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91.
Nicklas Bonander Tore Vnngrd Li-Chu Tsai Vratislav Langer Herbert Nar Lennart Sjlin 《Proteins》1997,27(3):385-394
The crystal structure of cobalt-substituted azurin from Pseudomonas aeruginosa has been determined to final crystallographic R value of 0.175 at 1.9 Å resolution. There are four molecules in the asymmetric unit in the structure, and these four molecules are packed as a dimer of dimers. The dimer packing is very similar to that of the wild-type Pseudomonas aeruginosa azurin dimer. Replacement of the native copper by the cobalt ion has only small effects on the metal binding site presumably because of the existence of an extensive network of hydrogen bonds in its immediate neighborhood. Some differences are obvious, however. In wild-type azurin the copper atom occupies a distorted trigonal bipyramidal site, while cobalt similar to zinc and nickel occupy a distorted tetrahedral site, in which the distance to the Met121,Sδ atom is increased to 3.3–3.5 Å and the distance to the carbonyl oxygen of Gly45 has decreased to 2.1–2.4 Å. The X-band EPR spectrum of the high-spin Co(II) in azurin is well resolved (apparent g values gx′ = 5.23; gy′ = 3.83; gz′ = 1.995, and hyperfine splittings Ax′ = 31; Ay′ = 20–30; Az′ = 53 G) and indicates that the ligand field is close to axial. Proteins 27:385–394, 1997. © 1997 Wiley-Liss, Inc. 相似文献
92.
Burger C Belskii E Eeva T Laaksonen T Mägi M Mänd R Qvarnström A Slagsvold T Veen T Visser ME Wiebe KL Wiley C Wright J Both C 《The Journal of animal ecology》2012,81(4):926-936
1.?Climate warming has led to shifts in the seasonal timing of species. These shifts can differ across trophic levels, and as a result, predator phenology can get out of synchrony with prey phenology. This can have major consequences for predators such as population declines owing to low reproductive success. However, such trophic interactions are likely to differ between habitats, resulting in differential susceptibility of populations to increases in spring temperatures. A mismatch between breeding phenology and food abundance might be mitigated by dietary changes, but few studies have investigated this phenomenon. Here, we present data on nestling diets of nine different populations of pied flycatchers Ficedula hypoleuca, across their breeding range. This species has been shown to adjust its breeding phenology to local climate change, but sometimes insufficiently relative to the phenology of their presumed major prey: Lepidoptera larvae. In spring, such larvae have a pronounced peak in oak habitats, but to a much lesser extent in coniferous and other deciduous habitats. 2.?We found strong seasonal declines in the proportions of caterpillars in the diet only for oak habitats, and not for the other forest types. The seasonal decline in oak habitats was most strongly observed in warmer years, indicating that potential mismatches were stronger in warmer years. However, in coniferous and other habitats, no such effect of spring temperature was found. 3.?Chicks reached somewhat higher weights in broods provided with higher proportions of caterpillars, supporting the notion that caterpillars are an important food source and that the temporal match with the caterpillar peak may represent an important component of reproductive success. 4.?We suggest that pied flycatchers breeding in oak habitats have greater need to adjust timing of breeding to rising spring temperatures, because of the strong seasonality in their food. Such between-habitat differences can have important consequences for population dynamics and should be taken into account in studies on phenotypic plasticity and adaptation to climate change. 相似文献
93.
Pathways followed by ricin and Shiga toxin into cells 总被引:16,自引:5,他引:16
Sandvig K Grimmer S Lauvrak SU Torgersen ML Skretting G van Deurs B Iversen TG 《Histochemistry and cell biology》2002,117(2):131-141
The plant toxin ricin and the bacterial toxin Shiga toxin belong to a group of protein toxins that inhibit protein synthesis in cells enzymatically after entry into the cytosol. Ricin and Shiga toxin, which both have an enzymatically active moiety that inactivates ribosomes and a moiety that binds to cell surface receptors, enter the cytosol after binding to the cell surface, endocytosis by different mechanisms, and retrograde transport to the Golgi apparatus and the endoplasmic reticulum (ER). The toxins can be used to investigate the various transport steps involved, both the endocytic mechanisms as well as pathways for retrograde transport to the ER. Recent studies show that not only do several endocytic mechanisms exist in the same cell, but they are not equally sensitive to removal of cholesterol. New data have revealed that there is also more than one pathway leading from endosomes to the Golgi apparatus and retrogradely from the Golgi to the ER. Trafficking of protein toxins along these pathways will be discussed in the present article. 相似文献
94.
Jacques Simard Dominique Bérubé Märten Sandberg Karl-Heinz Grzeschik Richard Gagné Vidar Hansson Tore Jahnsen 《Human genetics》1992,88(6):653-657
Summary A cDNA for the human catalytic subunit (C) of cAMP-dependent protein kinase (PKA) has been cloned from a testis cDNA library. In the present study, we have determined the chromosomal localization of this gene using a cDNA for C as a probe. Southern blot analysis of genomic DNA from human/mouse cell hybrids revealed that the presence or absence of a 20-kbXbaI fragment, which hybridized with the C probe, was concordant with the presence of human chromosome 1.In situ hybridization to metaphase chromosome confirmed the somatic cell hybrid data and regionally mapped the C gene of PKA to the p36 band on chromosome 1. 相似文献
95.
96.
Catching the WAVEs of Plant Actin Regulation 总被引:3,自引:0,他引:3
Plants, as all other eukaryotic organisms, depend on a dynamic actin cytoskeleton for proper function and development. Actin
dynamics is a complex process, regulated by a number of actin-binding proteins and large multiprotein complexes like ARP2/3
and WAVE. The ARP2/3 complex is recognized as a nucleator of actin filaments, and it generates a highly branched network of
interlaced microfilaments. Results from multiple organisms show that ARP2/3 activity is regulated through multiple pathways.
Recent results from plants point to a signaling pathway leading from the small GTPase RAC/ROP through a protein complex containing
the ARP2/3-activating protein WAVE. This signaling pathway appears to be evolutionarily conserved. Support for this regulatory
mechanism comes from studies of mutations in genes encoding subunits of the putative ARP2/3 complex and the WAVE complex in
Arabidopsis. Several such mutants have defects of actin filament organization, leading to a conspicuous “distorted” trichome phenotype.
Multiple growth and developmental phenotypes reported for napp/gnarled/atnap, pirp/pirogi/atpir, and distorted3 mutants reveal that these WAVE proteins are also required for a wider variety of cellular functions in addition to regulating
trichome cell growth. These results have implications for the current view on cell morphogenesis in plants. 相似文献
97.
Dana M. Bergstrom Arko Lucieer Kate Kiefer Jane Wasley Lee Belbin Tore K. Pedersen Steven L. Chown 《Journal of Applied Ecology》2009,46(5):1133-1136
1. The management of non-indigenous species is not without its complications. In Bergstrom et al. 's (2009) study, we demonstrated that feral cats Felis catus on sub-Antarctic Macquarie Island were exerting top-down control on the feral rabbit Oryctolagus cuniculus population, and that the eradication of the cats led to a substantial increase in rabbit numbers and an associated trophic cascade.
2. Dowding et al. (2009) claim our modelling was flawed for various reasons, but primarily that a reduction in the application of the rabbit control agent, Myxoma virus, coinciding with cat removal, was a major driver of rabbit population release.
3. We explore this proposition (as well as others) by examining rates of Myxoma viral release between 1991 and 2006 (with an attenuation factor for the years, 2003–2006) in association with presence/absence of cats against two estimates of rabbit population size. Myxoma viral release was a significant factor in the lower estimates of rabbit population, but the effect was small, and was not significant for higher rabbit population estimates. By contrast, the presence or absence of cats remained highly significant for both estimates.
4. Synthesis and applications. We re-affirm our position that top-down control of rabbit numbers by cats, prior to their eradication, was occurring on Macquarie Island. Nonetheless, we agree with Dowding et al. (2009) that systems with multiple invasive species represent complex situations that require careful scrutiny. Such scrutiny should occur in advance of, during, and following management interventions. 相似文献
2. Dowding et al. (2009) claim our modelling was flawed for various reasons, but primarily that a reduction in the application of the rabbit control agent, Myxoma virus, coinciding with cat removal, was a major driver of rabbit population release.
3. We explore this proposition (as well as others) by examining rates of Myxoma viral release between 1991 and 2006 (with an attenuation factor for the years, 2003–2006) in association with presence/absence of cats against two estimates of rabbit population size. Myxoma viral release was a significant factor in the lower estimates of rabbit population, but the effect was small, and was not significant for higher rabbit population estimates. By contrast, the presence or absence of cats remained highly significant for both estimates.
4. Synthesis and applications. We re-affirm our position that top-down control of rabbit numbers by cats, prior to their eradication, was occurring on Macquarie Island. Nonetheless, we agree with Dowding et al. (2009) that systems with multiple invasive species represent complex situations that require careful scrutiny. Such scrutiny should occur in advance of, during, and following management interventions. 相似文献
98.
Alexander Plotkin Oliver Voigt Endre Willassen Hans Tore Rapp 《Organisms Diversity & Evolution》2017,17(1):45-66
Polymastiidae Gray, 1867 is a worldwide distributed sponge family, which has a great significance for understanding of the demosponge deep phylogeny since the former order Hadromerida Topsent, 1894 has been recently split based on the molecular evidence and a new separate order has been established for the polymastiids. However, molecular data obtained from Polymastiidae so far are scarce, while the phylogenetic reconstruction based on morphology has faced a deficit of characters along with the vagueness of their states. The present study is a phylogenetic reconstruction of Polymastiidae based on novel data on two molecular markers, cytochrome oxidase subunit I and large subunit ribosomal DNA, obtained from a broad set of species. Monophyly of the family and nonmonophyly of four polymastiid genera are revealed, suggesting a high level of homoplasy of morphological characters, which are therefore not an appropriate base for the natural classification of Polymastiidae. Although the presented phylogenies cannot yet provide an alternative classification scheme, several strongly supported clades, which may be used as reference points in future classification, are recovered and three taxonomic actions are proposed: transfer of one species from Radiella to Polymastia Bowerbank, 1862; transfer of three species from Radiella Schmidt, 1870 to Spinularia Gray, 1867; and the consequent abandonment of Radiella. 相似文献
99.
100.
Rachel Knevel Diederik PC de Rooy Tore Saxne Elisabet Lindqvist Martha K Leijsma Nina A Daha Bobby PC Koeleman Roula Tsonaka Jeanine J Houwing-Duistermaat Joris JM Schonkeren Rene EM Toes Tom WJ Huizinga Elisabeth Brouwer Anthony G Wilson Annette HM van der Helm-van Mil 《Arthritis research & therapy》2014,16(3):R108