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排序方式: 共有169条查询结果,搜索用时 15 毫秒
61.
62.
Ch. Fusch B. Scharrer E. Hungerland H. Moeller 《Isotopes in environmental and health studies》2013,49(1-2):125-131
Abstract Body composition of 165 healthy children was measured using the well-established method of deuterium oxide (2H2O) dilution. After distribution of an oral load of 2.0 ml 2H2O/kg body weight body water was estimated from the 2H2O concentration in urine. Lean body mass was then calculated from body water using previously published age dependent ratios of the water content of the lean body mass. Fat mass was calculated as the difference of body weight and lean body mass. A good correlation was found between body water and body weight. Linear regression revealed TBW = 0.589 BW + 0.728 (r = 0.99). Body water, lean body mass and fat mass were found to change with age. The fat content of the body increases during the first six months of life. It then decreases until four to five years then rising again until 15 years of age. 相似文献
63.
Intramolecular anodic olefin coupling reactions can be compatible with the presence of dithioketal protecting groups even though the dithioketal oxidizes at a lower potential than either of the groups participating in the cyclization. In such cases, product formation is controlled by the Curtin-Hammett Principle. In this study, the generality of such reactions is examined along with the use of alternative reaction conditions to suppress unwanted side reactions. 相似文献
64.
Toennes SW Schneider K Kauert GF Wunder C Moeller MR Theunissen EL Ramaekers JG 《Analytical and bioanalytical chemistry》2011,400(1):145-152
Cannabis is not only the most widely used illicit drug worldwide but is also regularly consumed along with ethanol. In previous
studies, it was assumed that cannabis users develop cross-tolerance to ethanol effects. The present study was designed to
compare the effects of ethanol in comparison to and in combination with a cannabis joint and investigate changes in pharmacokinetics.
In this study, 19 heavy cannabis users participated and received three alcohol dosing conditions that were calculated to achieve
steady blood alcohol concentrations (BAC) of about 0, 0.5 and 0.7 g/l during a 5-h time window. Subjects smoked a Δ9-tetrahydrocannabinol (THC) cigarette (400 μg/kg) 3 h post-onset of alcohol dosing. Blood samples were taken between 0 and
4 h after smoking. During the first hour, samples were collected every 15 min and every 30 min thereafter. Mean steady-state
BACs reached 0, 0.36 and 0.5 g/l. The apparent elimination half-life of THC was slightly prolonged (1.59 vs. 1.93 h, p < 0.05) and the concentration 1 h after smoking was slightly lower (24 vs. 17 ng/ml, p < 0.05) with the higher ethanol dose. The prolonged THC elimination might be explained by a small ethanol-mediated change
in distribution to and from deep compartments. Concentrations and pharmacokinetics of 11-hydroxy-THC and 11-nor-9-carboxy-THC
(THCA) were not significantly influenced by ethanol. However, THCA concentrations appeared lower in both ethanol conditions,
which might also be attributable to changes in distribution. Though not significant in the present study, this might be relevant
in the interpretation of cannabinoid concentrations in blood. 相似文献
65.
Lincke J Lässig D Stein K Moellmer J Kuttatheyil AV Reichenbach C Moeller A Staudt R Kalies G Bertmer M Krautscheid H 《Dalton transactions (Cambridge, England : 2003)》2012,41(3):817-824
The newly synthesized Zn(4)O-based MOF (3)(∞)[Zn(4)(μ(4)-O){(Metrz-pba)(2)mPh}(3)]·8 DMF (1·8 DMF) of rare tungsten carbide (acs) topology exhibits a porosity of 43% and remarkably high thermal stability up to 430 °C. Single crystal X-ray structure analyses could be performed using as-synthesized as well as desolvated crystals. Besides the solvothermal synthesis of single crystals a scalable synthesis of microcrystalline material of the MOF is reported. Combined TG-MS and solid state NMR measurements reveal the presence of mobile DMF molecules in the pore system of the framework. Adsorption measurements confirm that the pore structure is fully accessible for nitrogen molecules at 77 K. The adsorptive pore volume of 0.41 cm(3) g(-1) correlates well with the pore volume of 0.43 cm(3) g(-1) estimated from the single crystal structure. 相似文献
66.
Preparation, purification, and stabilization of functional (meth)acrylates with a high dipole moment are complex, laborious, and expensive processes. In order to avoid purification and stabilization of the highly reactive functional monomers, a concept of cascade reactions was developed comprising enzymatic monomer synthesis and radical polymerization. Transacylation of methyl acrylate (MA) and methyl methacrylate (MMA) with different functional alcohols, diols, and triols (1,2,6‐hexanetriol and glycerol) in the presence of Novozyme 435 led to functional (meth)acrylates. After the removal of the enzyme by means of filtration, removal of excess (meth)acrylate and/or addition of a new monomer, e.g., 2‐hydroxyethyl (meth)acrylate the (co)polymerization via free radical (FRP) or nitroxide mediated radical polymerization (NMP) resulted in poly[(meth)acrylate]s with predefined functionalities. Hydrophilic, hydrophobic as well as ionic repeating units were assembled within the copolymer. The transacylation of MA and MMA with diols and triols carried out under mild conditions is an easy and rapid process and is suitable for the preparation of sensitive monomers.
67.
Pavel Pakhomov Svetlana Khizhnyak Vladimir Galitsyn Brigitte Hartmann Eleonora Moeller Valentin Nikitin 《Journal of Macromolecular Science: Physics》2013,52(6):1096-1107
A series of gels originated from ultra-high-molecular-weight polyethylene reactor powders, differing in morphology due to their different synthesis prehistory, were utilized for obtaining oriented fibers through the gel technology. The source powders, gels, and drawn fibers were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and low-frequency Raman spectroscopy. A comparison of the SEM images of powders with their straight chain segment (SCS) length distributions derived from the Raman spectra showed that the samples with pronounced fibrous morphology exhibited bimodal distribution functions, whereas the granular morphological pattern was specified by the unimodal SCS length distribution. Some remnant features of the ordered structure inherent in the powders were revealed in the gels. The drawability of gel-derived fibers was found to be dependent on the SCS length distributions in the gels and, indirectly, on the morphology of the reactor powders. 相似文献
68.
69.
70.
Beulen MW Bugler J de Jong MR Lammerink B Huskens J Schonherr H Vancso GJ Boukamp BA Wieder H Offenhauser A Knoll W van Veggel FC Reinhoudt DN 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(7):1176-1183
We have developed synthesis routes for the introduction of short and long dialkylsulfides onto the primary side of alpha-, beta-, and gamma-cyclodextrins. Monolayers of these cyclodextrin adsorbates were characterized by electrochemistry, wettability studies, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and atomic force microscopy (AFM). The differences in thickness and polarity of the outerface of the monolayers were measured by electro-chemistry and wettability studies. On average about 70% of the sulfide moieties were used for binding to the gold, as measured by XPS. Tof-SIMS measurements showed that the cyclodextrin adsorbates adsorb without any bond breakage. AFM measurements revealed for beta-cyclodextrin monolayers a quasi-hexagonal lattice with a lattice constant of 20.6 A, which matches the geometrical size of the adsorbate. The alpha-cyclodextrin and gamma-cyclodextrin monolayers are less ordered. Interactions of the anionic guests 1-anilinonaphthalene-8-sulfonic acid (1,8-ANS) and 2-(p-toluidinyl)naphthalene-6-sulfonic acid (2,6-TNS) and the highly ordered monolayers of heptapodant beta-cyclodextrin adsorbates were studied by surface plasmon resonance (SPR) and electrochemical impedance spectroscopy. The SPR measurements clearly showed interactions between a beta-cyclodextrin monolayer and 1,8-ANS. Electrochemical impedance spectroscopy measurements gave high responses even at low guest concentrations (< or = 5 microM). The association constant for the binding of 1,8-ANS (K = 289,000 +/- 13,000M-1) is considerably higher than the corresponding value in solution. (Partial) methylation of the secondary side of the beta-cyclodextrin strongly decreases the binding. 相似文献