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排序方式: 共有424条查询结果,搜索用时 46 毫秒
41.
The quality of aquatic habitat in a stormwater management facility located in Toronto, Ontario, was assessed by examining ecotoxicological responses of benthic invertebrates exposed to sediment and water from this system. Besides residential stormwater, the facility receives highway runoff contaminated with trace metals, polycyclic aromatic hydrocarbons (PAHs), and road salt. The combined flow passes through two extended detention ponds (in series) and a vegetated outlet channel. Toxicity of surficial sediment collected from 14 longitudinally arrayed locations was assessed based on 10 acute and chronic endpoints from laboratory tests with four benthic organisms. Greatest overall toxicity was observed in sediment from sites in the upstream pond, where mortality to amphipods and mayflies reached up to 100%. Downstream pond sediment was less toxic on average than the upstream pond sediment, but not the outlet channel sediment where untreated stormwater discharges provided additional sources of contamination. Macroinvertebrate communities in sediment cores were depauperate and dominated by oligochaetes and chironomids, with minimum densities and diversity at the deeper central pond sites. While sediment toxicity was associated with high concentrations of trace metals and high-molecular weight PAHs, benthic community impoverishment appeared related to high water column salinity. 相似文献
42.
Jiri A. Mares Martin Nikl Alena Beitlerova Karel Blazek Petr Horodysky Karel Nejezchleb Carmelo D’Ambrosio 《Optical Materials》2011,34(2):424-427
Scintillation properties of Pr3+-doped LuAG and YAG crystals were investigated and compared with those of Ce3+-doped ones. The highest L.Y.’s were observed with the longest shaping time 10 μs. They can reach up to ~16,000 ph/MeV or ~23,500 ph/MeV for LuAG:Pr and LuAG:Ce, respectively. Energy resolutions (FWHM) are a bit better with LuAG:Pr than those of LuAG:Ce, e.g. at 662 keV FWHM are around 6% and between 8–12%, respectively. There were observed no large changes in proportionality of Pr3+- or Ce3+-doped LuAG or YAG crystals but the best proportionality has YAP:Ce crystal. Pr3+- or Ce3+-doped LuAG crystals exhibit slow decay components in the time range 1.5–3.5 μs while those of YAG ones have shorter decay components between 0.3–1.7 μs. 相似文献
43.
A cold physical model to a scale of 1:33 of a solid waste incinerator was designed and constructed of transparent material. Experimentation aimed at optimizing gas flow patterns in the furnace for low-pollutant combustion. Flames were simulated by acid-base neutralization. Secondary air flow distribution and direction were identified as the controlling parameters of the flow pattern. The best possible air distribution for a desired flame shape and gas mixing was determined. Streamline plots for verification of the mathematical models were obtained. 相似文献
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45.
A short review of the works concerning parameter estimation in kinetic experiments was performed. An adaptive random search algorithm was applied to evaluate the parameters and parameter confidence intervals of Langmuir-Hinshelwood models. The kinetic parameters were determined using the Box - Draper criterion. The parameter confidence regions were found by using the likelihood ratio. Three heterogeneously catalyzed hydrogenations were studied. 相似文献
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Martina Stekrova Hana Minarikova Eliska Vyskocilova Jiri Kolena Libor Cerveny 《Journal of Porous Materials》2014,21(5):757-767
The presented report focuses on the testing of heterogenized methyltrioxorhenium (MTO) in indene epoxidation. A range of mesoporous materials with different SiO2/Al2O3 ratios, namely aluminosilicates type Siral and MCM-41 silica and fumed silica, were used as supports for immobilization of MTO. The tested support materials and prepared catalytic systems exhibited high surface area, well-defined regular structure and narrow pore size distribution of mesopores and therefore represent good quality catalysts for various reactions. The immobilized MTO on various supports was tested for the preparation of 1,2-epoxyindane using two forms of hydrogen peroxide as oxidation agents, namely aqueous solution of hydrogen peroxide and its anhydrous form, urea-hydrogen peroxide. The prepared catalysts were successfully used for the preparation of 1,2-epoxyindane with achieved 100 % selectivities to the desired product at high conversions of indene. 相似文献
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Alexander Pyattaev Jiri Hosek Kerstin Johnsson Radko Krkos Mikhail Gerasimenko Pavel Masek Aleksandr Ometov Sergey Andreev Jakub Sedy Vit Novotny Yevgeni Koucheryavy 《ETRI Journal》2015,37(5):877-887
This paper is a first‐hand summary on our comprehensive live trial of cellular‐assisted device‐to‐device (D2D) communications currently being ratified by the standards community for next‐generation mobile broadband networks. In our test implementation, we employ a full‐featured 3GPP LTE network deployment and augment it with all necessary support to provide real‐time D2D connectivity over emerging Wi‐Fi‐Direct (WFD) technology. As a result, our LTE‐assisted WFD D2D system enjoys the required flexibility while meeting the existing standards in every feasible detail. Further, this paper provides an account on the extensive measurement campaign conducted with our implementation. The resulting real‐world measurements from this campaign quantify the numerical effects of D2D functionality on the resultant system performance. Consequently, they shed light on the general applicability of LTE‐assisted WFD solutions and associated operational ranges. 相似文献
50.
Data are reviewed indicating that allosteric modulators can enhance the affinities of muscarinic receptors for their antagonists and agonists, that the enhancement of the affinity for agonists is relevant functionally, and that the allosterically induced conformational change also affects the interaction between the receptors and the G proteins. 相似文献