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It has been proposed that hydrogen produced from basalt-ground-water interactions may serve as an energy source that supports the existence of microorganisms in the deep subsurface on Earth and possibly on other planets. However, experiments demonstrated that hydrogen is not produced from basalt at an environmentally relevant, alkaline pH. Small amounts of hydrogen were produced at a lower pH in laboratory incubations, but even this hydrogen production was transitory. Furthermore, geochemical considerations suggest that previously reported rates of hydrogen production cannot be sustained over geologically significant time frames. These findings indicate that hydrogen production from basalt-ground-water interactions may not support microbial metabolism in the subsurface. 相似文献
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Zhong D Franke JH Podiyanachari SK Blömker T Zhang H Kehr G Erker G Fuchs H Chi L 《Science (New York, N.Y.)》2011,334(6053):213-216
In contrast to the many methods of selectively coupling olefins, few protocols catenate saturated hydrocarbons in a predictable manner. We report here the highly selective carbon-hydrogen (C-H) activation and subsequent dehydrogenative C-C coupling reaction of long-chain (>C(20)) linear alkanes on an anisotropic gold(110) surface, which undergoes an appropriate reconstruction by adsorption of the molecules and subsequent mild annealing, resulting in nanometer-sized channels (1.22 nanometers in width). Owing to the orientational constraint of the reactant molecules in these one-dimensional channels, the reaction takes place exclusively at specific sites (terminal CH(3) or penultimate CH(2) groups) in the chains at intermediate temperatures (420 to 470 kelvin) and selects for aliphatic over aromatic C-H activation. 相似文献
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Natural populations of guppies were subjected to an episode of directional selection that mimicked natural processes. The resulting rate of evolution of age and size at maturity was similar to rates typically obtained for traits subjected to artificial selection in laboratory settings and up to seven orders of magnitude greater than rates inferred from the paleontological record. Male traits evolved more rapidly than female traits largely because males had more genetic variation upon which natural selection could act. These results are considered in light of the ongoing debate about the importance of natural selection versus other processes in the paleontological record of evolution. 相似文献
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B. Vijaya Ramnath C. Elanchezhian P. V. Nirmal G. Prem Kumar V. Santhosh Kumar S. Karthick S. Rajesh K. Suresh 《Fibers and Polymers》2014,15(6):1251-1262
Present technological development and innovation needs a better class of material that meets all the practical applications along with its environmental friendly nature and economical value. Hybrid natural fiber composites, a sector of natural composites meets these requirements. This paper deals with fabrication, mechanical characterization of a hybrid (Jute+Flax+GFRP) composite and also the comparison of it with the (Jute+GFRP) based composite. These composites are fabricated using hand lay-up technique. The arrangement of hybrid composite is such that a layer of vertically laid flax fiber is flanked between layers of horizontally laid jute fiber. Epoxy resin alongside with HY951 hardener is used as the binding agent throughout the layer. Glass fiber laminates are used on both sides for improving the surface finish and surface hardness. The volumetric fraction is such that one third of total volume is occupied by Jute and Flax fibers. Test results shows that the hybrid natural composite has excellent properties under tensile, flexural loading. At last failure morphology analysis is done using Scanning Electron Microscope (SEM) and the internal structure of the broken specimen is discussed. 相似文献
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Girish PS Anjaneyulu AS Viswas KN Santhosh FH Bhilegaonkar KN Agarwal RK Kondaiah N Nagappa K 《Veterinary research communications》2007,31(4):447-455
Chicken (Gallus gallus), duck (Anas platyrhynchos), turkey (Meleagris gallopavo), guinea fowl (Numida meleagris) and quail (Coturnix japonica) are the common poultry species consumed as meat throughout the world. In this work, a molecular technique has been developed
for identification and differentiation of meat originating from these species. This tool helps in detection of misrepresentation
of different poultry meats. The technique involves the extraction of DNA from the given sample, polymerase chain reaction
(PCR) amplification of mitochondrial 12S rRNA gene using universal primers, restriction analysis with selected restriction
enzymes, followed by identification of meat species based on restriction fragment length polymorphism (RFLP) pattern. In this
study, we used HinfI, Mph1103I, MvaI, and Eco47I to identify and differentiate to poultry species referred to above. This species identification technique has also been
applied successfully to processed meat products including those cooked at 120∘C for 30 min. Simplicity of interpretation of results combined with versatility makes this a convenient and appropriate technique
in the hands of meat analysts for identifying poultry meat species. 相似文献
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Cardioprotective effects of Picrorrhiza kurroa against isoproterenol-induced myocardial stress in rats 总被引:1,自引:0,他引:1
The cardioprotective effect of the ethanol extract of Picrorrhiza kurroa rhizomes and roots (PK) on isoproterenol-induced myocardial infarction in rats with respect to lipid metabolism in serum and heart tissue has been investigated. Oral pre-treatment with PK (80 mg kg(-1) day(-1) for 15 days) significantly prevented the isoproterenol-induced myocardial infarction and maintained the rats at near normal status. 相似文献
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V.S. Santhosh Mithra J. Sreekumar C.S. Ravindran 《Archives of Agronomy and Soil Science》2013,59(4):603-623
In this article, a process model (SIMCAS) for simulating the growth of cassava is proposed. Crop phenology was simulated as a function of growing degree days (GDD). New algorithms are used in this model to simulate different components of crop phenology. Branching is simulated as a function of the number of leaves and total dry matter produced. Standard methods were followed to compute solar radiation and photosynthesis. Sensitivity analysis confirmed the importance of canopy size on tuber yield. Algorithms for estimating stress due to a shortage of water, nitrogen and potassium are also included in this model. An attempt was made to predict the final yield under field conditions by multiplying stress values by potential yield. The model was tested under different environments. The tuber yield predicted by this model is in good agreement with the corresponding observed values in most of the cases. Estimation of stress due to a shortage of nitrogen, potassium and water is the key aspect of this model. This information can be used to manage stress and thereby achieve the potential yield. By improving the stress algorithm, this model will serve as a useful tool for achieving maximum cassava yield at optimum input level. 相似文献