全文获取类型
收费全文 | 254篇 |
免费 | 4篇 |
专业分类
化学 | 153篇 |
晶体学 | 2篇 |
力学 | 7篇 |
数学 | 13篇 |
物理学 | 83篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 22篇 |
2021年 | 16篇 |
2020年 | 9篇 |
2019年 | 12篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 24篇 |
2012年 | 10篇 |
2011年 | 14篇 |
2010年 | 9篇 |
2009年 | 15篇 |
2008年 | 16篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2005年 | 14篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1950年 | 2篇 |
排序方式: 共有258条查询结果,搜索用时 0 毫秒
21.
22.
Hofmann CC Lindner SM Ruppert M Hirsch A Haque SA Thelakkat M Köhler J 《Physical chemistry chemical physics : PCCP》2010,12(43):14485-14491
A flexible organic triad consisting of two perylene bisimide antennas covalently linked to a [60]fullerene by flexible spacers has been synthesized and studied by electrochemistry, steady-state and time-resolved spectroscopy. We found that π-π-stacking of the two antenna subunits has considerable impact on the photophysics of the system and leads to a reduction of the effective light-harvesting efficiency of the assembly. This finding is important for light harvesting in flexible materials based on the dye antenna-fullerene concept. 相似文献
23.
24.
Recently we have proposed a phenomenological approach in terms of two coexisting macroscopic order parameters corresponding
to the superconducting and insulating states and have discussed the electrodynamical responses of the superconducting ceramics.
In this paper we discuss the fluctuations of the order parameters both in static and dynamical situations in the mean field
approach and obtain results for the electrical conductivity which possesses anomalies as in granular materials. 相似文献
25.
Wei Zhang Muhammad W. Saif Ginger E. Dutschman Xin Li Wing Lam Scott Bussom Zaoli Jiang Min Ye Edward Chu Yung-Chi Cheng 《Journal of chromatography. A》2010,1217(37):5785-5793
Traditional Chinese Medicine (TCM) is increasingly being used in combination with Western medicine. In general, TCM is comprised of multiple components in sharp contrast to Western medicine, where a single active chemical is used. Presently, there are no well-established standards for most of the chemical compounds of TCM and their respective metabolites. Moreover, there are no formal analytical methods for the identification of these chemicals, especially in trace amounts. The ability to measure the pharmacokinetic behaviors of chemicals and their metabolites from these herbal formulations are critical in understanding of the action of TCM. This paper describes the use of LC/MS/MS along with enzyme treatments and n-octanol/water partition coefficient, to investigate the chemical components of PHY906 and their metabolites in the plasma of a patient with metastatic colorectal cancer (mCRC) treated with irinotecan and PHY906. The chemicals from an aqueous extract of PHY906 and the plasma from a patient was prepared and separated on an Agilent ZORBAX-SB C18 column, and eluted with acetonitrile/0.05% (v/v) formic acid. From the PHY906 aqueous extract, a total of 57 compounds and 27 metabolites were identified and tentatively assigned structures based on their identified mass spectrometry, enzyme digestion and n-octanol/water partition coefficient. In contrast, analysis of patient plasma identified only 33 chemicals and new metabolites. These findings demonstrated that LC/MS/MS was and effective and reliable method for studying the parent chemicals of the Chinese herbal medicine PHY906 and their metabolites in a patient with metastatic colorectal cancer. 相似文献
26.
Park J Lee G Wolff-Fabris F Koh YY Eom MJ Kim YK Farhan MA Jo YJ Kim C Shim JH Kim JS 《Physical review letters》2011,107(12):126402
We report the observation of highly anisotropic Dirac fermions in a Bi square net of SrMnBi(2), based on a first-principles calculation, angle-resolved photoemission spectroscopy, and quantum oscillations for high-quality single crystals. We found that the Dirac dispersion is generally induced in the (SrBi)(+) layer containing a double-sized Bi square net. In contrast to the commonly observed isotropic Dirac cone, the Dirac cone in SrMnBi(2) is highly anisotropic with a large momentum-dependent disparity of Fermi velocities of ~8. These findings demonstrate that a Bi square net, a common building block of various layered pnictides, provides a new platform that hosts highly anisotropic Dirac fermions. 相似文献
27.
We prove an invariant Harnack’s inequality for operators in non-divergence form structured on Heisenberg vector fields when the coe?cient matrix is uniformly positive definite, continuous, and symplectic. The method consists in constructing appropriate barriers to obtain pointwise-to-measure estimates for supersolutions in small balls, and then invoking the axiomatic approach developed by Di Fazio, Gutiérrez, and Lanconelli to obtain Harnack’s inequality. 相似文献
28.
An observer for a class of disturbance driven nonlinear systems 总被引:2,自引:0,他引:2
An observer design for a class of nonlinear systems driven by disturbances or uncertainties is presented. The design is based on a high gain strategy, and the gain of the proposed observer is explicitly given. 相似文献
29.
30.
The recurrence tracking microscope for probing nanostructures on a surface is based on the quantum recurrence phenomenon. We report that condensed atoms bouncing off on the atomic mirror, connected to a cantilever, modify the quantum recurrences. The times at which the recurrences occur depend on the initial energy of the bouncing condensates above the atomic mirror, which change with the density of condensed atoms. 相似文献