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291.
292.
- . , , , . , . 相似文献
293.
Zusammenfassung Durch Behandlung mit Glutardialdehyd wirdNaja-naja-Gift weitgehend entgiftet. Einzeldosen bis zu 20 mg pro Kaninchen können ohne Nebenwirkungen injiziert werden. Durch Immunisierung von Kaninchen wird eine gute Antikörperbildung gegenNajanaja-Gift — und vor allem auch gegen die niedermolekularen Toxine — erzielt. 相似文献
294.
G. Szabó Elisabeth Anda E. Vándor 《Cellular and molecular life sciences : CMLS》1972,28(12):1429-1430
Zusammenfassung Nach 3 1/2 stündiger Muskelischämie wurde bei Hunden mit Ductus thoracicus-Fistel eine signifikante Zunahme der Milchsäuredehydrogenase-Aktivität im Blutserum und in der Lymphe der anoxischen Extremität bei gleichzeitiger signifikanter arterovenöser Aktivitätsdifferenz beobachtet. Auch Muskelarbeit verursachte eine Erhöhung der Enzymaktivität im Serum und in der Lymphe. Durch Unterbrechen der Verbindung zwischen Venen und Lymphsystem konnte das direkte Eindringen des Enzymproteins in die Blutkapillaren bewiesen werden. 相似文献
295.
296.
Crystallization of a second adenovirus protein (the fibre) 总被引:5,自引:0,他引:5
297.
The hepatitis C viruses (HCVs) are a group of small enveloped RNA viruses that have been viewed as a leading cause of chronic
hepatitis in humans. Infections by HCV represent a serious global health problem, because millions of people worldwide are
infected and no efficient treatment is available at the present time. Since HCV was identified in 1989, considerable effort
has been devoted to the discovery and development of novel molecules to treat HCV-related diseases. One of the approaches
is the development of novel inhibitors that interrupt the normal functions of HCV NS5B, an RNA-dependent RNA polymerase essential
to HCV replication. This review summarizes recent advances in the biochemical and structural understanding of HCV NS5B polymerase
as well as in the development of antiviral agents targeting this important enzyme.
Received 19 March 2002; received after revision 23 April 2002; accepted 23 April 2002 相似文献
298.
Malaria results in up to 2.5 million deaths annually, with young children and pregnant women at greatest risk. The great
majority of severe disease is caused by Plasmodium falciparum. A characteristic feature of infection with P. falciparum is the accumulation or sequestration of parasite-infected red blood cells (RBCs) in various organs, such as the brain, lung
and placenta, and together with other factors is important in the pathogenesis of severe forms of malaria. Sequestration results
from adhesive interactions between parasite-derived proteins expressed on the surface of infected RBCs and a number of host
molecules on the surface of endothelial cells, placental cells and uninfected RBCs. Some receptors for parasite adhesion have
been implicated in particular malaria syndromes, such as intercellular adhesion molecule 1 in cerebral malaria and chondroitin
sulfate A and hyaluronic acid in placental infection. The principal parasite ligand and antigen on the RBC surface, P. falciparum erythrocyte membrane protein 1 encoded by a multigene family termed var, is clonally variant, enabling evasion of specific immune responses. An understanding of these host-parasite interactions
in the context of clinical disease and immunity may reveal potential targets to prevent or treat severe forms of malaria.
Received 25 June 2001; received after revision 22 August 2001; accepted 24 August 2001 相似文献
299.
Chemical investigation of hassium (element 108) 总被引:5,自引:0,他引:5
Düllmann ChE Brüchle W Dressler R Eberhardt K Eichler B Eichler R Gäggeler HW Ginter TN Glaus F Gregorich KE Hoffman DC Jäger E Jost DT Kirbach UW Lee DM Nitsche H Patin JB Pershina V Piguet D Qin Z Schädel M Schausten B Schimpf E Schött HJ Soverna S Sudowe R Thörle P Timokhin SN Trautmann N Türler A Vahle A Wirth G Yakushev AB Zielinski PM 《Nature》2002,418(6900):859-862
The periodic table provides a classification of the chemical properties of the elements. But for the heaviest elements, the transactinides, this role of the periodic table reaches its limits because increasingly strong relativistic effects on the valence electron shells can induce deviations from known trends in chemical properties. In the case of the first two transactinides, elements 104 and 105, relativistic effects do indeed influence their chemical properties, whereas elements 106 and 107 both behave as expected from their position within the periodic table. Here we report the chemical separation and characterization of only seven detected atoms of element 108 (hassium, Hs), which were generated as isotopes (269)Hs (refs 8, 9) and (270)Hs (ref. 10) in the fusion reaction between (26)Mg and (248)Cm. The hassium atoms are immediately oxidized to a highly volatile oxide, presumably HsO(4), for which we determine an enthalpy of adsorption on our detector surface that is comparable to the adsorption enthalpy determined under identical conditions for the osmium oxide OsO(4). These results provide evidence that the chemical properties of hassium and its lighter homologue osmium are similar, thus confirming that hassium exhibits properties as expected from its position in group 8 of the periodic table. 相似文献
300.
Increasing dominance of large lianas in Amazonian forests 总被引:1,自引:0,他引:1
Phillips OL Vásquez Martínez R Arroyo L Baker TR Killeen T Lewis SL Malhi Y Monteagudo Mendoza A Neill D Núñez Vargas P Alexiades M Cerón C Di Fiore A Erwin T Jardim A Palacios W Saldias M Vinceti B 《Nature》2002,418(6899):770-774
Ecological orthodoxy suggests that old-growth forests should be close to dynamic equilibrium, but this view has been challenged by recent findings that neotropical forests are accumulating carbon and biomass, possibly in response to the increasing atmospheric concentrations of carbon dioxide. However, it is unclear whether the recent increase in tree biomass has been accompanied by a shift in community composition. Such changes could reduce or enhance the carbon storage potential of old-growth forests in the long term. Here we show that non-fragmented Amazon forests are experiencing a concerted increase in the density, basal area and mean size of woody climbing plants (lianas). Over the last two decades of the twentieth century the dominance of large lianas relative to trees has increased by 1.7-4.6% a year. Lianas enhance tree mortality and suppress tree growth, so their rapid increase implies that the tropical terrestrial carbon sink may shut down sooner than current models suggest. Predictions of future tropical carbon fluxes will need to account for the changing composition and dynamics of supposedly undisturbed forests. 相似文献