全文获取类型
收费全文 | 19661篇 |
免费 | 629篇 |
国内免费 | 113篇 |
专业分类
化学 | 14103篇 |
晶体学 | 189篇 |
力学 | 378篇 |
综合类 | 1篇 |
数学 | 2956篇 |
物理学 | 2776篇 |
出版年
2022年 | 149篇 |
2021年 | 197篇 |
2020年 | 294篇 |
2019年 | 290篇 |
2018年 | 186篇 |
2017年 | 182篇 |
2016年 | 406篇 |
2015年 | 357篇 |
2014年 | 451篇 |
2013年 | 930篇 |
2012年 | 977篇 |
2011年 | 1269篇 |
2010年 | 620篇 |
2009年 | 524篇 |
2008年 | 1014篇 |
2007年 | 1092篇 |
2006年 | 1074篇 |
2005年 | 1038篇 |
2004年 | 882篇 |
2003年 | 746篇 |
2002年 | 736篇 |
2001年 | 250篇 |
2000年 | 256篇 |
1999年 | 231篇 |
1998年 | 223篇 |
1997年 | 260篇 |
1996年 | 285篇 |
1995年 | 227篇 |
1994年 | 212篇 |
1993年 | 245篇 |
1992年 | 206篇 |
1991年 | 185篇 |
1990年 | 163篇 |
1989年 | 141篇 |
1988年 | 140篇 |
1987年 | 158篇 |
1986年 | 135篇 |
1985年 | 202篇 |
1984年 | 249篇 |
1983年 | 178篇 |
1982年 | 220篇 |
1981年 | 241篇 |
1980年 | 180篇 |
1979年 | 181篇 |
1978年 | 214篇 |
1977年 | 159篇 |
1976年 | 157篇 |
1975年 | 150篇 |
1974年 | 165篇 |
1973年 | 140篇 |
排序方式: 共有10000条查询结果,搜索用时 734 毫秒
881.
882.
883.
In this article, an ALE finite element method to simulate the partial melting of a workpiece of metal is presented. The model includes the heat transport in both the solid and liquid part, fluid flow in the liquid phase by the Navier–Stokes equations, tracking of the melt interface solid/liquid by the Stefan condition, treatment of the capillary boundary accounting for surface tension effects and a radiative boundary condition. We show that an accurate treatment of the moving boundaries is crucial to resolve their respective influences on the flow field and thus on the overall energy transport correctly. This is achieved by a mesh‐moving method, which explicitly tracks the phase boundary and makes it possible to use a sharp interface model without singularities in the boundary conditions at the triple junction. A numerical example describing the welding of a thin‐steel wire end by a laser, where all aforementioned effects have to be taken into account, proves the effectiveness of the approach.Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
884.
Piotr T. Chruściel Erwann Delay Paul Klinger Andreas Kriegl Peter W. Michor Armin Rainer 《Letters in Mathematical Physics》2018,108(9):2009-2030
We prove existence of large families of solutions of Einstein-complex scalar field equations with a negative cosmological constant, with a stationary or static metric and a time-periodic complex scalar field. 相似文献
885.
886.
887.
888.
889.
890.
Seow Jecg Chin Peter Hornsby Damjan Vengust Dragan Mihailović J. Mitra Paul Dawson Tony McNally 《先进技术聚合物》2012,23(2):149-160
Composites of poly(ε‐caprolactone) (PCL) and molybdenum sulfur iodine (MoSI) nanowires were prepared using twin‐screw extrusion. Extensive microscopic examination of the composites revealed the nanowires were well dispersed in the PCL matrix, although bundles of Mo6S3I6 ropes were evident at higher loadings. Secondary electron imaging (SEI) showed the nanowires had formed an extensive network throughout the PCL matrix, resulting in increased electrical conductivity of PCL, by eight orders of magnitude, and an electrical percolation threshold of 6.5 × 10?3 vol%. Thermal analysis (DSC), WAXD, and hot stage polarized optical microscopy (HSPOM) experiments revealed Mo6S3I6 addition altered PCL crystallization kinetics, nucleation density, and crystalline content. A greater number of smaller spherulites were formed via heterogeneous nucleation. The onset of thermal decomposition (TGA) of PCL decreased by 70°C, a consequence of the thermal degradation of Mo6S3I6 to MoO3, which in turn accelerates the formation of volatile gases during the first stage of PCL decomposition. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献