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81.
《Journal of Coordination Chemistry》2012,65(6):1093-1106
The syntheses of platinum(II) complexes of bis(dimethylphosphinylmethylene)amine and bis(aminomethyl)phosphinic acid were investigated. In the case of bis(dimethyl-phosphinylmethylene)amine the reaction with K2[PtCl4] yields the potassium amino-trichloroplatinate K[PtCl3L] (L?=?bis(dimethylphosphinylmethylene)amine), which was characterized by multinuclear (1H, 13C, 31P, and 195Pt) NMR spectroscopy in solution. Bis(aminomethyl)phosphinic acid reacts with K2[PtCl4] under strictly controlled pH conditions to give colorless crystals of the cisplatin analog K[PtCl2L′] (L′?=?bis(aminomethyl)phosphinate). This complex was characterized by multinuclear NMR spectroscopy in solution as well as by single-crystal X-ray diffraction in the solid state. The bis(aminomethyl)phosphinate coordinates to platinum via both amino functions, thus acting as a chelating ligand. 相似文献
82.
采用自组装技术在单晶硅表面制备了3-氨基丙基三乙氧基硅烷(APTES)-SiO2-APTES复合膜,并对其表面的组成、结构及摩擦性能进行了表征.结果表明:复合膜表面对水的接触角约为63°,且表面平整、致密,其平均粗糙度(Ra)约为0.963nm.通过原子力显微镜(AFM)和透射电子显微镜(TEM)观察到夹层中SiO2颗粒的粒径约为20-50nm,较均匀地分布在第一层APTES膜的表面.与APTES自组装单层膜(SAMs)相比,APTES-SiO2-APTES复合膜由于纳米SiO2颗粒的引入而表现出更低的摩擦系数和更长的耐磨寿命. 相似文献
83.
The synthesis of a series of lanthanide tetracyanoplatinates all incorporating 2,2′:6′,2″-terpyridine (terpy) have been carried out by reaction of Ln3+ nitrate salts with terpy and potassium tetracyanoplatinate. The incorporation of different Ln3+ cations results in the isolation of [Ln(DMF)2(C15H11N3)(H2O)2(NO3)]Pt(CN)4 (Ln=La-Nd, Sm-Yb) under otherwise identical reaction conditions. These compounds have been isolated as single crystals and X-ray diffraction has been used to investigate their structural features. All of the reported compounds are isostructural. Crystallographic data for the representative Eu3+ compound (EuPt) are (MoKα, λ=0.71073 Å): monoclinic, space group P21/c, a=10.1234(4) Å, b=18.7060(7) Å, c=17.1642(5) Å, β=97.249(3)°, V=3224.4(2), Z=4, R(F)=2.78% for 426 parameters with 7724 reflections with I>2σ(I). The structure consists of a zero-dimensional, ionic salt containing complex [Eu(DMF)2(C15H11N3)(H2O)2(NO3)]2+ cations and anions. The complex cations contain the Eu3+ ions in a tri-capped trigonal prismatic coordination environment with one terdentate 2,2′:6′,2″-terpyridine molecule, one bidentate nitrate anion, two O-bound dimethylformamide molecules, and two coordinated water molecules. Photoluminescence data illustrate that EuPt displays intramolecular energy transfer from the coordinated terpy molecule to the Eu3+ cation. The uncoordinated tetracyanoplatinate anion also exhibits visible emission. 相似文献
84.
Changes in structure and dielectric properties at elevated temperatures have been investigated on single-crystals of sodium potassium niobate, Na0.5K0.5NbO3, grown by the flux method. Single-crystal X-ray diffraction studies revealed that the crystals underwent orthorhombic-tetragonal and tetragonal-cubic phase transitions at 465 and 671 K during heating and 446 and 666 K during cooling, respectively. Both transitions were accompanied by volumetric discontinuities of collapse upon heating and expansion upon cooling, suggesting that the transitions were of the first order. The coordination numbers of an Nb showed a decreasing tendency with decreasing temperature, i.e., 6 in cubic, 5+1 in tetragonal and 4+2 in orthorhombic. An Na atom occupied a slightly different position from the K atom in 12-fold coordination, resulting in fewer coordination numbers of 8+4 in cubic and tetragonal and 7+5 in orthorhombic. The spontaneous polarisation (Ps) estimated from the atom positions and formal charges were approximately 0.29 C m−2 in orthorhombic and 0.18 C m−2 in tetragonal. The contribution of the alkaline oxide components to Ps was estimated to be approximately 15% in both ferroelectric forms. The temperature-induced transitions were also confirmed through the dielectric constant and dielectric loss at various frequencies and the differential scanning calorimetry. 相似文献
85.
E.Yu. Zarechnaya N. Dubrovinskaia L. Dubrovinsky Y. Filinchuk D. Chernyshov V. Dmitriev 《Journal of Crystal Growth》2010,312(22):3388-3394
A method of the high-pressure high-temperature synthesis of single crystals of orthorhombic high-pressure boron B28 from metal solutions is presented. The method is based on the high-pressure multi-anvil technique. The feasibility of single-crystal growth was demonstrated in a number of experiments conducted at various pressure–temperature conditions with various precursors including β-boron of 99.99% purity and various metals (Cu, Au, and Pt) used as fluxes and capsule materials. It was found that after dissolution in metals at high pressures and high temperatures, boron crystallizes in the form of single crystals at low temperature. The process is accompanied by chemical reactions resulting in the formation of borides. The maximum length of the B28 crystals achieved is ∼100 μm. 相似文献
86.
Helmut Ehrenberg P.C. Schmidt R. McSweeney K.C. Mishra 《Journal of solid state chemistry》2006,179(4):968-973
Strontium borophosphate phosphate (Sr6BP5O20, SrBP), activated by divalent europium ions is a bluish-green phosphor emitting in a broad band with the emission peak near 480 nm. In this paper, we report the crystal structure of SrBP determined from an analysis of the X-ray diffraction pattern of a prismatic single crystal (size 60 μm×50 μm×40 μm). This crystal was chosen from undoped phosphor powder samples prepared for this purpose by solid-state reaction. SrBP is observed to crystallize in a body-centered tetragonal lattice with the lattice parameters and , the associated space group being (space group 120). Using the structural data from this study, we have also calculated its electronic structure using the augmented spherical wave method and the local density approximation (LDA). We show the ordering of the electronic states by the density of states (DOS) and the partial DOS plots. The LDA gives a direct optical band gap at the Γ point of about 5 eV. The significance of the crystal structure and associated electronic structure is discussed with respect to maintenance of this phosphor in Hg-discharge lamps. 相似文献
87.
A new member of the A2MP2O7 diphosphate family, Li2MnP2O7, has been synthesized by solid-state reaction and characterized using single-crystal X-ray diffraction. Li2MnP2O7 crystallizes in the monoclinic space group P21/a (#14) with the cell parameters a=9.9158(6) Å, b=9.8289(6) Å, c=11.1800(7) Å, β=102.466(5)°, Z=8 and V=1063.9(1) Å3. Its mixed framework exhibits an original Mn2O9 unit, built up of one MnO5 trigonal bipyramid sharing one edge with one MnO6 octahedron. These Mn2O9 units are sharing corners with P2O7 diphosphate groups, forming the undulating [Mn4P8O32]∞ layers. The [MnP2O7]∞ 3D framework, resulting from the interconnection of the undulating [Mn4P8O32]∞ layers, exhibits different kinds of intersecting tunnels containing the Li cations. 相似文献
88.
The compounds UOS, UOSe, NpOS, and NpOSe have been synthesized and their structures determined by means of single-crystal X-ray diffraction methods. The results provide more detailed crystallographic information, including more precise interatomic distances, than earlier determinations from powder diffraction data. These isostructural compounds adopt the PbFCl structure type. Each An atom is surrounded by four O and five Q atoms in a distorted monocapped square-antiprismatic arrangement. 相似文献
89.
Robin T. Macaluso Melanie Francisco Shane Stadler Urs Geiser Mercouri G. Kanatzidis 《Journal of solid state chemistry》2011,184(12):3185-3189
Single crystals of a new intermetallic gallide, R-CePd3Ga8, have been synthesized from excess molten gallium. Single-crystal X-ray diffraction reveals that R-CePd3Ga8 crystallizes in the R-3m space group with a=b=c=8.4903(10) Å and α=β=γ=89.993(17). R-CePd3Ga8 is a variant of the cubic BaHg11 structure type with three structural units: a Ce-centered polyhedron, a distorted cube of Pd2Ga6 and a Pd-centered cuboctahedron. The distortions of these units are compared to undistorted analogous units in intermetallic compounds with BaHg11 structure type. Field and temperature-dependent magnetization measurements on R-CePd3Ga8 reveal a paramagnetic material with strong antiferromagnetic correlations and a magnetization consistent with Ce3+. Electrical resistance measurements indicate Kondo behavior between localized Ce3+ magnetic moments. 相似文献
90.
《International Journal of Solids and Structures》2014,51(15-16):2754-2764
The behavior of a model of single-crystal strain-gradient viscoplasticity is investigated. The model is an extension of a rate-independent version, and includes a new hardening relation that has recently been proposed in the small-deformation context (Gurtin and Reddy, 2014), and which accounts for slip-system interactions due to self and latent hardening. Energetic and dissipative effects, each with its corresponding length scale, are included. Numerical results are presented for a single crystal with single and multiple slip systems, as well as an ensemble of grains. These results provide a clear illustration of the effects of accounting for slip-system interactions. 相似文献