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1.
Background: A critical trait for successful urban dwelling by birds is the ability to tolerate high levels of disturbing stimulation by humans. If such tolerance is partly acquired gradually after colonization, species with a long history of residence in cities are likely to be more tolerant of such stimulation than recent urban colonists, but this has not often been tested.Methods: We tested whether introduced Rock(Columba livia) and Spotted(Streptopelis chinensis) Doves, historically long-term residents of Melbourne, Australia, were more tolerant of disturbance by humans than the very recent colonist, the native Crested Pigeon(Ochyphaps lophotes) by comparing the Flight Initiation Distances(FID) and time allocations to vigilance during foraging of all three species in urban Melbourne. That all three species are members of the Columbiformes reduces the possibility that any species differences in tolerance are simply phylogenetic in origin.Results: Flight initiation distance was shorter in Rock Doves than in the other two species, which did not differ in approachability by a human. Rock Doves retreated from an approaching human mainly by walking a relatively short distance, Crested Pigeons mainly by running a relatively short distance and Spotted Doves primarily by flying a comparatively long distance. The time allocation to anti-predator vigilance of Rock Doves was smaller than that of the other two species, whose allocations were similar.Conclusions: The very recent colonist of eastern Melbourne, the Crested Pigeon, was not the least tolerant of disturbance by humans of the three related species. Natural selection for tolerance therefore probably cannot entirely explain the pattern of tolerance evident among these urban dove species and behavioural flexibility is probably involved. Length of residency in a city is not an infallible guide to a species’ level of tolerance of disturbance by humans.  相似文献   
2.
In view of the current interest in in vivo murine models for acquired immunodeficiency syndrome (AIDS), the interaction between human immunodeficiency virus type 1 (HIV-1) and endogenous murine leukemia virus (MuLV)-related retroviruses was investigated with a human leukemic T cell line (PF-382x) that acquired xenotropic MuLV (X-MuLV) after in vivo passage in immunosuppressed mice. Despite similar levels of membrane CD4 expression and HIV-1 125I-labeled gp 120 binding, a dramatic acceleration in the time course of HIV-1 infection was observed in PF-382x compared to its X-MuLV-negative counterpart (PF-382). Moreover, PF-382 cells coinfected by X-MuLV and HIV-1 generated a progeny of phenotypically mixed viral particles, enabling HIV-1 to productively infect a panel of CD4- human cells, including B lymphoid cells and purified normal peripheral blood CD4-/CD8+ T lymphocytes. Mixed viral phenotypes were also produced by human CD4+ T cells coinfected with an amphotropic MuLV-related retrovirus (A-MuLV) and HIV-1. These data show that endogenous MuLV acquired by human cells transplanted into mice can significantly interact with HIV-1, thereby inducing important alterations of HIV-1 biological properties.  相似文献   
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Fisheries governance systems designed to regulate fishing are often described as being highly diverse across countries. However, there is little systematic work that directly examines and describes the (dis)similarities across such systems, and how socio-political and economic contexts drive such variation at a global scale. In this paper, we use 68 indicators from a novel dataset to examine the fisheries governance systems in place to constrain overfishing in national waters across 142 countries. We found that countries cluster in just two distinct governance groups which display different traits to constrain overfishing. Where one group takes a tougher stance on aspects regarding access to its fisheries resources, the other is more focused on gathering fisheries information and publicizing the data. The 10 greatest differences between groups relate to the gathering of information and monitoring of their fisheries, the effectiveness of compliance systems and the existence of policies around sustainability. On these key differences, one group consistently displays more far-reaching governance traits. The overall governance capacity of a country and the national socio-economic importance of fisheries are identified as potential drivers of this variation. Despite their differences, the two groups show substantial overlap for many indicators, particularly those that are inexpensive, but also for certain costly policies. These patterns prompt hypotheses of policy transfer or convergence across fisheries governance systems, most notably regarding ‘low-hanging fruit’ policies.  相似文献   
5.
Reconstructing the evolutionary history, demographic signal and dispersal processes from viral genome sequences contributes to our understanding of the epidemiological dynamics underlying epizootic events. In this study, a Bayesian phylogenetic framework was used to explore the phylodynamics and spatio-temporal dispersion of the O CATHAY topotype of foot-and-mouth disease virus (FMDV) that caused epidemics in the Philippines between 1994 and 2005. Sequences of the FMDV genome encoding the VP1 showed that the O CATHAY FMD epizootic in the Philippines resulted from a single introduction and was characterised by three main transmission hubs in Rizal, Bulacan and Manila Provinces. From a wider regional perspective, phylogenetic reconstruction of all available O CATHAY VP1 nucleotide sequences identified three distinct sub-lineages associated with country-based clusters originating in Hong Kong Special Administrative Region (SAR), the Philippines and Taiwan. The root of this phylogenetic tree was located in Hong Kong SAR, representing the most likely source for the introduction of this lineage into the Philippines and Taiwan. The reconstructed O CATHAY phylodynamics revealed three chronologically distinct evolutionary phases, culminating in a reduction in viral diversity over the final 10 years. The analysis suggests that viruses from the O CATHAY topotype have been continually maintained within swine industries close to Hong Kong SAR, following the extinction of virus lineages from the Philippines and the reduced number of FMD cases in Taiwan.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-014-0090-y) contains supplementary material, which is available to authorized users.  相似文献   
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Arabidopsis VRN genes mediate vernalization, the process by which a long period of cold induces a mitotically stable state that leads to accelerated flowering during later development. VRN1 encodes a protein that binds DNA in vitro in a non-sequence-specific manner and functions in stable repression of the major target of the vernalization pathway, the floral repressor FLC. Overexpression of VRN1 reveals a vernalization-independent function for VRN1, mediated predominantly through the floral pathway integrator FT, and demonstrates that VRN1 requires vernalization-specific factors to target FLC.  相似文献   
9.

Objective

To determine the agreement of invasive blood pressure measured in the facial, metatarsal and carotid arteries, and evaluate the effects of two haemodynamic conditions on agreement.

Study design

Prospective randomized study.

Animals

A group of eight horses aged 7 (4–23) years with a body weight of 493 ± 33 kg.

Methods

Horses were anaesthetized and positioned in dorsal recumbency. Invasive blood pressure was measured simultaneously via catheters placed in the facial, metatarsal and carotid arteries. Cardiovascular function and agreement between arteries was assessed before and during administration of phenylephrine and sodium nitroprusside. These were administered until carotid mean pressure (MAPc) increased or decreased from baseline (65 ± 5) to >90 or <50 mmHg, respectively. Data recorded at each sample time included systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures for carotid (c), facial (f) and metatarsal (m) arteries as well as cardiac output (Q˙t) and systemic vascular resistance (SVR). Bland–Altman analysis was used to assess agreement between peripheral and central sites, and regression analysis to determine influence of Q˙t and SVR.

Results

The largest difference was observed in SAPc and SAPm with a bias and limits of agreement (LOA) of 2 (?15 to 19) mmHg. The bias (LOA) for MAPc and MAPf was 2 (?4 to 9) mmHg and for MAPc and MAPm was 5 (?4 to 14) mmHg. The best agreement for DAP was seen between DAPc and DAPf with bias (LOA) of 1 (?3 to 5) mmHg. Regression analysis indicated marginal influence on agreement by Q˙t on MAPc and MAPf.

Conclusions and clinical relevance

MAP and DAP of the carotid artery were higher than those of the peripheral arteries, which may lead to overzealous treatment of hypotension, albeit maintaining central pressures. Q˙t and SVR did not largely influence the difference between sites.  相似文献   
10.
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