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1.
The method of neutron diffraction is used to construct temperature dependences of the intensity of 110 antiferromagnetic reflection under the influence of compressive stresses = 0–150 MPa along [001]. Application of the stresses leads to an increase in the transition temperature, the transition being delayed in proportion to the increase in the load. On the other hand, the loading leads to a reduction in the magnetization jump for the antiferromagnetic sublattices. Thus, at > 100 MPa, the antiferromagnetic transformation takes on features of a second-order phase transformation. The transition which takes place in the stressed state is characterized by smoother rearrangment of short-order antiferromagnetic order into long-range order, as is evidenced by erosion of the transition boundary. The model proposed here — which does not ascribe the usual effect to uniaxial stresses on the antiferromagnetic transition in -Mn alloys — is based on the anomalous temperature dependence of the elastic constants.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 92–97, March, 1987.  相似文献   
2.
Conclusion Thus, the crystallography and the character of antiferromagnetic transformations in manganese alloys determine several specific features of the manifestation of the shape memory effect in these materials. Among these features are: clearer manifestation of reversible deformation, even in the case of small initial strains; a broad temperature range associated with deformation; the practically hysteresis-free character of the reversible deformation in polycrystalline materials; the existence of alternating reversible deformation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 104–117, May, 1985.  相似文献   
3.
The crystal structure of a novel antimony(III) fluoride complex, ammonium undecafluorotriantimonate(III) (NH4)2Sb3F11, was determined. The crystals are triclinic: a = 7.780(2) Å, b = 8.370(2) Å, c = 10.620(1) Å, = 71.06(1)°, = 89.03(1)°, = 63.58(1)°, V = 579.1(2) Å3, Z = 2, (calcd) = 3.500 g/cm3, (exp) = 3.51 g/cm3, F(000) = 548.0, space group P . The structure consists of anionic [Sb3F11]2– chains and ammonium cations combined into a framework by the N–H···F hydrogen bonds.  相似文献   
4.
The crystal structures of complex antimony(III) fluorides RbSbF4 (I) and (C2N4H5)SbF4 (II) were determined. The crystals of I and II are monoclinic; for I: a = 4.628(1) Å, b = 6.167(1) Å, c = 7.922(1) Å, = 100.582(3)°, V = 222.24(7) Å3, Z = 2, (calcd.) = 4.23 g/cm3, (exp.) = 4.25 g/cm3, F(000) = 248, space group P21/m, R = 0.0395; for II: a = 4.678(1) Å, b = 7.339(4) Å, c = 10.185(1) Å, = 90.88(2)°, V = 349.6(2) Å3, Z = 2, (calcd.) = 2.69 g/cm3, (exp.) = 2.70 g/cm3, F(000) = 264, space group P21. The structure of I is formed by Rb+ cations and [SbF4] n n anionic chains composed of SbF5E octahedra with two bridging fluorine atoms. The structure of IIis formed by (C2N4H5)+ cations and isolated [SbF4] anions in which the antimony polyhedra are SbF4E trigonal bipyramids. The relationship between the crystal structures and electrophysical and biological properties of single-charged cation tetrafluoroantimonates(III) was studied.  相似文献   
5.
Na2Sb5F9O3(NCS)2, a new complex, has been synthesized from NaSCN and SbF3 aqueous solutions and studied by chemical, X-ray diffraction, and thermal analyses and IR, 121,123Sb NQR, and 19F NMR spectroscopy. Its layered structure (triclinic symmetry system, a = 6.9998(1) Å, b = 9.4180(1) Å, c = 13.1094(2) Å, α = 74.815(1)°, β = 78.188(1)°, γ = 82.779(1)°, Z = 2, space group P $\bar 1$ ) is built of Na+ cations and [Sb10F18O6(NCS)4]4? decanuclear complex anions that consist of two [Sb5F9O3(NCS)2]2? pentanuclear complex anions linked by two weak Sb-F ionic bonds (2.529(2) Å). Decanuclear complex anions are linked into layers by secondary Sb…F bonds and Na-F bonds. Van der Waals interactions link these layers into a framework. The complex is stable up to 200°C.  相似文献   
6.
(NH4)Sb4F13 crystals (I) are synthesized and their crystal structure (tetragonal crystal system: a = 9.6431(2) Å, c = 6.5503(2) Å, V = 609.11(3) Å3, Z = 2, d calc = 4.100 g/cm3, F(000) = 664, space group I4?) is determined. The main structural units of I are tetranuclear anionic [Sb4F13]? complexes and [NH4]+ cations. The anionic complexes are built of four SbF3 groups linked together by tetrahedral bridging fluorine atom. At room temperature the (NH4)Sb4F13 crystals are isostructural to previously studied МSb4F13 (М = K, Rb, Cs, and Tl). The study of 121,123Sb NQR spectra of compound I is performed in a range of 77-370 K, which shows that when the temperature decreases (<250 K) the substance exhibits piezoelectric properties, as do other compounds of this group, but with a violation of their isostructurality.  相似文献   
7.
Single crystal X-ray diffraction analysis is used to determine the crystal structure of a newly synthesized molecular complex compound of antimony(III) fluoride with L-leucine of the composition SbF3(C6H13NO2) (orthohombic crystal system: a = 5.7948(8) ?, b = 6.2433(9) ?, c = 28.594(4) ?, Z = 4, P212121 space group). The structure consists of SbF3 molecules and L-leucine bound into polymer chains by bidentate bridging carboxyl groups of amino acid molecules. Weak Sb…F(1)b bonds combine the adjacent chains into polymer ribbons organized by N-H…. F and N-H…. O hydrogen bonds into a framework.  相似文献   
8.
The crystal structure of L-leucinium tetrafluoroantimonate(III) of the composition (C6H14NO2)SbF4 (orthorhombic symmetry: a = 6.1459(6) Å, b = 14.994(1) Å, c = 24.789(2) Å, Z = 8, P 212121 space group) synthesized for the first time is determined. The (C6H14NO2)SbF4 structure represents a new structure type of tetrafluoroantimonate(III). It is formed by (C6H14NO2)+ cations and chain complex [Sb2F8]n 2n anions composed of Sb2F8 dimers linked into chains by bridging F atoms. The Sb2F8 dimers consist of SbF3 and SbF5 groups bound by bridging fluoride atoms of the SbF5 group. Chains in the structure are linked by N-H…F, N-H…O, and O-H…F hydrogen bonds into a three-dimensional framework.  相似文献   
9.
Neutron scattering studies of a diffuse peak at the (100) and (001) r.l. points ware performed in Mn-Fe and Mn-Cu fct single-crystal single-domain samples. Temperature dependence of integrated intensity of (001) peak in Mn-Fe follows closely the sublattice magnetization, while in Mn-Cu it shows a maximum at TN. The origin of the scattering present at (100) — Z.B. point in Mn-Cu remains unknown.  相似文献   
10.
The life of solid lubricating coatings of the VNII NP type, based on molybdenum disulfides and various binders, has been experimentally investigated under deep vacuum conditions (10–8–5 · 10–9 torr) together with the composition of the gas released in the friction process. It is shown that both under atmospheric conditions and in a deep vacuum the life of the coatings depends on the chemical nature of the film-former. The depth of the vacuum also has an important influence on the life of the coatings, both the mechanism and the end result of this effect depending to a large extent on the physicochemical properties of the bind. On the interval 10–1–10–2 torr there is a sudden change in the life of the coating.Physicotechnical Institute of Low Temperatures, Academy of Sciences of the Ukrainian SSR, Khar'kov. Translated from Mekhanika Polimerov, No. 6, pp. 1070–1075, November–December, 1970.  相似文献   
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