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531.
532.
533.
Edmund Kwiatkowski Marek Kwiatkowski Urszula Dettlaff-Weglikowska Douglas M. Ho 《Journal of chemical crystallography》1992,22(4):411-419
The products of monocondensation of penta-2,4,-dione with 1,2-diaminoethane, HAE, and with 1,3-diaminopropane, HAT, react with copper nitrate hemipentahydrate to give catena--nitrato (7-amino-5-aza-4-methyl-3-hepten-2-onato) copper(II), [Cu(AE)NO3]n and a mixture of
3-hydroxo-tris (-8-amino-5-aza-4-methyl-3-octen-2-onato) tricopper(II) dinitrate [Cu3(AT)3OH]-(NO3)2 and [Cu(AT)NO3]x, respectively. The structure of [Cu(AE)NO3]n has been determined from 1601 diffractometer data and refined by least squares methods toR=0.0306. The compound crystallizes in the monoclinic space groupP21/a witha=16.856(3)Å,b=8.109(4)Å,c=7.518(3)Å,=90.15(2)°,D
c
=1.725 g cm–3,D
o=1.72 g cm–3 andZ=4. Copper atoms in [Cu(AE)NO3]n are in a 4+1+1* environment and are linked by the pseudobidentate and bridging nitrato group into infinite chains. The structure of [Cu3(AT)3OH](NO3)2 has been determined from 3178 diffractometer data and refined toR=0.0544. The compound crystallizes in the triclinic space groupP¯1 witha=11.918(2)Å,b=14.478(2)Å,c=11.501(3)Å,=98.04(2)°,=117.72(2)°, =99.80(1)°,D
c
=1.580 g cm–3,D
o=1.59 g cm–3 andZ=2. The compound is associated in hexanuclear clusters due to hydrogen bonding interactions. Coordination about Cu is best described as square pyramidal. Magnetic susceptibility data indicate a weak antiferromagnetic exchange within the trinuclear core withJ=–14 cm–1. 相似文献
534.
To obtain a more reliable temperature dependence of the kinetic deuterium isotope effect in a 1,5-hydrogen shift, the title compound has been designed to repress compromising side reactions, arguably arising from second-order ene-ene unions. The values of kH/kD, 4.58-5.15, in the range 185.8-153.8 degrees C, on extrapolation by the derived Arrhenius equation, lead to 8-14 at 25 degrees C. Another goal is the evaluation of the effect on rates of the free rotation available to the phenyl groups in 2,4-diphenyl-1,3(Z)-pentadiene compared to the constraint to coplanarity of the phenyl groups in the title compound. The effect is insignificant. Incidental to the presence of the sterically effective methyl groups in the title compound, participation of the hydrogen atoms of an aromatic methyl group as part of the 1,3(Z)-pentadienyl system has been uncovered in 6,8-dimethyl-1-methylene-1,2,3,4-tetrahydronaphthalene. The rate of the rearrangement is too slow to compromise the kinetics of the hydrogen shifts in the title compound. A reassessment of the conventional procedure for estimating uncertainties in Arrhenius parameters based on a small number of rate constants has led to the proposal of an alternative procedure based on the statistically more significant uncertainties associated with the individual rate constants. 相似文献
535.
The garnets Li3Nd3W2O12 and Li5La3Sb2O12 have been prepared by heating the component oxides and hydroxides in air at temperatures up to 950 °C. Neutron powder diffraction has been used to examine the lithium distribution in these phases. Both compounds crystallise in the space group with lattice parameters a=12.46869(9) Å (Li3Nd3W2O12) and a=12.8518(3) Å (Li5La3Sb2O12). Li3Nd3W2O12 contains lithium on a filled, tetrahedrally coordinated 24d site that is occupied in the conventional garnet structure. Li5La3Sb2O12 contains partial occupation of lithium over two crystallographic sites. The conventional tetrahedrally coordinated 24d site is 79.3(8)% occupied. The remaining lithium is found in oxide octahedra which are linked via a shared face to the tetrahedron. This lithium shows positional disorder and is split over two positions within the octahedron and occupies 43.6(4)% of the octahedra. Comparison of these compounds with related d0 and d10 phases shows that replacement of a d0 cation with d10 cation of the same charge leads to an increase in the lattice parameter due to polarisation effects. 相似文献
536.
537.
Zhi Fang Xinguo Wang Ruping Shao Yuchang Qiu Kuffel Edmund 《Journal of Electrostatics》2011,69(1):60-66
Polyethylene terephthalate (PET) films are modified using non-equilibrium plasma generated by DBD in atmospheric air, and the effects of discharge power density on the surface modification are studied. It is found that increasing discharge power density can induce more effective treatment of PET films, because this leads to a faster decrease in water contact angle and a faster increase in surface energy due to more creation of polar groups and more obvious etching occurring on the PET surface. So the treatment time needed to achieve the same level of surface treatment can be reduced by increasing the discharge power density. 相似文献
538.
Meredith C. K. Sellers Edmund G. Seebauer 《Applied Physics A: Materials Science & Processing》2011,104(2):583-586
Mn-doped anatase TiO2 (Mn: 1.2, 2.4 at%) thin films were grown on Si(100) via atomic layer deposition (ALD). The synthesis utilized Ti(OCH(CH3)2)4 and H2O as ALD precursors and Mn(DPM)3 as a dopant source. X-ray photoelectron spectroscopy measurements indicate that Mn is successfully doped in the TiO2 matrix and reveal information about film composition and elemental chemical states. Microstructure, crystallinity, and density
were investigated with scanning electron microscopy, X-ray diffraction, and X-ray reflectivity. All ALD-synthesized films
exhibited room-temperature ferromagnetism; the microstructure, density, and magnetic field-dependent magnetization of the
TiO2 varied with the concentration of Mn. ALD permits precise composition and thickness control, and much higher process throughput
compared to alternative techniques. 相似文献
539.
Geometric and Hydrodynamic Characteristics of Three-dimensional Saturated Prefractal Porous Media Determined with Lattice Boltzmann Modeling 总被引:1,自引:0,他引:1
Jung-Woo Kim Michael C. Sukop Edmund Perfect Yakov A. Pachepsky Heechul Choi 《Transport in Porous Media》2011,90(3):831-846
Fractal and prefractal geometric models have substantial potential for contributing to the analysis of flow and transport
in porous media such as soils and reservoir rocks. In this study, geometric and hydrodynamic parameters of saturated 3D mass
and pore–solid prefractal porous media were characterized using the lattice Boltzmann model (LBM). The percolation thresholds
of the 3D prefractal porous media were inversely correlated with the fraction of micro-pore clusters and estimated as 0.36
and 0.30 for mass and pore–solid prefractal porous media, respectively. The intrinsic permeability and the dispersivity of
the 3D pore–solid prefractals were larger than those of the 3D mass prefractals, presumably because of the occurrence of larger
solid and pore cluster sizes in the former. The intrinsic permeability and dispersivity of both types of structure increased
with increasing porosity, indicating a positive relationship between permeability and dispersivity, which is at odds with
laboratory data and current theory. This discrepancy may be related to limitations of the convection dispersion equation at
the relatively high porosity values employed in the present study. 相似文献
540.