全文获取类型
收费全文 | 120篇 |
免费 | 16篇 |
出版年
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 3篇 |
2011年 | 8篇 |
2010年 | 4篇 |
2009年 | 11篇 |
2008年 | 8篇 |
2007年 | 8篇 |
2006年 | 5篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1987年 | 4篇 |
1984年 | 1篇 |
排序方式: 共有136条查询结果,搜索用时 312 毫秒
61.
Males exhibit striking variation in the degree to which they invest in offspring, from merely provisioning females with sperm, to providing exclusive post-zygotic care. Paternity assurance is often invoked to explain this variation: the greater a male's confidence of paternity, the more he should be willing to provide care. Here, we report a striking exception to expectations based on paternity assurance: despite high levels of female promiscuity, males of a marine snail provide exclusive, and costly, care of offspring. Remarkably, genetic paternity analyses reveal cuckoldry in all broods, with fewer than 25% of offspring being sired by the caring male, although caring males sired proportionally more offspring in a given clutch than any other fathers did individually. This system presents the most extreme example of the coexistence of high levels of female promiscuity, low paternity, and costly male care, and emphasises the still unresolved roles of natural and sexual selection in the evolution of male parental care. 相似文献
62.
Backhaus K Buchwald U Heppeler N Schmitz HP Rodicio R Heinisch JJ 《European journal of cell biology》2011,90(9):745-750
The milk yeast Kluyveromyces lactis is an alternative model yeast to the well established Saccharomyces cerevisiae. The cell wall of these fungi consists of polysaccharides (i.e. long chains of β-1,3- and β-1,6-linked sugar chains and some chitin) and mannoproteins, both of which are continually adapted to environmental conditions in terms of their abundance and organization. This implies the need to perceive signals at the cell surface and to transform them into a proper cellular response. The signal transduction cascade involved in this process is generally referred to as the cell wall integrity (CWI) pathway. CWI signaling and cell wall composition have been extensively studied in the Baker's yeast S. cerevisiae and are also of interest in other yeast species with commercial potential, such as K. lactis. We here summarize the results obtained in the past years on CWI signaling in K. lactis and use a comparative approach to the findings obtained in S. cerevisiae to highlight special adaptations to their natural environments. 相似文献
63.
Richter HG Benson GM Bleicher KH Blum D Chaput E Clemann N Feng S Gardes C Grether U Hartman P Kuhn B Martin RE Plancher JM Rudolph MG Schuler F Taylor S 《Bioorganic & medicinal chemistry letters》2011,21(4):1134-1140
Structure-guided lead optimization of recently described benzimidazolyl acetamides addressed the key liabilities of the previous lead compound 1. These efforts culminated in the discovery of 4-{(S)-2-[2-(4-chloro-phenyl)-5,6-difluoro-benzoimidazol-1-yl]-2-cyclohexyl-acetylamino}-3-fluoro-benzoic acid 7g, a highly potent and selective FXR agonist with excellent physicochemical and ADME properties and potent lipid lowering activity after oral administration to LDL receptor deficient mice. 相似文献
64.
Grether GF 《Integrative and comparative biology》2011,51(5):807-818
Territorial animals can be expected to distinguish among the types of competitors and noncompetitors that they encounter on a regular basis, including prospective mates and rivals of their own species, but they may not correctly classify individuals of other species. Closely related species often have similar phenotypes and this can cause confusion when formerly allopatric populations first come into contact. Errors in recognizing competitors can have important ecological and evolutionary effects. I review what is known about the mechanisms of competitor recognition in animals generally, focusing on cases in which the targets of recognition include other species. Case studies include damselflies, ants, skinks, salamanders, reef fishes, and birds. In general, recognition systems consist of a phenotypic cue (e.g., chemical, color, song), a neural template against which cues are compared, a motor response (e.g., aggression), and sensory integration circuits for context dependency of the response (if any). Little is known about how competitor recognition systems work at the neural level, but inferences about specificity of cues and about sensory integration can be drawn from the responses of territory residents to simulated intruders. Competitor recognition often involves multiple cues in the same, or different, sensory modalities. The same cues and templates are often, but not always, used for intraspecific and interspecific recognition. Experiments have shown that imprinting on local cues is common, which may enable templates to track evolved changes in cues automatically. The dependence of aggression and tolerance on context is important even in the simplest systems. Species in which mechanisms of competitor recognition are best known offer untapped opportunities to examine how competitor-recognition systems evolve (e.g., by comparing allopatric and sympatric populations). Cues that are gene products (peptides, proteins) may provide insights into rates of evolution. There are many avenues for further research on the important but understudied question of how animals recognize competitors. 相似文献
65.
Kammermann M Denelavas A Imbach A Grether U Dehmlow H Apfel CM Hertel C 《Biochemical and biophysical research communications》2011,(3):419-424
Ligand-biased receptor signaling has been proposed for several G-protein coupled receptors including the niacin receptor GPR109A. Coupling to the Gi/o pathway has been shown to be responsible for the well described triglyceride lowering effect of nicotinic acid in mice, while activation of the β-arrestin pathway has been suggested to be responsible for its peripheral vasodilatory effect that causes cutaneous flushing. Several ligands have been described to selectively induce triglyceride lowering without inducing flushing.Cellular impedance has been demonstrated to determine G-protein coupled receptors activation in a G-protein specific manner. Agonists, which induce triglyceride lowering, but not flushing show a profile in cellular impedance that is distinct from the one induced by niacin and those compounds that induce triglyceride lowering as well as flushing. The strength of the signal correlates with the activation of β-arrestin. 相似文献
66.
67.
The water mite Hydrachna guanajuatensis Cook, 1980 is recorded as an ectoparasite of Ranatra sp. (Nepidae), Notonecta sp., Buenoa sp. (Notonectidae), Krizousacorixa femorata (Guérin, 1857), Trichocorixella mexicana (Hungerford, 1927), and Hesperocorixa laevigata (Uhler, 1893) (Corixidae). The host body region, where the larvae and protonymph attach, depends significantly on the heteropteran species: χ2 = 3969.43, p < 0.05 and χ2 = 1893.6, p < 0.05, respectively. We performed a cross tabulation with a correspondence analysis and found three associations for the larvae: 1) dorsal side of abdomen underneath the wings of the two species of Notonectidae, 2) head, wings, and hind legs of two of the species of Corixidae (T. mexicana and K. femorata), and 3) thorax and fore and middle legs of the single species of Nepidae. These different patterns are discussed according to morphological and ecological characteristics of the hosts. This is the first study that deals with the spatial distribution patterns within the same species of ectoparasite. 相似文献
68.
Berenice Calderón-Pérez Beatriz Xoconostle-Cázares Rosalía Lira-Carmona Rosaura Hernández-Rivas Jaime Ortega-López Roberto Ruiz-Medrano 《PloS one》2014,9(1)
Plasmodium falciparum secretes a homologue of the translationally controlled tumor protein (TCTP) into serum of infected individuals, although its role in pathogenesis or virulence is unknown. To determine the effect of P. falciparum TCTP on B cells as compared to human TCTP, fluorescently labeled proteins were incubated on primary cultures of mouse splenic B cells and analyzed by flow cytometry and confocal microscopy. Our results indicate that both recombinant proteins are incorporated into B cells, but differ significantly in their rate and percentage of incorporation, being significantly higher for P. falciparum TCTP. Furthermore, P. falciparum TCTP showed a lower B cell proliferative effect than human TCTP, suggesting a mechanism through which the former could interfere in the host''s immune response. 相似文献
69.