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121.
4-Diazo-1,2,3-triazoles thermolyze and photolyze to 4-1,2,3-triazolylidenes which (1) convert benzenes to 4-phenyl-1,2,3-triazoles or/and (2) isomerize to α-diazonitriles which react carbenically with benzenes by addition, ring-expansion or substitution processes. 相似文献
122.
在水介质中,研究了新型的过氧化氢/N-甲基苯胺盐酸盐引发体系对 AM 与 PVA 的接枝共聚。产物经紫外光谱、红外光谱和 ~1H-核磁共振进行表征,并提出了引发机理。 相似文献
123.
The γ-substituted β-diketonate 2,4-dioxo-3-pentyl 4-[4-(n-octyloxy)cinnamoyl]oxybenzoate 1 and its pyrazole and isoxazole derivatives (2 and 3 respectively) have been synthesized and characterized by the spectroscopic methods and elemental analysis. The mesogenic properties of these compounds have been studied by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). A monotropic nematic mesophase was observed for the β-diketonate 1, in contrast, the pyrazole 2 displays an enantiotropic smectic A and isoxazole 3 exhibits an enantiotropic nematic mesophase. The relationship between the structure and liquid crystalline properties has also been discussed. 相似文献
124.
Lei He Hui‐Min Liu Xiao‐Lan Luo Wen‐Qin Zhang 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(2):o104-o106
The title compound, 2‐{N‐[2‐(2‐hydroxybenzamido)ethylammonioethyl]aminocarbonyl}phenolate, C18H21N3O4, crystallizes in a zwitterionic form as a result of intermolecular proton transfer and possesses a negatively charged phenolate group and a protonated amino group. The 2‐hydroxybenzamide and 2‐(aminocarbonyl)phenolate moieties attached to the two ends of the C—C—N—C—C backbone adopt a cis conformation in relation to this backbone. All N‐ and O‐bound H atoms are involved in hydrogen‐bond formation; the zwitterions are first linked into head‐to‐tail dimers, which are further organized into a two‐dimensional network parallel to the crystallographic bc plane. 相似文献
125.
Anomalous room-temperature specific heats have been seen experimentally by Knapp and coworkers in highT
c
superconductors. The measurements depart from 3N k
B
+
0
T by an amount of order
0
T. We present a theory for this, based on the fact that electronphonon interactions cause both electron band energies
k
n
and phonon frequencies
Q
µ
to be weakly temperature-dependent. First an observation is made which we call Brook's Theorem: the shiftE
k
n
(Q
µ) of the electron energy
k
n
due to adding one phonon in modeQ
µ, is identical to the shift
Q
µ
(k
n) of the phonon energy
Qµ due to adding one electron in the statek
n. Second, we assert that to sufficient accuracy whenT>
D
, entropy of the system of interacting electrons and phonons equals the entropy which would be calculated for non-interacting particles, except that theT-dependent energiesE
kn
(T) and
Q
µ
(T) should be used. A proof to orderu
2 (whereu is phonon displacement amplitude) was given in the thesis of one of us. Third, we use Brook's Theorem to show that the corrections C
el and C
ph to the specific heat due toT-dependence of electron and phonon energies respectively, are identically equal and have order of magnitude
0
T. All these results are valid in adiabatic approximation to orderu
2, and fail at low temperatures where non-adiabatic corrections are large. 相似文献
126.
Storage-Reduction of NOx over Combined Catalysts of Pt/Ba/Al2O3-Mn/Ba/Al2O3: Carbon Monoxide as Reductant 下载免费PDF全文
Sha Deng Xuehui Li Jianhua Xiao Furong Wang Lefu Wang 《天然气化学杂志》2007,16(2):213-216
Storage-reduction of NOx by carbon monoxide was investigated over combined catalysts of Mn/Ba/Al2O3-Pt/Ba/Al2O3. Combination of Mn/Ba/Al2O3 and Pt/Ba/Al2O3 catalysts in different ways showed excellent NOx storage-reduction performance and the content of Pt could be reduced by 50%. Not only the addition of 5Mn/15Ba/Al2O3 to lPt/15Ba/Al2O3 could improve its storage ability, but also enhance the NOx conversion consequently. NOx conversion over the combined catalysts (the combined catalysts I and II) was increased under dynamic lean-rich burn conditions, the maximum NOx conversion increased from 69.4% to respectively 78.8% and 75.7% over two combined catalysts. 相似文献
127.
连续一级反应的热动力学研究 总被引:1,自引:0,他引:1
本文把时间比法引入热动力学研究,建立了连续一级反应的热动力学研究法,并用来研究了一个连续反应体系的热动力学,验证了该方法的正确性. 相似文献
128.
Studies of the electrochemical behavior of epinephrine at a homocysteine self-assembled electrode 总被引:6,自引:0,他引:6
The self-assembled electrode with the homocysteine monolayer (Hcy/Au) has been characterized by infrared spectroscopy and ac impedance spectroscopy in electrolyte. The Hcy/Au electrode is demonstrated to promote the electrochemical response of epinephrine (E) by cyclic voltammetry. A pair of well-defined redox waves was obtained and the calculated standard rate constant (ks) is 2.1×10−2 cm s−1 at the self-assembled electrode. The reduction peak of E can be used to determine the concentration of E in presence of ascorbic acid (AA) owing to the Hcy/Au also promoting the electrochemical oxidation of AA. 相似文献
129.
A novel poly(vinyl alcohol) grafting 4-vinylpyridine self-gelatinizable copolymer was adapted to immobilize glucose oxidase. The reduction of hydrogen peroxide (H2O2) was detected at a Prussian Blue (PB) modified graphite electrode. A stable and sensitive glucose amperometric biosensor is described. The copolymer is a good biocompatible polymer in which the glucose oxidase retains high activity. Moreover, the copolymer can adhere firmly to the inorganic PB membrane. The sensor showed an apparent Michaelis-Menten constant of 18 +/- 0.2 mM and a maximum current density of 1.14 microA cm-2 mM-1. The linear range is from 5 microM to 4.5 mM glucose and the detection limit is 0.5 microM glucose. The catalytic efficiency of PB for the reduction of H2O2 is higher than that for the oxidation of H2O2. Glucose concentrations in serum samples from healthy persons and diabetic patients were determined using the sensor. The results compared well with those provided by the hospital using a spectroscopy method. 相似文献
130.
Four new 28‐noroleanane‐derived spirocyclic triterpenoids, compounds 1 – 4 , were isolated from the rhizomes of Phlomis umbrosa. Their structures were elucidated on the basis of 1D‐ and 2D‐NMR analyses, in combination with high‐resolution MS experiments. 相似文献