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61.
62.
对德国康斯坦茨大学的本科有机化学实验初级阶段和高级阶段的教学方式,从实验前准备、实验内容、实验教学模式、实验考核方式、实验室安全管理等方面进行了综合阐述,可为我国高校相关专业有机化学实验教学与改革提供参考,提高教学质量。 相似文献
63.
Taking the chemical equilibria including acid-base equilibrium, complexation equilibrium, precipitation equilibrium and redox equilibrium as an example, the application of the mind mapping combined with problem-based learning in university chemistry teaching is introduced. 相似文献
64.
The low temperature (1.3–20.0 K) heat capacity of the weak itinerant electron ferromagnet Sc3In was measured in magnetic fields up to ~ 10 T. The heat capacity peak observed around Tc = 6.0 K in zero field becomes smaller with increasing fields and at 9.98 T its magnetic entropy is ≈ 18% of the zero field value. Above Tc, the spin fluctuation contribution to the heat capacity, which is enhanced by the magnetic field at lower fields (?5 T), is quenched at higher fields (?5 T). This depression of the spin fluctuation contibution to the heat capacity by the high magnetic fields occurs at lower magnetic fields than had been considered possible heretofore. Our results suggest that the itinerant ferromagnetism is Sc3In is completely quenched at 12 T. 相似文献
65.
Doubly differential cross sections, in energy and angle, are reported for the electron transfer reaction between potassium and nitrogen dioxide in a crossed beam apparatus at relative collision energies between 2.7 and 30.8 eV. The formation of NO?2 in its ground 1A1 and excited 3B1 state has been observed. Theoretical consideration of these processes indicates that bond bending during the collision has a stronger influence on ion-pair formation than bond stretching. At the lower collision energies most of the excess energy is converted into internal energy of NO?2. 相似文献
66.
67.
M. Jaros 《Solid State Communications》1978,25(12):1071-1074
It is argued that the recent quantitative results concerning localized defects in semiconductors (e.g. GaAs) are consistent with the possibility of large Auger-type cross sections associated with recombination at these centers.It is proposed that many of the capture cross sections reported to be in the range 10?13–10?16cm2, which exhibit only weak temperature dependence, and which do not depend on carrier concentration, might be explained by this mechanism. 相似文献
68.
Max Herberhold Cornelius G. Kreiter Siegfried Stüber Günter O. Wiedersatz 《Journal of organometallic chemistry》1975,96(1):89-94
The methoxy signals in the 1H NMR spectrum of cyclopentadienylmanganese dicarbonyl tetramethoxyethylene, C5H5Mn(CO)2[C2(OCH3)4], show a definite temperature-dependence. In CS2 solution the variations of the signals are observed within a single temperature range, while in toluene-d8 two regions of change are found to exist. These data are explained on the basis of two mutually independent ligand movements: a hindered rotation of the olefin ligand around the metalligand bond (ΔG3194 = 9.8 ± 0.6 kcal/mol), and a hindered movement of the four methoxy groups (ΔG3263 = 13.8 ± 0.3 kcal/mol, both in toluene-d8. Chiral conformations of the ligand are assumed to be formed when the movement of the methoxy substituents ceases. 相似文献
69.
The crystal structure of bicyclo [3.3.3]undecane-1,5-diol has been determined. It is monoclinic, P21/c, a = 12.99(2), b = 14.16(2), c = 12.50(1)A,β = 112.42(2)°, with two independent molecules in the asymmetric unit. One of these is disordered, but the other has almost exact C3h symmetry and its conformation and precise molecular geometry agree well with previous calculations by molecular mechanics. The molecule shows considerable angle strain, having bridge angles in the range 118–121° 相似文献
70.
The behaviour of commercial, membrane-covered dissolved oxygen detectors is considerably more complicated than the orginal model of Mancy et al. would suggest. For example, the steady-state current is dependent both on the thickness and nature of the electrolyte behind the membrane. And transient currents obtained for switch-on of the detector are not completely described by the simple diffusional model. This paper examines these examples of more complicated behaviour. An analysis of the transient current for a step change in dissolved oxygen concentration is also given. 相似文献