全文获取类型
收费全文 | 12073篇 |
免费 | 994篇 |
国内免费 | 816篇 |
专业分类
化学 | 1561篇 |
晶体学 | 11篇 |
力学 | 348篇 |
综合类 | 85篇 |
数学 | 1443篇 |
物理学 | 2949篇 |
综合类 | 7486篇 |
出版年
2024年 | 40篇 |
2023年 | 92篇 |
2022年 | 253篇 |
2021年 | 282篇 |
2020年 | 249篇 |
2019年 | 188篇 |
2018年 | 245篇 |
2017年 | 258篇 |
2016年 | 265篇 |
2015年 | 326篇 |
2014年 | 618篇 |
2013年 | 655篇 |
2012年 | 629篇 |
2011年 | 764篇 |
2010年 | 616篇 |
2009年 | 665篇 |
2008年 | 688篇 |
2007年 | 815篇 |
2006年 | 671篇 |
2005年 | 665篇 |
2004年 | 560篇 |
2003年 | 545篇 |
2002年 | 484篇 |
2001年 | 457篇 |
2000年 | 457篇 |
1999年 | 343篇 |
1998年 | 325篇 |
1997年 | 246篇 |
1996年 | 241篇 |
1995年 | 207篇 |
1994年 | 161篇 |
1993年 | 149篇 |
1992年 | 125篇 |
1991年 | 114篇 |
1990年 | 94篇 |
1989年 | 86篇 |
1988年 | 72篇 |
1987年 | 72篇 |
1986年 | 35篇 |
1985年 | 27篇 |
1984年 | 18篇 |
1983年 | 8篇 |
1982年 | 16篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1968年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
21.
22.
23.
王启玮 《西安石油大学学报(自然科学版)》1992,(2)
摘要首先从库仑定律出发导出了地层介质塑性流动条件。其结果类似于一般塑性力学中的Tresca,Mises条件。其次列出了轴对称地层塑性流动的微分方程组,并推出了其简化近似方程。最后提出了简化方程的特征线解法,并举例说明。 相似文献
24.
Europium (Eu+) ions were confined in a Paul trap and detected by non-destructive method. Storage time of Eu+ ions achieved in vacuum was improved by orders of magnitude employing buffer gas cooling. The experimentally detected signal
was fitted to the ion response signal and the total number of ions trapped was estimated. It is found that the peak signal
amplitude as well as the product of FWHM and the peak signal amplitude is proportional to the total number of trapped ions.
The trapped ion secular frequency was swept at different rates and its effect on the absorption line profile was studied both
experimentally and theoretically. 相似文献
25.
We show that the refined analytic torsion is a holomorphic section of the determinant line bundle over the space of complex representations of the fundamental group of a closed oriented odd-dimensional manifold. Further, we calculate the ratio of the refined analytic torsion and the Farber-Turaev combinatorial torsion. As an application, we establish a formula relating the eta-invariant and the phase of the Farber-Turaev torsion, which extends a theorem of Farber and earlier results of ours. This formula allows to study the spectral flow using methods of combinatorial topology. 相似文献
26.
An infinite row of periodically spaced, identical rigid circularcylinders is excited by an acoustic line source which is parallelto the generators of the cylinders. A method for calculatingthe scattered field accurately and efficiently is presented.When the cylinders are sufficiently close together, Rayleigh–Blochsurface waves that propagate energy to infinity along the arrayare excited. An expression is derived which enables the amplitudesof these surface waves to be computed without requiring thesolution to the full scattering problem. 相似文献
27.
28.
The plastic deformation field near the horizontal surface of a half space of perfectly plastic material associated with an indenting rotating rigid tooth is studied using slip line theory. The tooth is one of many on a roll surface and indents first into the half-space material and then rotates about the roll center. A slip line field is proposed for the deforming plastic region and a solution scheme is outlined. The emphasis is on determining the shape of the deforming region, especially that of the free surface. The study has a potential application in roughness transfer in metal forming processing. 相似文献
29.
Yu. D. Perfiliev V. S. Rusakov L. A. Kulikov A. A. Kamnev K. Alkhatib 《Hyperfine Interactions》2006,167(1-3):881-885
To explain line broadening in emission Mössbauer spectra as compared to the corresponding absorber measurements, the model of trapped electrons has been proposed. Auger electrons (emitted, e.g. after electron capture by 57Co or after the converted isomeric transition of 119mSn), as well as secondary electrons, may be trapped in the proximity to the nucleogenic ion. Electrons captured by lattice traps at different distances from the daughter ion induce an asymmetric distribution of quadrupole splitting in the resulting emission spectra, as shown in a few examples. This model is supported by estimates of quadrupole splitting values which may be caused by such trapped electrons located at specified distances from the nucleogenic atom. 相似文献
30.
文章用特征线法给出一类仓库货物储存模型解的递推表达式,并证明其光滑性从而得到了经典解的存在唯一性。 相似文献