全文获取类型
收费全文 | 97549篇 |
免费 | 924篇 |
国内免费 | 517篇 |
专业分类
化学 | 30857篇 |
晶体学 | 859篇 |
力学 | 7133篇 |
综合类 | 3篇 |
数学 | 33040篇 |
物理学 | 16624篇 |
无线电 | 10474篇 |
出版年
2023年 | 132篇 |
2022年 | 517篇 |
2021年 | 516篇 |
2020年 | 462篇 |
2019年 | 541篇 |
2018年 | 12124篇 |
2017年 | 11670篇 |
2016年 | 7514篇 |
2015年 | 1330篇 |
2014年 | 976篇 |
2013年 | 1506篇 |
2012年 | 4958篇 |
2011年 | 12345篇 |
2010年 | 7348篇 |
2009年 | 7216篇 |
2008年 | 7615篇 |
2007年 | 10034篇 |
2006年 | 540篇 |
2005年 | 1864篇 |
2004年 | 1940篇 |
2003年 | 2354篇 |
2002年 | 1230篇 |
2001年 | 336篇 |
2000年 | 352篇 |
1999年 | 220篇 |
1998年 | 237篇 |
1997年 | 205篇 |
1996年 | 253篇 |
1995年 | 154篇 |
1994年 | 118篇 |
1993年 | 118篇 |
1992年 | 94篇 |
1991年 | 103篇 |
1990年 | 87篇 |
1989年 | 100篇 |
1988年 | 96篇 |
1987年 | 100篇 |
1986年 | 95篇 |
1985年 | 89篇 |
1984年 | 79篇 |
1983年 | 62篇 |
1982年 | 69篇 |
1981年 | 57篇 |
1980年 | 71篇 |
1979年 | 65篇 |
1978年 | 55篇 |
1914年 | 45篇 |
1912年 | 40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 0 毫秒
1.
2.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献
3.
4.
A sensitive and efficient method for trace analysis of some phenolic compounds using simultaneous derivatization and air‐assisted liquid–liquid microextraction from human urine and plasma samples followed by gas chromatography–nitrogen phosphorous detection 下载免费PDF全文
Mir Ali Farajzadeh Mohammad Reza Afshar Mogaddam Ali Akbar Alizadeh Nabil 《Biomedical chromatography : BMC》2015,29(12):1921-1931
In present study, a simultaneous derivatization and air‐assisted liquid–liquid microextraction method combined with gas chromatography–nitrogen phosphorous detection has been developed for the determination of some phenolic compounds in biological samples. The analytes are derivatized and extracted simultaneously by a fast reaction with 1‐flouro‐2,4‐dinitrobenzene under mild conditions. Under optimal conditions low limits of detection in the range of 0.05–0.34 ng mL?1 are achievable. The obtained extraction recoveries are between 84 and 97% and the relative standard deviations are less than 7.2% for intraday (n = 6) and interday (n = 4) precisions. The proposed method was demonstrated to be a simple and efficient method for the analysis of phenols in biological samples. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
6.
7.
8.
Correction to: Cloud-based vehicular networks: a taxonomy,survey, and conceptual hybrid architecture
Jabbarpour Mohammad Reza Marefat Alireza Jalooli Ali Zarrabi Houman 《Wireless Networks》2019,25(2):913-913
Wireless Networks - The original version of this article unfortunately contained a mistake in the title. The correct title has been published with this erratum. 相似文献
9.
10.
In this paper, the deformation of the Heisenberg algebra, consistent with both the generalized uncertainty principle and doubly special relativity, has been analyzed. It has been observed that, though this algebra can give rise to fractional derivative terms in the corresponding quantum mechanical Hamiltonian, a formal meaning can be given to them by using the theory of harmonic extensions of function. Depending on this argument, the expression of the propagator of the path integral corresponding to the deformed Heisenberg algebra, has been obtained. In particular, the consistent expression of the one dimensional free particle propagator has been evaluated explicitly. With this propagator in hand, it has been shown that, even in free particle case, normal generalized uncertainty principle and doubly special relativity show very much different result. 相似文献