نتایج جستجو برای: transition metals
تعداد نتایج: 320706 فیلتر نتایج به سال:
The presence of aryl sulfides in biologically active compounds has resulted in the development of new methods to form carbon-sulfur bonds. The synthesis of aryl sulfides via metal catalysis has significantly increased in recent years. Historically, thiolates and sulfides have been thought to plague catalyst activity in the presence of transition metals. Indeed, strong coordination of thiolates ...
Highly reactive transition metals, such as copper and iron play an obligatory role in generating of reactive oxygen species (ROS). Many neurodegenerative diseases including Alzheimer's disease (AD) and Parkinson's disease (PD) show increased accumulation of these metals. Phosphoinositide metabolism is altered in neurodegenerative diseases. In the present study, we examined the effect of CuSO(4)...
alfalfa and maize are important agricultural plants for animal consumption. in this survey, accumulation quantity of heavy metals (fe,zn,mn,cd,pb,ni,cr) in plants irrigated by sewage and well water were compared statistically together and with normal or standard(permeable) limits in plants or foraging, during 2005. the results were as following 1-maize: the value of accumulation in maize irriga...
In contrast to the growing interest with the polysilane, the method of preparation hitherto known is highly limited. So far, the almost only practical method is the condensation of organodichlorosilane with alkali metal (Wurtz type condensation). This method, however, requires drastic reaction conditions and hence, is very much limited in the type of substituent that is allowed to be located on...
Transition-metal-substituted (TMS) polyoxometalates of the general formula [SiW9M3O39], (where M = first row transition metal), has been synthesized and supported on anatase by sol–gel method under oil-bath condition. The tetrabutylammonium (TBA) salts of the Keggin-type polyoxotungstates [SiW9M3O39], (M = VII, CrII, MnII, FeII CoII and NiII), proved to be green, reusable, and ...
Attachment of a laterally non-symmetric cryptand and a macrocycle at the 9- and 10-positions of anthracene leads to a fluorescent signaling system L1 which gives fluorescence enhancement in the simultaneous presence of alkali and transition metal ions.
This article systematically overviews the grain size effect on deformation twinning and detwinning in face-centered cubic (fcc) metals. With decreasing grain size, coarse-grained fcc metals become more difficult to deform by twinning, whereas nanocrystalline (nc) fcc metals first become easier to deform by twinning and then become more difficult, exhibiting an optimum grain size for twinning. T...
A sample-pretreatment method using a chitosan-based chelating resin, ethylenediamine-N,N,N'-triacetate-type chitosan (EDTriA-type chitosan), was developed for the preconcentration of trace metals in seawater and separation of the seawater matrix prior to their determination by inductively coupled plasma-mass spectrometry (ICP-MS). The resin showed very good adsorption for transition metals and ...
The standard enthalpy of formation of a compound is the energy associated with the reaction to form the compound from its component elements. The standard enthalpy of formation is a fundamental thermodynamic property that determines its phase stability, which can be coupled with other thermodynamic data to calculate phase diagrams. Calorimetry provides the only direct method by which the standa...
Some plants can hyperaccumulate metal ions that are toxic to virtually all other organisms at low dosages. This trait could be used to clean up metal-contaminated soils. Moreover, the accumulation of heavy metals by plants determines both the micronutrient content and the toxic metal content of our food. Complex interactions of transport and chelating activities control the rates of metal uptak...
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