1000 resultados para Siglo 19º
Resumo:
Référence bibliographique : Rol, 55060
Resumo:
Référence bibliographique : Rol, 54215
Resumo:
Référence bibliographique : Rol, 55049
Resumo:
Référence bibliographique : Rol, 55048
Resumo:
Référence bibliographique : Rol, 55156
Resumo:
Référence bibliographique : Rol, 55155
Resumo:
Référence bibliographique : Rol, 55154
Resumo:
Référence bibliographique : Rol, 55152
Resumo:
Référence bibliographique : Rol, 55148
Resumo:
Référence bibliographique : Rol, 55361
Resumo:
Référence bibliographique : Rol, 55360
Resumo:
Fa més d'un quart de segle que Xipre està dividit, després que l'exèrcit turc intervingués a l'illa, davant l'intent de cop d'estat greco-xipriota recolzat per Grècia. Aquest episodi va concloure amb l'ocupació turca de la part nord de l'illa i el transvasament de població entre nord i sud fins a configurar dos territoris ètnicament homogenis i separats físicament per la "Línia verd" de Nacions Unides. Aquest conflicte que secciona l'illa ha quedat congelat fins als nostres dies, tot i els repetits intents i propostes de pau promoguts per la comunitat internacional1. L'11 de novembre de 2002, el Secretari General de Nacions Unides, Kofi Annan, va presentar un nou pla als líders xipriotes i als governs dels estats garants Grècia, Turquia i el Regne Unit. Donada la conjuntura actual, sobretot arran del procés d'ampliació europea, aquesta proposta constitueix una oportunitat "històrica" per desbloquejar la situació i arribar a un acord definitiu. En aquestes pàgines, plantegem els possibles escenaris de futur per Xipre, tenint en compte els diferents elements que poden condicionar les polítiques exteriors dels actors implicats en el contenciós.
Resumo:
19-Norandrosterone (19-NA) as its glucuronide derivative is the target metabolite in anti-doping testing to reveal an abuse of nandrolone or nandrolone prohormone. To provide further evidence of a doping with these steroids, the sulfoconjugate form of 19-norandrosterone in human urine might be monitored as well. In the present study, the profiling of sulfate and glucuronide derivatives of 19-norandrosterone together with 19-noretiocholanolone (19-NE) were assessed in the spot urines of 8 male subjects, collected after administration of 19-nor-4-androstenedione (100mg). An LC/MS/MS assay was employed for the direct quantification of sulfoconjugates, whereas a standard GC/MS method was applied for the assessment of glucuroconjugates in urine specimens. Although the 19-NA glucuronide derivative was always the most prominent at the excretion peak, inter-individual variability of the excretion patterns was observed for both conjugate forms of 19-NA and 19-NE. The ratio between the glucuro- and sulfoconjugate derivatives of 19-NA and 19-NE could not discriminate the endogenous versus the exogenous origin of the parent compound. However, after ingestion of 100mg 19-nor-4-androstenedione, it was observed in the urine specimens that the sulfate conjugates of 19-NA was detectable over a longer period of time with respect to the other metabolites. These findings indicate that more interest shall be given to this type of conjugation to deter a potential doping with norsteroids.
Resumo:
In so-called unisexual teleost fishes, a broad spectrum of evolutionaty stages with varying amounts of sexual elements has evolved. These range from pure sperm-dependent parthenogenesis (gynogenesis) without or with different amounts of paternal leakage to hybridogenesis with hemiclonal diploid gametogenesis or genome elimination folowed by meiosis (meiotic hybridogenesis). All of these phenomena are hybrid origin. Many of these fish form complexes which involve the coexistence of one or more sexually reproducing species with derived all-female forms that have various ploidy levels and reproductive modes, including gynogenesis, (meiotic) hybridogenesis nnd sexual reproduction. In teleosts, parthenogenetic reproduction is strictly dependent on sperm to initate embryonic development. As opposed to true parthenogenesis, sperm-dependent parthenogenetic teleost lineages must primarily coexist with their "sperm donor", usually males from a parental sexual lineage or from a related sexual species. In some systems, gynogens were able to escape from their initial sperm donors ("host switch") and therefore, to enlarge their ranges and ecological niches. Sperm donors normally do not contribue genetically to the next generation. However, paternal leakage is observed in many systems contributing differing amounts of genetic material (from microchromosomes to entire chromosome sets) allowing interaction between genomes of different origin. Hybridogenesis is similar to gynogenesis in depending upon coexisence with sexual species but incorporates recombined genetic material by true fertilizazion. While hybridogens usually form clonal gametes, some triploids are capable of genome elimination followed by a normal diploid meiosis. Sperm-dependent parthenogenesis and hybridogenesis combine disadvantages and advantages from both sexuality and asexuality. Here, we give an overview of sperm-dependent breeding complexes in fishes, discuss the evolutionary consequences of paternal leakage, and speculate about the evolutionary significance of intergenomic (re)combination.
