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991.
Single Crystal Investigations on Fluoroperovskites MPdF3 (M = Rb, K) and PdF2 Single crystal investigations on PdF2 (violet) confirm the tetragonale rutile structure [1, 2] with a = 495.44(3) pm, c = 338.48(3) pm, Z = 2, space group P42/mnm-D (No. 136) (xF = 0.3058(8)). RbPdF3 and KPdF3 have been obtained. RbPdF3 and KPdF3 both ruby-red single crystals crystallize cubic (perovskite-structure), space group Pm3m-O (No. 221) with a = 429.41(8) pm (RbPdF3) respectively a = 424.30(4) pm (KPdF3). 相似文献
992.
2H-吡喃-2-酮及其衍生物是有机合成的蓬要中间体。对于它们的合成已有许多报道,例如利用烯醇醚或烯醇砖醚与丁酰氯反应;羰基化合物与甲氧亚甲螭丙二酸二甲酯反应;α-苯基丙醛酸酯与丙酮的成环缩合2,6-二氯-3-三氯甲基吡啶与亚甲基丁二酸酯的反应,邻氰基苯乙炔、二苯乙二酮和丙酮的反应。但上述方法往往原料较难得到,产率较低或操作麻烦。 相似文献
993.
Determination of 1-aminocyclopropane-1-carboxylic acid in apple extracts by capillary electrophoresis with laser-induced fluorescence detection 总被引:1,自引:0,他引:1
A rapid and sensitive method for the determination of 1-aminocyclopropane-1-carboxylic acid (ACC) in apple tissues has been described. This method is based on the derivatization of ACC with 3-(2-furoyl)quinoline-2-carboxaldehyde (FQ), and separation and quantification of the resulting FQ-ACC derivative by capillary electrophoresis coupled to laser-induced fluorescence detection (CE-LIF). Our results indicated that ACC derivatized with FQ could be well separated from other interfering amino acids using 20 mM borate buffer (pH 9.35) containing 40 mM sodium dodecyl sulfate and 10 mM Brij 35. The linearity of ACC was determined in the range from 0.05 to 5 microM with a correlation of 0.9967. The concentration detection limit for ACC was 10 nM (signal-to-noise = 3). The sensitivity and selectivity of this described method allows the analysis of ACC in crude apple extracts without extra purification and enrichment procedure. 相似文献
994.
聚丙烯共混物反应挤出过程中的降解抑制 总被引:4,自引:0,他引:4
聚丙烯/(丙烯腈-苯乙烯)共聚物在过氧化二异丙苯存在下反应共混挤出时,加入亚油酸三甘酯可以有效地抑制过程的降解,从挤出物中分离出聚丙烯组分测试熔体流动速率表明,加入亚油酸三甘酯后,其熔体流动速率有很大下降,扫描电子显微镜的观察表明,调节过氧化二异丙苯和亚油酸三甘酯的加入量,可有效控制降解并生成较多的接枝物相容性,显著改善相形态。 相似文献
995.
Földvári M. Kovács-Pálffy P. Nagy N. M. Kónya J. 《Journal of Thermal Analysis and Calorimetry》1998,53(2):547-558
Various cation-exchanged montmorillonites (Li+, Na+, Ba2+, Mg2+, Ca2+, Mn2+, Co2+, Cu2+, Ag+, Cd2+, Hg2+, Al3+, Pb2+ and NH4+)
were prepared from calcium montmorillonite and their properties were studied by means of X-ray diffraction and thermal analysis.
The two methods give information on the cation exchange in the interlayer space only. X-ray diffraction studies at room temperature
are mainly suitable for estimation of the exchange of cations of different valencies. At 500°C, when the structure is completely
collapsed, the d value of montmorillonite depends on the non-hydrated ionic radius of the interlayer cation, but the measurement
interval is limited for fine interpretation. The thermoanalytical method is suitable for a better distinction of different
exchangeable cations of higher hydration energy on the basis of the DTG or DDTG curve.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
996.
M. Röder J. Hahn U. Falke S. Schulze F. Richter M. Hietschold 《Mikrochimica acta》1997,125(1-4):283-286
A series of BN films was deposited by means of r.f. magnetron sputtering of a h-BN target onto Si(1OO) surfaces. Hereby, the substrate bias voltage was varied. Special interest is focussed to the influence of the deposition parameters on the orientation of the growing hexagonal BN film with respect to the substrate. For structural investigation, cross section samples were prepared. In addition to HRTEM and diffraction investigations, especially electron energy loss spectroscopy (EELS) was applied successfully for phase identification. For negative bias voltages of U
B
=–300 V and U
B
=–350V, we found a phase system consisting of a first-grown 25 nm thick layer of hexagonal structure with the c axis parallel to the substrate surface followed by the cubic phase.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday 相似文献
997.
P. A. Barnes G. M. Parkes P. Sheridan 《Journal of Thermal Analysis and Calorimetry》1994,42(5):841-854
Analysis of very small particles can present problems. This paper describes the application of temperature programmed solid insertion probe mass spectrometry (TP-SIP-MS), scanning electron microscopy and SEM X-ray microanalysis to the identification of foreign particles present in an industrial product. The relative advantages and limitations of the techniques are discussed. It is shown that TP-SIP-MS is a powerful tool for such work and complements the use of more conventional microanalytical methods. 相似文献
998.
Summary The results of various quantum chemical calculations, the Hartree-Fock (HF) method, the Møller-Plesset perturbation theory (MP2), and the Hartree-Fock-Slater (HFS) method are compared. Atomic charges, dipole moments, topological properties of the electron density distribution and polarizabilities, and first hyperpolarizabilities are calculated. Atomic charges obtained with the HFS method are found to be very close to those calculated with the MP2 method, from which we conclude that the HFS method describes to some extent electron correlation effects. Performing an MP2 calculation after an HF calculation improves the molecular dipole moments considerably, yielding values close to the experimental ones. HFS calculations are computationally less demanding than MP2 and yield comparable results for the electron density distributions, dipole moments and polarizabilities. 相似文献
999.
New secondary and tertiary amine borane derivatives were prepared in a one-pot reaction starting from primary amine boranes. The reaction involves treatment of an amine borane with 2 equivalents of s-BuLi at −78 °C. In general, mixtures of mono and di metallated products were obtained. Alkyl iodides and benzyl chloride reacted with the lithiated amine, but aldehydes and ketones were reduced. Conversion was high as determined by NMR, but moderate to low yields were obtained after chromatography, possibly due to decomposition on silica. Crystal structures were obtained for the compounds 3a, 3b and 3c. 相似文献
1000.
Kamal M. Dawood 《Tetrahedron》2007,63(39):9642-9651
The catalytic activity of benzothiazole-based Pd(II)-complexes was evaluated in Suzuki-Miyaura and Heck-Mizoroki C-C cross-coupling reactions of aryl chlorides and bromides with olefins and arylboronic acids both under thermal as well as microwave irradiation conditions in water. The factors affecting the optimization of such reactions as well as the reusability of the Pd-precatalysts are studied. 相似文献