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排序方式: 共有768条查询结果,搜索用时 9 毫秒
21.
J. Žofka 《Czechoslovak Journal of Physics》1982,32(3):321-325
Hypernuclear structure models are briefly reviewed. Phenomena related to hypernuclear polarization are displayed. A discussion is given of nuclear and hypernuclear neutron orbitals extraction. Preliminary results on
– angular distributions for the reaction6Li(K
–, –)
6
Li are presented.Presented at the symposium Mesons and Light Nuclei, Liblice, Czechoslovakia, June 1981.The collaboration of Dr. M. Sotona and Dr. L. Majling in the speedy preparation of the AD results and discussions with them and with Prof. B. Povh are greatly acknowledged. 相似文献
22.
Tomislav P. Živković 《Journal of mathematical chemistry》2002,32(1):39-71
Interaction of quantum system S
a
described by the generalised × eigenvalue equation A|
s
=E
s
S
a
|
s
(s=1,...,) with quantum system S
b
described by the generalised n×n eigenvalue equation B|
i
=
i
S
b
|
i
(i=1,...,n) is considered. With the system S
a
is associated -dimensional space X
a
and with the system S
b
is associated an n-dimensional space X
n
b
that is orthogonal to X
a
. Combined system S is described by the generalised (+n)×(+n) eigenvalue equation [A+B+V]|
k
=
k
[S
a
+S
b
+P]|
k
(k=1,...,n+) where operators V and P represent interaction between those two systems. All operators are Hermitian, while operators S
a
,S
b
and S=S
a
+S
b
+P are, in addition, positive definite. It is shown that each eigenvalue
k
i
of the combined system is the eigenvalue of the × eigenvalue equation
. Operator
in this equation is expressed in terms of the eigenvalues
i
of the system S
b
and in terms of matrix elements
s
|V|
i
and
s
|P|
i
where vectors |
s
form a base in X
a
. Eigenstate |
k
a
of this equation is the projection of the eigenstate |
k
of the combined system on the space X
a
. Projection |
k
b
of |
k
on the space X
n
b
is given by |
k
b
=(
k
S
b
–B)–1(V–
k
P})|
k
a
where (
k
S
b
–B)–1 is inverse of (
k
S
b
–B) in X
n
b
. Hence, if the solution to the system S
b
is known, one can obtain all eigenvalues
k
i
} and all the corresponding eigenstates |
k
of the combined system as a solution of the above × eigenvalue equation that refers to the system S
a
alone. Slightly more complicated expressions are obtained for the eigenvalues
k
i
} and the corresponding eigenstates, provided such eigenvalues and eigenstates exist. 相似文献
23.
Tanja Vidaković-Koch Tamara Miličić Luka A. Živković Hoon Seng Chan Ulrike Krewer Menka Petkovska 《Current Opinion in Electrochemistry》2021
The nonlinear frequency response analysis (NFRA) can be seen as an extension of electrochemical impedance spectroscopy. NFRA gives a full and detailed representation of the system response and can establish a connection between model parameters and the experimentally observed phenomena. In this article, different theoretical NFRA approaches and the most recent application examples are discussed. A simple electrochemical example is used to showcase the benefits and disadvantages of analyzing the system response by using different approaches. In addition, it was shown how to extract experimental harmonic values and analyze them. 相似文献
24.
25.
26.
The kinetics of the thermal decomposition of solid complexes of the type Ni(NCS)2L2 (L=pyridine,β-picoline and quinoline), of pseudooctahedral configuration, were studied by using isothermal methods, on the basis of losses of weight, in the temperature range 90–191?. The most suitable reaction order for all the complexes under investigation was found to ben=2/3, i.e. the total decomposition rate is determined by the chemical process proper. The calculated values ofE a(in kcal · mole?1) decrease in the following order: Ni(NCS)2py2 (29.4)>Ni(NCS)2(β-pic)2 (27.6)>Ni(NCS)2Q2 (24.3). With increasing volume of the ligand L the reaction rate also increases, and this suggests that the reaction proceeds by dissociative activation. For all the investigated complexes it was found that δH>E A; this may be explained by a several-step mechanism and the complex Ni(NCS)2L is then considered an intermediate. 相似文献
27.
Predrag Džodić Ljiljana Živanović Ana Protić Mira Zečević Biljana Jocić 《Chromatographia》2009,70(9-10):1343-1351
A chemometrical approach was applied to develop a reversed-phase liquid chromatographic method for simultaneous determination of carbamazepine and its impurities iminostilbene and iminodibenzyl in solid dosage form. According to contemporary literature, no method was developed for simultaneous determination of carbamazepine and these impurities by chemometrical approach. The fractional factorial design was used for selection of variables significantly influencing the chromatographic separation of the investigated substances. The investigated variables were: temperature of the column, the percentage of organic modifier, the acetate buffer concentration and pH of water phase. The first three variables were proved to be significant and were optimized by face centered, central composite design. Investigation was performed using C18 XBridge Shield analytical column (50 mm × 4.6 mm i.d., particle size 3.5 µm). The optimal conditions for the separation were established with the mobile phase composition of methanol–10 mM acetate buffer (pH adjusted to 2.21 with glacial acetic acid) (50:50, v/v) at a flow rate of 1.5 mL min?1, 25 °C column temperature and detection at 260 nm. Total analysis time was shortened to about 8 min. Finally, the method was successfully validated and subsequently applied to the analysis of commercially available carbamazepine tablets. 相似文献
28.
Erik Rakovský Ľudmila Žúrková Jaromír Marek 《Monatshefte für Chemie / Chemical Monthly》2002,133(3):277-283
Summary. Anhydrous 1,6-hexanediammonium dihydrogendecavanadate ((HdaH2)2H2V10O28, 1) was prepared by reaction of V2O5 with 1,6-hexanediamine in aqueous solution. The crystal structure of 1 was determined, and the proton positions in the H2V10O28
4− anion were calculated by the bond length/bond number method. The protons are bound to the centrosymmetrically oriented μ–OV3 groups of the decavanadate anion. Based on the analysis of IR spectra of 1 prepared from H2O and D2O, the absorption band at 871 cm−1 can be attributed to δ(V–Ob–H) vibrations.
Received August 3, 2001. Accepted (revised) October 8, 2001 相似文献
29.
George SJ Tomović Ž Schenning AP Meijer EW 《Chemical communications (Cambridge, England)》2011,47(12):3451-3453
Preferred handedness in the supramolecular chirality of self-assembled achiral oligo(p-phenylenevinylene) (OPV) derivatives is induced by chiral solvents and spectroscopic probing provides insight into the mechanistic aspects of this chiral induction through chiral solvation. 相似文献
30.
Dr. Christopher J. Shaffer Dr. Detlef Schröder Dr. Christian Alcaraz Dr. Ján Žabka Dr. Emilie‐Laure Zins 《Chemphyschem》2012,13(11):2688-2698
Even in the highly diluted gas phase, rather than electron transfer the benzene dication C6H62+ undergoes association with dinitrogen to form a transient C6H6N22+ dication which is best described as a ring‐protonated phenyl diazonium ion. Isotopic labeling studies, photoionization experiments using synchrotron radiation, and quantum chemical computations fully support the formation of protonated diazonium, which is in turn a prototype species of superacidic chemistry in solution. Additionally, reactions of C6H62+ with background water involve the transient formation of diprotonated phenol and, among other things, afford a long‐lived C6H6OH22+ dication, which is attributed to the hydration product of Hogeveen’s elusive pyramidal structure of C6H62+, as the global minimum of doubly ionized benzene. Nitrogen is essential for the formation of the C6H6OH22+ dication in that it mediates the formation of the water adduct, while the bimolecular encounter of the C6H62+ dication with water only leads to (dissociative) electron transfer. 相似文献