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991.
Gerhard Miksche Andreas Wolf Ingeborg Trummer Kurt Thomke 《Monatshefte für Chemie / Chemical Monthly》1987,118(3):355-362
A novel equipment for a multistep deuteration process of organic compounds was developed. As an example the deuteration of propanone by deuterium oxide over magnesia and thoria was examined. The degree of deuteration of the organic compound and of the catalysts was determined by on-line mass-spectrometry. Percentages of deuterium uptake of the organic compound up to 90% were found. These degrees of deuteration were higher than those measured at the catalysts' surface. This fact can be explained by the kinetic isotope effect. 相似文献
992.
本文叙述了用自己研制的六道中性粒子分析器(即中性粒子谱仪),测量HL-1托卡马克装置离子温度的实验,给出了在1986年进行的一组放电实验所得等离子体的离子温度及其随放电时间变化的结果,测得的中心离子温度的典型值为474eV,在相应等离子体参数下,Artsimovich经验公式给出450eV 相似文献
993.
Among the most frequent protein binding sites served by Mg(II), we identify those which have higher affinity towards Al(III). We also estimate the free energies of metal exchange for all these binding sites taking into account solvent effects explicitly. The obtained results show that thermodynamically favored Mg(II)/Al(III) exchange reactions take place at a number of these metal binding sites, which could possibly be related to some dysfunctions of Mg(II)-dependent biological processes. Additionally, they shed light on the molecular basis of the toxicity of Al(III) in living organisms. 相似文献
994.
Shane O’Malley 《Tetrahedron letters》2007,48(51):9003-9007
We report both the preparation and sensor evaluation of a new metal-free calixarene bridged binuclear phthalocyanine. 相似文献
995.
Summary A general form of computer program which can assist in method development for any natural water has been developed. Necessary input data, sequence of main operations, necessary mathematical relationships and the output data are specified. The development of the structure of the computer program was based on experiences with real samples. 相似文献
996.
Detailed theoretical investigations into asphericity in the Fermi surface (FS) and Fermi energy (FE) ofNa1_xKx, Na1_xRbx, and Na1_xCsx binary solid solutions are carried out for the first time. The alloying behavior ofthe K, Rb, and Cs with the Na generates the Fermi surface distortion (FSD) of bce simple metals. The FS of Na-K,Na-Rb, and Na-Cs solid solution is a distorted sphere with the largest deviation along [110]. We have found that theimpact of local-field correction function on FSD is maximun at [100] point and minimum at [111] point. The exchangeand correlation effect is found to suppress the value of FE. 相似文献
997.
《Electroanalysis》2006,18(16):1552-1557
Ion‐selective electrodes are described, with membranes tailored for measurements of tetrabutylammonium ions in aqueous and formamide solutions, and for measurements of cesium and calcium ions in the presence of tetrabutylammonium. It is shown that reliable measurements of cesium ions are possible when a correction is introduced for interference from tetrabutylammonium, using Nikolsky selectivity coefficient. A novel membrane composition is described which ensures high selectivity to calcium ions over tetrabutylammonium. 相似文献
998.
Doppler broadening spectroscopy (DBS) coupled to a slow positron beam has been used to investigate the formation of He-cavities in the presence of high vacancy concentrations in Cz-Si (1 1 1). Si samples were first implanted with MeV Si ions in order to create a damaged Si layer. DBS measurements show the presence of divacancy (SV2/SSi lattice=1.052,WV2/WSi lattice=0.83) from the surface up to 4.2 μm depth with a concentration higher than 1018 cm−3. The thickness of this damaged layer was confirmed by spreading resistance measurements. In the second step, samples were implanted with 50 keV 3He with fluence of 1016 cm−2. DBS results show that the apparent divancancy concentration decreases at 3He implantation depth ∼435 nm due to 3He passivation of vacancies that occurs during the implantation process. After 900 °C annealing, large defects are detected at depth up to 2 μm and (S, W) values suggest the detection of cavities at the implantation depth. We also report the possible presence of impurity complexes. The formation of these complexes is attributed to the gettering of metallic impurities present in the Si sample. 相似文献
999.
ZHANG Changwen LI Hua DONG Jianmin WANG Yongjuan PAN Fengchun ZHANG Jian GUO Yongquan & LI Wei . School of Physics Microelectronics Shandong University Jinan China . Institute of Functional Materials Central Iron Steel Research Institute Beijing China 《中国科学G辑(英文版)》2005,48(3)
1 Introduction The rare-earth transition-metal intermetallic compounds have been widely investi-gated for many years, among them the Sm-Co series compounds with 1:5 and 2:17 crys-tal structures. These compounds have been used as sintered and bonded permanent magnets since the 1960s[1,2]. Interest recently has been focused on the TbCu7-type struc-ture Sm-Co intermetallic compounds with a strong uniaxial magnetocrytalline anisot-ropy and a low temperature coefficient (β = ?0.11%)[3―6] due t… 相似文献
1000.
The engineering design of 60 kV, 55 A, 2 s bucket ion source for HL-2A has been finished. The current design is based on an extraction-acceldecel extraction system that is composed of plasma electrode, acceleration electrode, deceleration electrode and grounded electrode. The primary and secondary particles due to beams ionization in each region of extraction system will hit the surface of electrode. The power loads on an electrode is estimated both theoretically and experimentally to be 1%-2% of the ion beam power, which may cause serious problems, such as thermal deformation followed by ion beam distortion and melting leading to water leaks. To ensure the mechanical reliability and no plastic deformation, it is important and necessary to analysis the temperature and stress distribution. 相似文献