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排序方式: 共有133条查询结果,搜索用时 31 毫秒
91.
Lunar surface magnetic fields and their interaction with the solar wind: results from lunar prospector 总被引:1,自引:0,他引:1
RP Lin DL Mitchell DW Curtis KA Anderson CW Carlson J McFadden MH Acuna LL Hood A Binder 《Science (New York, N.Y.)》1998,281(5382):1480-1484
The magnetometer and electron reflectometer experiment on the Lunar Prospector spacecraft has obtained maps of lunar crustal magnetic fields and observed the interaction between the solar wind and regions of strong crustal magnetic fields at high selenographic latitude (30 degreesS to 80 degreesS) and low ( approximately 100 kilometers) altitude. Electron reflection maps of the regions antipodal to the Imbrium and Serenitatis impact basins, extending to 80 degreesS latitude, show that crustal magnetic fields fill most of the antipodal zones of those basins. This finding provides further evidence for the hypothesis that basin-forming impacts result in magnetization of the lunar crust at their antipodes. The crustal magnetic fields of the Imbrium antipode region are strong enough to deflect the solar wind and form a miniature (100 to several hundred kilometers across) magnetosphere, magnetosheath, and bow shock system. 相似文献
92.
Guilherme Lobato Menezes Alan Figueiredo de Oliveira Frederico Patrus Ananias de Assis Pires Lúcio Carlos Gonçalves Rafael Araújo de Menezes Pamella Grossi de Sousa Paulo Henrique Arruda de Medeiros Matheus Morais de Pinho Ângela Maria Quintão Lana Vânia Eloisa de Araújo Diogo Gonzaga Jayme 《Grass and Forage Science》2023,78(1):1-22
The effects of different additives on farm-scale silage quality and beef cattle performance are inconsistent. This study aimed to carry out a systematic review and meta-analysis to evaluate the efficacy of chemical and microbial additives to silage on beef cattle performance. Systematic searches were performed using databases and scientific journals, and 42 articles were selected. Data for all variables were grouped into subgroups according to the additive type. For dry matter intake and average daily gain, the data were also grouped by forage type due to greater comparison numbers. The treatment mean differences and 95% confidence intervals (p < 0.05) were analysed using a random-effects model. The use of homo- and heterofermentative microbial inoculant mixtures and chemical additives (Ch) increased the average daily gain of beef cattle fed maize/sorghum silage. Homofermentative microbial inoculant (Ho), Ch, and a mixture of microbial inoculant and chemical additives also increased the average daily gain of beef cattle fed temperate grasses. Only Ch increased dry matter intake. Ch increased feed efficiency, and Ch and Ho increased carcass weight. The evaluated additives improved the silage fermentation process mainly via pH and ammonia nitrogen reduction. Overall, this meta-analysis demonstrated that silage additives improved the ensiling process and beef cattle performance, with better results with Ch use. Due to the aerobic stability and microbiological profile analyses being carried out more in laboratory-scale silos, more studies are needed to determine these silage parameters after opening the silo at the farm scale. 相似文献
93.
Ramos MI Siqueira EM Isomura CC Barbosa AM Arruda SF 《Journal of agricultural and food chemistry》2007,55(8):3186-3190
Carotenoid bioavailability is influenced by various factors including the food matrix. The release of those molecules from the food matrix is the initial and most important step in the absorption process. The relative bioavailability of bocaiuva pulp beta-carotene in relation to pure beta-carotene was assayed by a hepatic retinol store, in vitamin A deficient Wistar rats. After the depletion period, the vitamin A deficient rats were separated into two groups and fed an AIN-93G modified diet, which contained 14 400 microg of pure beta-carotene (beta-carotene diet) or 13 475 microg of beta-carotene from 275 g of bocaiuva pulp (bocaiuva diet) per 1 kg of the diet as a vitamin A source. Both experimental diets resulted in similar body weight gains. The bioavailability, estimated as Retinol Accumulation Factor, was 7.3 and 3.5 for the beta-carotene and the Bocaiuva group, respectively. These results show that in spite of the matrix of the bocaiuva pulp, the beta-carotene bioavailability from this fruit was higher than the pure beta-carotene. 相似文献
94.
95.
Silva Patrícia F. N. Alfieri Alice F. Barry Aline F. de Arruda Leme Raquel Gardinali Noemi R. van der Poel Wim H. M. Alfieri Amauri Alcindo 《Tropical animal health and production》2015,47(1):237-241
Tropical Animal Health and Production - Norovirus (NoV) is a member of the Caliciviridae family and is considered an emerging human enteric pathogen. NoVs are detected in farm animals such as... 相似文献
96.
Andreia G. Arruda Zvonimir Poljak Robert Friendship Jane Carpenter Karen Hand 《Canadian journal of veterinary research》2015,79(4):268-278
The objectives of this study were to describe demographics, basic biosecurity practices, ownership structure, and prevalence of porcine reproductive and respiratory syndrome (PRRS) in swine sites located in 3 regions in Ontario, and investigate the presence of spatial clustering and clusters of PRRS positive sites in the 3 regions. A total of 370 swine sites were enrolled in Area Regional Control and Elimination projects in Niagara, Watford, and Perth from 2010 to 2013. Demographics, biosecurity, and site ownership data were collected using a standardized questionnaire and site locations were obtained from an industry organization. Status was assigned on the basis of available diagnostic tests and/or assessment by site veterinarians. Spatial dependence was investigated using the D-function, the spatial scan statistic test and the spatial relative risk method. Results showed that the use of strict all-in all-out (AIAO) pig flow and shower before entry are uncommon biosecurity practices in swine sites, but a larger proportion of sites reported having a Danish entry. The prevalence of PRRS in the 3 regions ranged from 17% to 48% and localized high and low risk clusters were detected. Sites enrolled in the PRRS control projects were characterized by membership in multiple and overlapping ownership structures and networks, which complicates the way the results of monitoring and disease management measures are communicated to the target population. 相似文献
97.
Comparison of two different centrifugation extenders for preservation of frozen equine semen
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M. Leão Freitas C. Silva Bouéres F. J. Gonçalves de Oliveira M. A. de Oliveira Viu R. Arruda de Oliveira 《Equine Veterinary Education》2015,27(8):410-413
This study compares a commercial semen extender (control group) to ultra high temperature (UHT) skimmed milk (treatment group) used during centrifugation for subsequent cryopreservation of equine semen. Following post‐thawing of semen samples parameters measured included motility, sperm motion kinetics (using computerised assisted semen analysis) as well as acrosome and plasmatic membrane integrity (using fluorescent dyes). After collection and analysis, the sperm‐rich fraction was divided and diluted with either: control (1:1 dilution in a skimmed milk‐glucose extender) or treatment (1:1 dilution in UHT skimmed milk). The milk used in this experiment was of the same source, commercial brand, of only one lot. After dilution, samples were subjected to centrifugation at 600 g for 10 min and sperm pellets were resuspended in a freezing extender to a concentration of 200 × 106 cells/ml. Aliquots were packed into 0.5 ml straws placed in a stainless steel support and kept inside the refrigerator (5°C) for 20 min. Subsequently, these straws were placed at a height of 6 cm over liquid nitrogen for 20 min in an isotherm box. No significant differences were observed in total sperm motility (42.71 vs. 38.29%), progressive sperm motility (12.29 vs. 7.86%), plasma membrane integrity (53.43 vs. 60.14%) or acrosomal membrane integrity (93.29 vs. 93.71%) with a P>0.05 calculated between the control and the treatment groups, respectively. Considering that UHT skimmed milk has a lower cost than the commercial semen extender, this could be an option used during the centrifugation protocol to decrease the expense of the equine semen cryopreservation process and increase shelf life. 相似文献
98.
Camille E. Granada Letícia Arruda Bruno Brito Lisboa Luciane M. P. Passaglia Luciano K. Vargas 《Biology and Fertility of Soils》2014,50(1):123-132
In this study, rhizobia strains isolated from white clover (Trifolium repens) root nodules were evaluated in an effort to identify an efficient nitrogen-fixing rhizobia strain that can also improve the growth of rice plants (Oryza sativa). White clover plants were collected from seven sites in south Brazil, and 78 native rhizobia isolates were obtained. The genetic diversity analysis of those isolates was carried out by BOX-polymerase chain reaction. Overall, the native rhizobia isolated showed a high genetic diversity, but when the bacterial isolates from the same site were compared, the diversity was lower. One native rhizobia, POA3 (isolated from the Porto Alegre locality), was able to promote the growth of both plants and is therefore a good candidate for new inoculant formulation. Finally, we can conclude that the community of native rhizobia symbiont of white clover plants in southern Brazil is highly diverse and the growth promotion effect of rhizobia inoculation on rice plants was more pronounced in a poor nutrient substrate condition than in a rich nutrient substrate condition. 相似文献
99.
Shirley Andrea Florez-Rodriguez Rubens Paes de Arruda Maíra Bianchi Rodrigues Alves Fernanda Jordão Affonso Henrique Fulaneti Carvalho Kleber Menegon Lemes Renata Lançoni André Furugen Cesar de Andrade Eneiva Carla Carvalho Celeghini 《Journal of Equine Veterinary Science》2014
The aim of this study was to assess extenders for cooling equine semen at 5°C and to be used in assisted reproductive technologies (ARTs). Four ejaculates were obtained from each of four stallions. Gel-free semen was diluted in three different extenders: (1) SMK, an opaque skim milk–based extender; (2) SMT, a skim milk (65%) and Tyrode medium (35%); and (3) BSAG, a clear extender containing 1% bovine serum albumin. Samples were packaged (10 mL; 50 × 106 sperm/mL) and stored in a cooling device at 5°C for 12 hours. Analyses were done at 0, 4, 8, and 12 hours after cooling. Semen was analyzed for sperm motility characteristics using a computer-assisted sperm analysis, for plasma membrane and acrosome integrity and mitochondrial membrane potential, using fluorescent probes (propidium iodide, Hoechst 33342, fluorescein isothiocyanate–conjugated Pisum sativum agglutinin, and 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolyl carbocyanine iodide [JC-1]). Morphology was evaluated with differential interference contrast microscopy and sperm chromatin integrity by the toluidine blue technique. Data were analyzed by analysis of variance and by Tukey test, with time as a repeated measure (SAS, 1998), when P < .05 was significant. In general, milk-based extenders (SMT and SMK) showed improved maintenance of semen quality compared with BSAG. Finally, the addition of skim milk to equine semen extender for cooling at 5°C for 12 hours seems to play a crucial role in sperm preservation. Although, optically clearer extenders are desired for use in ARTs, such as sperm sexing, the milk-free extender (BSAG) is less efficient for cooled-stored equine semen. 相似文献
100.