全文获取类型
收费全文 | 410337篇 |
免费 | 3610篇 |
国内免费 | 965篇 |
专业分类
化学 | 191652篇 |
晶体学 | 6313篇 |
力学 | 21460篇 |
综合类 | 7篇 |
数学 | 60153篇 |
物理学 | 135327篇 |
出版年
2021年 | 3200篇 |
2020年 | 3408篇 |
2019年 | 3830篇 |
2018年 | 11966篇 |
2017年 | 12651篇 |
2016年 | 10610篇 |
2015年 | 4929篇 |
2014年 | 7257篇 |
2013年 | 16207篇 |
2012年 | 16046篇 |
2011年 | 25071篇 |
2010年 | 16974篇 |
2009年 | 16941篇 |
2008年 | 22040篇 |
2007年 | 24805篇 |
2006年 | 12505篇 |
2005年 | 16087篇 |
2004年 | 12663篇 |
2003年 | 11588篇 |
2002年 | 9974篇 |
2001年 | 10566篇 |
2000年 | 7996篇 |
1999年 | 6050篇 |
1998年 | 5047篇 |
1997年 | 4850篇 |
1996年 | 4692篇 |
1995年 | 3999篇 |
1994年 | 3947篇 |
1993年 | 3818篇 |
1992年 | 4185篇 |
1991年 | 4392篇 |
1990年 | 4191篇 |
1989年 | 4103篇 |
1988年 | 3865篇 |
1987年 | 4000篇 |
1986年 | 3765篇 |
1985年 | 4722篇 |
1984年 | 4782篇 |
1983年 | 3981篇 |
1982年 | 4063篇 |
1981年 | 3785篇 |
1980年 | 3738篇 |
1979年 | 3984篇 |
1978年 | 3980篇 |
1977年 | 3909篇 |
1976年 | 3926篇 |
1975年 | 3689篇 |
1974年 | 3642篇 |
1973年 | 3700篇 |
1972年 | 2619篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
171.
172.
Solid‐state 31P NMR investigation on the status of guanine nucleotides in paclitaxel‐stabilized microtubules
下载免费PDF全文
![点击此处可从《Magnetic resonance in chemistry : MRC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ga Hyang Lee Su Young Oh Kwon Joo Yeo Taslima Ferdous Meeyeon Cho Younkee Paik 《Magnetic resonance in chemistry : MRC》2015,53(5):330-336
Microtubule dynamics is a target for many chemotherapeutic drugs. In order to understand the biochemical effects of paclitaxel on the GTPase activity of tubulin, the status of guanine nucleotides in microtubules was investigated by 31P cross‐polarization magic angle spinning (CPMAS) NMR. Microtubules were freshly prepared in vitro in the presence of paclitaxel and then lyophilized in sucrose buffer for solid‐state NMR experiments. A 31P CPMAS NMR spectrum with the SNR of 25 was successfully acquired from the lyophilized microtubule sample. The broadness of the 31P spectral lines in the spectrum indicates that the molecular environments around the guanine nucleotides inside tubulin may not be as crystalline as reported by many diffraction studies. Deconvolution of the spectrum into four spectral components was carried out in comparison with the 31P NMR spectra obtained from five control samples. The spectral analysis suggested that about 13% of the nucleotides were present as GTP and 37% as GDP in the β‐tubulin (E‐site) of the microtubules. It was found that most of the GDPs were present as GDP‐Pi complex in the microtubules, which seems to be one of the effects of paclitaxel binding. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
173.
174.
175.
176.
177.
178.
Ieva
Dauickait Amos S. Lawless Jennifer A. Scott Peter Jan van Leeuwen 《Numerical Linear Algebra with Applications》2020,27(5)
We consider the large sparse symmetric linear systems of equations that arise in the solution of weak constraint four‐dimensional variational data assimilation, a method of high interest for numerical weather prediction. These systems can be written as saddle point systems with a 3 × 3 block structure but block eliminations can be performed to reduce them to saddle point systems with a 2 × 2 block structure, or further to symmetric positive definite systems. In this article, we analyse how sensitive the spectra of these matrices are to the number of observations of the underlying dynamical system. We also obtain bounds on the eigenvalues of the matrices. Numerical experiments are used to confirm the theoretical analysis and bounds. 相似文献
179.
180.
Gelikonov G. V. Ksenofontov S. Yu. Shilyagin P. A. Gelikonov V. M. 《Radiophysics and Quantum Electronics》2019,62(3):228-236
Radiophysics and Quantum Electronics - We propose and experimentally test a numerical method for correction of the influence of fluctuations in the distance to objects during noncontact probing in... 相似文献