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481.
Youhei ShimogoriTakefumi Hamamatsu Takeshi FujinamiHiroaki Hagiwara Naohide Matsumoto Nazzareno ReJerzy Mrozinski Yuichi IshikawaAsako Igashira-Kamiyama Takumi Konno 《Polyhedron》2011,30(6):1127-1133
A linear tetranuclear CuII-GdIII-CuII-GdIII complex [CuIILdpen(meso)GdIII(thd)2(H2O)]2 was synthesized from the reaction of [NaCuIILdpen(meso)(DMF)] with [GdIII(thd)3(H2O)2], and the structures and magnetic properties were investigated, where H3Ldpen(meso) = meso-1,2-diphenyl-1-(2-hydroxybenzamido)-2-(2-hydroxy-3-ethoxybenzylideneamino)ethane and Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione. The CuII complex component [NaCuIILdpen(meso)(DMF)] has a one-dimensional (1D) chain structure, in which the Na+ ion is coordinated by two phenoxo and an ethoxy oxygen atoms of a CuII complex and an amido oxygen atom of the adjacent CuII unit to produce the 1D structure, in which the diphenylethylenediamine moieties have the array of {(1R,2S)-Na-(1S,2R)}1∞. The assembly reaction of the CuII and GdIII components gave a linear complex with the array of Cu(1)-Gd(1)-Cu(2)-Gd(2), in which two diphenylethylenediamine moieties have the same chirality of (1R,2S)-(1R,2S) or (1S,2R)-(1S,2R). Two linear Cu(1)-Gd(1)-Cu(2)-Gd(2) units are linked by hydrogen bonds through two water molecules to give a cyclic structure with a center of symmetry. The temperature dependence of the magnetic susceptibilities and field-dependent magnetization revealed the ferromagnetic interaction between the CuII and GdIII ions within the linear chain. 相似文献
482.
The solvent-mediated crystal-to-crystal transformation was observed from yellow crystal of NiCl2(CH3OH)2(1,4-dioxane)0.5 (1) to green crystal of [NiCl2(H2O)2(1,4-dioxane)](1,4-dioxane) (2) under high humidity or adding of H2O in CH3OH/1,4-dioxane solution. The μ-Cl2 bridge in 1 replaced by 1,4-dioxane bridge in 2. In 1, the chlorine-bridged linear chains of NiCl2(CH3OH)2 and 1,4-dioxane molecules stack along the b- and c-axis alternatively with hydrogen bonds intrachain, interchain, between chain and solvent. These hydrogen bonds and dipolar interaction between ferromagnetic coupling chlorine-bridged chains result in long-range ferromagnetic ordering at 3.1 K and a strong frequency dependence of the ac-susceptibilities associated to domain structures with very large shape anisotropy was observed below 3.1 K. In 2, layers of 1,4-dioxane-bridged linear chains of NiCl2(H2O)2(1,4-dioxane) are intercalated by layer of 1,4-dioxane molecules with hydrogen bonds between chain and solvent. Compound 2 is paramagnet to 2 K. 相似文献
483.
Firasat Hussain Stefan Sandriesser Greta R. Patzke 《Journal of solid state chemistry》2011,184(1):214-219
A series of head-on complexes of lanthanoid containing germanotungstates was isolated from a one pot reaction in an acetate buffer at pH 4.5. This convenient approach brought forward the [{Ln(CH3COO)GeW11O39(H2O)}2]12− (Ln=EuIII, GdIII, TbIII, DyIII, HoIII, ErIII, TmIII, and YbIII) family with acetate chelators in the rarely observed μ2: η2-η1 mode. All compounds were structurally characterized using various solid state analytics, such as single crystal X-ray diffraction, FT-IR spectroscopy, and thermogravimetric analysis. The isostructural polyanions crystallize in the monoclinic system (S.G. P21/c). Temperature-dependent magnetic susceptibility measurements were performed on the GdIII-complex which exhibits near perfect Curie-type behavior. 相似文献
484.
Jens Burghaus Moulay T. Sougrati Anne Möchel Andreas Houben Raphaël P. Hermann Richard Dronskowski 《Journal of solid state chemistry》2011,184(9):2315-2321
Prior investigations of the ternary nitride series Ga1-xFe3+xN (0≤x≤1) have indicated a transition from ferromagnetic γ′-Fe4N to antiferromagnetic “GaFe3N”. The ternary nitride “GaFe3N” has been magnetically and spectroscopically reinvestigated in order to explore the weakening of the ferromagnetic interactions through the gradual incorporation of gallium into γ′-Fe4N. A hysteretic loop at RT reveals the presence of a minority phase of only 0.1-0.2 at%, in accord with the sound two-step synthesis. The composition of the gallium-richest phase “GaFe3N” was clarified by Prompt Gamma-ray Activation Analysis and leads to the berthollide formula Ga0.91(1)Fe3.09(10)N1.05(7). Magnetic measurements indicate a transition around 8 K, further supported by Mössbauer spectral data. The weakening of the ferromagnetic coupling through an increasing gallium concentration is explained by a simple Stoner argument. In Ga0.9Fe3.1N, the presence of iron on the gallium site affects the magnetism by the formation of 13-atom iron clusters. 相似文献
485.
486.
By means of the first-principles full potential linearized augmented plane-wave method within the local density approximation for the exchange-correlation functional, we have investigated the magnetism and electronic structure of Mn- and V-doped zinc blende ZnTe. Total energy calculations show that, for high doping concentration (12.5%), ZnTe:Mn has an antiferromagnetic ground state while the ferromagnetic state is more favorable than the antiferromagnetic state for ZnTe:V. Furthermore, ZnTe with a low doping of Mn (6.25%) has a stable ferromagnetic ground state, which is in agreement with the experimental results. The calculated magnetic moment of ZnTe doped with Mn (V) mainly originates from transition metal Mn (V) atom with a little contribution from Te atom due to the hybridization between Mn (V) 3d and Te 5p electrons. Electronic structure indicates that Mn-doped ZnTe is a semiconductor, but V-doped ZnTe shows a half-metallic characteristic. We also discuss the difference between electronic and magnetic properties for ZnTe doped with 12.5% and 6.25% Mn. 相似文献
487.
V.P.S. Awana Anand PalBhasker Gahtori H. Kishan 《Journal of magnetism and magnetic materials》2011,323(11):1460-1464
We present detailed magnetization and magneto-transport studies on the title compound SmCoAsO. In a recent paper we reported (Awana et al., 2010 [1]) the complex magnetism of this compound. SmCoAsO undergoes successive paramagnetic (PM)-ferro-magnetic (FM)-anti-ferro-magnetic (AFM) transitions with decrease in temperature. This is mainly driven via the c-direction interaction of Sm4f (SmO layer) spins with adjacent (CoAs layer) ordered Co3d spins. In this article we present an evidence of kinetic arrest for FM-AFM transition. The isothermal magnetization (MH) loops for SmCoAsO exhibited the meta-magnetic transitions at 6, 8 and 10 K at around 80, 60 and 50 kOe fields, respectively, with characteristic hysteresis shoulders along with the non-zero moment at the origin, thus suggesting the possibility of kinetic arrest. Suggested kinetic arrest is further evident in zero field-cooled (ZFC) and field-cooled (FC) hysteresis under high fields of up to 140 kOe magnetization (MT) and the magneto-transport measurements R(T)H during FM-AFM transition. The time dependent moment experiments exhibited very small (∼2-3%) increase of the same below 20 kOe and decrease for 30 kOe at 15 K. 相似文献
488.
Results of magnetic measurements suggested that Bi2S3 and ZnS nanocrystalline powders prepared by hydrothermal method could possibly exhibit room temperature ferromagnetism. The measured saturation magnetization of the powders increases with an increase of annealing temperature from 300 to 500 °C. Ab initio calculations suggested that the cation vacancies on the surface of Bi2S3 and ZnS nanograins could be responsible for the observed magnetic moments. Heat-treatment of Bi2S3 or ZnS nanocrystalline powders in Bi or Zn vapor could bring about an enhancement of ferromagnetism. The calculation results indicated that the interstitial Bi or Zn atoms in Bi2S3 (0 0 1) or ZnS (0 0 1) surface could induce magnetic moments. 相似文献
489.
Electrical and magnetic properties of {[Ru(bpy)3][Fe(dca)3]2}n (bpy=2,2′-bipyridine, dca=dicyanamide) have been studied. The compound is a non-extrinsic type of semiconductor and paramagnetic in nature. Mössbauer spectroscopy has established the presence of high spin Fe(II) as one major species in this compound, and no high spin-low spin transition of Fe(II) was detected down to 80 K under dark. The photo-response of electrical conductivity with time shows interesting behavior with repeated exposure. 相似文献
490.
Miaojuan Ren Xianyang Feng Ping Li Xiaojing Liu Zhong Zhang 《Solid State Communications》2011,151(11):864-866
The electronic structures and magnetic properties of Pd-doped ZnO have been studied by the full-potential linear augmented plane wave (FLAPW) method using the generalized gradient approximation (GGA). We find that Pd-doped ZnO becomes 100% spin polarized when Pd substitutes for Zn in the 2×2×2 ZnO supercell. The supercell magnetic moment reaches 2.0μB. Long-range ferromagnetic (FM) coupling is obtained with all Pd dopant configurations, and a Curie temperature as high as 860 K is predicted for the ground-state configuration. The hybridized Pd(4d)-O(2p)-Zn(4d)-O(2p)-Pd(4d) chain formed through p-d-like coupling is responsible for the long-range room-temperature FM coupling. We discuss the effect of O vacancies or Zn vacancies on the magnetism as well. 相似文献