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991.
Human hemoglobin (Hb) is a metalloprotein used by pathogens as a source of iron during invasive process. It can support the
Helicobacter pylori growth and several proteins are induced during iron starvation. However, the identity of those proteins remains unknown.
In this work, by in silico analysis we identified FrpB2 in H. pylori genome. This protein was annotated as an iron-regulated outer membrane protein. Multiple amino acid alignment showed the
motifs necessary for Hb-binding. We demonstrate the ability of FrpB2 to bind Hb by overlay experiments. In addition, the overexpression
of this gene allowed the cell growth in media without free iron but supplemented with Hb. All these results support the idea
that frpB2 is a gene of H. pylori involved in iron acquisition when Hb is used as a sole iron source. 相似文献
992.
The present study applied the comet assay to erythrocytes of Oreochromis niloticus with the aim of improving protocols to detect DNA damage in these cells, by using two distinct pHs (pH = 12.1 and pH > 13) and evaluating whether there is a correspondence between silver and ethidium bromide staining. Comets were visually examined and, the frequency of cells with and without damage was obtained, as well as the distribution of classes and scores. By using the Kruskal-Wallis test, our results revealed that pH 12.1 is more effective, although both pHs can be used. Our findings also suggest that silver staining can substitute ethidium bromide, an expensive and highly toxic stain that requires specific equipment for examination. 相似文献
993.
Elke Rabbow Gerda Horneck Petra Rettberg Jobst-Ulrich Schott Corinna Panitz Andrea L’Afflitto Ralf von Heise-Rotenburg Reiner Willnecker Pietro Baglioni Jason Hatton Jan Dettmann René Demets Günther Reitz 《Origins of life and evolution of the biosphere》2009,39(6):581-598
Following an European Space Agency announcement of opportunity in 1996 for ”Externally mounted payloads for 1st utilization phase” on the International Space Station (ISS), scientists working in the fields of astrobiology proposed experiments aiming at long-term exposure of a variety of chemical compounds and extremely resistant microorganisms to the hostile space environment. The ESA exposure facility EXPOSE was built and an operations´ concept was prepared. The EXPOSE experiments were developed through an intensive pre-flight experiment verification test program. 12 years later, two sets of astrobiological experiments in two EXPOSE facilities have been successfully launched to the ISS for external exposure for up to 1.5 years. EXPOSE-E, now installed at the balcony of the European Columbus module, was launched in February 2008, while EXPOSE-R took off to the ISS in November 2008 and was installed on the external URM-D platform of the Russian Zvezda module in March 2009. 相似文献
994.
Dordio AV Duarte C Barreiros M Carvalho AJ Pinto AP da Costa CT 《Bioresource technology》2009,100(3):1156-1161
A study was conducted to assess Typha spp.'s ability to withstand and remove, from water, a metabolite of blood lipid regulator drugs, clofibric acid (CA). At a concentration of 20 microg L(-1), Typha had removed >50% of CA within the first 48h, reaching a maximum of 80% by the end of the assay. Experimental conditions assured that photodegradation, adsorption to vessel walls and microbial degradation did not contribute to the removal. Exposure to higher CA concentrations did not affect Typha's photosynthetic pigments but the overall increase in enzyme activity (ascorbate and guaiacol peroxidases, catalase, superoxide dismutase) indicates that both roots and leaves were affected by the xenobiotic. Eventually, Typha seemed able to cope with the CA's induced oxidative damage suggesting its ability for phytoremediation of CA contaminated waters. 相似文献
995.
Westerhoff HV Kolodkin A Conradie R Wilkinson SJ Bruggeman FJ Krab K van Schuppen JH Hardin H Bakker BM Moné MJ Rybakova KN Eijken M van Leeuwen HJ Snoep JL 《Journal of mathematical biology》2009,58(1-2):7-34
Systems Biology is the science that aims to understand how biological function absent from macromolecules in isolation, arises when they are components of their system. Dedicated to the memory of Reinhart Heinrich, this paper discusses the origin and evolution of the new part of systems biology that relates to metabolic and signal-transduction pathways and extends mathematical biology so as to address postgenomic experimental reality. Various approaches to modeling the dynamics generated by metabolic and signal-transduction pathways are compared. The silicon cell approach aims to describe the intracellular network of interest precisely, by numerically integrating the precise rate equations that characterize the ways macromolecules’ interact with each other. The non-equilibrium thermodynamic or ‘lin–log’ approach approximates the enzyme rate equations in terms of linear functions of the logarithms of the concentrations. Biochemical Systems Analysis approximates in terms of power laws. Importantly all these approaches link system behavior to molecular interaction properties. The latter two do this less precisely but enable analytical solutions. By limiting the questions asked, to optimal flux patterns, or to control of fluxes and concentrations around the (patho)physiological state, Flux Balance Analysis and Metabolic/Hierarchical Control Analysis again enable analytical solutions. Both the silicon cell approach and Metabolic/Hierarchical Control Analysis are able to highlight where and how system function derives from molecular interactions. The latter approach has also discovered a set of fundamental principles underlying the control of biological systems. The new law that relates concentration control to control by time is illustrated for an important signal transduction pathway, i.e. nuclear hormone receptor signaling such as relevant to bone formation. It is envisaged that there is much more Mathematical Biology to be discovered in the area between molecules and Life. 相似文献
996.
Luciana Albuquerque Catarina Ferreira David Tomaz Igor Tiago António Veríssimo Milton S. da Costa M. Fernanda Nobre 《Systematic and applied microbiology》2009
Four red-pigmented isolates, with optimum growth temperatures of approximately 55–60 °C and an optimum pH for growth between 7.5 and 8.5, were recovered from hot springs in Central France. Phylogenetic analysis of the 16S rRNA gene sequences showed that these organisms represented a new species of the genus Meiothermus. The new isolates could be distinguished from other strains of the species of the genus Meiothermus primarily by the glycolipid profile and fatty acid composition because these organisms lacked the hydroxy fatty acids and the glycolipid variant GL-1a found in all other isolates of the species of Meiothermus examined. On the basis of the results presented here we propose the name Meiothermus rufus for the new species, which is represented by strains CAL-4T (=DSM 22234T=LMG 24878T) and CAL-12 (=DSM 22235=LMG 24879). We also propose emending the genus Meiothermus to include strains that have only one glycolipid instead of two glycolipid variants. 相似文献
997.
Amanda Ferreira da Silva Mendes Luciana Cardoso Cidade Maria Luiza Peixoto de Oliveira Wagner Campos Otoni Walter Dos Santos Soares-Filho Marcio Gilberto Cardoso Costa 《Plant Cell, Tissue and Organ Culture》2009,97(3):331-336
Identification of beta-lactam antibiotics that have negligible effects on plant regeneration is a critical step towards the
establishment of a reliable Agrobacterium-mediated transformation protocol for perennial trees. In the present report, we have evaluated the effects of the novel beta-lactam
antibiotics meropenem and timentin on plant regeneration of a perennial woody fruit plant, Citrus sinensis, in comparison with the commonly used beta-lactam cefotaxime. It was observed that, in contrast to cefotaxime, meropenem
and timentin had a positive or no detrimental effect on the shoot regeneration from epicotyl explants. Residual effects of
the beta-lactams from shoot regeneration medium also affected the subsequent ability of the roots to elongate. The addition
of meropenem and/or timentin in the rooting medium mostly improved or did not affect the rooting ability of the adventitious
shoots. These data indicated that meropenem and timentin can positively replace cefotaxime in Agrobacterium-mediated transformation of C. sinensis. 相似文献
998.
María Prez-Caro Csar Cobaleda Ins Gonzlez-Herrero Carolina Vicente-Dueas Camino Bermejo-Rodríguez Margarita Snchez-Beato Alberto Orfao Beln Pintado Teresa Flores Manuel Snchez-Martín Rafael Jimnez Miguel A Piris Isidro Snchez-García 《The EMBO journal》2009,28(1):8-20
In human cancers, all cancerous cells carry the oncogenic genetic lesions. However, to elucidate whether cancer is a stem cell-driven tissue, we have developed a strategy to limit oncogene expression to the stem cell compartment in a transgenic mouse setting. Here, we focus on the effects of the BCR-ABLp210 oncogene, associated with chronic myeloid leukaemia (CML) in humans. We show that CML phenotype and biology can be established in mice by restricting BCR-ABLp210 expression to stem cell antigen 1 (Sca1)+ cells. The course of the disease in Sca1-BCR-ABLp210 mice was not modified on STI571 treatment. However, BCR-ABLp210-induced CML is reversible through the unique elimination of the cancer stem cells (CSCs). Overall, our data show that oncogene expression in Sca1+ cells is all that is required to fully reprogramme it, giving rise to a full-blown, oncogene-specified tumour with all its mature cellular diversity, and that elimination of the CSCs is enough to eradicate the whole tumour. 相似文献
999.
Taras Y. Nechitaylo Michail M. Yakimov Miguel Godinho Kenneth N. Timmis Elena Belogolova Boris A. Byzov Alexander V. Kurakov David L. Jones Peter N. Golyshin 《Microbial ecology》2010,59(3):574-587
Earthworms ingest large amounts of soil and have the potential to radically alter the biomass, activity, and structure of
the soil microbial community. In this study, the diversity of eight bacterial groups from fresh soil, gut, and casts of the
earthworms Lumbricus terrestris and Aporrectodea caliginosa were studied by single-strand conformation polymorphism (SSCP) analysis using both newly designed 16S rRNA gene-specific
primer sets targeting Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Bacteroidetes, Verrucomicrobia,
Planctomycetes, and Firmicutes and a conventional universal primer set for SSCP, with RNA and DNA as templates. In parallel,
the study of the relative abundance of these taxonomic groups in the same samples was performed using fluorescence in situ
hybridization. Bacteroidetes, Alphaproteobacteria, and Betaproteobacteria were predominant in communities from the soil and
worm cast samples. Representatives of classes Flavobacteria and Sphingobacteria (Bacteroidetes) and Pseudomonas spp. (low-abundant Gammaproteobacteria) were detected in soil and worm cast samples with conventional and taxon-targeting
SSCP and through the sequence analysis of 16S rRNA clone libraries. Physiologically active unclassified Sphingomonadaceae
(Alphaproteobacteria) and Alcaligenes spp. (Betaproteobacteria) also maintained their diversities during transit through the earthworm intestine and were found
on taxon-targeting SSCP profiles from the soil and worm cast samples. In conclusion, our results suggest that some specific
bacterial taxonomic groups maintain their diversity and even increase their relative numbers during transit through the gastrointestinal
tract of earthworms. 相似文献
1000.
Two new manganese(II) complexes, [Mn(L1)(L1H)(ClO4)(H2O)][ClO4]2·0.5CH3CN·H2O (1) [L1 = trans-(±)2-(2,5-di(pyridin-2-yl)-4,5-dihydro-1H-imidazol-4-yl)pyridine)] and [Mn2(μ-L2)2(H2O)3(CH3CN)3][ClO4]4·2CH3CN (2) [L2 = cis-(±)2-(2,5-di(pyridin-2-yl)-4,5-dihydro-1H-imidazol-4-yl)pyridine)], have been prepared and examined by single-crystal X-ray diffraction analysis, showing that complex 1 is a mononuclear compound, whereas complex 2 is a dinuclear species. The cis/trans isomers L1 and L2 have similar coordination properties, but behave as bidentate and tridentate chelating ligands, respectively, giving distorted octahedral metal coordination geometries. X-ray diffraction studies revealed that the molecular and crystal structures are stabilized by a series of intra- and intermolecular interactions. In both cases extended supramolecular networks are generated, in compound 1 through O-H···O, O-H···N, N-H···O, N-H···N, C-H···O, C-H···N, C-H···π and π···π interactions, and in compound 2 through O-H···O, O-H···N, C-H···O and π···π interactions. The observed structural differences between the two metal complexes might be a consequence of these stabilizing effects. 相似文献