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991.
El-Hawiet A Kitova EN Kitov PI Eugenio L Ng KK Mulvey GL Dingle TC Szpacenko A Armstrong GD Klassen JS 《Glycobiology》2011,21(9):1217-1227
The binding of recombinant fragments of the C-terminal cell-binding domains of the two large exotoxins, toxin A (TcdA) and toxin B (TcdB), expressed by Clostridium difficile and a library consisting of the most abundant neutral and acidic human milk oligosaccharides (HMOs) was examined quantitatively at 25°C and pH 7 using the direct electrospray ionization mass spectrometry (ES-MS) assay. The results of the ES-MS measurements indicate that both toxin fragments investigated, TcdB-B1 and TcdA-A2, which possess one and two carbohydrate binding sites, respectively, bind specifically to HMOs ranging in size from tri- to heptasaccharides. Notably, five of the HMOs tested bind to both toxins: Fuc(α1-2)Gal(β1-4)Glc, Gal(β1-3)GlcNAc(β1-3)Gal(β1-4)Glc, Fuc(α1-2)Gal(β1-3)GlcNAc(β1-3)Gal(β1-4)Glc, Gal(β1-3)[Fuc(α1-4)]GlcNAc(β1-3)Gal(β1-4)Glc and Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-3)Gal(β1-4)Glc. However, the binding of the HMOs is uniformly weak, with apparent affinities ≤10(3?)M(-1). The results of molecular docking simulations, taken together with the experimental binding data, suggest that a disaccharide moiety (lactose or lactosamine) represents the core HMO recognition element for both toxin fragments. The results of a Verocytotoxicity neutralization assay reveal that HMOs do not significantly inhibit the cytotoxic effects of TcdA or TcdB. The absence of protection is attributed to the very weak intrinsic affinities that the toxins exhibit towards the HMOs. 相似文献
992.
Ji?í Reif Pavel Marhoul Old?ich ?í?ek Martin Konvi?ka 《Biodiversity and Conservation》2011,20(14):3645-3662
The European landscape is under pervasive attack of massive land use changes, such as agricultural intensification, urbanization
and land abandonment. These changes resulted in population decline of birds living in open habitats. Despite a good understanding
on the effects of these driving forces on bird populations, effective conservation actions are difficult to conduct as these
forces are closely connected with socioeconomic development of particular countries and thus almost impossible to reverse.
It is hence necessary to conserve refuge sites with a limited influence of these negative factors. We surveyed birds in 42
abandoned military training sites (AMTS) in a central European country, the Czech Republic, and we have found these sites
are valuable, and to date overlooked, refuges for bird conservation. Birds of high conservation concern and open habitats
birds (such as Miliaria calandra, Saxicola torquata or Lullula arborea) were more abundant in AMTS than predicted by their total population size in the Czech Republic. The most important characteristics
predicting attractiveness of AMTS for birds of conservation concern were low altitude, low proportion of forest/dense scrubland,
high proportion of sparse scrubland/bare ground and large area. Former military activity was beneficial for declining open
habitat birds by maintaining moderate disturbance levels, which are rarely found elsewhere in current landscapes. Owing to
reduction of armed forces across Europe AMTS provide continental-wide network of high-quality sites for bird conservation.
Nevertheless, AMTS are subject to pressure from building activities or loss of openness due to overgrowth of forest or scrub
plant communities. 相似文献
993.
Dong LF Jameson VJ Tilly D Prochazka L Rohlena J Valis K Truksa J Zobalova R Mahdavian E Kluckova K Stantic M Stursa J Freeman R Witting PK Norberg E Goodwin J Salvatore BA Novotna J Turanek J Ledvina M Hozak P Zhivotovsky B Coster MJ Ralph SJ Smith RA Neuzil J 《Free radical biology & medicine》2011,50(11):1546-1555
994.
Dorr CR Yemets S Kolomitsyna O Krasutsky P Mansky LM 《Bioorganic & medicinal chemistry letters》2011,21(1):542-545
Triterpene derivatives were analyzed for anti-HIV-1 activity and for cellular toxicity. Betulinic aldehyde, betulinic nitrile, and morolic acid derivatives were identified to have anti-HIV-1 activity. These derivatives inhibit a late step in virus replication, likely virus maturation. 相似文献
995.
Franta Z Sojka D Frantova H Dvorak J Horn M Srba J Talacko P Mares M Schneider E Craik CS McKerrow JH Caffrey CR Kopacek P 《International journal for parasitology》2011,41(12):1253-1262
Intracellular proteolysis of ingested blood proteins is a crucial physiological process in ticks. In our model tick, Ixodes ricinus, cathepsin L (IrCL1) is part of a gut-associated multi-peptidase complex; its endopeptidase activity is important in the initial phase of haemoglobinolysis. We present the functional and biochemical characterisation of this enzyme. We show, by RNA interference (RNAi), that cathepsin L-like activity that peaks during the slow feeding period of females is associated with IrCL1. Recombinant IrCL1 was expressed in bacteria and yeast. Activity profiling with both peptidyl and physiological protein substrates (haemoglobin and albumin) revealed that IrCL1 is an acidic peptidase with a very low optimum pH (3-4) being unstable above pH 5. This suggests an endo/lysosomal localisation that was confirmed by indirect fluorescence microscopy that immunolocalised IrCL1 inside the vesicles of digestive gut cells. Cleavage specificity determined by a positional scanning synthetic combinatorial library and inhibition profile indicated that IrCL1 has the ligand-binding characteristics of the cathepsin L subfamily of cysteine peptidases. A non-redundant proteolytic function was demonstrated when IrCL1-silenced ticks had a decreased ability to feed compared with controls. The data suggest that IrCL1 may be a promising target against ticks and tick-borne pathogens. 相似文献
996.
Ji?í?NeustupaEmail author Jan??t’astny Katarína?Nemjová Petra?Mazalová Emma?Goodyer Aloisie?Poulí?ková Pavel??kaloud 《Hydrobiologia》2011,667(1):223-239
Morphological species of freshwater microalgae often have broad geographic distribution. However, traditional species concepts
have been challenged by the results of molecular phylogenetic analyses that mostly indicate higher diversity than was previously
recognized by purely morphological approaches. A degree of phenotypic differentiation or different geographic distribution
of species defined by molecular data remains largely unknown. In this study, we analyzed a pair of well-known and widely distributed
desmid species (Micrasterias fimbriata and M. rotata) and tested for their phylogenetic and morphological homogeneity as well as their geographic distribution. Geometric morphometric
and morphological attributes of cells were used in combination with genetic analysis of the trnG
ucc
sequences of 30 strains isolated from a variety of European locations and obtained from culture collections. Micrasterias rotata proved to be phylogenetically homogenous across Europe while M. fimbriata turned out to be composed of two firmly delimited lineages, differing by molecular as well as by morphometric and morphological
data. Published records of traditional M. fimbriata were also included in the classification discrimination analysis and were placed into the newly identified lineages upon
comparison to the morphometric data collected from living material. Largely disparate geographic patterns were revealed within
traditional M. fimbriata. One phylogenetic lineage is frequent in central and eastern Europe, but occurs also in the British Isles. A second lineage
has been recorded in North America and in Western Europe, where its distribution is possibly limited to the west of the Rhine
River. Interestingly, the morphometric analyses of the published records illustrated that the geographic differences have
remained largely unchanged since the 1850s indicating a previously unknown distributional stability among microalgal species
groups such as the desmids. 相似文献
997.
Hájková Z Bugajev V Dráberová E Vinopal S Dráberová L Janáček J Dráber P Dráber P 《Journal of immunology (Baltimore, Md. : 1950)》2011,186(2):913-923
Activation of mast cells by aggregation of the high-affinity IgE receptors (FcεRI) initiates signaling events leading to the release of inflammatory and allergic mediators stored in cytoplasmic granules. A key role in this process play changes in concentrations of intracellular Ca(2+) controlled by store-operated Ca(2+) entry (SOCE). Although microtubules are also involved in the process leading to degranulation, the molecular mechanisms that control microtubule rearrangement during activation are largely unknown. In this study, we report that activation of bone marrow-derived mast cells (BMMCs) induced by FcεRI aggregation or treatment with pervanadate or thapsigargin results in generation of protrusions containing microtubules (microtubule protrusions). Formation of these protrusions depended on the influx of extracellular Ca(2+). Changes in cytosolic Ca(2+)concentration also affected microtubule plus-end dynamics detected by microtubule plus-end tracking protein EB1. Experiments with knockdown or reexpression of STIM1, the key regulator of SOCE, confirmed the important role of STIM1 in the formation of microtubule protrusions. Although STIM1 in activated cells formed puncta associated with microtubules in protrusions, relocation of STIM1 to a close proximity of cell membrane was independent of growing microtubules. In accordance with the inhibition of Ag-induced Ca(2+) response and decreased formation of microtubule protrusions in BMMCs with reduced STIM1, the cells also exhibited impaired chemotactic response to Ag. We propose that rearrangement of microtubules in activated mast cells depends on STIM1-induced SOCE, and that Ca(2+) plays an important role in the formation of microtubule protrusions in BMMCs. 相似文献
998.
999.
The diversity of eukaryotic microorganisms is far from fully described, as indicated by the vast number of unassigned genotypes retrieved by environmental sequencing or metagenomics. We isolated several strains of unicellular green algae from algal biofilms growing on tree bark in a Southeast Asian tropical rainforest and determined them to be relatives of an unidentified lineage of environmental 18S rDNA sequences, thus uncovering its cellular identity. Light, confocal, and electron microscope observations and sequencing the 18S rRNA gene revealed that the strains represent two different species within an apparently new genus, described here as Jenufa gen. nov. Both species formed minute coccoid cells with an irregular globular outline, a smooth cell wall, and a single parietal chloroplast without a pyrenoid. The two species, described herein as J. perforata and J. minuta, differed in chloroplast morphology and cell wall structure. Phylogenetic analyses of 18S rRNA gene sequences showed a firm relationship between the two species and placed the Jenufa lineage in an unresolved position within the CS clade (Chlamydomonadales + Sphaeropleales) of the class Chlorophyceae, although possible affinities to the genus Golenkinia were suggested both by maximum‐likelihood (ML) and Bayesian methods. Furthermore, two almost identical environmental 18S rDNA sequences from an endolithic microbial community occurring in dolomite rock in the central Alps turned out to be specifically related to, yet apparently distinct from, the sequence of J. minuta, indicating the existence of an undescribed Jenufa species occurring in the temperate zone. 相似文献
1000.
Pavel Hrouzek Tomáš Řezanka Jitka Jezberová Klára Řeháková Daniel Hisem Jaroslava Komárková 《Journal of phycology》2011,47(5):1152-1163
The genera Dolichospermum (Ralfs ex Bornet et Flahault) Wacklin, L. Hoffm. et Komárek and Sphaerospermopsis Zapomělová, Jezberová, Hrouzek, Hisem, K. ?eháková et Komárk.‐Legn. represent a highly diversified group of planktonic cyanobacteria that have been recently separated from the traditional genus Anabaena Bory ex Bornet et Flahault. In this study, morphological diversity, phylogeny of the 16S rRNA gene, production of fatty acids, and secondary metabolite profiles were evaluated in 33 strains of 14 morphospecies isolated from the Czech Republic. Clustering of the strains based on 16S rRNA gene sequences corresponded to wider groups of species in terms of morphology. The overall secondary metabolite and fatty acid profiles, however, were not correlated to each other and neither were they correlated to the 16S rRNA phylogeny nor the morphology of the strains. Nevertheless, a minor part of the detected secondary metabolites (19% of all compounds) was present only in close relatives and can be thus considered as autapomorphic features. 相似文献