نتایج جستجو برای: silica boron

تعداد نتایج: 55027  

Journal: :The Journal of antibiotics 2004
Yuichi Sakano Masaaki Shibuya Yuichi Yamaguchi Rokuro Masuma Hiroshi Tomoda Satoshi Omura Yutaka Ebizuka

From a fungal strain FKI-0929, two compounds designated epohelmins A and B, were isolated as new natural products with inhibitory activity against recombinant human lanosterol synthase. The crude extract from the whole broth of this strain was fractionated by silica gel column chromatography and HPLC to afford two isolated inhibitors. Detailed spectroscopic analyses led to the identification of...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علوم پایه دامغان - دانشکده شیمی 1391

اخیراً استفاده از معرف های تثبیت شده بر روی جامدات به دلیل سهولت جداسازی از محیط واکنش گسترش یافته است. در اینجا قصد داریم کاربرد h2so4-silica را به عنوان کاتالیزور اسیدی جامد که از سولفوریک اسید و سیلیکاژل تهیه می شود را برای تهیه نیترو فنول ها و کینولین ها گزارش کنیم. نیترو فنول ها از واکنش بین مشتق های فنول با استرانسیم نیترات در مجاورت h2so4-silica در دمای اتاق و شرایط بدون حلال تهیه شدند. م...

2008
C.

DETERMINATION OF SILICA OXIDE iron ores usually are found in intimate association with sllica and phosphorus compounds. heir quantitative separation and purification sometimes present difficult problems to the chemist. Silicic acids may represent various degrees of dehydration. They are exceedingly weak, but combine with metallic oxides and form some of the most stable , oxides in nature, the s...

Journal: :progress in biological sciences 2012
razieh moalemi mahnaz aghdasi faezeh ghanati

boron (b) is a non-metal micronutrient which is essential for plants growth and development. formation of boron complex with cell wall matrix and phenolic compounds is a definite influence of boron in physiological process. it has been suggested that b-toxicity and deficiency may induce excess production of reactive oxygen species thereby promote defense responses by antioxidant enzymes or non-...

Journal: :Bor dergisi 2021

The membrane filtration is an effective way to produce water for human consumption, industrial use, or irrigation purpose. In this study, the potential of a brackish reverse osmosis (BWRO) was practically investigated obtain with quality from geothermal water. produced analyzed understand applicability in agricultural use boron-sensitive crops. effects feed solution composition and pretreatment...

Journal: :Nanotechnology 2015
ShuJun Ye MingHui Song Hiroaki Kumakura

A 3 nm coronene coating and a 4 nm amorphous carbon coating with a uniform shell-core encapsulation structure for nanosized boron (B) powders are formed by a simple process in which coronene is directly mixed with boron particles without a solvent and heated at 520 °C for 1 h or at 630 °C for 3 h in a vacuum-sealed silica tube. Coronene has a melting point lower than its decomposition temperatu...

Journal: :journal of agricultural science and technology 2010
h. rezaei m. j. malakouti

cotton (gossypium hirsutum l. cv. varamin ) an important industrial crop of iran, is grown in 300,000 ha, with an average seed -cotton yield of 1750 kg.ha-1. the main obstacle in the way of increasing average cotton yield is imbalanced fertilizer use. along with urea and triple super phosphate, cotton growers also need k, mg, zn, fe, mn, cu, and b, so these elements’ critical levels should ...

S. Rezayati S. Sajjadifar

A mild and green method has been developed for the preparation of coumarins derivatives through the one-pot reactions. In our study,various phenols and ethyl acetoacetate compound in which we used silica-supported boron sulfonic acid [SiO2/B(SO4H)3] as a new, highly efficient and tri-functional inorganic Brønsted acid catalyst were processed under solvent-free condition and thermal. The catalys...

Journal: :Accounts of chemical research 2014
Alina P Sergeeva Ivan A Popov Zachary A Piazza Wei-Li Li Constantin Romanescu Lai-Sheng Wang Alexander I Boldyrev

Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center-two-electron (2c-2e) σ bonds on the periphery and delocalized multicenter-two-electron (nc-2e) bonds in both σ and π frameworks. Electron delocalization...

Journal: :Cancer research 1994
S L Kraft P R Gavin C W Leathers C E DeHaan W F Bauer D L Miller R V Dorn M L Griebenow

Borocaptate sodium (Na2B12H11SH) is a potentially useful compound for boron neutron capture therapy of intracranial tumors. Tumor and normal tissue boron concentrations were evaluated in 30 dogs with naturally occurring intracranial tumors after i.v. borocaptate sodium infusion (55 mg boron/kg). Postmortem tissue boron concentrations were measured for three postinfusion time periods (2, 6, and ...

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