全文获取类型
收费全文 | 106039篇 |
免费 | 5582篇 |
国内免费 | 4297篇 |
专业分类
化学 | 44902篇 |
晶体学 | 1096篇 |
力学 | 8518篇 |
综合类 | 209篇 |
数学 | 35134篇 |
物理学 | 26059篇 |
出版年
2024年 | 57篇 |
2023年 | 625篇 |
2022年 | 709篇 |
2021年 | 1033篇 |
2020年 | 1231篇 |
2019年 | 1240篇 |
2018年 | 11199篇 |
2017年 | 10997篇 |
2016年 | 7436篇 |
2015年 | 2289篇 |
2014年 | 2074篇 |
2013年 | 2514篇 |
2012年 | 6436篇 |
2011年 | 13043篇 |
2010年 | 7464篇 |
2009年 | 7818篇 |
2008年 | 8496篇 |
2007年 | 10365篇 |
2006年 | 1820篇 |
2005年 | 2657篇 |
2004年 | 2558篇 |
2003年 | 2807篇 |
2002年 | 1903篇 |
2001年 | 965篇 |
2000年 | 903篇 |
1999年 | 800篇 |
1998年 | 712篇 |
1997年 | 602篇 |
1996年 | 670篇 |
1995年 | 557篇 |
1994年 | 401篇 |
1993年 | 395篇 |
1992年 | 303篇 |
1991年 | 305篇 |
1990年 | 257篇 |
1989年 | 238篇 |
1988年 | 211篇 |
1987年 | 161篇 |
1986年 | 142篇 |
1985年 | 133篇 |
1984年 | 100篇 |
1983年 | 78篇 |
1982年 | 79篇 |
1981年 | 65篇 |
1980年 | 58篇 |
1979年 | 51篇 |
1978年 | 42篇 |
1914年 | 45篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
We report a spatially modulated polarimetry scheme by using a zero-order vortex half-wave retarder(ZVHR)and a spatial Fourier analysis method.A ZVHR is employed to analyze the input polarized light and convert it into a vectorial optical field,and an analyzer is set after the ZVHR to form an hourglass intensity pattern due to the spatial polarization modulation.Then,the input light’s Stokes parameters can be calculated by spatial Fourier analysis of the hourglass pattern with a single shot.The working principle of the polarimeter has been analyzed by the Stokes-Mueller formalism,and some quantitative measuring experiments of different polarization states have been demonstrated.The experimental results indicate that the proposed polarimeter is accurate,robust,and simple to use. 相似文献
42.
43.
Nonlinear Dynamics - Based on a mixed control strategy, this study addresses the finite-time stabilization with extended dissipativity for Markov jump systems (MJSs) with unreliable... 相似文献
44.
Peng-Yan Gui Xiao-Hui Yan Wen-Juan Yuan Yuan-Liang Ma Xiao Ding Shuai Liu 《Natural product research》2019,33(19):2830-2836
A new A, D-seco limonoid, named 12-acetyloxyperforatin (1), along with three known ones, were isolated from the leaves of Harrisonia perforata. Their structures were elucidated on the basis of spectroscopic analysis, including extensive NMR techniques and computational modelling. These compounds showed no inhibitory activity against the 11β-HSD1 enzyme. 相似文献
45.
Sun Yuan Luo Shunlong Lei Xiangyun 《International Journal of Theoretical Physics》2021,60(9):3211-3224
International Journal of Theoretical Physics - Gram matrices arise naturally in the consideration of pair-wise overlap of a family of vectors or quantum pure states, and play an important role in... 相似文献
46.
47.
本文基于新的Kronecker型替换,给出两个由黑盒表示的稀疏多项式的新确定性插值算法.令f∈R[x1,……,xn]是一个稀疏黑盒多项式,其次数上界为D.当R是C或者是有限域时,相对于已有算法,新算法具有更好的计算复杂度或者关于D的复杂度更低.特别地,对于一般黑盒模型,D是复杂度中的主要因素,而在所有的确定性算法中,本文的第二个算法的复杂度关于D是最低的. 相似文献
48.
Luo Dajuan Liu Bingqian Gao Rong Su Lixia Su Yonghuan 《Journal of Solid State Electrochemistry》2022,26(3):749-759
Journal of Solid State Electrochemistry - Cortisol, a steroid hormone, has been confirmed as a kind of biomarker that reflects the stress response of psychobiology and related adverse health... 相似文献
49.
50.
Yifeng Xiang Xi Tang Changjun Min Guanghao Rui Yan Kuai Fengya Lu Pei Wang Hai Ming Qiwen Zhan Xiaocong Yuan Joseph R. Lakowicz Douguo Zhang 《Annalen der Physik》2020,532(4):1900497
Near-field optical trapping can be realized with focused evanescent waves that are excited at the water–glass interface due to the total internal reflection, or with focused plasmonic waves excited on the water–gold interface. Herein, the performance of these two kinds of near-field optical trapping techniques is compared using the same optical microscope configuration. Experimental results show that only a single-micron polystyrene bead can be trapped by the focused evanescent waves, whereas many beads are simultaneously attracted to the center of the excited region by focused plasmonic waves. This difference in trapping behavior is analyzed from the electric field intensity distributions of these two kinds of focused surface waves and the difference in trapping behavior is attributed to photothermal effects due to the light absorption by the gold film. 相似文献