全文获取类型
收费全文 | 273181篇 |
免费 | 2325篇 |
国内免费 | 735篇 |
专业分类
化学 | 127265篇 |
晶体学 | 3991篇 |
力学 | 14545篇 |
综合类 | 7篇 |
数学 | 42172篇 |
物理学 | 88261篇 |
出版年
2021年 | 991篇 |
2020年 | 1112篇 |
2019年 | 1127篇 |
2018年 | 10440篇 |
2017年 | 11407篇 |
2016年 | 6533篇 |
2015年 | 2846篇 |
2014年 | 2609篇 |
2013年 | 7819篇 |
2012年 | 10750篇 |
2011年 | 20841篇 |
2010年 | 12438篇 |
2009年 | 12586篇 |
2008年 | 18258篇 |
2007年 | 21895篇 |
2006年 | 7208篇 |
2005年 | 13883篇 |
2004年 | 9558篇 |
2003年 | 8563篇 |
2002年 | 6394篇 |
2001年 | 6188篇 |
2000年 | 4866篇 |
1999年 | 3515篇 |
1998年 | 2671篇 |
1997年 | 2632篇 |
1996年 | 2743篇 |
1995年 | 2370篇 |
1994年 | 2244篇 |
1993年 | 2100篇 |
1992年 | 2405篇 |
1991年 | 2379篇 |
1990年 | 2090篇 |
1989年 | 2076篇 |
1988年 | 2108篇 |
1987年 | 2040篇 |
1986年 | 1945篇 |
1985年 | 2859篇 |
1984年 | 2850篇 |
1983年 | 2296篇 |
1982年 | 2473篇 |
1981年 | 2355篇 |
1980年 | 2312篇 |
1979年 | 2277篇 |
1978年 | 2355篇 |
1977年 | 2228篇 |
1976年 | 2194篇 |
1975年 | 2168篇 |
1974年 | 2068篇 |
1973年 | 2190篇 |
1972年 | 1232篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
An approach of dynamic mesh adaptation for simulating 3‐dimensional unsteady moving‐immersed‐boundary flows
下载免费PDF全文
![点击此处可从《国际流体数值方法杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this paper, we present an approach of dynamic mesh adaptation for simulating complex 3‐dimensional incompressible moving‐boundary flows by immersed boundary methods. Tetrahedral meshes are adapted by a hierarchical refining/coarsening algorithm. Regular refinement is accomplished by dividing 1 tetrahedron into 8 subcells, and irregular refinement is only for eliminating the hanging points. Merging the 8 subcells obtained by regular refinement, the mesh is coarsened. With hierarchical refining/coarsening, mesh adaptivity can be achieved by adjusting the mesh only 1 time for each adaptation period. The level difference between 2 neighboring cells never exceeds 1, and the geometrical quality of mesh does not degrade as the level of adaptive mesh increases. A predictor‐corrector scheme is introduced to eliminate the phase lag between adapted mesh and unsteady solution. The error caused by each solution transferring from the old mesh to the new adapted one is small because most of the nodes on the 2 meshes are coincident. An immersed boundary method named local domain‐free discretization is employed to solve the flow equations. Several numerical experiments have been conducted for 3‐dimensional incompressible moving‐boundary flows. By using the present approach, the number of mesh nodes is reduced greatly while the accuracy of solution can be preserved. 相似文献
22.
23.
24.
25.
26.
Su X. F. Zhang Y. L. Maximov A. L. Zhang K. Xin Q. Feng C. Q. Bai X. F. Wu W. 《Russian Journal of Applied Chemistry》2020,93(1):127-136
Russian Journal of Applied Chemistry - Nanoscale ZSM-5 (AlZ5-D) and Ga-substituted ZSM-5 zeolites ((Al,Ga)Z5-D and GaZ5-D) were synthesized by a green dry-gel conversion strategy. For comparison,... 相似文献
27.
28.
V. A. Bespalov V. M. Glazov E. A. Il’ichev Yu. A. Klimov S. V. Kuklev A. E. Kuleshov R. M. Nabiev G. N. Petrukhin B. G. Potapov G. S. Rychkov D. S. Sokolov V. V. Fandeev E. A. Fetisov S. S. Yakushov 《Technical Physics》2015,60(4):553-560
The results of investigation of optical image detectors designed for the largest problem, near-VUV, range of the spectrum are presented. The possibility of using a dual-stage image detection system to appreciably lower the sensitivity threshold and make computer data processing feasible is considered. The integration of a UV module into a wideband image detector is studied. 相似文献
29.
30.
A. Lashgari S. Ghammamy R. Ramirez-Tagle G. Salgado-Moran 《Journal of Structural Chemistry》2015,56(8):1505-1513
Two new compounds of fluorine: (C2H5)4N[I2F] and (C2H5)4N[Br2F], have been easily synthesized in a nearly quantitative by a direct reaction of (C2H5)4NF, I2 and Br2. The products were isolated and characterized by elemental analysis and spectroscopic methods such as: Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). These compounds have been studied computationally with the Scalar ZORA relativistic level of theory using the ADF program package. The molecular parameters, and vibrational spectra were calculated. The excitation energies were found by timedependent perturbation density functional theory (TD-DFT). Molecule optimization, frequencies and excitation energies were calculated with standard Slatertype-orbital (STO) basis sets with triple-zeta quality double plus polarization functions (TZ2P) for all atoms. The FTIR, UV-Vis spectra and assignment of principal transitions and total density of state (TDOS) were extracted using the GaussSum 2.2 program. The comparison between experimental and calculated values showes that the experimental results correlate well with the predicted data. 相似文献