Andrey V Pashenko Anja G Chernikova Jürgen Drescher Jens Jordan Jens Tank 《Journal of applied physiology》2007,103(1):156-161
Impaired autonomic control represents a cardiovascular risk factor during long-term spaceflight. Little has been reported on blood pressure (BP), heart rate (HR), and heart rate variability (HRV) during and after prolonged spaceflight. We tested the hypothesis that cardiovascular control remains stable during prolonged spaceflight. Electrocardiography, photoplethysmography, and respiratory frequency (RF) were assessed in eight male cosmonauts (age 41-50 yr, body-mass index of 22-28 kg/m2) during long-term missions (flight lengths of 162-196 days). Recordings were made 60 and 30 days before the flight, every 4 wk during flight, and on days 3 and 6 postflight during spontaneous and controlled respiration. Orthostatic testing was performed pre- and postflight. RF and BP decreased during spaceflight (P < 0.05). Mean HR and HRV in the low- and high-frequency bands did not change during spaceflight. However, the individual responses were different and correlated with preflight values. Pulse-wave transit time decreased during spaceflight (P < 0.05). HRV reached during controlled respiration (6 breaths/min) decreased in six and increased in one cosmonaut during flight. The most pronounced changes in HR, BP, and HRV occurred after landing. The decreases in BP and RF combined with stable HR and HRV during flight suggest functional adaptation rather than pathological changes. Pulse-wave transit time shortening in our study is surprising and may reflect cardiac output redistribution in space. The decrease in HRV during controlled respiration (6 breaths/min) indicates reduced parasympathetic reserve, which may contribute to postflight disturbances. 相似文献
179.
Behrens Jane W. Ryberg Marie P. Einberg Heli Eschbaum Redik Florin Ann-Britt Grygiel Wlodzimierz Herrmann Jens Peter Huwer Bastian Hssy Karin Knospina Elina Nomaa Kristiina Oesterwind Daniel Polte Patrick Smoliski Szymon Ustups Didzis van Deurs Mikael Ojaveer Henn 《Biological invasions》2022,24(2):527-541
Biological Invasions - Native to the Ponto-Caspian region, the benthic round goby (Neogobius melanostomus) has invaded several European inland waterbodies as well as the North American Great Lakes... 相似文献
180.
Gargan Laura M. Brooks Paul R. Vye Siobhan R. Ironside Joseph E. Jenkins Stuart R. Crowe Tasman P. Carlsson Jens 《Biological invasions》2022,24(3):635-648
Biological Invasions - Artificial coastal structures associated with coastal defences, energy generation, ports, marinas and other developments, are known to support lower levels of biodiversity... 相似文献