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141.
Jana Woelfel Rhena Schumann Florian Peine Anita Flohr Aleksandra Kruss Jaroslaw Tegowski Philippe Blondel Christian Wiencke Ulf Karsten 《Polar Biology》2010,33(9):1239-1253
During summer 2007, Arctic microphytobenthic potential primary production was measured at several stations around the coastline
of Kongsfjorden (Svalbard, Norway) at ≤5 m water depth and at two stations at five different water depths (5, 10, 15, 20,
30 m). Oxygen planar optode sensor spots were used ex situ to determine oxygen exchange in the overlying water of intact sediment
cores under controlled light (ca. 100 μmol photons m−2 s−1) and temperature (2–4°C) conditions. Patches of microalgae (mainly diatoms) covering sandy sediments at water depths down
to 30 m showed high biomass of up to 317 mg chl a m−2. In spite of increasing water depth, no significant trend in “photoautotrophic active biomass” (chl a, ratio living/dead cells, cell sizes) and, thus, in primary production was measured at both stations. All sites from ≤5 to
30 m water depth exhibited variable rates of net production from −19 to +40 mg O2 m−2 h−1 (−168 to +360 mg C m−2 day−1) and gross production of about 2–62 mg O2 m−2 h−1 (17–554 mg C m−2 day−1), which is comparable to other polar as well as temperate regions. No relation between photoautotrophic biomass and gross/net
production values was found. Microphytobenthos demonstrated significant rates of primary production that is comparable to
pelagic production of Kongsfjorden and, hence, emphasised the importance as C source for the zoobenthos. 相似文献
142.
Lassing I Schmitzberger F Björnstedt M Holmgren A Nordlund P Schutt CE Lindberg U 《Journal of molecular biology》2007,370(2):331-348
An essential consequence of growth factor-mediated signal transduction is the generation of intracellular H2O2. It operates as a second messenger in the control of actin microfilament dynamics, causing rapid and dramatic changes in the morphology and motile activity of stimulated cells. Little is understood about the molecular mechanisms causing these changes in the actin system. Here, it is shown that H2O2 acts directly upon several levels of this system, and some of the mechanistic effects are detailed. We describe the impact of oxidation on the polymerizability of non-muscle β/γ-actin and compare with that of muscle α-actin. Oxidation of β/γ-actin can cause a complete loss of polymerizability, crucially, reversible by the thioredoxin system. Further, oxidation of the actin impedes its interaction with profilin and causes depolymerization of filamentous actin. The effects of oxidation are critically dependent on the nucleotide state and the concentration of Ca2+. We have determined the crystal structure of oxidized β-actin to a resolution of 2.6 Å. The arrangement in the crystal implies an antiparallel homodimer connected by an intermolecular disulfide bond involving cysteine 374. Our data indicate that this dimer forms under non-polymerizing and oxidizing conditions. We identify oxidation of cysteine 272 in the crystallized actin dimer, likely to a cysteine sulfinic acid. In β/γ-actin, this is the cysteine residue most reactive towards H2O2 in solution, and we suggest plausible structural determinants for its reactivity. No other oxidative modification was obvious in the structure, highlighting the specificity of the oxidation by H2O2. Possible consequences of the observed effects in a cellular context and their potential relevance are discussed. 相似文献
143.
Michael F?ller Ravi S Kasinathan Christophe Duranton Thomas Wieder Stephan M Huber Florian Lang 《Cellular physiology and biochemistry》2006,17(5-6):201-210
Prostaglandin-E2 (PGE2) is known to trigger suicidal death of nucleated cells (apoptosis) and enucleated erythrocytes (eryptosis). In erythrocytes PGE2 induced suicidal cell death involves activation of nonselective cation channels leading to Ca2+ entry followed by cell shrinkage and triggering of Ca2+ sensitive cell membrane scrambling with phosphatidylserine (PS) exposure at the cell surface. The present study was performed to explore whether PGE2 induces apoptosis of nucleated cells similarly through cation channel activation and to possibly disclose the molecular identity of the cation channels involved. To this end, Ca2+ activity was estimated from Fluo3 fluorescence, mitochondrial potential from DePsipher fluorescence, phosphatidylserine exposure from annexin binding, caspase activation from caspAce fluorescence, cell volume from FACS forward scatter, and DNA fragmentation utilizing a photometric enzyme immunoassay. Stimulation of K562 human leukaemia cells with PGE2 (50 microM) increased cytosolic Ca2+ activity, decreased forward scatter, depolarized the mitochondrial potential, increased annexin binding, led to caspase activation and resulted in DNA fragmentation. Gene silencing of the Ca2+-permeable transient receptor potential cation channel TRPC7 significantly blunted PGE2-induced triggering of PS exposure and DNA fragmentation. In conclusion, K562 cells express Ca2+-permeable TRPC7 channels, which are activated by PGE2 and participate in the triggering of apoptosis. 相似文献
144.
145.
Daniela Niemeyer Thomas Zillinger Doreen Muth Florian Zielecki Gabor Horvath Tasnim Suliman Winfried Barchet Friedemann Weber Christian Drosten Marcel A. Müller 《Journal of virology》2013,87(22):12489-12495
Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe acute respiratory infection with as yet unclear epidemiology. We previously showed that MERS-CoV counteracts parts of the innate immune response in human bronchiolar cells. Here we analyzed accessory proteins 3, 4a, 4b, and 5 for their abilities to inhibit the type I interferon response. Accessory protein 4a was found to block interferon induction at the level of melanoma differentiation-associated protein 5 (MDA5) activation presumably by direct interaction with double-stranded RNA. 相似文献
146.
Lucia Vojtech Sangsoon Woo Sean Hughes Claire Levy Lamar Ballweber Renan P. Sauteraud Johanna Strobl Katharine Westerberg Raphael Gottardo Muneesh Tewari Florian Hladik 《Nucleic acids research》2014,42(11):7290-7304
Semen contains relatively ill-defined regulatory components that likely aid fertilization, but which could also interfere with defense against infection. Each ejaculate contains trillions of exosomes, membrane-enclosed subcellular microvesicles, which have immunosuppressive effects on cells important in the genital mucosa. Exosomes in general are believed to mediate inter-cellular communication, possibly by transferring small RNA molecules. We found that seminal exosome (SE) preparations contain a substantial amount of RNA from 20 to 100 nucleotides (nts) in length. We sequenced 20–40 and 40–100 nt fractions of SE RNA separately from six semen donors. We found various classes of small non-coding RNA, including microRNA (21.7% of the RNA in the 20–40 nt fraction) as well as abundant Y RNAs and tRNAs present in both fractions. Specific RNAs were consistently present in all donors. For example, 10 (of ∼2600 known) microRNAs constituted over 40% of mature microRNA in SE. Additionally, tRNA fragments were strongly enriched for 5’-ends of 18–19 or 30–34 nts in length; such tRNA fragments repress translation. Thus, SE could potentially deliver regulatory signals to the recipient mucosa via transfer of small RNA molecules. 相似文献
147.
Carina Hüwe Jennifer Schmeichel Florian Brodkorb Sophia Dohlen Katrin Kalbfleisch Martin Kreyenschmidt 《Biofouling》2018,34(4):378-387
Antimicrobial surfaces are one approach to prevent biofilms in the food industry. The aim of this study was to investigate the effect of poly((tert-butyl-amino)-methyl-styrene) (poly(TBAMS)) incorporated into linear low-density polyethylene (LLDPE) on the formation of mono- and mixed-species biofilms. The biofilm on untreated and treated LLDPE was determined after 48 and 168 h. The comparison of the results indicated that the ability of Listeria monocytogenes to form biofilms was completely suppressed by poly(TBAMS) (Δ168 h 3.2 log10 cfu cm?2) and colonization of Staphylococcus aureus and Escherichia coli was significantly delayed, but no effect on Pseudomonas fluorescens was observed. The results of dual-species biofilms showed complex interactions between the microorganisms, but comparable effects on the individual bacteria by poly(TBAMS) were identified. Antimicrobial treatment with poly(TBAMS) shows great potential to prevent biofilms on polymeric surfaces. However, a further development of the material is necessary to reduce the colonization of strong biofilm formers. 相似文献
148.
Leuschner F Dutta P Gorbatov R Novobrantseva TI Donahoe JS Courties G Lee KM Kim JI Markmann JF Marinelli B Panizzi P Lee WW Iwamoto Y Milstein S Epstein-Barash H Cantley W Wong J Cortez-Retamozo V Newton A Love K Libby P Pittet MJ Swirski FK Koteliansky V Langer R Weissleder R Anderson DG Nahrendorf M 《Nature biotechnology》2011,29(11):1005-1010
Excessive and prolonged activity of inflammatory monocytes is a hallmark of many diseases with an inflammatory component. In such conditions, precise targeting of these cells could be therapeutically beneficial while sparing many essential functions of the innate immune system, thus limiting unwanted effects. Inflammatory monocytes-but not the noninflammatory subset-depend on the chemokine receptor CCR2 for localization to injured tissue. Here we present an optimized lipid nanoparticle and a CCR2-silencing short interfering RNA that, when administered systemically in mice, show rapid blood clearance, accumulate in spleen and bone marrow, and localize to monocytes. Efficient degradation of CCR2 mRNA in monocytes prevents their accumulation in sites of inflammation. Specifically, the treatment attenuates their number in atherosclerotic plaques, reduces infarct size after coronary artery occlusion, prolongs normoglycemia in diabetic mice after pancreatic islet transplantation, and results in reduced tumor volumes and lower numbers of tumor-associated macrophages. 相似文献
149.
150.