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71.
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73.
High temperature oxidation of metals leads to residual stresses in the metal and in the oxide. In this work, we try to predict the evolution of the residual stresses in the growing oxides layers, during isothermal oxidation. The origin of these stresses is based on the microstructural model of Clarke, however, another justification is proposed, assuming a proportional dependence of the growth strain with the oxide layer thickness. Using the mechanics of thin layers, as well as the analysis proposed to describe the growth strain, a system of equations are deduced that predict the stresses evolution with oxidation time. Numerical analysis is performed, leading to a set of theoretical curves. 相似文献
74.
Discrete-time GI/Geo/1 queue with multiple working vacations 总被引:2,自引:0,他引:2
Consider the discrete time GI/Geo/1 queue with working vacations under EAS and LAS schemes. The server takes the original
work at the lower rate rather than completely stopping during the vacation period. Using the matrix-geometric solution method,
we obtain the steady-state distribution of the number of customers in the system and present the stochastic decomposition
property of the queue length. Furthermore, we find and verify the closed property of conditional probability for negative
binomial distributions. Using such property, we obtain the specific expression for the steady-state distribution of the waiting
time and explain its two conditional stochastic decomposition structures. Finally, two special models are presented.
相似文献
75.
In this paper, the entangled mapping approach (EMA) is applied to obtain variable separation solutions of (1 1)-dimensional and (3 1)-dimensional systems. By analysis, we firstly find that there also exists a common formula to describe suitable physical fields or potentials for these (1 1)-dimensional models such as coupled integrable dispersionless (CID) and shallow water wave equations. Moreover, we find that the variable separation solution of the (3 1)-dimensional Burgers system satisfies the completely same form as the universal quantity U1 in (2 1 )-dimensional systems. The only difference is that the function q is a solution of a constraint equation and p is an arbitrary function of three independent variables. 相似文献
76.
为了求解各向异性接合材料界面端部奇异性应力场,建立了一种新型杂交元模型.该模型的独特之处在于:基于有限元特征法得到的奇异性场数值特征解建立了一种新型界面端奇异单元.通过算例证明,新型杂交元模型能够利用较少的单元数获得较为精确的数值结果.当前模型应用范围广泛,能够用于复杂结构的界面端部场求解. 相似文献
77.
An intrinsic principle of least action is presented for the intrinsic dynamism of chemical reactions. Then, as the stationary trajectory, a meta-IRC (intrinsic reaction coordinate) draws a geodesic curve in a rigged Riemannian space. This establishes a geodesic law for the intrinsic dynamism. Moreover, a diagrammatic perturbation theory is formulated for the intrinsic dynamism, and a dynamical interaction between a chemically reacting system and a background system is investigated. Then, the structural stability of the system is discussed using a new concept of the dynamical potential field. An example is given in order to elucidate the present theory.Dedicated to Prof. Hermann Hartmann on the occasion of his 65th birthday. 相似文献
78.
根据出现在质谱中的各种大小的碳原子簇的相对丰度,分析了由激光产生的碳原子簇离子的统计分布,研究了这些统计分布与碳原子簇结构的关联。研究结果表明:相同构型的原子簇的相对丰度可以由同一条对数正态分布曲线来描述,由此能够获得碳原子簇构型的变化情况。质谱中分布曲线的数目对应于具有不同构型或不同结构稳定性的原子簇的数目。如果某些簇离子的谱峰明显地高出分布曲线,它们的结构应特别稳定,其成簇原子数就是所谓的“奇幻数”(magicnumber),例如在石墨质谱中的C_(60)就属于这种情况。原子簇的统计分布还与它们的生成过程有关,由此可能揭示出原子簇的产生机理。 相似文献
79.
The ab initio molecular fragment approach is applied to a characterization study of the ground state of the zwitterion of glycine. Included among the properties studied are the — conformational energy surface, the electronic structure, and the magnitude and direction of the dipole moment. The results of the present study are compared to the results of other theoretical and experimental studies.This work was supported in part by the National Science Foundation, the University of Kansas, and the Upjohn Company, Kalamazoo, Michigan 49001.NSF Trainee (1969-1972).Alfred P. Sloan Research Fellow (1971–1973). 相似文献
80.
Chan?Yoon?Jung Hoe?Jin?Hah Seung?Hoon?Han Hong-Woo?Park Sang?Man?KooEmail author 《Journal of Sol-Gel Science and Technology》2005,33(1):81-85
Tin oxide-doped hybrid particles were prepared by a wet chemical process with organic-inorganic (phenyl/silica) hybrid particles in an alcoholic solution. The phenyl/silica hybrid particles, with a diameter of ca. 790 nm were used as a new support material for tin oxide (SnO2) particles from tin(IV) chloride. The surface of the particles was modified via nitration of aromatic groups in the particles, to promote formation of the tin oxide coating on the particles. The thickness and surface morphology of the tin oxide layer coated on the nitrated-phenyl/silica hybrid particles could be controlled by varying the tin(IV) chloride concentration and reaction time. The size and morphology of the resultant particles were investigated with field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The particles obtained were also characterised by infrared (FTIR) and solid-state 13C magic angle spinning nuclear magnetic resonance (13C-CP/MAS NMR) spectroscopy. The effect of processing parameters on the crystallinity and structure of the doped hybrids were confirmed by X-ray diffraction (XRD) patterns. 相似文献