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111.
Yuri Vlasov 《Mikrochimica acta》1991,104(1-6):363-377
MOSFET-sensors can be considered as membrane-oxide-semiconductor field-effect transistors. MOSFETs can be divided into ISFETs, GasFETs, BioFETs, these sensors being sensitive to ion, gas, biomolecules respectively and there is also a possibility to fabricate MOSFET reference electrode (RefFET). The development and theoretical treatment of various type of MOSFET-sensors are presented in this paper. 相似文献
112.
Paramagnetic metal ions bound to proteins generate a dipolar field that can be accurately probed by pseudocontact shifts (PCS) displayed by the protein's nuclear spins. PCS are highly useful for determining the coordinates of individual spins in the molecule and for rapid structure determinations of entire protein-protein and protein-ligand complexes. However, PCS measurements require reliable resonance assignments for the molecule in its paramagnetic state and in a diamagnetic reference state. This article discusses different approaches for pairwise resonance assignments, with emphasis on a strategy which exploits chemical exchange between the two states. 相似文献
113.
114.
医用聚丙烯酰胺水凝胶理化性能测试 总被引:2,自引:0,他引:2
测试了医用聚丙烯酰胺水凝胶产品的pH值、折射率、重金属含量、红外光谱、化学热稳定性和丙烯酰胺单体残留量等主要理化性能,重点研究了样品中残留单体丙烯酰胺的高效液相色谱分析法。 相似文献
115.
R. Bruce King 《Theoretical chemistry accounts》1980,56(4):269-296
The following procedure is described for investigating the qualitative dynamics of simple chemical systems: 1) A so-called influence diagram is generated representing the relationships between the reference reactants (phase-determining intermediates); 2) This influence diagram is used to generate a truth table indicating possible transitions between state vectors representing the signs of the time derivatives of of the reference reactant concentrations; 3) The truth table is used to determine a state transition diagram representing the flow topology around unstable equilibrium points; 4) The characteristic equation of the adjacency matrix of the influence diagram is solved in order to determine the presence of such unstable equilibrium points. The two types of qualitative dynamics possible for chemical systems containing two reference reactants and one feedback circuit are bifurcation between two attracting regions (bistability) and limit cycle oscillation. However, in two reference reactant systems oscillation requires an additional self-activating loop to generate the unstable equilibrium point required for its realization. Bistability and limit cycle oscillation are also two of the possible types of qualitative dynamics for chemical systems containing three reference reactants. However, chemical systems with three reference reactants and two or more feedback circuits can also contain interlocking limit cycles, which can lead to toroidal oscillations or chaos. The influence diagrams are given for the systems exhibiting these various types of dynamic behavior along with a summary of the important properties of all 729 possible influences for simple chemical systems containing three reference reactants. 相似文献
116.
117.
118.
Soonam Park Feng Liao John M. Larson Steven L. Girshick Michael R. Zachariah 《Plasma Chemistry and Plasma Processing》2004,24(3):353-372
A molecular beam mass spectrometry system for in situ measurement of the concentration of gas phase species including radicals impinging on a substrate during thermal plasma chemical vapor deposition (TPCVD) has been designed and constructed. Dynamically controlled substrate temperature was achieved using a variable thermal contact resistance method via a backside flow of an argon/helium mixture. A high quality molecular beam with beamtobackground signal greater than 20 was obtained under film growth conditions by sampling through a small nozzle (75 m) in the center of the substrate. Mass discrimination effects were accounted for in order to quantify the species measurements. We demonstrate that this system has a minimum detection limit of under 100 ppb. Quantitative measurements of hydrocarbon species (H, H2, C, CH3, CH4, C2H2, C2H4) using Ar/H2/CH4 mixtures and silicon species (Si, SiH, SiH2, SiCl, SiCl2, Cl, HCl) using Ar/H2/SiCl4 mixtures were obtained under thermal plasma chemical vapor deposition conditions. 相似文献
119.
The calculations of clusters modeling the fluorine-doping and oxygen deficiency of YBa2Cu307 have been performed by the method of all-electronab initio Hartree-Fock with self-consistent crystal field. Results show that in CuO planes electric charge significantly increases,
the chemical valence of Cu decreases and the covalent bonding of Cu-O greatly weakens owing to oxygen deficiency, while the
effect of F restores the local electronic structure of YBa2Cu3O7. The reported opinion that F occupied the oxygen vacancy in Cu-O chains seems disputable according to the calculated bonding
characteristics
Project supported by the National Natural Science Foundation of China. 相似文献
120.
In the context of the density functional theory of the local electron density the valence and differential density distribution in crystalline sulfates of M2SO4 (M is Li, Rb, and Cs) and double sulfates of MLiSO4 were calculated using the pseudopotential method in the basis set of numerical atomic pseudo-orbitals. It is shown that in lithium sulfate crystallographically inequivalent oxygen atoms are in different charge states and have a different force of chemical bonding with sulfur. Anions are bonded to each other through lithium atoms that form tetrahedral complexes with oxygen. In rubidium sulfates the electron clouds of the anions overlap and chain structures form. Chemical bonding between the anion and the cation has an ionic nature. These features of the electron structure manifest themselves in double sulfates, where LiO4 complexes that link the anionic chains also form, and heavy metals serve as cations. 相似文献