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11.
Susanne Bredendiek-Kämper Holger Jenett Henning Bubert Jacek Drozak Bernhard Wielage 《Mikrochimica acta》1990,101(1-6):91-99
This paper reports on the use of Auger electron spectroscopy (AES)/ depth profile analysis for the investigation of plasma-sprayed coatings. Prior to spraying the St 37 substrates are heated to 300 °C or 500 °C for ceramic or metallic layers, respectively. Studies of the starting materials and of the interfaces are important if the adhesion mechanism is to be understood. Therefore the initial components—the unheated and heated substrates and the powder particles NiCrAl, Al2O3 and ZrO2-7.25Y2O3—are analyzed. Depth profiles obtained from two coatings St 37/NiCrAl and St 37/Al2O3 show the influence of plasmaspraying on substrate surfaces and sprayed particles. Plasma-spraying mainly causes a decrease of superficial carbon contamination for both coating layers. In the case of St 37/NiCrAl incorporation of carbon in the sprayed layer is observed. The whole layer is almost completely oxidized except for some areas where substrate and particle material are present. It is assumed that these areas are identical with so-called adherence zones.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday 相似文献
12.
G. E. Schröder-Turk A. Fogden S. T. Hyde 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(4):509-524
Balanced infinite periodic minimal surface families that contain the cubic Gyroid (G), Diamond (D) and Primitive (P) surfaces
are studied in terms of their global packing and local curvature properties. These properties are central to understanding
the formation of mesophases in amphiphile and copolymer molecular systems. The surfaces investigated are the tetragonal, rhombohedral
and hexagonal tD, tP, tG, rG, rPD and H surfaces. These non-cubic minimal surfaces furnish topology-preserving transformation
pathways between the three cubic surfaces. We introduce `packing (or global) homogeneity', defined as the standard deviation
Δd of the distribution of the channel diameter throughout the labyrinth, where the channel diameter d is determined from the
medial surface skeleton centered within the labyrinthine domains. Curvature homogeneity is defined similarly as the standard
deviation ΔK of the distribution of Gaussian curvature. All data are presented for distinct length normalisations: constant
surface-to-volume ratio, constant average Gaussian curvature and constant average channel diameter. We provide first and second
moments of the distribution of channel diameter for all members of these surfaces complementing curvature data from [A. Fogden,
S. Hyde, Eur. Phys. J. B 7, 91 (1999)]. The cubic G and D surfaces are deep local minima of Δd along the surface families (with G more homogeneous than
D), whereas the cubic P surface is an inflection point of Δd with adjacent, more homogeneous surface members. Both curvature
and packing homogeneity favour the tetragonal route between G and D (via tG and tD surfaces) in preference to the rhombohedral
route (via rG and rPD). 相似文献
13.
在混合溶剂中通过"grafting to"的方法将2种分子量不同的聚乙二醇单甲醚(MPEG M_w=750,4000)接枝到氨基修饰的St?ber法二氧化硅(SiO_2-NH_2)表面,制备双分布纳米接枝复合物.采用二步法,先将带环氧端基的低分子量聚乙二醇单甲醚(MPEG-EO)与SiO_2-NH_2在甲苯溶剂中充分反应后,与高分子量的MPEG-EO在甲苯和正癸烷的混合溶剂中使用相同的反应条件和后处理方法,能便捷制备出具有双分布接枝的纳米复合物.在接枝反应体系中,分子链的链段尺寸和接枝密度之间存在着密切关系.一定的范围内,接枝密度随链段尺寸减小而增大.通过改变混合溶剂比例来调控接枝链段的尺寸,可以很好控制聚合物的接枝密度.在双分布接枝的纳米复合物中,低分子量的接枝密度为0.85 chains/nm~2,高分子量的接枝密度能达到0.40 chains/nm~2,体现出了简单、高效、可控的特点,与聚环氧乙烷(PEO)共混后分散良好,对于制备出均匀分散的纳米复合材料起到了一定的指导作用. 相似文献
14.
Simultaneous determination of soluble manganese(III), manganese(II) and total manganese in natural (pore)waters 总被引:1,自引:0,他引:1
A new spectrophotometric protocol was developed for the simultaneous determination of soluble Mn(III), Mn(II) and total Mn [sum of soluble Mn(III) and Mn(II)] in sediment porewaters using a water soluble meso-substituted porphyrin [α,β,γ,δ-tetrakis(4-carboxyphenyl)porphine (T(4-CP)P)]. A simple kinetic rate model is used to quantify soluble Mn(II), Mn(III) and total Mn concentrations during a metal substitution reaction. Under optimized conditions, the method accurately determines soluble Mn(II) and Mn(III) within a concentration range of 100 nM-10 μM. The detection limit of total soluble Mn is 50 nM. Using this method, soluble Mn(II) and Mn(III) concentrations were determined in standard solutions within 0.4-2% of the known values and agreed closely with results of inductively coupled plasma mass spectrometric and voltammetric analyses. The procedure was successfully applied to determine soluble Mn(II), Mn(III) and total Mn in sediment porewaters of the Lower St. Lawrence Estuary. Mn(III) represented up to 85% of the total soluble Mn pool in surface sediments. 相似文献
15.
Gui-Jun Ding Rong-Gang Ping Mu-Lin Yan 《The European Physical Journal A - Hadrons and Nuclei》2006,28(3):351-360
X(1835) has been treated as a baryonium with sizable gluon content, and to be almost flavor singlet. This picture allows us
to rationally understand X(1835) production in J/ψ radiative decays, and its large couplings with pˉ, η′ππ. The processes ϒ(1S) → γX(1835) and J/ψ → ωX(1835) have been examined. It has been found that Br(ϒ(1S) → γX(1835))Br(X(1835) → pˉ) < 6.45×10-7, which is compatible with CLEO's recent experimental result (Phys. Rev. D 73, 032001 (2006) hep-ex/0510015). The branching fractions Br(J/ψ → ωX(1835)), Br(J/ψ → ρX(1835)) with X(1835) → pˉ and X(1835) → η′π+π- have been estimated by the quark-pair creation model. We show that they are heavily suppressed, so the signal of X(1835) is very difficult, if not impossible, to be observed in these processes. The experimental checks for these estimations
are expected. The existence of the baryonium nonet is conjectured, and a model-independent derivation of their production
branching fractions is presented. 相似文献
16.
C. Haupt B. Metsch H. -R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2006,28(2):213-225
We show that static properties like the charge radius and the magnetic moment of relativistic three-fermion bound states with
instantaneous interactions can be formulated as expectation values with respect to intrinsically defined wave functions. The
resulting operators can be given a natural physical interpretation in accordance with relativistic covariance. We also indicate
how the formalism may be generalized to arbitrary moments. The method is applied to the computation of static baryon properties
with numerical results for the nucleon charge radii and the baryon octet magnetic moments. In addition, we make predictions
for the magnetic moments of some selected nucleon resonances and discuss the decomposition of the nucleon magnetic moments
in contributions of spin and angular momentum, as well as the evolution of these contributions with decreasing quark mass. 相似文献
17.
The processes of acceleration of nonlinear waves in a weakly inhomogenous plasma and slowing down due to nonlinear Landau damping are compared. For initially standing waves the time needed for reaching equilibrium between these oppossing tendencies is estimated. 相似文献
18.
H.P. Dhar 《Surface science》1977,66(2):449-462
Reflectance changes at lead electrodes have been measured as a function of surface charge at 45° and 70° angles of incidence using solutions of sodium fluoride and quaternary ammonium salts. These solutions were chosen so as to provide quite different composition for the inner layer at the metal/solution interface, and hence different optical contributions there from. Linear reflectance-surface charge relation has been observed for NaF solutions only at a number of wavelengths. The optical effects from the inner layer has been recognized but could not be separated out from the main er effect by comparative measurements at two angles of incidence. This has been rationalized on the basis of similar variation of the er effect and the optical effect from the double-layer as a function of angle of incidence of light. 相似文献
19.
The infrared spectra of dimethyl oxalate and dimethyl oxalate-d6 have been recorded in the liquid phase. These spectra are compared with both the infrared and Raman spectra recorded in solid phase. It is shown that dimethyl oxalate exists as a conformational equilibrium mixture in the liquid phase. The most stable conformer is that present exclusively in the crystal, the planar, cis-ester C2h structure. The second conformer is probably one formed by rotation about the carbonyl carbon-oxygen bonds of the molecule. 相似文献
20.