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A series of N, N– disubstituted piperazines and homopiperazines were prepared and evaluated for binding to natural α4β2* and α7* neuronal nicotinic acetylcholine receptors (nAChRs) using whole brain membrane. Some compounds exhibited good selectivity for α4β2* nAChRs and did not interact with the α7* nAChRs subtype. The most potent analogs were compounds 8-19 (Ki = 10.4 μM), 8–13 (Ki = 12.0 μM), and 8–24 (Ki = 12.8 μM). Thus, linking together a pyridine π-system and a cyclic amine moiety via a homopiperazine ring affords compounds with low affinity but with good selectivity for α4β2* nAChRs.  相似文献   
2.
Endocytosis in plants: fact or artefact?   总被引:2,自引:0,他引:2  
Whilst plant cells are apparently equipped with all the necessary molecular machinery for receptor-mediated endocytosis, the physiological role of this process in these cells remains an enigma. In this article, we consider current opinions of endocytosis in plants and define some of the problems that have impeded progress in our under-standing of the part played by endocytosis in the vesicle trafficking pathway.  相似文献   
3.
Medical tourism (MT) can be conceptualized as the intentional pursuit of non‐emergency surgical interventions by patients outside their nation of residence. Despite increasing popular interest in MT, the ethical issues associated with the practice have thus far been under‐examined. MT has been associated with a range of both positive and negative effects for medical tourists' home and host countries, and for the medical tourists themselves. Absent from previous explorations of MT is a clear argument of how responsibility for the harms of this practice should be assigned. This paper addresses this gap by describing both backward looking liability and forward looking political responsibility for stakeholders in MT. We use a political responsibility model to develop a decision‐making process for individual medical tourists and conclude that more information on the effects of MT must be developed to help patients engage in ethical MT.  相似文献   
4.
Abstract: Accurate assessments of local population size of the black-tailed prairie dog (Cynomys ludovicianus) are essential because of their overall decline and importance to prairie ecosystems. We describe the use of mark-resight methodology to estimate black-tailed prairie dog population size and density. Study colonies include isolated urban habitat fragments in Denver, Colorado, USA, and unfragmented control colonies in the Pawnee National Grassland, USA. We compare results from various mark-resight estimators to those derived from linear transformations of visual counts of active prairie dogs. Our results suggest that mark-resight methods are feasible in both urban and rural systems, and reveal extremely high densities for isolated prairie dogs in urban sites. Our methodology can be used to obtain reliable, unbiased estimates of local population size and density.  相似文献   
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Abstract: Noninvasive sampling methods provide a means for studying species such as large mammalian carnivores that are difficult to survey using traditional techniques. Focusing on bobcat (Lynx rufus), we compared the effectiveness of noninvasive hair and scat genetic sampling in terms of field sample collection, species identification, and individual identification. We describe a novel hair-snare design and sampling protocol that successfully sampled 4 sympatric carnivore species, bobcat, mountain lion (Felis concolor), coyote (Canis latrans), and gray fox (Urocyon cinereoargenteus), in 3 habitat blocks in coastal southern California, USA. Scat surveys were also successful at sampling bobcats and other carnivores in the area. Hair and scat sampling methods had similar species identification success (81% and 87%, respectively) using mitochondrial DNA amplification and restriction enzyme digestion patterns. Therefore, for studies focused on the distribution and activity of a suite of carnivore species, we recommend a combination of noninvasive methodologies, for example, targeting hair and scat surveys toward species and sites where they are most effective. Because of a higher success rate for scat (85%) than for hair samples (10%) when using 4 microsatellite loci and a multiple-tubes approach to verify individual genotypes, we suggest scat sampling is a better choice for studies that require individual identification of bobcats.  相似文献   
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