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71.
André Andrian Padial João Carlos Nabout Tadeu Siqueira Luis Mauricio Bini José Alexandre Felizola Diniz-Filho 《Scientometrics》2010,85(1):1-12
Citation frequency has been considered a biased surrogate of publication merit. However, previous studies on this subject
were based on small sample sizes and were entirely based on null-hypothesis significance testing. Here we evaluated the relative
effects of different predictors on citation frequency of ecological articles using an information theory framework designed
to evaluate multiple competing hypotheses. Supposed predictors of citation frequency (e.g., number of authors, length of articles)
accounted for a low fraction of the total variation. We argue that biases concerning citation are minor in ecology and further
studies that attempt to quantify the scientific relevance of an article, aiming to make further relationships with citation,
are needed to advance our understanding of why an article is cited. 相似文献
72.
Priscilla Carvalho José Alexandre Felizola Diniz-Filho Luis Mauricio Bini 《Scientometrics》2005,62(1):53-66
Summary Programs in global environmental change research call for sweeping international cooperation and the creation of global networks. This paper analyzes to what extent research institutions in the field of global environmental change have responded to this call. Several bibliometric indicators of internationalization are discussed. A German and a U.S. sample are compared. The results indicate that a very discernable trend of recent internationalization can be observed. This is in line with a general internationalization trend across all fields, but at a much higher level. Given the political emphasis on capacity building in developing countries in this research field, however, there is only weak evidence of a more encompassing globalization process which also includes marginal world regions. Finally, the internationalization trend does not coincide with de-nationalization. 相似文献
73.
Fish crackers are semi-prepared starch-based products which must be expanded just prior to consumption. This work aims at the experimental and theoretical study of the thin-layer drying process of fish crackers in a thin disc geometry. The process was carried out in an insulated cabinet dryer and the experimental kinetic drying data were fitted using the analytical solutions resulting from both a drying model governed by the Fick' s second law and a model based on the lumped system, highlighting the adequacy of each of them. Therefore, it was possible to calculate the mass transfer coefficients for seven different blends offish crackers. Also, the effect of the drying time on the bulk density of the puffed product was evaluated for these seven blends. Both the kinetic drying parameters and the optimal bulk density responses were analyzed using the Simplex-Lattice Design over a mixture triangle within a minimal number of experiments. 相似文献
74.
Coupled reliability model of biodeterioration, chloride ingress and cracking for reinforced concrete structures 总被引:1,自引:0,他引:1
Emilio Bastidas-Arteaga Mauricio Snchez-Silva Alaa Chateauneuf Moema Ribas Silva 《Structural Safety》2008,30(2):110-129
Maintaining and operating civil infrastructure systems has been recognized as a critical issue worldwide. Among all possible causes of safety reduction during the structural lifetime, deterioration is particularly important. Structural deterioration is usually a slow time-dependent process controlled by safety and operation threshold specifications. This paper presents a model of RC deterioration by coupling biodeterioration (i.e., chemical, physical and mechanical action of live organisms), steel corrosion, and concrete cracking. The final purpose of the model is to compute the reduction of the concrete section and the area of steel reinforcement in order to assess the change of structural capacity with time. Given the uncertainties in both the parameters and the model, the probabilistic nature of loads, the material properties and the diffusion process are taken into account to evaluate structural reliability. The model is illustrated with an example where the inelastic behavior of a pile subject to random loading is considered. The results of the analysis have shown that the effect of biodeterioration on the structural performance is significant and can cause an important reduction of its lifetime. On the whole, the paper states that modeling the effects of biodeterioration in RC structures should be included as part of infrastructure planning and design, especially, when they are located in aggressive environments. 相似文献
75.
Simultaneous bilateral ablation of the teleost telencephalon was confirmed to impair the retention, extinction, and reversal learning of a preoperatively learned instrumental avoidance response in a shuttle box. The focus of the experiment, using 30 goldfish, was on whether 2-stage serial unilateral ablations of the teleost telencephalon would ameliorate the effects seen following 1-stage bilateral ablation and whether such amelioration would be a function of S's experiences between the staged ablations. The degree of retention, relearning, and extinction of the avoidance response was not modulated by the serial ablation procedure whether or not there was interoperation retraining experience. However, reversal learning, in which the previous warning signal became the safety signal and the previous safety signal became the new warning signal, was less impaired following serial ablations than following single-stage bilateral ablation. Results are contrasted with those from experiments with mammalian Ss. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
Silicon carbide square tiles of different areal geometries and manufactured via two different processing routes have been bonded to polycarbonate layers to evaluate their ballistic performance. Four ceramic tile sizes were tested: 85 mm, 60 mm, 50 mm and 33 mm. In each case the residual depth-of-penetration into a polycarbonate semi-infinite backing was recorded. To elucidate the penetration and failure mechanisms, a computational model using the JH-1 ceramic model [Holmquist TJ, Johnson GR. Response of silicon carbide to high velocity impact. J Appl Phys 2002;91:5858–66] of the projectile used in the experimental study penetrating into a silicon carbide-faced polycarbonate was implemented in the hydrocode AUTODYN-2D. This paper shows that there is a critical dimension of tile that should be used in a silicon carbide-based ceramic-faced mosaic armour system design to ensure optimum system performance when each tile is struck centrally. 相似文献
77.
Mauricio Osorio Marcela Carvajal Alejandra Vergara Estefania Butassi Susana Zacchino Carolina Mascayano Margarita Montoya Sophia Mejías Marcelo Cortez-San Martín Yesseny Vsquez-Martínez 《International journal of molecular sciences》2021,22(11)
Prenylated flavonoids are an important class of naturally occurring flavonoids with important biological activity, but their low abundance in nature limits their application in medicines. Here, we showed the hemisynthesis and the determination of various biological activities of seven prenylated flavonoids, named 7–13, with an emphasis on antimicrobial ones. Compounds 9, 11, and 12 showed inhibitory activity against human pathogenic fungi. Compounds 11, 12 (flavanones) and 13 (isoflavone) were the most active against clinical isolated Staphylococcus aureus MRSA, showing that structural requirements as prenylation at position C-6 or C-8 and OH at positions C-5, 7, and 4′ are key to the antibacterial activity. The combination of 11 or 12 with commercial antibiotics synergistically enhanced the antibacterial activity of vancomycin, ciprofloxacin, and methicillin in a factor of 10 to 100 times against drug-resistant bacteria. Compound 11 combined with ciprofloxacin was able to decrease the levels of ROS generated by ciprofloxacin. According to docking results of S enantiomer of 11 with ATP-binding cassette transporter showed the most favorable binding energy; however, more studies are needed to support this result. 相似文献
78.
Reaction of CrCl3(THF)3 with K[HB(pz)3] in THF leads to the formation of the complex K[CrCl3{HB(pz)3}] (1). The salt metathesis of complex 1 with [Ph4P]Br in CH2Cl2 yields the complex [Ph4P][CrCl3{HB(pz)3}](2). The structure of complex 2 · CHCl3 has been determined by single crystal X-ray diffraction. In the anion the metal centre shows a distorted octahedral geometry with the hydrotris(1-pyrazolyl)borate bonded as N,N′,N″-donor tripod ligand and three chloride atoms completing the co-ordination sphere. Complex 2 in the presence of MAO leads to the formation of an active catalyst for the polymerization of ethylene. 相似文献
79.
Carrillo Zeledón G Redondo Solano M Arias Echandi ML 《Archivos latinoamericanos de nutrición》2010,60(2):175-178
Listeria monocytogenes is a bacteria associated with the production of severe infectious disease in human being, but also with the formation of biofilms in different surfaces related to the food production environment. Biofilm represents a serious problem in food industry, since it is a constant and important contamination source and also, bacteria present in it have an increased resistance towards physical and chemical agents of common use. The capacity of biofilm formation of L. monocytogenes strains previously isolated from soft cheese samples from Costa Rica was studied under different temperature and culture conditions. The microplate technique was performed using different culture media (BHIB, TSB 1:20 and cheese serum) and at different incubation temperatures (refrigeration, environmental and 35 degrees C). Biofilm formation capacity was classified according to the optical density obtained at 620 nm. None of the strains evaluated was classified as strong biofilm former under any of the variables studied, nevertheless, weak and moderate formers were detected. The results obtained show the influence of the nutrient content of the culture media used over biofilm formation; BHIB was the only culture media that allowed the expression of moderate biofilm forms, contrary to cheese serum that did not promote biofilm production. Biofilm formation is a multifactorial process, where adsorption level depends on several variables and its study must be promoted in order to develop methodologies that allow its reduction or elimination, so food industries may offer safe food products to consumers. 相似文献
80.
John Hurtado Andrés Ibañez René Rojas Mauricio Valderrama 《Inorganic chemistry communications》2010,13(9):1025-1028
The reaction of 3,5-bis(bromomethyl)toluene with 1H-indazole in toluene, in the presence of triethylamine, yields the ligand 3,5-bis(indazol-2-ylmethyl)toluene (1). Compound 1 reacts with Pd(OAc)2 in refluxing acetic acid, followed by a metathetic reaction with lithium chloride and with [PdCl2(cod)] (cod = 1,5-cyclooctadiene) in refluxing acetonitrile to give the complexes [PdCl{3,5-bis(indazol-2-ylmethyl)tolyl-N,C,N}] (2) and [PdCl2{3,5-bis(indazol-2-ylmethyl)toluene-N,N}] (3), respectively. Compounds 1–3 were characterized by elemental analyses, mass spectra and IR and NMR (1H, 13C) spectroscopies. The molecular structure of 1 was also determined by single-crystal X-ray diffraction. The palladium(II) complexes (2,3) were tested as catalysts in ethylene polymerization and in C–C coupling reactions involving aryl halides substrates. 相似文献