نتایج جستجو برای: no carrier added
تعداد نتایج: 3440391 فیلتر نتایج به سال:
The emerging service-dominant logic requires cooperation between several partners in a value-added network or value chain. Information asymmetry and information gaps may lead to uncovered and unused knowledge. This paper addresses how this problem can be solved by suggesting an approach based on contingency theory. The core idea consists of supporting and improving value-added partnerships by e...
No-carrier-added fluorine-18-labeled fluoroprednisone ([18F]21-fluoroprednisone) was synthesized by tosylate displacement in 2%-8% radiochemical yield in 80 min end of cyclotron bombardment (EOB), and its metabolism and distribution were investigated. After intravenous administration to rats, [18F]21-fluoroprednisone was rapidly cleared from the blood and biotransformed into [18F]20-dihydro-21-...
A no-carrier added synthesis of [11C]thymidine from cyclotron produced [11C]methyl iodide is presented. The bis-silylated derivative of the lithium salt of 5-bromo-2'-deoxyuridine is treated with [11C]methyl iodide in THF at -50 degrees C giving 20-30 mCi [11C]thymidine in a 40-70% radiochemical yield. Purification is performed by reversed phase chromatography on a C18 column. The whole procedu...
We describe the first catalytic decarboxylative fluorination reaction based on the nucleophilic fluoride ion. The reported method allows the facile replacement of various aliphatic carboxylic acid groups with fluorine. Moreover, the potential of this method for PET imaging has been demonstrated by the successful (18) F labeling of a variety of carboxylic acids with radiochemical conversions up ...
Resin-supported [18F]fluoride ion has been prepared and applied to a rapid, convenient synthesis of [18F]FDG. "No-carrier-added" [18F]fluoride ion is collected on a quaternary 4-(N,N-dialkylamino)-pyridinium functionalized polystyrene anion exchange resin directly from a [18O]water target, dried by rinsing with acetonitrile, and then reacted with 1,3,4,6-tetra-O-acetyl-2-O-trifluoromethanesulfo...
This brief review gives an overview of newer developments in (18)F-chemistry with the focus on small (18)F-labelled molecules as intermediates for modular build-up syntheses. The short half-life (<2 h) of the radionuclide requires efficient syntheses of these intermediates considering that multistep syntheses are often time consuming and characterized by a loss of yield in each reaction step. R...
Import of tRNA into the mitochondrial matrix of Trypanosoma brucei was reconstituted in vitro. Efficient import required the hydrolysis of externally added ATP and was shown to be a carrier-mediated process depending on proteinaceous receptors on the surface of mitochondria. A partly synthetic tRNA(Tyr) as well as a physiological tRNA(Lys) were imported along the same pathway. Contrary to impor...
Background : Finding an association between HFE mutations and hepatitis C especially in those with iron overload is the focus of recent researches. We examined the frequency of these mutations and ferritin level in a group of patients with different stages of hepatitis B and healthy individuals. Materials and methods : A total of 75 (18 carrier, 57 chronic) cases of HBsAg positive patients and...
In Germany, four different drug eluting stents (DES) systems are currently commercially available. Whereas sirolimus has been clinically tested in only a single type of stent with a single type of coating in only a single dose, paclitaxel has been tested on various stent designs, in various dose densities, and in various release formulations with or without a polymer carrier. Therefore, the que...
just as motivation is important in sla research, demotivation constitutes an important factor, too. there are many studies done on demotivation and burnout of teachers. many of these studies have been conducted on one or two aspects of english instruction. consequently, there are few studies which have been done on more than two aspects of english teaching. the aim of this study is to find out ...
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