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961.
962.
《Surface and interface analysis : SIA》2005,37(9):765-769
Two γ‐TiAl alloys, Ti‐47at%Al‐2at%Nb‐2at%Cr (MJ12) and Ti‐47at%Al‐2at%Nb‐2at%Mn‐0.8at%TiB2 (MJ47), were nitrided by direct metal–gas reaction at 1000–1300 K in 10 cm3s?1NH3. X‐ray diffraction revealed formation of TiN at 1100–1300 K. Knoop microhardness values of the alloys were increased with an increase in the nitridation temperature. Microhardness values of MJ12 and MJ47 with 1300 K nitridation were respectively improved to 1.65 and 1.38 times those of the controls. Nitridation depth at a variety of temperature determined by Rutherford backscattering spectrometry was increased with an increase in the temperature. Ti, Al and N concentrations at a variety of depths analysed by scanning electron microscopy and energy dispersive X‐ray linescanning are also explained. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
963.
The change in structure of several amorphous alloys as Fe-P-C, Fe-B and Pd-Au-Si alloys during isothermal ageing was examined using small angle X-ray scattering technique as well as transmission electron microscopy. The SAXS intensity was related to two different types of scattering sources depending on ageing period and temperature. As-splatted amorphous alloys and the specimens aged for short period at relatively low temperature, where specimens remained in amorphous state, showed a weak and spreaded SAXS intensity. This indicates an existence of electron density fluctuation in amorphous phase. The dimension of their scattering regions was estimated to be 1.8 to 2.4 nm for Fe-P-C alloys, and 1.2 to 0.8 rim. for Fe-B alloys, respectively, by analysing the electron density-density correlation function derived from observed SAXS intensity. The origin has been discussed based on one dimensional model. A compositional fluctuation was made clear to occur in fine scale of about 1 nm in amorphous Fe-B and Fe-P-C alloys. When the alloys were aged for longer period below their crystallization temperatures, fine crystalline particles precipitate; those are a two phase lamella structure of Fe3P and-Fe for a Fe83P10C7 alloy, an Ferich single phase for Fe83B17 alloy, and a Pd-rich single phase for Pd76Au6Si188 alloy, respectively. Their size and structure were determined from the analysis of SAXS data and TEM observation. 相似文献
964.
The extractions of alloys of the nominal composition “KE2.25” with ethylenediamine (en), (2,2,2)crypt, and toluene (tol) lead in good yields to paramagnetic compounds of the composition [K-(2,2,2-crypt)]6E9E9 · 1.5 en · 0.5 tol (E = Sn ( 2 b ), Pb ( 2 c )). X-ray single crystal structure analyses show that two different E9 clusters per asymmetric unit are present with configurations of distorted tricapped trigonal prismatic polyhedra. 2 b : space group P21/c (No. 14), Z = 4, a = 28.042(8), b = 23.527(5), c = 27.703(8) Å, β = 93.46(2)°; 2 c : space group P21/c (No. 14), Z = 4, a = 28.356(8), b = 23.757(5), c = 27.885(8) Å, β = 94.01(2)°. 相似文献
965.
Pd–Rh alloys were prepared by electrochemical codeposition. Bulk compositions of the alloys were determined by the energy
dispersive X-ray analysis method, while surface compositions were determined from the potential of the surface oxide reduction
peak. Cyclic voltammograms, recorded in 0.5 M H2SO4 for Pd–Rh alloys of different bulk and surface compositions, are intermediate between curves characteristic of Pd and Rh.
The influence of potential cycling on electrochemical properties and surface morphologies of the alloys was studied. Due to
electrochemical dissolution of metals, both alloy surface and bulk become enriched with Pd. Carbon oxides were adsorbed at
a constant potential from the range of hydrogen adsorption. The presence of adsorbed CO2 causes remarkable diminution of hydrogen adsorption but it does not significantly influence hydrogen insertion into the alloy
bulk. On the other hand, in the presence of adsorbed CO, both hydrogen absorption and adsorption are strongly suppressed.
Oxidative removal of the adsorbates results in a characteristic voltammetric peak, whose potential increases with the decrease
in Rh surface content. Electron per site (eps) values calculated for the oxidation of the adsorbates change with alloy surface
composition, more for CO2 than CO adsorption, indicating the variation of the structure and composition of CO2 and CO adsorption products. The course of the dependence of eps values on surface composition suggests that the products
of CO2 and CO adsorption on Pd–Rh alloys are similar but not totally identical. 相似文献
966.
Adolf Mikula 《Monatshefte für Chemie / Chemical Monthly》1986,117(12):1379-1385
On liquid Bi—Pb alloys emf measurements were carried out. From the emf data the thermodynamic properties were calculated. In the temperature range between 643 to 923 K no anomalies in the thermodynamic properties were found. The emf varies linearly with temperature and the activity of Pb shows a slight negative deviation fromRaoult's law. However, when H
M
/x is plotted against (1–x) the results are two staight lines which intersect at approximately 35 at% Bi. This could be interpreted that Bi—Pb melts change from one regular behaviour to another.Herrn Prof. Dr.K. L. Komarek mit den besten Wünschen zum 60. Geburtstag gewidmet. 相似文献
967.
Thermal plasma synthesis of transition metal nitrides and alloys 总被引:1,自引:0,他引:1
Applications of arc plasma processing to high-temperature chemistry of Group V nitrides and Si and Ge alloys are studied. The transition metal nitrides -VN, -NbN, and -TaN are directly synthesized in a dc argon-nitrogen plasma from powders of the metals. A large excess of N2 is required to form stoichiometric -VN, while the Nb and Ta can only be synthesized with a substoichiometric N content. In a dc argon plasma the alloys V3Si, VSi2, NbSi2, NbGe2, Cr3Si, and Mo3Si are obtained from powder mixtures of the corresponding elements. The compounds are identified by x-ray diffraction patterns and particle shape and size are studied by electron microscopy. 相似文献
968.
In this paper, pseudo-binary (Ag0.365Sb0.558Te)x-(Bi0.5Sb1.5Te3)1−x (x=0-1.0) alloys were prepared using spark plasma sintering technique, and the composition-dependent thermoelectric properties were evaluated. Electrical conductivities range from 7.9×104 to 15.6×104 Ω−1 m−1 at temperatures of 507 and 318 K, respectively, being about 3.0 and 8.5 times those of Bi0.5Sb1.5Te3 alloy at the corresponding temperatures. The optimal dimensionless figure of merit (ZT) of the sample with molar fraction x=0.025 reaches 1.1 at 478 K, whereas that of the ternary Bi0.5Sb1.5Te3 alloy is 0.58 near room temperature. The results also reveal that a direct introduction of Ag0.365Sb0.558Te in the Bi-Sb-Te system is much more effective to the property improvement than naturally precipitated Ag0.365Sb0.558Te in the Ag-doped Ag-Bi-Sb-Te system. 相似文献
969.
《Surface and interface analysis : SIA》2006,38(8):1204-1210
The spectrum of electrons elastically backscattered from the surface and within its vicinity reflects the probability of electron elastic backscattering on the surface atoms, quasi‐elastic scattering and the inelastic scattering visible in the low energy side of the elastic peak. The method for investigating the processes of electron elastic backscattering on the surface atom is called the elastic peak electron spectroscopy (EPES). In the present work, AuNi alloys of different compositions are investigated using X‐ray photoelectron spectroscopy (XPS) and the EPES method with the aid of the line shape analysis called the fuzzy k‐nearest neighbour (fkNN) rule. The line shape analysis was found to be applicable for EPES spectroscopy. It allows distinguishing the surfaces exhibiting various surface roughness, texture and grain size, and quantifying the selected information depths. The quantitative results obtained from the XPS analysis and the EPES spectra line shape analysis indicated Au surface segregation with Au surface enriched profile. Quantitative discrepancies are discussed within the non‐uniform concentration profiles of constituents due to sputter cleaning and annealing, different diffusion coefficients for Au and Ni, differences in the information depths sampled by XPS and EPES methods and differences in electron elastic backscattering cross‐sections for Ni and Au. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
970.
A complete investigation of the Fourier space of complex intermetallic Mg39Al61 is reported. X-ray patterns reveal the reciprocal space of the whole system consisting in selective reflections and coherent diffuse scattering. Their temperature dependence are studied. Selective reflections are interpreted as incommensurately modulated states and a structural analysis of the coherent diffuse scattering is presented. The same type of coherent diffuse scattering curve was also observed in several quasicrystalline alloys. In all the studied cases, the disorder is interpreted by the presence of icosahedral arrangements that are reminiscent of Frank units in supercooled alloys. 相似文献