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81.
This article presents the results of a survey on how people perceive the Klimkówka storage reservoir located on the Ropa River in the Polish Carpathians. The analysis focused on establishing the role of various factors which impact the assessment of the reservoir by the local community. Community perception of the reservoir was analyzed in relation to several aspects linked to the reservoir itself, e.g. the risk of dam failure, feeling of safety, pros and cons, and how accustomed people were to the reservoir. A crucial issue was to identify how the real threat of a flood, experienced by people living below the dam, affected the way people perceived the reservoir. As a result of the analysis, a hierarchy of factors which determine people's assessment of large hydraulic structures was established. The results can be applied to determine specific measures aimed at limiting negative community perception of water infrastructure.  相似文献   
82.
In‐stream chinook salmon (Oncorhynchus tschawytscha) spawning habitat in California's Central Valley has been degraded by minimal gravel recruitment due to river impoundment and historic gravel extraction. In a recent project marking a new direction for spawning habitat rehabilitation, 2450 m3 of gravel and several boulders were used to craft bars and chutes. To improve the design of future projects, a test was carried out in which a commercial modelling package was used to design and evaluate alternative gravel configurations in relation to the actual pre‐ and post‐project configurations. Tested scenarios included alternate bars, central braid, a combination of alternate bars and a braid, and a flat riffle with uniformly spaced boulders. All runs were compared for their spawning habitat value and for susceptibility to erosion. The flat riffle scenario produced the most total, high, and medium quality habitat, but would yield little habitat under flows deviating from the design discharge. Bar and braid scenarios were highly gravel efficient, with nearly 1 m2 of habitat per 1 m3 of gravel added, and yielded large contiguous high quality habitat patches that were superior to the actual design. At near bankfull flow, negligible sediment entrainment was predicted for any scenario. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
83.
LaMnO3-based mixed oxides with perovskite-like structure both bulk and supported on La–Al2O3, show high catalytic activity in dehydrogenation of n-butanol to an aldehyde, which then undergoes a secondary reaction to produce a symmetrical ketone. Partial substitution of Cu, V or Sr into LaMnO3 structure does not destroy the perovskite-like structure and enables to control the acid–base surface properties. It allows linking up these qualitative and quantitative features with activity and selectivity of these materials. The degree of n-butanol conversion depends on the total concentration of basic and acidic sites. Selectivity to butyraldehyde can be related with the share of basic sites. Selectivity to dipropyl ketone is affected both by the acidity and concentration of acidic sites. LaMnO3/La–Al2O3 seems to posses an optimum set of surface characteristics for the examined ketonization of a primary alcohol.  相似文献   
84.
National shares of worldwide publications in the Science Citation Index (SCI) have shifted recently. The long-term decline in U.S. share accelerated in the mid-1990s, and now the EU has joined this decline. Not coincidentally, the shares of some countries have increased sharply, particularly those of China, S. Korea, Taiwan, and Singapore. Since the SCI constantly adds new journals, one reason might be that newly added journals were more favorable to them. To test this, the database was partitioned into “old journals” (added before 1995) and “new journals,” added afterward. The analysis was done for eight of the 20 fields of science defined by the National Science Indicator CD. In some fields, new journals were indeed much more favorable to the Asians. In some fields, however, new journals were actually more favorable to the U.S. In aggregate over the eight fields analyzed, the size of this effect was too small to account for much of the sharp changes in national shares. Furthermore tests between old and new journals find that differences in most fields are not statistically significant. The results provide evidence that the SCI can be used to accurately track national publication changes over time.  相似文献   
85.
The recent discovery of the natural product platensimycin as a new antibiotic lead structure has triggered the synthesis of numerous organic derivatives for structure–activity relationship studies. Herein, we describe the synthesis, characterization and biological evaluation of the first organometallic antibiotic inspired by platensimycin. Two bioorganometallic compounds containing (η6‐pentamethylbenzene)Cr(CO)3 ( 2 ) and (η6‐benzene)Cr(CO)3 ( 3 ), linked by an amide bond to the aromatic part of platensimycin, were synthesized. Their antibiotic activities were tested against B. subtilis 168 (Gram positive) and E. coli W3110 (Gram negative) bacterial strains. Both compounds were found to be inactive against E. coli but derivative 2 inhibits B. subtilis growth at a moderate MIC value of 0.15 mM . To test the intrinsic toxicity of chromium, several chromium salts along with {η6‐(3‐pentamethylphenyl propionic acid)}Cr(CO)3 ( 5 ) and {η6‐(3‐phenyl propionic acid)}Cr(CO)3 ( 6 ) were tested against both bacterial strains. No activity was observed against E. coli for any of the compounds; B. subtilis growth was not inhibited by Cr(NO3)3 and only very weakly by 5 , K2Cr2O7 and Na2CrO4 at MIC values of 0.5, 0.68 and 1.24 mM , respectively. Compounds 2 , 3 , 5 and 4 (the pure organic analogue of 2 ) show similar cytotoxicity against HeLa, HepG2 and HT‐29 mammalian cell lines. Furthermore, the cellular uptake and the intracellular distribution of compounds 2 , 3 and Cr(NO3)3 in B. subtilis were studied using atomic absorption spectroscopy to gain insight in to the possible cellular targets. Compound 2 was found to be readily taken up and distributed almost equally among cytosol, cell debris and cell membrane in B. subtilis.  相似文献   
86.
In this paper, we derive a model for the two-phase freezing process of supercooled fluids. Especially, we take density changes along the phase interfaces into account. Thus, besides heat diffusion and the interface phenomena, mass transport and convection in the fluid phase which is given by the full Navier–Stokes equations has to be considered. For the 2D case we implemented an algorithm for the numerical solution of the mathematical model using uniform volume cells for a finite difference discretization. Additionally, the phase boundaries are captured by a surface tracking method. We report on the mathematical model and its derivation, describe the numerical algorithm and present numerical experiments. Received: 11 September 1997 / Accepted: 19 June 1998  相似文献   
87.
88.
Moment stability for linear systems with a random parametric excitation   总被引:1,自引:0,他引:1  
Moment stability for linear systems with a nonwhite parametric noise is considered. A method of reduction of the study of this stability to the study of stability for large-scale matrices is proposed. Mean square stability diagrams for random harmonic oscillator are presented.  相似文献   
89.
An intermediate moisture food (IMF), has been developed in our laboratory for elder people, over 60 years. The IMF is based on a cereal: legume mixture with calcium and flavour, it supplies proteins, carbohydrates and vegetable oils; as well as, high energetic density (3.22 cal/g) and covers up to 51% of calcium needed. It can be easily consumed as a tasty and soft food. It has a water activity of 0.80, for it can be stored at room conditions. It is very likely that IMF becomes a good alternative to improve and vary elder peoples diet.  相似文献   
90.
The present review describes the work carried out during the last 20 years in the field of the radioprotective activity and toxicity of several classes of organosilicon and organogermanium compounds (i.e. metallathiazolidines, metalladithioacetals, metallatranes and germathianes).  相似文献   
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