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51.
Gerald Schwarzenbacher Marion S. Gangl Marian Goriup Martin Winter Matthias Grunert Franz Renz Wolfgang Linert Robert Saf 《Monatshefte für Chemie / Chemical Monthly》2001,7(1):519-529
11-(4H-1,2,4-Triazol-4-yl)-undecylmethacrylate (1), a new ligand for Fe(II) spin-crossover (SCO) complexes containing a polymerizable group, was synthesized and characterized.
The complex [Fe·1
3](BF4)2 (2) was obtained by reaction of 1 with Fe(BF4)2·6H2O (molar ratio 1/Fe(II) = 3/1) in THF. Complex 2 showed a gradual spin-crossover between 80 and 230 K. The methacrylate units in the ligands of complex 2 could be oligomerized radically in solution (initiator: azoisobutyronitrile) without loss of the spin-crossover behaviour. 相似文献
52.
Viktor Gutmann Gerhard Resch Wolfgang Kantner Wolfgang Linert 《Monatshefte für Chemie / Chemical Monthly》1989,120(1):11-20
Summary Plastic deformation of a copper electrode in an aqueous 10–4
M Cu(ClO4)2 solution leads to greater potential shifts, to smaller post strain effects and to greater relaxation rates as the ratio interfacial area: volume of copper is increased. It is suggested that its system organization is improved, as the interfacial area is increased. The system organization appears also to be improved as oxidic superstructures are developing at the interface, where the highest hierarchic levels of both electrode and electrolyte are in immediate contact. Further hints as to the system organization of the whole system Cu/CuSO4 solution are obtained from the fact that atpH=2 andc
Cu + +=10–1 mol/l the redox potential is independent of the pretreatment of the electrode and independent of the presence of oxidic superstructures. It is underlined that the passivity due to the presence of an oxidic superstructure is maintained only atpH >2, whereas at lowerpH-values copper is more readily dissolved. It is suggested that atpH=2 the system is in an optimal state of system organization (OSO), similar to those reported in the course of phase transformations, in extremely thin metal films and in solutions at the isokinetic temperature. 相似文献
53.
54.
W. Linert K. Stiglbrunner V. Gutmann 《Monatshefte für Chemie / Chemical Monthly》1984,115(8-9):905-920
Potential shifts have been measured in the course of mechanical deformation of copper electrodes in aqueous electrolytes. The potential values depend on the pretreatment of the electrodes, on the composition of the electrolyte and on the rate of deformation. The great influence of the oxygen content on the electrode surface seems evident. The potential values can be interpreted in terms of mixed potentials between an ideal copper electrode reaction and a copper oxide reaction. These findings are, however, not in agreement with the observedpH-stabilities of the electrode surfaces, which extend over apH-range not expected for Cu-Cu2O-mixtures. It may be anticipated that oxidic superstructures of variable properties are present, which may show semiconductor properties in the immediate surface regions. 相似文献
55.
A formalism has been developed that describes spin crossover equilibrium in the solid state by taking into account the effects
of n nearest neighbours of a given molecule on its partition function. In this way binary and many-body interactions of the order
n + 1 are included into the theoretical model and represented by non-ideality parameters connected with the splitting of free
energy levels. Binary interactions are characterised by the main splittings whereas higher order interactions manifest themselves
in asymmetries of splittings within multiplets. The contribution of molecular interactions can also be written in terms of
formal excess free energies of the second, third, fourth and higher orders. Simple relationships between excess free energies
and parameters of multiplets have been found for binary, ternary and quaternary interactions. This formalism is reduced to
that of the model of binary interactions when effects of surroundings are additive leading to equidistant free energy multiplets.
Higher order interactions may cause an abrupt spin crossover but in a limited range of compositions around the transition
point. The regression of experimental transition curves of one-step spin crossover may yield estimates of excess energies
up to the fifth order. 相似文献
56.
Summary A kinetic study of the anaerobic oxidation of cysteine (H2
L) by iron(III) has been performed over thepH-range 2.5 to 12 by use of a stopped-flow high speed spectrophotometric method. Reaction is always preceded by complex formation. Three such reactive complex species have been characterized spectrophotometrically: FeL
+ (max=614 nm, =2 820 M–1cm–1); Fe(OH)L (max=503 nm; shoulder at 575 nm, =1 640 M–1cm–1); Fe(OH)L
2
2–
(max=545 nm; shoulder at 445 nm, =3 175 M–1 cm–1). Formation constants have been evaluated from the kinetic data: Fe3++L
2– FeL
+: logK
1
M
=13.70±0.05; Fe(OH)2++L
2– Fe(OH)L: logK
1
MOH
=10.75±0.02; Fe(OH)L+L
2– Fe(OH)L
2
2–
; logK
2
MOH
=4.76±0.02. Furthermore the hydrolysis constant for iron(III) was also obtained: Fe(OH)2++H+ Fe
aq
3+
: logK
FeOH=2.82±0.02). Formation of the mono-cysteine complexes, FeL
+ and Fe(OH)L, is via initial reaction of Fe(OH)2+ with H2
L (k=1.14·104M–1s–1), the final product depending on thepH. FeL
+ (blue) formed at lowpH decomposes following protonation with a second-order rate constant of 1.08·105M–1s–1. Fe(OH)L (purple) decomposes with an apparent third order rate constant ofk=3.52·109M–2s–1 via 2 Fe(OH)L+H+ products, which implies that the actual (bimolecular) reaction involves initial dimer formation. Finally, Fe(OH)L
2
2–
(purple) is remarkably stable and requires the presence of Fe(OH)L for electron transfer. A rate constant of 8.36·103M–1s–1 for the reaction between Fe(OH)L and Fe(OH)L
2
2–
is evaluated.Dedicated to Prof. Dr. mult. Viktor Gutmann on the occasion of his 70th birthday 相似文献
57.
Grunert CM Schweifer J Weinberger P Linert W Mereiter K Hilscher G Müller M Wiesinger G van Koningsbruggen PJ 《Inorganic chemistry》2004,43(1):155-165
[micro-Tris(1,4-bis(tetrazol-1-yl)butane-N4,N4')iron(II)] bis(hexafluorophosphate), [Fe(btzb)(3)](PF(6))(2), crystallizes in a three-dimensional 3-fold interlocked structure featuring a sharp two-step spin-crossover behavior. The spin conversion takes place between 164 and 182 K showing a discontinuity at about T(1/2) = 174 K and a hysteresis of about 4 K between T(1/2) and the low-spin state. The spin transition has been independently followed by magnetic susceptibility measurements, (57)Fe-M?ssbauer spectroscopy, and variable temperature far and midrange FTIR spectroscopy. The title compound crystallizes in the trigonal space group P3 (No. 147) with a unit cell content of one formula unit plus a small amount of disordered solvent. The lattice parameters were determined by X-ray diffraction at several temperatures between 100 and 300 K. Complete crystal structures were resolved for 9 of these temperatures between 100 (only low spin, LS) and 300 K (only high spin, HS), Z = 1 [Fe(btzb)(3)](PF(6))(2): 300 K (HS), a = 11.258(6) A, c = 8.948(6) A, V = 982.2(10) A(3); 100 K (LS), a = 10.989(3) A, c = 8.702(2) A, V = 910.1(4) A(3). The molecular structure consists of octahedral coordinated iron(II) centers bridged by six N4,N4' coordinating bis(tetrazole) ligands to form three 3-dimensional networks. Each of these three networks is symmetry related and interpenetrates each other within a unit cell to form the interlocked structure. The Fe-N bond lengths change between 1.993(1) A at 100 K in the LS state and 2.193(2) A at 300 K in the HS state. The nearest Fe separation is along the c-axis and identical with the lattice parameter c. 相似文献
58.
M. Vlad I. Labádi L. Saity R. Tudose W. Linert O. Costisor 《Journal of Thermal Analysis and Calorimetry》2008,91(3):925-928
The heterometallic complex [Cu(VO)2(C10H8N2)2(C2O4)3·2H2O] has been prepared and characterised by electronic and IR spectra, molecular electrical conductivity and thermal behaviour.
A polymeric structure is proposed with oxalate and 4,4′-dipyridine acting as bridging ligands and VO(IV) of C4v symmetry and Cu(II) in octahedral surrounding the oxalate anion V4h. 相似文献
59.
Formalism is developed in which contributions of binary and ternary interactions towards free energy of a mixture of low-spin (A) and high-spin (B) isomers of spin crossover compounds as well as effects of ordering are taken into account. Parameters characterising non-ideality in this formalism are the excess free energy (ΔF ex) and absolute asymmetries (Δ A , Δ B ) of splittings of free energy levels. The excess free energy characterises the effects of binary interactions whereas asymmetries arise from ternary interactions. According to this model, the plateau in the spin crossover transition curve originates from the phenomenon of ordering taken into account in the Gorsky-Bragg-Williams approximation. 相似文献
60.