نتایج جستجو برای: silica boron
تعداد نتایج: 55027 فیلتر نتایج به سال:
Selective deprotection of 4-(alkoxysilyl)benzaldehyde diethyl acetals 1a-1c in the two-solvent system of hydrochloric acid and chloroform gave 4-(alkoxysilyl)benzaldehydes 2a-2c in good yields. Under these conditions, undesired hydrolysis of the alkoxysilyl group was minimized. The reaction of benzaldehydes 2a and 2b with pyrrole in the presence of boron trifluoride diethyl etherate led to 5,10...
Structure and properties of magnesium silicate borate melts glasses were investigated by using newly parameterized interaction potentials in molecular dynamics simulations compared with those calcium borate. The competition between the depolymerization silica network formation new bonds modifier ions leads to enhancement elastic moduli increasing content alkaline earth glasses. Compared silicat...
The paper is based on the development of a wood preservative without metal salts to be used in use classes 3 and 4 (EN 335), eco-friendly and harmless to humans and animals. Boric acid was used as a biocide, due to its effectiveness against fungi and insects. It is also known to be easily leached from wood exposed to weather action. Colloidal silica was therefore added in the formulations to gu...
It was recently proposed that boron might be the most important nutrient structuring tree species distributions in tropical forests. Here we combine observational and experimental studies to test this hypothesis for lowland tropical forests of Panama. Plant-available boron is uniformly low in tropical forest soils of Panama and is not significantly associated with any of the > 500 species in a ...
introduction: boron possesses widespread properties and is important for human and animal nutrition. since boron is rapidly bioavailable, the objective of the present study was to determine whether acute (hourly or daily), and weekly supplementationcould have any significant biological effects on the synthesis of steroids as well as inflammatory biomarkers. methods: eight male volunteers partic...
New and exciting developments in boron research in the past few years greatly contributed to better understanding of the role of boron in plants. Purification and identification of the first boron-polyol transport molecules resolved much of the controversy about boron phloem mobility. Isolation and characterization of the boron-polysaccharide complex from cell walls provided the first direct ev...
boron toxicity is one of the most important disorders for plant cultivation in the arid and semi-arid regions. boron accumulation usually occurs in deeper soil layers due to leaching and therefore improvement of such a soil in this situation is difficult. an experiment was conducted to find out the effect of boron on the vegetative and physiological aspects of olive trees. six concentrations of...
A novel hierarchical nanotemplated carbon monolithic rod (NTCM) was prepared using a novel facile nanotemplating approach. The NTCM was obtained using C60-fullerene modified silica gels as hard templates, which were embedded in a phenolic resin containing a metal catalyst for localized graphitization, followed by bulk carbonization, and template and catalyst removal. TEM, SEM, and BET measureme...
The silica boron sulfuric acid nanoparticles (SBSANs) as an efficient heterogeneous solid acid catalyst with both Brønsted and Lewis acidic sites catalyzed the preparation of bis-4-hydroxycoumarin derivatives using reaction of aldehydes and 4-hydroxycoumarin under mild and solvent-free condition at room temperature. This new and efficient methodology has advantages in comparison with currently ...
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