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排序方式: 共有733条查询结果,搜索用时 15 毫秒
721.
Baduel C Monge ME Voisin D Jaffrezo JL George C Haddad IE Marchand N D'Anna B 《Environmental science & technology》2011,45(12):5238-5244
This work explores the heterogeneous reaction between HUmic-LIke Substances (so-called HULIS) and ozone. Genuine atmospheric HULIS were extracted from aerosol samples collected in Chamonix (France) in winter and used in coated flow tube experiments to evaluate heterogeneous uptake of O? on such mixtures. The uptake coefficient (γ) was investigated as a function of pH (from 2.5 to 10), O? concentration (from 8 to 33 × 1011 molecules cm?3), relative humidity (20 to 65%) and photon flux (from 0 to 1.66 × 101? photons cm?2 s?1). Reactive uptake was found to increase in the irradiated experiment with pH, humidity and photon flux. The extract was characterized before and after exposure to O? and/or UV light in the attempt to elucidate the effect of the photochemical aging. Carbon content measurements, UV-vis spectroscopy and functional groups analysis revealed a decrease of the UV absorbance as well as of the carbon mass content, while the functionalization rate (COOH and C═O) and therefore the polarity increased during the simulated photochemical exposure. 相似文献
722.
Tiwari A Vanleeuwen JA Dohoo IR Keefe GP Haddad JP Tremblay R Scott HM Whiting T 《Journal of dairy science》2007,90(2):659-669
The primary purpose of this research was to determine associations among seropositivity for bovine leukemia virus (BLV), bovine viral diarrhea virus (BVDV), Mycobacterium avium ssp. paratuberculosis (MAP), and Neospora caninum (NC) and each of 3 outcome variables (305-d milk, fat, and protein production) in Canadian dairy cattle. Serum samples from up to 30 randomly selected cows from 342 herds on monthly milk testing were tested for antibodies against BLV (IDEXX ELISA; IDEXX Corporation, Westbrook, ME), MAP (IDEXX or Biocor ELISA; Biocor Animal Health, Inc., Omaha, NE), and NC (IDEXX or Biovet ELISA; Biovet Inc., St. Hyacinthe, Quebec, Canada). Up to 5 unvaccinated cattle over 6 mo of age were tested for virus-neutralizing antibodies to the Singer strain of type 1 BVDV. Dairy Herd Improvement records were obtained electronically for all sampled cows. Linear mixed models with herd and cow as random variables were fit, with significant restricted maximum likelihood estimates of outcome effects being obtained, while controlling for potential confounding variables. Bovine leukemia virus seropositivity was not associated with 305-d milk, 305-d fat, or 305-d protein production. Cows in BVDV-seropositive herds (at least one unvaccinated animal with a titer ≥1:64) had reductions in 305-d milk, fat, and protein of 368, 10.2, and 9.5 kg, respectively, compared with cows in BVDV-seronegative herds. Mycobacterium avium ssp. paratuberculosis seropositivity was associated with lower 305-d milk of 212 kg in 4+-lactation cows compared with MAP-seronegative 4+-lactation cows. Neospora caninum seropositivity in primiparous cows was associated with lower 305-d milk, fat, and protein of 158, 5.5, and 3.3 kg, respectively, compared with NC-seronegative primiparous cows. There were no interactions among seropositivity for any of the pathogens and their effects on any of the outcomes examined, although the low MAP seroprevalence limited this analysis. Results from this research will contribute to understanding the economic impacts of these pathogens and justify their control. 相似文献
723.
L. Najafian A. Ghodsvali M.H. Haddad Khodaparast L.L. Diosady 《Food research international (Ottawa, Ont.)》2009,42(1):171-175
In the present study, the effects of olive variety (Kroneiki, Iranian Native Oleaginous and Mission), enzyme type (Pectinex Ultra SP-L and Pectinase 1.6021) and concentration (zero, low and high concentration) on the yield, total polyphenols, turbidity, colour, acidity, peroxide value and iodine value of three enzyme-treated virgin olive oil were investigated. A 3 × 2 × 3 completely randomized experimental design (CRD) with replications was carried out. The enzyme concentration had a highly significant effect (p < 0.01) on the yield, colour, turbidity and total polyphenol level of oil, but there were not significant effects (p < 0.05) on acidity, peroxide value and iodine value. Colour and phenolic compounds content in the oils showed significant differences (p < 0.05) between 13.0–62.2% and 13.9–72.6%, respectively, as compared with control. Turbidity was reduced significantly (p < 0.01) 25.9–67.4%. On the basis of our results, the yield of oil was significantly (p < 0.01) increased (from 0.9% to 2.4%) by using processing aid. Pectinex Ultra SP-L was more effective than Pectinase 1.06021. In the case of applying Ultra pectinex SP-L, the additional income due to extra recovered oil will be 18.8 times as much production overhead. 相似文献
724.
P Haddad JF Thaell JM Kiely EG Harrison RH Miller 《Canadian Metallurgical Quarterly》1976,38(4):1862-1866
Ninety-four patients with lymphoma involving the extradural space with spinal cord compression proven at the time of laminectomy were reviewed. There were about three times as many patients with non-Hodgkin's lymphoma than with Hodgkin's disease. The majority of those with Hodgkin's disease had a proven histologic diagnosis before the onset of the spinal cord compression syndrome, whereas only 15% of those with non-Hodgkin's lymphoma had previously been so diagnosed. Plain roentgenograms of the spine were suggestive of tumor involvement in less than one-third of the patients, whereas myelograms were invariably abnormal. As noted by others, the outlook for functional recovery and extended life expectancy is relatively good for patients with this type of cancer, in contrast to reports in the literature regarding prognosis for patients who have metastatic carcinoma with extradural spinal cord compression. 相似文献
725.
Hollow metallic nanostructures exhibit important applications in catalysis, sensing, and phototherapy due to their increased surface areas, reduced densities, and unique optical and electronic features. Here we report a facile photocatalytic process to synthesize and tune hollow platinum (Pt) nanostructures. Through hierarchically structured templates, well-defined hollow Pt nanostructures are achieved. These nanostructures possess interconnected nanoporous framework as shell with high surface area for enhanced catalytic performance/mass transport for methanol oxidation. 相似文献
726.
This contribution deals with the discrimination between stratiform and convective cells in meteorological radar images. This study is based on a textural analysis of the latter and their classification using a support vector machine(SVM). First, we apply different textural parameters such as energy, entropy, inertia, and local homogeneity. Through this experience, we identify the different textural features of both the stratiform and convective cells. Then, we use an SVM to find the best discriminating parameter between the two types of clouds. The main goal of this work is to better apply the Palmer and Marshall Z-R relations specific to each type of precipitation. 相似文献
727.
Atiyeh Bozorgi Omid Bozorg‐Haddad Somayeh Sima Hugo A. Loiciga 《Water and Environment Journal》2021,35(1):218-228
Reservoirs are the key infrastructure of water resources management. A controlling variable of reservoir operation is evaporation, which in semi‐arid and arid regions may consume a large fraction of reservoir storage annually. This paper assesses the role of evaporation and the choice of evaporation methods on reservoir operation. The operation of the reservoir is calculated with the standard operation policy (SOP). Several efficiency criteria are employed to rank the evaporation‐calculation methods with the technique for the order of preference by similarity to ideal solution (TOPSIS). The method presented in this paper is illustrated by applying its application to Karkheh reservoir, the largest in Iran. 相似文献
728.
Mechab Belaïd Chioukh Nadji Mechab Boubaker Serier Boualem 《Journal of Failure Analysis and Prevention》2018,18(6):1643-1651
Journal of Failure Analysis and Prevention - In this paper, we present a probabilistic fracture mechanics methodology to analyze elastic and elastic–plastic fracture of semi-elliptical... 相似文献
729.
Buppo R.T. Bernstein D.S. Chellaboina V.S. Haddad W.M. 《Automatic Control, IEEE Transactions on》2000,45(4):776-780
Finite settling time control of the double integrator is considered. The approach taken is to design a compensator based on a virtual lossless absorber which is tuned so that, at some predetermined time, the virtual subsystem possesses all of the system's energy. At this time the controller is turned off, and the double integrator remains at rest at the origin. This strategy gives the appearance of instantaneously removing all of the system's energy as if a trap door had been sprung. A practically useful feature of the virtual trap-door absorber is that only position measurement is required. Parameters for the virtual trap-door absorber controller are chosen, and the resulting controller is compared to the classical minimal-time and minimal-energy controllers, which require measurements of both position and velocity 相似文献
730.
VijaySekhar Chellaboina Wassim M. Haddad Dennis S. Bernstein David A. Wilson 《Mathematics of Control, Signals, and Systems (MCSS)》2000,13(3):216-239
In this paper we develop explicit formulas for induced convolution operator norms and their bounds. These results generalize established induced operator norms for linear dynamical systems with various classes of input–output signal pairs. Date received: April 1, 1999. Date revised: February 21, 2000. 相似文献