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1.
2.
Eugen Jóna Marian Koman Anton Sirota 《Journal of inclusion phenomena and macrocyclic chemistry》1998,30(1):1-12
The stoichiometry and spectral properties of [Ni(4-Etpy)4(NCS)2]nG clathrates have been studied where n = 2 for G = 1-BrN (N = naphthalene), n = 1 or 2 for G = 1-MeN, and n = 0.5 for 2-MeN and 2-BrN. The complexes under study show electronic absorption spectra typical of an octahedral environment of the Ni(II) central atom. The differences found in IR spectra for the (CN) and (Ni–-NNCS) vibrations are discussed. The crystal structure of [Ni(4-Etpy)4(NCS)2]1-MeN was determined by X-ray diffraction and refined to R = 0.0586. Discrete non-centrosymmetric [Ni(4-Etpy)4(NCS)2] molecules form layers of a host structure and the space between the layers is occupied by 1-MeN. The relationship between interatomic distances in the host complex of similar clathrates are discussed. 相似文献
3.
The band gap for three ferroelectrics (triglycine selenate, triglycine fluorine berryllate and triglycine sulfate) is determined using an optic method. A shift of self-absorption edge towards longer wave lengths is observed when exposed to irradiation by γ rays with a dosage of ∽ (2 ÷ 7) · 107 r as well as corresponding decrease of band gap. The observed changes are connected with the chemical nature of the studied substances. 相似文献
4.
Investigation of the kinetics of the inversion of modifications sphalerite—wurtzite in zinc sulphide
The kinetics of isothermal transition of wurtzite into sphalerite at temperatures below the equilibrium temperature of transition (T < Tk) and sphalerite into wurtzite at (T > Tk) is studied. The diagrams of stability of the overheated and supercooled phases are drawn, and the temperature of the equilibrium transition is defined more precisely. 相似文献
5.
Kinetics of isothermal crystallization has been studied in the temperature range from 375 to 525°C. The kinetic curves are obtained and the rate of isothermal transformation of amorphous films into crystalline ones has been determined. Using experimentally determined kinetic curves the stability diagram of the amorphous films has been plotted in the temperature range from 400 to 525°C. The value of effective activation energy has been defined. 相似文献
6.
Neutron diffraction studies have been carried out on two series of lanthanum manganite compositions obtained under different technological regimes. Based on the plot of angle dependence β° characterizing the degree of monoclinic distortions on “tolerance factor” t Mn3+ concentration is determined in the compositions obtained by us. With partial oxygen pressure increasing in annealing atmosphere the crystalline transition (orthorhomb-cube) temperature lowers from 583 ± 10°K to 508 ± 10°K. The correlation between magnetic properties of the compositions obtained and the degree of orthorhombic distortions γ′ = \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm b}\sqrt {{\rm 2/c}} $\end{document}\end{document} is established. Neutron diffraction studies of magnetic properties of LaMnO3 compositions show that with decrease of orthorhombic distortion degree the decrease of antiferromagnetic component and lowering of the Néel point occur, while the ferromagnetic contribution increases and the Curie point rises. 相似文献
7.
D. P. Singh B. Sirota S. Talpatra P. Kohli C. Rebholz S. M. Aouadi 《Journal of nanoparticle research》2012,14(4):781
Silver molybdate microrods are self-assembled into micron sized, broom-like and flower-like structures. Our investigations
indicate that through a simple hydrothermal process, large scale production of such structure is possible. Using ammonium
molybdate and silver nitrate solutions as precursors, we were able to show that the self assembled architectures were dependent
on the pH of the starting precursor material. To understand the formation and destructions of the flower-like morphology,
a systematic broad range (from acidic to basic) of pH-controlled experiments were performed and its influence on the structure/microstructure
of synthesized materials was investigated. Scanning electron microscopy studies revealed that the morphology and microstructure
of the products varied significantly by changing pH values from 3 to 8 during mixing of the reactants. pH = 3 and 4 resulted
in the self assembly of monoclinic Ag2(Mo2O7) microrods into broom-like structures, whereas pH = 5 resulted into the flower-like morphology of mixed phase of monoclinic
and triclinic Ag2Mo2O7. We also found that increasing the pH after a certain threshold value (for example pH > 6) resulted in total collapse of
the flower-like morphology. Further increase of the pH to 7 and 8 resulted, the formation of microparticles of Ag2MoO4. A tentative scheme based on the pH-driven evolution of the self-assembly has been given to explain the formation of the
observed heterostructures. Preliminary electrical characterization of thin films of the flower-like structures rendered non-linear
current–voltage (I–V) responses. We also observed a strong hysteresis in the I–V responses of the flower-like structures developed
under high bias conditions. 相似文献
8.
The Debye-Waller factors and the mean-square dynamics displacements of the Be and O ions in beryllium oxide are obtained from X-ray diffraction powder data over the temperature range from 10 to 720 K for different crystallographic directions. The observed anisotropy of these mean-square displacements is discussed. 相似文献
9.
N. N. Sirota V. I. Pavlov A. K. Bogush A. P. Karvay 《Crystal Research and Technology》1981,16(10):1151-1157
The magnetic field effect on conductivity and intensity of the magnetic neutron diffraction reflections as well as magnetization of lanthanum manganite with different crystal lattice distortions in the ferromagnetic-paramagnetic transitions range are investigated. It is shown that in the investigated samples near the paramagnetic-ferromagnetic transition temperature at H = 0 there exists a relatively wide transition range where the magnetic ordering occurs with a relatively small external magnetic field applied. 相似文献
10.
N. N. Sirota 《Russian Physics Journal》1975,18(6):817-819
The buildup kinetics of F1 centers in KCl is studied. The dosage dependence of their densities contains two stages, a rapid stage and a slow stage. The rapid stage consists of two elementary components of the form (1-exp). The slow stage contains two linear components. A passage from the first to the second stage occurs sharply with a “deflection.” It is shown that this passage can be described by taking into account track effects. 相似文献