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71.
钯(Ⅱ)-芳香氮碱-氨基酸三元配合物中的电子效应和芳环堆积作用 总被引:3,自引:0,他引:3
用pH-电位滴定法测定了Pd(L)(Aa)+三元配合物及相应的二元配合物,在25±0.5℃,30%的乙醇水溶液(体积分数),I=0.1(KNO3)条件下的稳定常数及表征常数。其中L=邻菲罗啉(phen)、苯并咪唑邻菲罗啉(PIP)、邻菲罗啉-5,6-二酮(dophen)、2,9-二甲基邻菲罗啉(dmphen)和联吡啶3,3′-二羧酸(BDA);Aa为甘氨酸(gly)、苯丙氨酸(phe)、酪氨酸(tyr)、S-苄基-半胱氨酸(bcys)、谷氨酰胺(glu)和γ-谷氨酰-α-萘胺(gnapa)。从配合物配体间的电子效应和芳环堆积等观点对配合物的附加稳定性进行了讨论,并计算了电子效应和芳环堆积效应各自对三元配合物附加稳定性的贡献。 相似文献
72.
73.
L.A. Isupova I.S. Yakovleva I.I. Gainutdinov Yu.T. Pavlyukhin V.A. Sadykov 《Reaction Kinetics and Catalysis Letters》2004,81(2):373-382
The phase composition and microstructure of samples of the La1-xCaxFeO3-y system prepared via a ceramic route were characterized by M?ssbauer spectroscopy. In all cases, iron was found in the 3+ state. The ordering
of anion vacancies in the samples with the composition in the range of 0.8 > x ≥ 0.4, which corresponds to a microheterogeneous
solid solution, generates new distorted octahedral and fivefold/tetrahedral sites revealed by two typical sextets. The disordering
of this solid solution and small (10-100 ?) sizes of domains with a perovskite, braunmillerite or Grenier phase structure
caused the appearance of a superparamagnetic doublet, which grows with the Ca content up to x = 0.8 but disappears in the
sample of pure braunmillerite. The appearance of Fe cations in a distorted coordination correlates with the increased activity
of the samples with a microheterogeneous structure in the CO catalytic oxidation and with their reducibility by H2.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
74.
9 氯甲基蒽 ( 1 )与 3 ,5 二甲氧基苄醇 ( 2 )在相转移催化剂存在下反应生成 9 ( 3 ,5 二甲氧基苄基氧甲基 )蒽 ( 3 ) .( 3 )的苯溶液在紫外光照射下发生蒽环与苯环间的分子内 [4π + 4π]光致环加成反应 ,定量地生成多环化合物 ( 4 ) .( 4 )在热的作用下发生逆反应 ,定量地转化成原料 ( 3 ) .这种光致可逆反应可应用于制备光开关材料 . 相似文献
75.
The geometries of the most stable isomers of gold telluride systems AuTe, Au2Te, and AuTe2 are determined using the MP2 method. The aspect of gold—telluride interaction, the electron correlation, and relativistic
effects on geometry and stability are investigated at the MP2 and CCSD(T) theoretical levels. The results show that the electron
correlation and relativistic effects are responsible not only for gold—gold attraction but also for additional gold—telluride
interaction. The gold—telluride interaction is strong enough to modify the known pattern of bare gold clusters. Both effects
are essential for determining the geometry and relative stability of this type of systems. 相似文献
76.
The reaction of cis-[ClP(μ-NtBu)]2 with N,N′-dimethylurea leads to the formation of both mono- and di-substituted derivatives [ClP(μ-NtBu)2P(NMeCON(H)Me)] and [(μ-NtBu)P(NMeCON(H)Me)]2, instead of monomeric, dimeric or higher oligomeric macrocycles. The structure of [ClP(μ-NtBu)2P(NMeCON(H)Me)] shows rare non-bonded P?Cl and intermolecular hydrogen bonding interactions leading to a 2D-sheet like structure. 相似文献
77.
Evaluation of the aerobic composting process of winery and distillery residues by thermal methods 总被引:1,自引:0,他引:1
F.C. Marhuenda-Egea E. Martínez-Sabater A. Sánchez-Sánchez M.A. Bustamante M.D. Pérez-Murcia 《Thermochimica Acta》2007,454(2):135-143
The possibility of using thermal analysis for a quick characterization of chemical changes was tested in the organic matter from composting materials. Differential thermal analysis (DTA), thermogravimetry (TG) and the first derivative of the TG (DTG) were calculated in oxidizing conditions on compost samples obtained from three composting piles. The composting piles were made by mixing winery and distillery residues with sewage sludge (pile 1), with cow manure (pile 2) and hen droppings (pile 3). The temperature values in the pile 1 showed a different evolution during the thermophilic stage of the composting process in relation to the piles 2 and 3. The thermophilic stage for pile 1 was 17 days, meanwhile for the piles 2 and 3 were around 80 and 110 days, respectively, and probably pile 1 was not well composted. The curves of ion current of CO2 have been recorded in order to shed light on changes occurring in organic matter during composting. Particularly DTG curves allowed us to distinguish between well (piles 2 and 3) and poor (pile 1) stabilized organic matter. The energy released was calculated for each sample by integrating the DTA curves and these results are agreed with the previous hypothesis. Information deriving from weight losses, registered by the TG and DTG curves, enables to follow the evolution state of the organic matter and therefore changes in its stability. These data could determine the final point of the composting process of winery and distillery residues and then reduce the time for compost harvest. 相似文献
78.
Crespi M. S. Silva A. R. Ribeiro C. A. Oliveira S. C. Santiago-Silva M. R. 《Journal of Thermal Analysis and Calorimetry》2003,72(3):1049-1056
The thermal behavior and non-isothermal kinetics of thermal decomposition of three different kinds of composting of the USR
like: stack with drilled PVC tubes (ST), revolved stack (SR) and stack with material of structure (SM), from the usine of
composing of Araraquara city, Săo Paulo state, Brazil, within a period of 132 days of composting were studied. Results from
TG, DTG and DSC curves obtained on inert atmosphere indicated that the cellulosic fraction present, despite the slow degradation
during the composting process, is thermally less stable than other substances originated from that process. Due to that behavior,
the cellulosic fraction decomposition could be kinetically evaluated through non-isothermal methods of analysis. The values
obtained were: average activation energy, Ea=248, 257 and 259 kJ mol-1 and pre- exponential factor, logA=21.4, 22.5, 22.7 min-1, to the ST, SR and SM, respectively. From Ea and logA values and DSC curves, Málek procedure could be applied, suggesting that the SB (Šesták-Berggren) kinetic model is the appropriated
one to the first thermal decomposition step.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
79.
80.
Supercritical fluid extraction of flumetralin in tobacco 总被引:2,自引:0,他引:2
Summary This work evaluates the level of Flumetralin residues in real tobacco samples. Conventional extraction methods were compared with SFE methods in both static and dynamic modes using CO2 and CO2 with modifier. Additionally, in the dynamic SFE mode, different collection approaches, such as collection at room temperature without solvent, collection at room temperature in the presence of solvent (hexane) and collection in an ice bath, without solvent, were studied. SFE showed itself to be a promising extraction technique for pesticide residues in tobacco samples. 相似文献