全文获取类型
收费全文 | 571篇 |
免费 | 40篇 |
国内免费 | 5篇 |
专业分类
化学 | 499篇 |
晶体学 | 1篇 |
力学 | 6篇 |
数学 | 75篇 |
物理学 | 35篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 6篇 |
2021年 | 9篇 |
2020年 | 23篇 |
2019年 | 18篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 28篇 |
2015年 | 27篇 |
2014年 | 37篇 |
2013年 | 39篇 |
2012年 | 62篇 |
2011年 | 71篇 |
2010年 | 48篇 |
2009年 | 29篇 |
2008年 | 37篇 |
2007年 | 34篇 |
2006年 | 22篇 |
2005年 | 19篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 11篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 1篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1981年 | 6篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有616条查询结果,搜索用时 15 毫秒
51.
52.
53.
Ann Kathrin Stark Michael Schilling Dirk Janasek Joachim Franzke 《Analytical and bioanalytical chemistry》2010,397(5):1767-1772
A novel electrospray interface is presented which induces an electric field by dielectric polarization through a non-conductive
barrier. Therefore, a square-wave high-voltage signal is applied. This technique allows mass spectrometric measurements in
the positive as well as in the negative mass spectrometry mode without changing the polarity of the potential applied, and
it decreases the risk of undesired discharges, induced by high electric currents. The applicability of this technique is demonstrated
by mass spectrometric determination of reserpine. 相似文献
54.
55.
Kathrin Bringmann Holly Swisher 《Proceedings of the American Mathematical Society》2008,136(4):1501-1501
This note gives a correction to formula (A.18) of Appendix A.
56.
57.
FT-IR spectroscopy and SFM were used to investigate the growth of thin films of the organic semiconductor 3,4,9,10-perylenetetracarboxylicdianhydride (PTCDA) deposited by vacuum sublimation onto various substrates, i.e. Ag(111) layers on mica, KBr(100), mica, oxidized Si, and TiO2 nanoparticles on Si. Layer thicknesses of PTCDA varied from 10 to 1500 nm.The anhydride vibrations of PTCDA differ for the used substrates, which can be connected to the orientation of the molecules relative to the substrate surface and the film morphology as detected in the SFM pictures. 相似文献
58.
59.
We report an x-ray photoelectron spectroscopy study of the oxidation of Al(111) surfaces at room temperature, which reveals that the limiting thickness of an aluminum oxide film can be tuned by using oxygen pressure. This behavior is attributed to a strong dependence of the kinetic potential on the oxygen gas pressure. The coverage of oxygen anions on the surface of the oxide film depends on the gas pressure leading to a pressure dependence of the kinetic potential. Our results indicate that a significantly large oxygen pressure (>1 Torr) is required to develop the saturated surface coverage of oxygen ions, which results in the maximum kinetic potential and therefore the saturated limiting thickness of the oxide film. 相似文献
60.
Human movement, as for example human gait, can be considered as an optimal realization of some given task. However, the criterion for which the naturally performed human motion is optimal, is generally not known. In this article we formulate an inverse optimal control problem to study the relevance of four different optimization criteria in human locomotion. As a walking model we use an actuated three dimensional spring loaded inverted pendulum (3D-SLIP), which is able to mirror the typical shape of the center of mass trajectory in human gait. Using a direct all-at-once approach, the weighting of the optimization criteria and the position of the footsteps are optimized in such a way, that the center of mass trajectory of the resulting optimal state fits real motion capture data as good as possible. Numerical experiments show, that whereas the so called capture point seems to have a great impact on human walking, minimization of the vertical center of mass movement does not show any relevance at all. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献