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101.
Dealing with uncertainty in landscape genetic resistance models: a case of three co‐occurring marsupials
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Rachael Y. Dudaniec Jessica Worthington Wilmer Jeffrey O. Hanson Matthew Warren Sarah Bell Jonathan R. Rhodes 《Molecular ecology》2016,25(2):470-486
Landscape genetics lacks explicit methods for dealing with the uncertainty in landscape resistance estimation, which is particularly problematic when sample sizes of individuals are small. Unless uncertainty can be quantified, valuable but small data sets may be rendered unusable for conservation purposes. We offer a method to quantify uncertainty in landscape resistance estimates using multimodel inference as an improvement over single model‐based inference. We illustrate the approach empirically using co‐occurring, woodland‐preferring Australian marsupials within a common study area: two arboreal gliders (Petaurus breviceps, and Petaurus norfolcensis) and one ground‐dwelling antechinus (Antechinus flavipes). First, we use maximum‐likelihood and a bootstrap procedure to identify the best‐supported isolation‐by‐resistance model out of 56 models defined by linear and non‐linear resistance functions. We then quantify uncertainty in resistance estimates by examining parameter selection probabilities from the bootstrapped data. The selection probabilities provide estimates of uncertainty in the parameters that drive the relationships between landscape features and resistance. We then validate our method for quantifying uncertainty using simulated genetic and landscape data showing that for most parameter combinations it provides sensible estimates of uncertainty. We conclude that small data sets can be informative in landscape genetic analyses provided uncertainty can be explicitly quantified. Being explicit about uncertainty in landscape genetic models will make results more interpretable and useful for conservation decision‐making, where dealing with uncertainty is critical. 相似文献
102.
Zhernakova A Stahl EA Trynka G Raychaudhuri S Festen EA Franke L Westra HJ Fehrmann RS Kurreeman FA Thomson B Gupta N Romanos J McManus R Ryan AW Turner G Brouwer E Posthumus MD Remmers EF Tucci F Toes R Grandone E Mazzilli MC Rybak A Cukrowska B Coenen MJ Radstake TR van Riel PL Li Y de Bakker PI Gregersen PK Worthington J Siminovitch KA Klareskog L Huizinga TW Wijmenga C Plenge RM 《PLoS genetics》2011,7(2):e1002004
103.
Horizontal transmission, vertical inactivation, and stochastic loss of mariner-like transposable elements 总被引:13,自引:5,他引:8
Horizontal transmission has been well documented as a major mechanism for
the dissemination of mariner-like elements (MLEs) among species. Less well
understood are mechanisms that limit vertical transmission of MLEs
resulting in the "spotty" or discontinuous distribution observed in closely
related species. In this article we present evidence that the genome of the
common ancestor of the melanogaster species subgroup of Drosophila
contained an MLE related to the mellifera (honey bee) subfamily. Horizontal
transmission, approximately 3-10 MYA, is strongly suggested by the
observation that the sequence of the MLE in Drosophila erecta is 97%
identical in nucleotide sequence with that of an MLE in the cat flea,
Ctenocephalides felis. The D. erecta MLE has a spotty distribution among
species in the melanogaster subgroup. The element has a high copy number in
D. erecta and D. orena, a moderate copy number in D. teissieri and D.
yakuba, and was apparently lost ("stochastic loss") in the lineage leading
to D. melanogaster, D. simulans, D. mauritiana, and D. sechellia. In D.
erecta, most copies are concentrated in the heterochromatin. Two copies
from D. erecta, denoted De12 and De19, were cloned and sequenced, and they
appear to be nonfunctional ("vertical inactivation"). It therefore appears
that the predominant mode of MLE evolution is vertical inactivation and
stochastic loss balanced against occasional reinvasion of lineages by
horizontal transmission.
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104.
Synchrotron x-ray diffraction studies of the cornea, with implications for stromal hydration. 总被引:5,自引:3,他引:2
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K M Meek N J Fullwood P H Cooke G F Elliott D M Maurice A J Quantock R S Wall C R Worthington 《Biophysical journal》1991,60(2):467-474
The intermolecular and interfibrillar spacings of collagen in bovine corneal stroma have been measured as a function of tissue hydration. Data were recorded from low- and high-angle x-ray diffraction patterns obtained using a high intensity synchrotron source. The most frequently occurring interfibrillar spacing varied from 34 nm in dry corneas to 76 nm at H = 5 (the hydration, H, is defined as the ratio of the weight of water to the dry weight). The most frequently occurring intermolecular Bragg spacing increased from 1.15 nm (dry) to approximately 1.60 nm at normal hydration (H approximately 3.2) and continued to increase only slowly above normal hydration. Most of the increase in the intermolecular spacing occurred between H = O and H = 1. Over this hydration range the interfibrillar and intermolecular spacings moved in tandem, which suggests that the initial water goes equally within and between the fibrils. Above H = 1 water goes preferentially between the fibrils. The results suggest that, even at normal hydration, water does not fill the interfibrillar space uniformly, and a proportion is located in another space or compartment. In dried-then-rehydrated corneas, a larger proportion of the water goes into this other compartment. In both cases, it is possible to postulate a second set or population of fibrils that are more widely and irregularly separated and therefore do not contribute significantly to the diffraction pattern. 相似文献
105.
106.
Hydroxyurea (10 mM) blocks the exponential growth of populations of Tetrahymena pyriformis (GL-I) by arresting progress through the cell cycle once the cells enter S phase. Fluoromicroscopic examination of euchrysine-stained exponential growth phase cells exposed to HU for a minimum of 90 min show a radical morphological change in the macronucleus. This phenomenon, termed the ‘halo-effect’, is characterized by the formation of apparently membrane-associated aggregates surrounding a constricted chromatin mass. Electron microscopic examination reveals a condensation of chromatin granules away from the surrounding network of membrane-associated nucleoli. Halo-induction by HU is S phase specific. Upon removal of the HU block, the halo remains until the first recovery division. The physiological significance of the halo effect is discussed. 相似文献
107.
Concentrations of histamine in brain of guinea pig and rat during dietary protein malnutration (Short Communication)
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Protein malnutrition produced marked elevations in brain contents of histamine in guinea pigs (+142%) and rats (+257%) in comparison with findings in the control adequately fed animals. Associated with accumulation of this biogenic amine in each set of animals was an increase of similar magnitude in brain content of free histidine. It was concluded that the elevated brain content of histamine in protein malnutrition was due mainly to increased availability of the precursor amino acid, and that such alterations in amounts of neurotransmitter amines in the central nervous system might underlie some of the behavioural abnormalities seen in malnourished animals. 相似文献
108.
D B Knaff T M Worthington C C White R Malkin 《Archives of biochemistry and biophysics》1979,192(1):158-163
Three membrane-bound cytochromes from the photosynthetic purple sulfur bacterium Chromatium vinosum have been partially separated from other membrane components by treatment with deoxycholate followed by ammonium sulfate fractionation and chromatography on Bio-Gel A1.5. Cytochrome c555, present in relatively small amounts in the deoxycholate extract, has an α-band that splits into two bands at 548 and 552.5 nm at liquid nitrogen temperature. The major components of the deoxycholate extract are cytochromes c553 and b560, which are present in essentially equimolar amounts through all the stages of the purification procedure. 相似文献
109.
Quigley JG Yang Z Worthington MT Phillips JD Sabo KM Sabath DE Berg CL Sassa S Wood BL Abkowitz JL 《Cell》2004,118(6):757-766
110.