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排序方式: 共有854条查询结果,搜索用时 46 毫秒
741.
742.
Russo Maria L. Jaber Lara R. Scorsetti Ana C. Vianna Florencia Cabello Marta N. Pelizza Sebastian A. 《Journal of pest science》2021,94(3):859-870
Journal of Pest Science - Fall armyworm (FAW), Spodoptera frugiperda, is a migratory polyphagous pest that causes major damage to economically important cultivated grasses, such as corn. Native to... 相似文献
743.
Watters TR Campbell B Carter L Leuschen CJ Plaut JJ Picardi G Orosei R Safaeinili A Clifford SM Farrell WM Ivanov AB Phillips RJ Stofan ER 《Science (New York, N.Y.)》2007,318(5853):1125-1128
The equatorial Medusae Fossae Formation (MFF) is enigmatic and perhaps among the youngest geologic deposits on Mars. They are thought to be composed of volcanic ash, eolian sediments, or an ice-rich material analogous to polar layered deposits. The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument aboard the Mars Express Spacecraft has detected nadir echoes offset in time-delay from the surface return in orbits over MFF material. These echoes are interpreted to be from the subsurface interface between the MFF material and the underlying terrain. The delay time between the MFF surface and subsurface echoes is consistent with massive deposits emplaced on generally planar lowlands materials with a real dielectric constant of approximately 2.9 +/- 0.4. The real dielectric constant and the estimated dielectric losses are consistent with a substantial component of water ice. However, an anomalously low-density, ice-poor material cannot be ruled out. If ice-rich, the MFF must have a higher percentage of dust and sand than polar layered deposits. The volume of water in an ice-rich MFF deposit would be comparable to that of the south polar layered deposits. 相似文献
744.
Esch F Fabris S Zhou L Montini T Africh C Fornasiero P Comelli G Rosei R 《Science (New York, N.Y.)》2005,309(5735):752-755
The high performance of ceria (CeO2) as an oxygen buffer and active support for noble metals in catalysis relies on an efficient supply of lattice oxygen at reaction sites governed by oxygen vacancy formation. We used high-resolution scanning tunneling microscopy and density functional calculations to unravel the local structure of surface and subsurface oxygen vacancies on the (111) surface. Electrons left behind by released oxygen localize on cerium ions. Clusters of more than two vacancies exclusively expose these reduced cerium ions, primarily by including subsurface vacancies, which therefore play a crucial role in the process of vacancy cluster formation. These results have implications for our understanding of oxidation processes on reducible rare-earth oxides. 相似文献
745.
Mumma MJ Dello Russo N DiSanti MA Magee-Sauer K Novak RE Brittain S Rettig T McLean IS Reuter DC Xu LH 《Science (New York, N.Y.)》2001,292(5520):1334-1339
In the current paradigm, Oort cloud comets formed in the giant planets' region of the solar nebula, where temperatures and other conditions varied greatly. The measured compositions of four such comets (Halley, Hyakutake, Hale-Bopp, and Lee) are consistent with formation from interstellar ices in the cold nebular region beyond Uranus. The composition of comet C/1999 S4 (LINEAR) differs greatly, which suggests that its ices condensed from processed nebular gas, probably in the Jupiter-Saturn region. Its unusual organic composition may require reevaluation of the prebiotic organic material delivered to the young Earth by comets. 相似文献
746.
Fabrizio Adani Giovanni Gigliotti Federico Valentini Rosanna Laraia 《Compost science & utilization》2013,21(2):144-151
Three respirometric methods were tested using 18 organic matrices. Two methods were performed in the solid state condition using static (SRI) and dynamic approaches (DRI) while the third was performed in the liquid state (SOUR). The results obtained showed that all methods were able to describe biological stability and were well correlated. SOUR gave results that differed from DRI and SRI, which, in turn, showed good agreement. SOUR showed a good correlation with dissolved organic carbon, above all with the hydrophilic fraction, indicating that water media was responsible for the high availability of soluble organic material during initial hours of the test. The use of SOUR cumulative data (OD12 and OD20) reduced the effect of the soluble fraction on the measurement, thereby increasing the correlation coefficient with the solid state methods. 相似文献
747.
Giovanni Vallini Antonio Pera Franco Cecchi Manuela M. Valdrighi Marco A. Sicurani 《Compost science & utilization》2013,21(2):49-53
? Data of preliminary trials leading with aerobic biostabilization (composting) of algal biomass from different origins are reported and discussed in this paper. The green macroalga Ulva sp. bloomed in the Lagoon of Venice was first used in composting experiments; then the macrophyte Chaetomorpha sp. drawn in the Lagune of Orbetello (South Tuscany) was considered. A controlled composting system has been adopted where biomass aeration by forced pressure ventilation and turning of the algae mixed with wood shavings were provided. Results indicate that intensive compost stabilization (50 days of process) seems to be reliable for the management of huge amounts of algal material which annually accumulate in Italian lagoon ecosystems. This treatment allows disposal of such a putrescible biomass and recovery of its fertilizing value through the production of an organic amendment. 相似文献
748.
Yanhong Xu Federico Rossi Giovanni Colica Songqiang Deng Roberto De Philippis Lanzhou Chen 《Biology and Fertility of Soils》2013,49(2):143-152
The importance of cyanobacterial polysaccharides of biological soil crusts in sand surface stabilization and soil nutrient retention has been long acknowledged. However, the role of cyanobacterial polysaccharides as a source of nutrition to vascular plants in crusted areas is ignored. In this study, the chemical composition of the polysaccharide synthesized by Phormidium tenue and the effects of its presence on seed germination and seedling metabolism of the shrub Caragana korshinskii were investigated. The crude polysaccharide synthesized by P. tenue was composed of 15 % protein and 58 % carbohydrate and showed the presence of 12 different types of monosaccharides. The addition of the polysaccharide significantly (P?<?0.05) increased seed germination and metabolic activity of the seedling of the shrub C. korshinskii. The optimal concentration for vigor index, root length, root vigor, and total N and P contents was 10 mg/L polysaccharide; for the germination rate, nitrate reductase activity, carbohydrate content, chlorophyll, and Mg2+ content, the optimal was 60 mg/L polysaccharide, while for K+ and Ca2+ contents, photosynthetic efficiency and superoxide dismutase activity was 120 mg/L. The presence of the polysaccharide increased seed germination rate, ion uptake, and photosynthetic activity by affecting the electron transport chain and decreased oxidative damage by eliminating reactive oxygen species in C. korshinskii, thus promoting shrub performance in crusted desert areas. 相似文献
749.
L. Fontanesi L. Buttazzoni G. Galimberti D.G. Calò E. Scotti V. Russo 《Livestock Science》2013,157(1):48-56
Melanocortin 4 receptor (MC4R) plays a key role in controlling energy homeostasis. Several studies have already reported effects on production traits of polymorphisms identified in the porcine MC4R gene. In this study we analysed data on 6 MC4R polymorphisms (c.-780C>G; c.-135C>T; c.175C>T; c.707G>A or p.Arg236His; and c.892G>A or p.Asp298Asn; c.?430A>T) genotyped from (1) two groups of Italian Large White pigs (280+280 animals) with extreme estimated breeding values (EBVs) for back fat thickness (BFT), selected among a performance tested population of about 12,000 pigs, and from (2) 19 Italian Duroc pigs. Two haplotypes, differentiated by the c.892G>A, were identified in the Duroc populations. Four haplotypes were identified in the Italian Large White population, one of which (haplotype 4) was identified for the first time in this study. Single marker and haplotype association analyses for BFT were obtained by comparing allele and haplotype frequency differences from the two extreme tails using χ2 and Cochran–Armitage trend tests. Results confirmed the effects of the c.892G>A single nucleotide polymorphism (SNP) on BFT, as also defined by different distributions in the two tails of haplotypes carrying the alternative nucleotides at this polymorphic site (P<0.01). In addition different distributions of haplotype 4 in the two extreme groups suggested that it might affect the same trait (P<0.10). Association analyses for several other traits (average daily gain, ADG; feed gain ratio, FGR; weight of lean cuts; ham weight) were carried out by using EBVs and Random Residuals: significant effects (P<0.05) were only found for the p.Asp298Asn mutation on ADG and FGR. Results did not support any relevant effect of the p.Arg236His mutation on any trait. Data reported in this study contribute to better understand the role of MC4R variants in affecting production traits in pigs, a prerequisite to consider polymorphisms in this gene for marker assisted selection. 相似文献
750.
Vos M Esposito G Edirisinghe JN Vilain S Haddad DM Slabbaert JR Van Meensel S Schaap O De Strooper B Meganathan R Morais VA Verstreken P 《Science (New York, N.Y.)》2012,336(6086):1306-1310
Human UBIAD1 localizes to mitochondria and converts vitamin K(1) to vitamin K(2). Vitamin K(2) is best known as a cofactor in blood coagulation, but in bacteria it is a membrane-bound electron carrier. Whether vitamin K(2) exerts a similar carrier function in eukaryotic cells is unknown. We identified Drosophila UBIAD1/Heix as a modifier of pink1, a gene mutated in Parkinson's disease that affects mitochondrial function. We found that vitamin K(2) was necessary and sufficient to transfer electrons in Drosophila mitochondria. Heix mutants showed severe mitochondrial defects that were rescued by vitamin K(2), and, similar to ubiquinone, vitamin K(2) transferred electrons in Drosophila mitochondria, resulting in more efficient adenosine triphosphate (ATP) production. Thus, mitochondrial dysfunction was rescued by vitamin K(2) that serves as a mitochondrial electron carrier, helping to maintain normal ATP production. 相似文献