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991.
Riguang ZhangHongyan Liu Huayan ZhengLixia Ling Zhong LiBaojun Wang 《Applied Surface Science》2011,257(11):4787-4794
The adsorption and dissociation of O2 on the perfect and oxygen-deficient Cu2O(1 1 1) surface have been systematically studied using periodic density functional calculations. Different kinds of possible modes of atomic O and molecular O2 adsorbed on the Cu2O(1 1 1) surface are identified: atomic O is found to prefer threefold 3Cu site on the perfect surface and Ovacancy site on the deficient surface, respectively. CuCUS is the most advantageous site with molecularly adsorbed O2 lying flatly over singly coordinate CuCUS-CuCSA bridge on the perfect surface. O2 adsorbed dissociatively on the deficient surface, which is the main dissociation pathway of O2, and a small quantity of molecularly adsorbed O2 has been obtained. Further, possible dissociation pathways of molecularly adsorbed O2 on the Cu2O(1 1 1) surface are explored, the reaction energies and relevant barriers show that a small quantity of molecularly adsorbed O2 dissociation into two O atoms on the deficient surface is favorable both thermodynamically and kinetically in comparison with the dissociation of O2 on the perfect surface. The calculated results suggest that the presence of oxygen vacancy exhibits a strong chemical reactivity towards the dissociation of O2 and can obviously improve the catalytic activity of Cu2O, which is in agreement with the experimental observation. 相似文献
992.
Hongyan Liu Riguang ZhangRuixia Yan Baojun Wang Kechang Xie 《Applied Surface Science》2011,257(21):8955-8964
A density-functional theory method has been conducted to investigate the adsorption of CHx (x = 0-4) as well as the dissociation of CHx (x = 1-4) on (1 1 1) facets of ordered NiCo alloy. The results have been compared with those obtained on pure Ni (1 1 1) surface. It shows that the adsorption energies of C and CH are decreased while it is increased for CH3 on NiCo (1 1 1) compared to those on pure Ni (1 1 1). Furthermore, on NiCo (1 1 1), dissociation of CHx prefers not to the top of Ni, but to the top of Co. The rate-determining step for CH4 dissociation is considered as the first step of dehydrogenation on NiCo (1 1 1), while it is the fourth step of dehydrogenation on Ni (1 1 1). Furthermore, the activation barrier in rate-determining step is slightly higher by 0.07 eV on Ni (1 1 1) than that on NiCo (1 1 1). From above results, it is important to point out that carbon is easy to form on NiCo (1 1 1) although the adsorption energy of C atom is slightly decreased compared to that on Ni (1 1 1). 相似文献
993.
The physics behind the spin (polarization)-dependent electromagnetic hot-spot phenomenon is due to the presence of the geometric phase resulting from the optical spin-orbit interaction in the interaction of light with the subwavelength microstructures. Unlike the tiny spin-dependent shift of light associated with the usual spin-Hall effect of light, here we present the distinct polarization-dependent angular shift by employing an array of subwavelength metallic apertures. More importantly, this novel electromagnetic precession is accompanied by the extraordinary optical transmission phenomenon and offers the exciting possibilities for novel applications for subwavelength structured metallic systems. 相似文献
994.
Serrano J Bosak A Krisch M Manjón FJ Romero AH Garro N Wang X Yoshikawa A Kuball M 《Physical review letters》2011,106(20):205501
Achieving comprehensive information on thin film lattice dynamics so far has eluded well established spectroscopic techniques. We demonstrate here the novel application of grazing incidence inelastic x-ray scattering combined with ab initio calculations to determine the complete elastic stiffness tensor, the acoustic and low-energy optic phonon dispersion relations of thin wurtzite indium nitride films. Indium nitride is an especially relevant example, due to the technological interest for optoelectronic and solar cell applications in combination with other group III nitrides. 相似文献
995.
996.
997.
The problem of confining a collisionless plasma by means of external electromagnetic fields is formulated as an optimal control or variational problem. The paper begins with a formal development of the equations governing the plasma motion. Then, various mathematical formulations of the confinement problem are discussed. Specific results are obtained for the simplified case where confinement is achieved by means of a spatially uniform, time-varying magnetic field. Physical interpretations of these results are also given.This work was supported by the Office of Scientific Research of the United States Air Force under Grant No. AFOSR-68-1547. 相似文献
998.
1000.
Zi-Long Li Xing-Yue Tan Zhu-Feng Zhang Zhen-Yang Wang Xin-Heng Guo 《中国物理C(英文版)》2023,47(1):013102-013102-8
In this study, we systematically investigated two-pseudoscalar meson systems with the Bethe-Salpeter equation in the ladder and instantaneous approximations. By solving the Bethe-Salpeter equation numerically with the kernel containing the one-particle exchange diagrams, we found that the \begin{document}$ K\bar{K} $\end{document} ![]()
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, \begin{document}$ DK $\end{document} ![]()
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, \begin{document}$ B\bar{K} $\end{document} ![]()
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, \begin{document}$ D\bar{D} $\end{document} ![]()
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, \begin{document}$ B\bar{B} $\end{document} ![]()
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, \begin{document}$ BD $\end{document} ![]()
![]()
, \begin{document}$ D\bar{K} $\end{document} ![]()
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, \begin{document}$ BK $\end{document} ![]()
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, and \begin{document}$ B\bar{D} $\end{document} ![]()
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systems with \begin{document}$ I=0 $\end{document} ![]()
![]()
can exist as bound states. We also studied the contributions from heavy meson (\begin{document}$ J/\psi $\end{document} ![]()
![]()
and \begin{document}$\Upsilon $\end{document} ![]()
![]()
) exchanges and found that the contributions from heavy meson exchanges cannot be ignored. 相似文献