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排序方式: 共有62条查询结果,搜索用时 31 毫秒
1.
R Schwaab HH Brackmann C Meyer J Seehafer M Kirchgesser A Haack K Olek EG Tuddenham J Oldenburg 《Canadian Metallurgical Quarterly》1995,74(6):1402-1406
The formation of factor VIII antibodies is a major problem for replacement therapy of haemophilia A patients. Antibodies occur in 5-30% of patients with severe haemophilia A. The reason for antibody formation is still unknown. In this study we correlate for the first time different factor VIII gene mutations, stop- and missense mutations, large and small deletions and intrachromosomal intron 22 recombinations to antibody formation. A total of 364 patients with known inhibitor status of our institute, of the database, and of 3 studies representing intron-22-inversion data are included. The results show that the risk for developing factor VIII antibodies is strongly related to stop mutations. large deletions and intrachromosomal recombinations. A probable explanation could be the complete lack of endogenous circulating factor VIII protein in these cases. Other factors that might be important for the pathogenesis of inhibitor formation, e. g. the antenatal period, as well as possible therapeutic effects, are discussed. 相似文献
2.
Samples of palladium supported on-alumina and a palladium foil were used as catalysts for methane oxidation at 550° C. The samples were quenched quickly in the reaction chamber to room temperature in flowing Ar and then transferred in vacuo for XPS analysis. Structure sensitivity was manifest from an increase in PdO stability and a decrease in carbon deposition relative to Pd with increasing particle size. The results were compared with recent ellipsometric data. 相似文献
3.
Kamal J. K. Gandhi Daniel W. Gilmore Robert A. Haack Steven A. Katovich Steven J. Krauth William J. Mattson John C. Zasada Steven J. Seybold 《Journal of chemical ecology》2009,35(12):1384-1410
From 2000 through 2003 we used semiochemical-baited traps in northeastern Minnesota, USA, to assess changes in assemblages
of subcortical forest insects after a catastrophic wind storm in 1999 and subsequent (1999–2000) fuel-reduction activities
(salvage-logging and prescribed-burning). We determined the regional efficacy of fifteen semiochemical blends (pheromones
and kairomones) as attractants for target and non-target subcortical insect species (Coleoptera: Anthribidae, Buprestidae,
Cerambycidae, Cleridae, Cucujidae, Curculionidae, Histeridae, Nemonychidae, Salpingidae, Scolytidae, Tenebrionidae, and Hymenoptera:
Siricidae). During the four summers, we trapped 86,471 subcortical insects (143 species) in baited and unbaited Lindgren funnel
traps, and 500 beetles (44 species) in baited and unbaited pitfall traps. We report 23 new state collection records of subcortical
insects from Minnesota. Trap catches of subcortical insects were greatest in the wind-disturbed areas 2 years after the event,
and declined thereafter. Similar trends were observed for subcortical insects in the burned areas. Both wind-disturbance and
burning increased the subcortical insect species richness and diversity on the landscape. The subcortical insect species compositions
of the salvaged and burned forest areas differed from those of the undisturbed and wind-disturbed areas. Trap catches of subcortical
insects in response to semiochemical treatments also varied with year of sampling and land-area treatment. The greatest diversity
of subcortical beetle species was in traps baited with attractants for the scolytids, Dendroctonus valens [(+)-α-pinene and (−)-β-pinene] and Dryocoetes spp. [exo-brevicomin and (−)-α-pinene], perhaps reflecting the generic nature of the baits. The most distinct species compositions
were collected in response to the woodborer and Dendroctonus simplex baits, whereas the species compositions in traps with the D. valens and Dryocoetes spp. baits, and the unbaited funnel trap were the most similar. The variation in trap catch with time and across landscapes
suggests that the responses of subcortical insects to semiochemicals are more complex than previously appreciated. 相似文献
4.
Barry N. Haack 《Remote sensing of environment》1983,13(3):265-275
Thematic mapper simulator data collected for the Los Angeles Basin in 1980 were examined to assess their utility for urban and near-urban land-cover delimitations. Spectral data for six of the thematic mapper channels were reprojected to a UTM grid and aggregated to 30-m resolution, 120 m for the thermal band. Statistics for 21 training sites representing 8 land-cover types were obtained and examined using transformed divergence calculations for intraclass variability, optimal number of channels for classification, and best channels for classification. Four channels of data are adequate for classification with the best results obtained by selection of one channel from each of the available major portions of the electromagnetic spectrum. The thermal channel data is useful for urban land-cover delineations at 30-m resolution, but its utility at 120-m resolution is not clear from this study. 相似文献
5.
This study quantified Escherichia coli (EC) and enterococci (ENT) in beach waters and dominant source materials, correlated these with ambient conditions, and determined selected EC genotypes and ENT phenotypes. Bathing-water ENT criteria were exceeded more frequently than EC criteria, providing conflicting interpretations of water quality. Dominant sources of EC and ENT were bird feces (10(8)/d/bird), storm drains (10(7)/d), and river water (10(11)/d); beach sands, shallow groundwater and detritus were additional sources. Beach-water EC genotypes and ENT phenotypes formed clusters with those from all source types, reflecting diffuse inputs. Some ENT isolates had phenotypes similar to those of human pathogens and/or exhibited high-level resistance to human-use antibiotics. EC and ENT concentrations were influenced by collection time and wind direction. There was a 48-72-h lag between rainfall and elevated EC concentrations at three southern shoreline beaches, but no such lag at western and eastern shoreline beaches, reflecting the influence of beach orientation with respect to cyclic (3-5 d) summer weather patterns. In addition to local contamination sources and processes, conceptual or predictive models of Great Lakes beach water quality should consider regional weather patterns, lake hydrodynamics, and the influence of monitoring method variables (time of day, frequency). 相似文献
6.
Dr. Bettina Sommer Dr. Holger von Moeller Martina Haack Dr. Farah Qoura Clemens Langner Dr. Gleb Bourenkov Dr. Daniel Garbe Dr. Bernhard Loll Prof. Dr. Thomas Brück 《Chembiochem : a European journal of chemical biology》2015,16(1):110-118
Isobutanol is deemed to be a next‐generation biofuel and a renewable platform chemical. 1 Non‐natural biosynthetic pathways for isobutanol production have been implemented in cell‐based and in vitro systems with Bacillus subtilis acetolactate synthase (AlsS) as key biocatalyst. 2 – 6 AlsS catalyzes the condensation of two pyruvate molecules to acetolactate with thiamine diphosphate and Mg2+ as cofactors. AlsS also catalyzes the conversion of 2‐ketoisovalerate into isobutyraldehyde, the immediate precursor of isobutanol. Our phylogenetic analysis suggests that the ALS enzyme family forms a distinct subgroup of ThDP‐dependent enzymes. To unravel catalytically relevant structure‐function relationships, we solved the AlsS crystal structure at 2.3 Å in the presence of ThDP, Mg2+ and in a transition state with a 2‐lactyl moiety bound to ThDP. We supplemented our structural data by point mutations in the active site to identify catalytically important residues. 相似文献
7.
The interplay of bake oven processing environment and surface/interfacial chemistry, and their effect on intercoat adhesion
has been investigated for a model primer/electrocoat paint system. X-ray photoelectron spectroscopy (XPS) surface analysis
established that a prominent ether component in the C 1s core level spectrum correlated with a polyether-based crater-control
additive in the electrocoat that surface-segregates during cure. Laboratory-simulated bake oven experiments confirmed that
better adhesion characteristics were realized by removal of this electrocoat overlayer through reaction with nitrogen oxides
and high levels of moisture present in the cure environment of production direct-fired ovens. Details of the effect of bake
oven atmosphere on cure chemistry for direct- versus indirect-fired ovens are presented. 相似文献
8.
The writers analyze the stresses in a model of the periodontal ligament of a maxillary central incisor. The model is assumed to be of paraboloidal shape, uniform thickness, and of a homogeneous, isotropic, and linearly elastic material. The inside surface of this paraboloidal shell is subject to rigid body displacement while the outside surface is assumed rigidly supported and stationary. The edge of the model is assumed to be stress free.
A system of paraboloidal coordinates is developed, and this system is fitted to the shape of the root of a typical maxillary central incisor. The displacement functions obtained by solving the differential equations of equilibrium are used to determine the stresses at the inside and outside surfaces of the model ligament. These stresses are subject to superposition so that the stresses associated with any combination of applied forces and couples may be determined. 相似文献
9.
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