全文获取类型
收费全文 | 536930篇 |
免费 | 4047篇 |
国内免费 | 1194篇 |
专业分类
化学 | 256574篇 |
晶体学 | 8268篇 |
力学 | 28889篇 |
综合类 | 10篇 |
数学 | 73676篇 |
物理学 | 174754篇 |
出版年
2021年 | 5084篇 |
2020年 | 5405篇 |
2019年 | 6317篇 |
2018年 | 9012篇 |
2017年 | 9295篇 |
2016年 | 12329篇 |
2015年 | 6450篇 |
2014年 | 11455篇 |
2013年 | 24057篇 |
2012年 | 19113篇 |
2011年 | 22622篇 |
2010年 | 17581篇 |
2009年 | 17864篇 |
2008年 | 21025篇 |
2007年 | 20776篇 |
2006年 | 18957篇 |
2005年 | 16492篇 |
2004年 | 15617篇 |
2003年 | 14082篇 |
2002年 | 14209篇 |
2001年 | 15642篇 |
2000年 | 11927篇 |
1999年 | 9145篇 |
1998年 | 8041篇 |
1997年 | 7722篇 |
1996年 | 7160篇 |
1995年 | 6322篇 |
1994年 | 6299篇 |
1993年 | 6179篇 |
1992年 | 6520篇 |
1991年 | 7050篇 |
1990年 | 6762篇 |
1989年 | 6698篇 |
1988年 | 6321篇 |
1987年 | 6501篇 |
1986年 | 6074篇 |
1985年 | 7391篇 |
1984年 | 7671篇 |
1983年 | 6468篇 |
1982年 | 6638篇 |
1981年 | 6212篇 |
1980年 | 6001篇 |
1979年 | 6624篇 |
1978年 | 6661篇 |
1977年 | 6807篇 |
1976年 | 6819篇 |
1975年 | 6383篇 |
1974年 | 6199篇 |
1973年 | 6383篇 |
1972年 | 4988篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
V. L. Tsymbalenko 《JETP Letters》2003,78(8):493-496
The kinetics of formation of an anomalous phase from a solution with a small 3He impurity was studied in the temperature range 0.2–0.7 K up to a supersaturation of ~30 mbar. The phase diagram was determined for normal and anomalous growths. It is found that, in the presence of impurities, the formation of a fast-growing state is retarded. This experimental fact indicates that the dissipative processes in fluids have an appreciable effect on the phase formation kinetics. The retardation is, possibly, caused by the direct interaction of an impurity with the crystal surface. 相似文献
982.
Baidyshev V. S. Udodov V. N. Popov A. A. Potekaev A. I. 《Russian Physics Journal》2003,46(12):1193-1198
The paper offers a method for calculating phase diagrams of polytype transformations in close-packed crystals based on the generalized axial Ising's model of finite dimensions at non-zero temperatures. Using the Metropolis algorithm, the behavior of systems with polytype transitions is studied under the conditions of changing external shear stress and temperature. The longest polytype period considered here is taken to be 30 close-packed planes. 相似文献
983.
984.
985.
986.
Behavior of a poro-elastic material bonded onto a vibrating plate is investigated in the low-frequency range. From the analysis of dissipation mechanisms, a model accounting for damping added by the porous layer on the plate is derived. This analysis is based on a 3-D finite element formulation including poro-elastic elements based on Biot displacement theory. First, dissipated powers related to thermal, viscous and viscoelastic dissipation are explicited. Then a generic configuration (simply-supported aluminium plate with a bonded porous layer and mechanical excitation) is studied. Thermal dissipation is found negligible. Viscous dissipation can be optimized as a function of airflow resistivity. It can be the major phenomenon within soft materials, but for most foams viscoelastic dissipation is dominant. Consequently an equivalent plate model is proposed. It includes shear in the porous layer and only viscoelasticity of the skeleton. Excellent agreement is found with the full numerical model. 相似文献
987.
H. Yamaguchi K. Kanisawa S. Miyashita Y. Hirayama 《Physica E: Low-dimensional Systems and Nanostructures》2004,23(3-4):285
We studied the structural, electrical, and mechanical properties of an InAs thin film grown on GaAs (1 1 1)A substrates by molecular beam epitaxy. In contrast to conventionally used (0 0 1) surfaces, where Stranski–Krastanov growth dominates the highly mismatched heteroepitaxy, layer-by-layer growth of InAs can be established. One of the largest advantages of this unique heteroepitaxial system is that it provides a two-dimensional electron gas system in the near-surface region without the problem of electron depletion. We review the fundamental properties and applications of this unique heteroepitaxial system. 相似文献
988.
The reasons for the existence of various scenarios for structural transformations in disordered condensed media, such as liquids and amorphous substances, where both smeared transformations and sharp first-order transitions may occur, were analyzed. The ratio between the spatial scale of structural correlations and the size of the smallest possible region occupied by a new phase in the matrix of initial modification is the key parameter determining the scenario for equilibrium phase transformations in liquids. In amorphous substances, the experimentally observed transformations occur far from equilibrium, and the possible size of the region occupied by the new phase corresponds to the minimal nucleus size. For some amorphous solids, quantitative analysis of the transformation width was carried out and the main classes of covalent substances, in which the smeared or sharp transitions occur, were revealed. Specific features of the interparticle interactions determining various transformation scenarios are discussed. 相似文献
989.
S.BOUZID Z.AZARI 《宁波大学学报(理工版)》2003,16(4):354-362
冲蚀过程是一个与颗粒反复冲击物体表面而移除物质相关的表面现象.本文研究了玻璃的冲蚀坑的几何尺寸和体积,给出了冲蚀移除物质如何依赖于颗粒流动速度、颗粒尺寸和冲击角的理论关系.通过理论与实验结果相比较,定义了一定冲蚀坑尺度的有效域. 相似文献
990.
We construct a multiplicative group structure in the class of integro-differential operators specific for a polydisk which was introduced by I. I. Bavrin. We indicate two applications of these operators to solution of functional equations. 相似文献