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排序方式: 共有118条查询结果,搜索用时 203 毫秒
71.
Zusammenfassung Dem vonStaudinger aus Äthylketencarbonsäureäthylester und Benzalanilin bei –20° dargestellten Addukt kommt die offenkettige, zwitterionische Struktur eines 4-Äthoxycarbonyl-1,2-diphenyl-2-azonia-1,3-hexadien-3-olats (3) zu.
Mit 1 Abbildung 相似文献
Reaction of ethyl 2-ethylketenecarboxylate with benzylidene aniline
The adduct obtained byStaudinger at –20° from ethoxycarbonyl ethyl ketene and benzylidene aniline has the open chain dipolar structure of 4-ethoxycarbonyl-1,2-diphenyl-2-azonia-1,3-hexadien-3-olate (3).
Mit 1 Abbildung 相似文献
72.
Zusammenfassung IR-spektroskopische Untersuchungen an disubstituierten Malonsäurechloriden haben ergeben, daß die Thermolyse—im Gegensatz zu der von monosubstituierten Malonsäurechloriden—je nach Substituenten am mittelständigen C-Atom der Malonsäure zu unterschiedlichen Produkten führt.
Thermolysis of disubstituted malonyl chlorides
It has been shown by infrared spectroscopic data that disubstituted malonyl chlorides do not react uniformly. This is in contradiction to the mode of reaction of monosubstituted malonyl chlorides.相似文献
73.
Polarization effects on population transfer by stimulated Raman transition using overlapping time dependent pump and Stokes
laser pulses from the ground X
1Σ
g
/+
(v
g=0, J
g=1) level of H2 to the final X
1Σ
g
/+
(v
f=1, J
f=1) level via the intermediate B
1Σ
u
/+
(v
i=14, J
i=0,2), C
1Π
u
/+
(v
i=3, J
i=2) and C
1Π
u
/−
(v
i=3, J
i=1) levels have been theoretically investigated by applying the density matrix formalism. We have studied in detail the dependence
of the population transfer on time delay between two pulses for the cases of on-resonance excitations considering linear parallel
and same-sense circular polarizations of the fields. The pump and Stokes fields are taken as having Gaussian pulse shapes
with peak intensities I
P
/0
(I
S
/0
)=2 × 106 and 1 × 107 W/cm2. Density matrix equations have been solved for each value of the magnetic quantum number M
g(0, ±1) of the initial ground level taking into account the M
g dependence of the Rabi frequencies. M
g — averaged population transfer to the final level has also been calculated. For resonance excitations to the B(14, 0) or C(3, 1) levels, appreciable population transfer is achieved for intuitive pulse order for some particular values of M
g and M
i (magnetic quantum number of the resonant intermediate level) depending on the nature of polarizations. The calculated values
of M
g — averaged population transfer for the two cases of polarizations show that for on-resonance excitation to the B(14, 0) or the C(3, 1) level, linear parallel polarization of the laser fields yield more transfer efficiency whereas for resonance excitation
to the B(14, 2) level, larger population transfer results from the same-sense circular polarizations. For resonance excitation to
the C(3, 2) level, M
g — averaged population is found to be almost polarization independent. The calculations for the six-level H2 system reveal some interesting features of polarization effects on the population transfer efficiency. 相似文献
74.
[Structure: see text] The asymmetric transfer hydrogenation of fluoroalkyl ketones mediated by [Ru(eta6-arene)((S,S)-R2NSO2DPEN)] catalysts using HCO2H-Et3N afforded the corresponding alcohols with high ee's and in excellent yields. 相似文献
75.
R. Albert K. Dax S. Seidl H. Sterk A. E. Stütz 《Journal of carbohydrate chemistry》2013,32(4):513-520
Starting from 1,2-O-isopropylidene-α-D-gluco- and -β-L-ido-furanurono-6,3-lactone, 5-deoxy-5-fluoro-α/β-D-gluco- and -L-idofuranose, respectively, were prepared by the following sequence of reactions: trifluoromethanesulfonylation, nucleophilic substitution with inversion of configuration, lactone reduction and deprotection. On the basis of H-H-, H-C-, H-F-, and C-F-couplings, the stereochemistry of the products is discussed. 相似文献
76.
In this paper the singularly perturbed initial boundary value problems for the nonlocal reaction diffusion system are considered. Unsing the iteration method and the comparison theorem, the existence, uniqueness and its asymptotic behavior of solution for the problem are studied. 相似文献
77.
Zsuzsanna Riedl György Hajós Gert Kollenz Heinz Sterk András Messmer 《Monatshefte für Chemie / Chemical Monthly》1992,123(12):1181-1191
Summary Eight new tetracyclic fused as-triazines (4–6,8,11–13, and15) have been synthesized by conversion and subsequent ring transformation of 1,2-diaminoisoquinolinium (2) and -quinolinium salts (9) with 4-benzoyl-5-phenylfuran-2,3-dione (1). Selective alkylations of the new products revealed that these reactions are governed mainly by the electronic density of the lone pairs as well as by steric effects.Dedicated to em. Univ. Prof. Dr. E. Ziegler on the occasion of his 80th birthday 相似文献
78.
Renate Dworczak Heinz Sterk Hans Junek 《Monatshefte für Chemie / Chemical Monthly》1990,121(2-3):189-193
Summary Addition of tetracyanoethylene to the 1,2,3,4-tetrahydro-isoquinoline-1,3-diones1 a–d yields 4-(dicyanomethylene)-1,2,3,4-tetrahydro-isoquinoline-1,3-diones3 or 4-(2-amino-1,1,3-tricyano-3-propylidene)-1,2,3,4-tetrahydro-1,3-diones4 depending on the substituent in position 2. Spectra of both types of derivatives are discussed. 相似文献
79.
We have investigated the superconducting properties of the Bi1.7 Pb0.3Sr2Ca2−xCe
x
Cu3O10+δ system with x=0.00, 0.02, 0.04, 0.08 and 0.1 by X-ray diffraction and magnetic susceptibility. The substitution of Ce for Ca has been found
to drastically change the superconducting properties of the system. X-ray diffraction studies on these compounds indicate
decrease in the c-parameter with increased substitution of Ce at Ca site and volume fraction of high T
c (2 : 2 : 2 : 3) phase decreases and low T
c phase increases. The magnetic susceptibility of this compound shows that the diamagnetic on set superconducting transition
temperature (onset) varies from 109 K to 51 K for x=0.00, 0.02, 0.04, 0.08 and 0.1. These results suggest the possible existence of Ce in a tetravalent state rather than a trivalent
state in this system; that is, Ca2+ → Ce4+ replacement changes the hole carrier concentration. Hole filling is the cause of lowering T
c of the system. 相似文献
80.
Zusammenfassung Injiziert man Ratten i. p. 1,1-Diäthoxy-4-hydroxy-2-penten, so wird die Verbindung rasch resorbiert und metabolisiert. Im Harn können 6 Metaboliten nachgewiesen werden. Zwei davon wurden als diastereomere Mercaptursäuren identifiziert, nämlich als die N-Acetyl-S-(d-bzw.l-1-diäthoxymethyl-3-oxobutyl)-l-cysteine. Der Bildungsweg dieser Verbindungen wird besprochem.
Mit 1 Abbildung
Herrn Prof. Dr. Dr. h. c.Otto Kratky mit den besten Wünschen zum 70. Geburtstag gewidmet. 相似文献
Mercapturic acid formation during detoxication of 1,1-diethoxy-4-hydroxy-2-pentene
Following intraperitoneal administration to rats 1.1-diethoxy-4-hydroxy-2-pentene is rapidly resorbed and metabolized. Among six metabolites excreted in rat urine two have been identified as the diastereomeric mercapturic acids, N-acetyl-S-(d-1-diethoxymethyl-3-oxo-butyl)-l-cysteine and N-acetyl-S-(l-1-diethoxymethyl-3-oxobutyl)-l-cysteine. The metabolic formation of these compounds is discussed.
Mit 1 Abbildung
Herrn Prof. Dr. Dr. h. c.Otto Kratky mit den besten Wünschen zum 70. Geburtstag gewidmet. 相似文献