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排序方式: 共有347条查询结果,搜索用时 15 毫秒
61.
U. Guth F. Gerlach M. Decker W. Oelßner W. Vonau 《Journal of Solid State Electrochemistry》2009,13(1):27-39
The availability and application of solid-state reference electrodes for potentiometric electrochemical sensors are briefly
reviewed. For a long time, considerable efforts have been made to combine solid-state indicator electrodes with equivalent
reference electrodes to take advantage of the absence of liquid system components to full capacity. In spite of various suggestions
to solve the problem, no type of solid-state reference electrode is so far available with properties completely identical
to conventional ones. 相似文献
62.
Rozhenko AB Schoeller WW Letzel MC Decker B Agena C Mattay J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(35):8995-9000
Host-guest complexes of tetramethylcavitand with different ammonium cations were investigated by using a quantum chemical method at the density functional level (BP86, B3 LYP). The NH4+ cation is strongly bound to the host. Increasing methyl substitution at the cation decreases its inclination towards the complex formation. The calculated data are in line with results from electrospray ionization mass spectrometry (ESI-MS) experiments. They reveal stable aggregates only for the NH4+ cation and for the primary alkylammonium cations. 相似文献
63.
Gidh AV Decker SR Vinzant TB Himmel ME Williford C 《Journal of chromatography. A》2006,1114(1):102-110
A method was developed using high-performance size exclusion liquid chromatography (HPSEC) with multi-angle laser light scattering (MALLS), quasi-elastic light scattering (QELS), interferometric refractometry (RI) and UV detection to characterize and monitor lignin. The combination proved very effective at tracking changes in molecular conformation of lignin molecules over time; i.e. changes in molecular weight distribution, radius of gyration, and hydrodynamic radius. Until this study, UV detection (280 nm) had been the primary lignin determination method for chromatography. Three different HPLC columns were used to study the effects of pH, flow conditions, and mobile phase compositions (dimethyl sulphoxide, water, 0.1M NaOH, and lithium bromide) on the chromatography of lignin. Since light scattering accuracy is highly dependent on solute concentration, both the UV and RI detectors were calibrated for use as concentration detectors. Shodex Asahipak GS-320 HQ column with 0.1M NaOH (pH 12.0) run at 0.5 ml/min was found to give the highest separation and most consistent recovery. The study also revealed that the lignin aggregated at pH below 8.5. This aggregation was detected only by MALLS and was not observed on UV or RI detectors. It is very important to take this loss in apparent concentration due to aggregation into consideration before collecting reliable depolymerization data. 相似文献
64.
C. A. Cooper J. B. Crews R. Schumer R. J. Breitmeyer H. Voepel D. L. Decker 《Transport in Porous Media》2014,104(2):335-347
A laboratory experiment of transient thermal convection in a 1-m-high cell was conducted to compare the length and time scales of plume development to theory. The temperature field was resolved to less than 1 mm and was measured by dissolving a solution of thermochromic crystals into the water–glycerin working fluid. The time-dependent experiment was run by applying heat at the bottom boundary that eventually was \(6\,^\circ \) C above the background temperature of the fluid. After development of a thermal boundary layer, the instability became visible at 26 min, with the development of 11, 3–4 cm width plumes growing from the boundary layer. The initially rapid growth rate reached a limiting velocity of approximately 0.5 cm min \(^{-1}\) , and then decelerated throughout the experiment. Plumes interacted primarily by merging together; by the end of the experiment only three plumes were present. The Nusselt number at the onset of convection was 10, although it dropped to 4 after 45 min, which would be expected of a barely unstable system. 相似文献
65.
Assem N Hili R He Z Kasahara T Inman BL Decker S Yudin AK 《The Journal of organic chemistry》2012,77(13):5613-5623
Unprotected aziridine aldehydes belong to the amphoteric class of molecules by virtue of their dual nucleophilicity/electrophilicity. The dimeric nature of these molecules, brought together by a weak and reversible aminal "connection", was found to be an important element of reactivity control. We present evidence that reversible dimer dissociation is instrumental in aziridine aldehyde transformations. We anticipate further developments that will unveil other synthetic consequences of remote control of selectivity through forging reversible covalent interactions. 相似文献
66.
67.
Ch. Niedermayer C. Bernhard T. Blasius A. Decker A. Golnik 《Hyperfine Interactions》1997,105(1-4):131-137
We have studied the magnetic phase diagram for the bilayer compound Y1-x Cax Ba2 Cu3 O6 in the regime of low doping (hole concentration within a CuO2 plane, psh < 0.1). For psh < 0.03, the data demonstrate the freezing of the spin degrees of freedom associated with the doped holes into a spin‐glass‐like
state which is superimposed on the preexisting long range order of the Cu2+ spins. Only a single spin‐glass like transition at a temperature Tg is observed for samples in the hole concentration range 0.03 < psh < 0.1. While the threshold for the occurrence of superconductivity is almost the same (psh > 0.06) for the Y1-x Cax Ba2 Cu3 O6 and the La2-x Srx CuO4 systems, the magnetic correlations that coexist with superconductivity are considerably stronger in the bilayer Y1-x Cax Ba2 Cu3 O6 system as indicated by significantly increased transition temperatures Tg.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
68.
Carl Friedheim O. Decker und E. Diem 《Fresenius' Journal of Analytical Chemistry》1905,44(11):665-686
Ohne ZusammenfassungAus dem anorganischen Laboratorium der Universität Bern. 相似文献
69.
A. Ruebner D. Kirsch S. Andrees W. Decker B. Roeder B. Spengler R. Kaufmann J.G. Moser 《Journal of inclusion phenomena and macrocyclic chemistry》1997,27(1):69-84
The aim of our investigation was to develop carrier systems for an application of inert drugs in photodynamic cancer therapy. -Cyclodextrin dimers linked at their primary and secondary faces by spacers of varying lengths were synthesized as carrier systems. The binding constants of the inclusion complexes of these cyclodextrin dimers and porphyrinoid photosensitizers were determined by competitive spectrofluorometry. Particularly the secondary face linked dimers exhibited extremely high binding constants with values of 106-107 L/mol. Theoretical studies were carried out on these inclusion complexes to confirm the influence of spacer length and connecting side on complex stability. 相似文献
70.
S. Bause M. Decker F. Gerlach J. Näther F. Köster P. Neubauer W. Vonau 《Journal of Solid State Electrochemistry》2018,22(1):51-60
A new iridium-based planar pH sensor for bioanalytical purposes is introduced. The fabrication of the sensor was carried out by a two-stage coating process of different iridium solutions on a platinum thick film surface. The pH response behaviour and the Nernstian characteristics of the double-layer electrode exhibited better results than the single iridium depositions. An almost theoretical Nernstian slope could be obtained as well as a pH response time of about 3 to 5 min in a pH range of 4.01 to 9.18. Furthermore, a biofilm growth of different microorganisms onto the iridium-coated electrodes could be achieved. Afterwards, the viability of the microorganisms was demonstrated via cell plating studies. 相似文献