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71.
梁板壳的几何大变形--从近似的非线性理论到有限变形理论 总被引:6,自引:0,他引:6
对梁板壳的线性理论、近似几何非线性理论与有限变形理论作了比较,介绍了有限转动理论,指出了应用有限变形理论求解梁板壳的大变形问题的高效率、高精度的巨大优越性。 相似文献
72.
新型IPTO(Pr Ti O3掺杂In2O3)薄膜的可见光透过率及导电性可与商业化的ITO薄膜媲美。采用双源电子束设备制备了一种新型的IPTO透明导电薄膜,通过开尔文探针法测试,其功函数为5.14 e V。为验证新型IPTO透明导电阳极对有机电致发光器件性能的影响,将IPTO替代商业化ITO作为阳极制备了有机电致发光器件。基于IPTO阳极的器件的亮度最大值为85 140 cd/m2,外量子效率最大值为3.16%,分别为以ITO为阳极的器件的3倍及1.13倍。这种性能的改善是由于IPTO具有较小的表面粗糙度及较高的功函数,可以降低阳极的注入势垒,有利于电荷向有机层注入,改善了器件内的空穴及电子的注入平衡。 相似文献
73.
An appropriate coupled cohesive law for predicting the mixed mode failure is established by combining normal separation and tangential separation of surfaces in the cohesive zone model(CZM) and the cohesive element method.The Xu-Needleman exponential cohesive law with the fully shear failure mechanism is one of the most popular models.Based on the proposed consistently coupled rule/principle,the Xu-Needleman law with the fully shear failure mechanism is proved to be a non-consistently coupled cohesive la... 相似文献
74.
Observations of sampling are often subject to rounding, but are modeled as though they were unrounded. This paper examines
the impact of rounding errors on parameter estimation with multi-layer ranked set sampling. It shows that the rounding errors
seriously distort the behavior of covariance matrix estimate, and lead to inconsistent estimation. Taking this into account,
we present a new approach to implement the estimation for this model, and further establish the strong consistency and asymptotic
normality of the proposed estimators. Simulation experiments show that our estimates based on rounded multi-layer ranked set
sampling are always more efficient than those based on rounded simple random sampling. 相似文献
75.
Underpotential deposition (UPD) of metals is analysed from the perspective of phenomeno-logical and statistical thermodynamic
considerations; the parameters influencing the UPD shift have been quantitatively indicated using a general formalism. The
manner in which the macroscopic properties pertaining to the depositing ions and solvent dipoles and the nature of the metallic
substrate influence the UPD process are highlighted; earlier correlations of the UPD shift with the work function differences
are rationalised. Anion-induced phase transitions which manifest as sharp peaks in experimental cyclic voltammograms are discussed
using statistical thermodynamic models. 相似文献
76.
Analysis on cohesive crack opening displacement considering the strain softening effect 总被引:4,自引:0,他引:4
In order to investigate the crack propagation in quasi-brittle materials like rock, ceramic and concrete, Hillerborg and his
co-researchers abstracted the fracture process zone in front of a stress free crack in terms of a “fictitious crack zone”.
On the fictitious crack zone, cohesive stresses distribute following a given softening relationship of stress vs. crack opening.
Based on the polynomial or power series expression of cohesive crack opening displacement, the relationship of the cohesive
stress vs. the crack opening displacement is established using elastic theory and integral equation, and some unknown physics
variables are obtained using variation approach. The calculation results gained in this paper are close to the experimentally
test ones. 相似文献
77.
本文针对V循环、W循环和多重网格法中最优光滑次数及循环体个数难以确定的缺点,以Helmholtz方程为例给出自适应的多重网格算法和自适应的完全多重网格算法。 相似文献
78.
A. Stierle C. TiegH. Dosch V. FormosoE. Lundgren J.N. AndersenL. Köhler G. Kresse 《Surface science》2003,529(3):L263
Using high resolution core level spectroscopy, a surface core level shift towards lower binding energy of −0.13 eV is determined for the 2p level of the outwardly relaxed Al surface atoms on NiAl(1 1 0). Density functional theory based calculations with inclusion of final state effects yield a value of −0.14 eV for this shift in excellent agreement with experiment. We show that the initial state approximation yields a value of +0.09 eV, i.e. the inclusion of final state relaxation effects is vital not only to obtain the correct value but even the correct sign for this shift. 相似文献
79.
We present a model of a new paramagnetic defect center which results from the interaction of atomic hydrogen with the MgO(1 0 0) surface. DFT calculations have been performed using periodic supercells and embedded cluster models where long-range polarization effects are included explicitly. The H atom promotes the creation of an oxygen vacancy (F center) by formation of the FS+(OH−) defect where an hydroxyl group is adsorbed near an electron trapped in an oxygen vacancy. This new center has some characteristics similar to those of the classical FS+ centers but a smaller formation energy; furthermore, being globally neutral, it can be treated also with supercell methods. 相似文献
80.
T. G. G. Maffeïs G. T. Owen C. Malag G. Martinelli M. K. Kennedy F. E. Kruis S. P. Wilks 《Surface science》2004,550(1-3):21-25
In this work, we report a scanning tunnelling spectroscopy (STS) study of 30 and 10 nm tin dioxide nanoparticles. The STS spectra give a surface band gap of 2.5 eV for both samples and show that the density of surface states in the band gap is around 6 times higher for the 30 nm particles than for the 10 nm particles. This provides direct experimental evidence for our theoretical model, which predicts a decrease in the surface state density as the particle size decreases, and partly accounts for the improved sensitivity of gas sensing devices fabricated with nanoparticles. 相似文献