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排序方式: 共有242条查询结果,搜索用时 46 毫秒
71.
Sangsritavong S Combs DK Sartori R Armentano LE Wiltbank MC 《Journal of dairy science》2002,85(11):2831-2842
Increased liver blood flow (LBF) resulting from elevated feed intake in lactating dairy cows may increase steroid metabolism. Continuous infusion of bromosulphthalein (BSP; specifically metabolized in liver) was used to measure LBF. Similarly, progesterone (P4) and estradiol-17beta (E2) were administered by continuous infusion. Circulating concentrations at steady state were used to calculate the metabolic clearance rate (MCR) of BSP, P4, and E2. Experiment 1: Variation in LBF was determined in thee nonlactating and four lactating cows over 3 d at 3 to 5 h after feeding. Coefficients of variation ranged from 14 to 31% among cows within day and from 4 to 8% within cows across days. Experiment 2: Six nonlactating cows were used in a 3 x 3 Latin-square design with three feed regimens: no feed, 0.5 maintenance diet (M), and 1.5 M. Experiment 3: Eight lactating cows were used in a 4 x 4 Latin-square design with four feed regimens: no feed, 0.5 M, 1.5 M, and 2.2 M. In experiments 2 and 3, LBF and MCR of P4 increased immediately after feed consumption and increases persisted longer at higher intakes. The LBF reached a maximum at 2 h after feeding and MCR of P4 reached maximum at 3 h after feeding with a positive correlation (r = 0.92) between LBF and MCR for P4. Experiment 4: A crossover design was used to determine MCR of E2 in unfed or full-fed lactating dairy cows. The MCR of E2 increased immediately after feeding and stayed elevated throughout the 4.5-h infusion period. Thus, LBF and steroid metabolism were acutely elevated by feed consumption in lactating and nonlactating cows. Higher rates of LBF and steroid metabolism in lactating than in nonlactating cows may indicate chronic effects of higher feed intakes as well. 相似文献
72.
Wolfgang Habel Peter Sartori Thomas Windmann 《Advanced Synthesis \u0026amp; Catalysis》1996,338(1):702-705
Carbon-branched Poly(phenylcarbosilanes) and Derivatives A series of carbon cross-linked poly(phenylcarbosilanes) was synthesized through the reaction of dichlorodiphenylsilane, α,α,α-trichlorotoluene and dibromomethane with sodium as the reducing agent. The oligomeric and solid products of the general composition [(Ph2Si)n+1,5(PhC) (CH2)n]x (with n = 2, 3, 5 or 10) were analysed and investigated by IR, 1H, 13C, 29Si NMR spectroscopy, and gel permeation chromatography. The ceramic yields were determined via pyrolysis at 1000 °C. The branched poly(carbosilane) [(Ph2Si)4,5(PhC)(CH2)3]x was chlorinated with HCl and the product obtained was transformed by the Grignard reaction with ethynylmagnesiumbromid into the unsaturated poly(carbosilane) [((HCC)2Si)4,5(PhC)(CH2)3]x. 相似文献
73.
„One-Pot”︁ Syntheses, Modifications and Applicabilities of Poly(carbosilanes) The modification of poly(carbosilanes) and the investigation of their application as binding agents and sintering additives in the production of pressurelessly sintered SiC-bulks as well as their effectiveness as precursors for SiC-fibers is of considerable interest. The synthesis of suitable compounds considers the variation of the carbosilane bridge, the following reactions of functional groups, the backbone branching at silicon and carbon atoms, and the insertion of heteroelements, especially boron and titanium. Different synthetic routes were used for the preparation of modified phenyl-containing poly(carbosilanes). The pyrolytic method, developed by YAJIMA and coworkers, transformed the methyl-containing poly(silanes) into poly(carbosilanes). The addition of polyborodiphenylsiloxane gave products with boron in the molecular sceleton. The development of a one step synthesis in analogy to the Wurtz-polycondensation leads to a series of methylene- and phenylethylene-bridged oligomeric compounds. Furthermore, branched and the heteroelements boron- and titanium-containing poly(carbosilanes) were obtained. The substitution of the functional phenyl groups leads to halogenated and alkyl-, alkenyl-, as well as alkynyl-substituted oligomers. Modified poly(carbosilanes) with unsaturated functional groups or SiH were prepared via Grignard-coupling. Beside benzylidene the units diphenylmethylene, p-xylylene and p-phenylene were used as carbosilane bridges. Directly synthesized copolymers were applicable as binding agents and sintering additives for the production of pressurelessly sintered SiC-bulks. Ethynyl-substituted poly(carbosilanes) were used as precursors for the production of oxygen-free SiC-fibers. 相似文献
74.
75.
F. Romanelli J. Paméla R. Kamendje M.L. Watkins S. Brezinsek Y. Liang X. Litaudon T. Loarer D. Moreau D. Mazon G. Saibene F. Sartori P.C. de Vries 《Fusion Engineering and Design》2009,84(2-6):150-160
In recent years the JET scientific programme has focussed on addressing physics issues essential for the consolidation of design choices and the efficient exploitation of ITER in parallel to qualifying ITER operating scenarios and developing advanced control tools. This paper reports on recent achievements in the following areas: mitigation of edge localised modes (ELMs), effects of toroidal field (TF) ripple, advanced tokamak scenarios, material migration and fuel retention. Active methods have been developed to mitigate ELMs without adversely affecting confinement. A systematic characterisation of the edge plasma, pedestal energy and ELMs, and their impact on plasma-facing components as well as their compatibility with material limits has been performed. The unique JET capability of varying the TF ripple from its normal low value δBT = 0.08% up to δBT = 1% has been used to elucidate the role of TF ripple on confinement and ELMs. Increased TF ripple in ELMy H-mode plasmas is found to have a detrimental effect on plasma stored energy and density, especially at low collisionality. The development of ITER advanced tokamak scenarios has been pursued. In particular, βN values above the ‘no-wall limit’ (βN ~ 3.0) have been sustained for a resistive time. Gas balance studies combined with shot-resolved measurements from deposition monitors and divertor spectroscopy have confirmed the strong role of fuel co-deposition with carbon in the retention mechanism through long-range migration and also provided further evidence for the important role of ELMs in the material migration process within the JET inner divertor leg. 相似文献
76.
Maria Antonia Calori-Domingues Carolina Maria Gil Bernardi Mariana Sartori Nardin Gláucia Vendramini de Souza Fernanda Gregório Ribeiro dos Santos Mirella de Abreu Stein 《Food Additives and Contaminants: Part B: Surveillance Communications》2016,9(2):142-151
Fusarium mycotoxins deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN) were investigated in wheat from the 2009 and 2010 crop years. Samples (n = 745) from commercial fields were collected in four wheat producing regions (WPR) which differed in weather conditions. Analyses were performed using HPLC-DAD. Contamination with ZEN, DON and NIV occurred in 56, 86 and 50%, respectively. Also, mean concentrations were different: DON = 1046 µg kg?1, NIV < 100 µg kg?1 and ZEN = 82 µg kg?1. Co-occurrence of ZEN, DON and NIV was observed in 74% of the samples from 2009 and in 12% from 2010. Wet/cold region WPR I had the highest mycotoxin concentration. Wet/moderately hot region WPR II had the lowest mycotoxin levels. Furthermore, the mean concentration of each mycotoxin was higher in samples from 2009 as compared with those from 2010. Precipitation during flowering or harvest periods may explain these results. 相似文献
77.
Rute Quelvia de Faria Amanda Rithieli Pereira dos Santos Yvan Gariepy Edvaldo Aparecido Amaral da Silva Maria Márcia Pereira Sartori Vijaya Raghavan 《Drying Technology》2020,38(5-6):676-684
AbstractThe heating and drying of various types of food using microwave improve the economy of time and energy. The physiological quality variation of the seeds submitted to microwave drying is known to some extent. In this context, some authors have reported excellent performance using this technique, on germination rates, after drying. The commercial use of microwave drying in seeds is irrelevant, which motivates more extensive research on the benefits and challenges of this technique that can increase its insertion in the post-harvest handling steps of agricultural products. Corn is a product of high worldwide relevance. Therefore, the use of microwaves in its drying process has excellent potential to arrive at significant savings in its production. Thus, this study is aimed to evaluate the effects on the physiological quality of the seeds submitted to different drying conditions, using the microwave radiation. To that end, corn seeds, with a water content of 20% on wet basis (w.b.), were dried at 40, 50, and 60?°C, at power ratings of 0, 0.6, and 1.2?W/g; in the vacuum condition. Drying occurred continuously, with intermittent power, until the seeds reached the 12% wet basis; in this condition, the seeds could be stored with secure. Germination tests performed shortly after drying showed that the temperature of 40?°C at a power of 0.6?W/g had a reduction in drying time of approximately 5?h when compared to conventional drying (40?°C and 0.0?W/g). The evaluation of the physiological quality of the seeds showed no significant difference in the germination, vigor, and longevity indices of the treated seeds. 相似文献
78.
Fluid Flow Effect and Mechanical Interactions during Drying of a Deformable Food Model 总被引:1,自引:0,他引:1
The purpose of this work was to evaluate a mathematical representation for the drying of a spherical food model, including the fluid flow effect and mechanical interactions. Drying kinetics data were obtained under a laminar fluid flow and the mechanical properties were evaluated through compression tests. The drying model considers two-dimensional mass transfer and the mechanical model was formulated from elasticity theory. The solution made possible the understanding of the fluid flow effect on mass transfer and the relationship between drying stresses and physical degradation of the food models. 相似文献
79.
80.
SC Humphreys SD Hodges A Patwardhan JC Eck LA Covington M Sartori 《Canadian Metallurgical Quarterly》1998,23(20):2180-2184
STUDY DESIGN: This study was intended to identify normal degenerative morphologic evolution in the bony foramen in asymptomatic subjects by decade in comparison with symptomatic subjects of like decades. OBJECTIVES: To determine normal degenerative changes in the cervical spine caused by the aging process that predispose a person to foraminal stenosis and radiculopathy. SUMMARY OF BACKGROUND DATA: Cervical radiculopathy is a common problem caused by degenerative changes as people age. The characteristics of the foramen that result in stenosis are not known. METHODS: Five to six symptomatic and asymptomatic people in each decade volunteered for magnetic resonance imaging. Lordosis, disc heights, and ratio of spinal cord diameter to spinal canal diameter were measured at C4-C5, C5-C6, and C6-C7 from sagittal magnetic resonance images. Foraminal heights, widths, and areas were measured at the isthmus of the same foramen from oblique images. RESULTS: Foraminal heights, widths, and areas were larger in asymptomatic patients than in symptomatic patients. Morphologic analysis showed that inferior facet hypertrophy tended to decrease the width of the foramen in aging people. Disc heights, lordosis, and ratio of spinal cord diameter to spinal canal diameter showed no significant differences. CONCLUSIONS: Foraminal height affects overall foraminal area but tends to change little with age. Width also affects overall area and not only decreases in older people but also significantly affects the available area for the exiting nerve root. 相似文献