全文获取类型
收费全文 | 561篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
化学 | 271篇 |
晶体学 | 1篇 |
力学 | 19篇 |
数学 | 146篇 |
物理学 | 130篇 |
出版年
2022年 | 7篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 23篇 |
2015年 | 7篇 |
2014年 | 11篇 |
2013年 | 17篇 |
2012年 | 20篇 |
2011年 | 21篇 |
2010年 | 14篇 |
2009年 | 16篇 |
2008年 | 20篇 |
2007年 | 20篇 |
2006年 | 30篇 |
2005年 | 22篇 |
2004年 | 28篇 |
2003年 | 25篇 |
2002年 | 16篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 12篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1985年 | 4篇 |
1983年 | 4篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1969年 | 4篇 |
1934年 | 4篇 |
1915年 | 5篇 |
1914年 | 3篇 |
1910年 | 3篇 |
1906年 | 3篇 |
1905年 | 3篇 |
1893年 | 3篇 |
1891年 | 3篇 |
1880年 | 3篇 |
排序方式: 共有567条查询结果,搜索用时 109 毫秒
561.
Bimetallic clusters display new characteristics that could not be obtained by varying either the size of pure metallic systems or the composition of bulk bimetals alone. Coating of pre-deposited clusters by vapour deposition is a typical synthesis process of bimetallic clusters. Here, we have demonstrated that hierarchical, gold cluster-decorated copper clusters as well as both heterogeneous and homogeneous Cu?CAu bimetallic clusters (4.6 to 10.7?nm) can be prepared by coating pre-deposited, size-selected Cu5000 (4.6?±?0.2?nm) with Au evaporation at various temperatures. These bimetallic clusters were analyzed by aberration-corrected scanning transmission electron microscopy and associated electron energy loss spectroscopy. The results indicate that the growth of bimetallic clusters is controlled by a competition between nucleation and diffusion of the coating Au atoms. 相似文献
562.
In this paper, we consider some well-known equilibrium problems and their duals in a topological Hausdorff vector space X for a bifunction F defined on K x K,where K is a convex subset of X. Some necessary conditions are investigated, proving different results depending on the behaviour of F on the diagonal set. The concept of proper quasimonotonicity for bifunctions is defined, and the relationship with generalized monotonicity is investigated. The main result proves that the condition of proper quasimonotonicity is sharp in order to solve the dual equilibrium problem on every convex set. 相似文献
563.
Desferrioxamine (DFO) is the current “gold standard” chelator for 89Zr4+, which is used to label monoclonal antibodies for applications in immunopositron emission tomography. Recently, controversial data have been reported regarding the speciation and the stability of the complexes formed by DFO with Zr4+ in solution. To shed some light on this point, we studied the coordination properties in solution ofa chromophoric DFO derivative bearing a substituted pyrimidine residue (DFO–Pm) toward several metal ions (Zr4+, Cu2+, Zn2+, Mg2+, Ca2+, Na+, K+). Potentiometric titrations showed that DFO–Pm and pristine DFO form complexes with very similar stoichiometry and stability. DFO–Pm, which can consequently be taken as a model system for DFO, provides a photochemical response to metal coordination that can be used to further define the complexes formed. In the critical case of Zr4+, spectrophotometric measurements allowed the verification of the formation of 1:1 and 2:3 complexes that, together with 2:2 complexes form the coordination model that was obtained through the use of our potentiometric measurements. Additionally, mass spectrometry measurements verified the formation of 1:1 and 2:3 complexes and showed that 1:2 species can be easily generated through the fragmentation of the 2:3 species. In conclusion, the results obtained with DFO–Pm validate the complexation model of Zr4+/DFO composed of 1:1, 2:2, and 2:3 metal-to-ligand complexes. Convergences and conflicts with other works are addressed. 相似文献
564.
Sono-photocatalytic degradation of 2-chlorophenol in water: kinetic and energetic comparison with other techniques. 总被引:16,自引:0,他引:16
The degradation of 2-chlorophenol in water was kinetically investigated using the following different techniques, employed either separately or simultaneously, always with the same experimental set-up: light irradiation (315-400 nm), sonication, photocatalysis with different types of TiO2, photocatalysis with sonication. The influence of the reaction volume and of different gas mixtures, containing Ar and O2, as well as O2/O3, was also investigated. Finally, an energetic comparison among these different techniques was performed, focused on an industrial application of some of them. 相似文献
565.
566.
γ-Al2O3 samples, both pure and Cr doped, were prepared by heating at 470°C sol–gel precursors obtained by using aluminum tri-sec-butoxide [Al(OC4H9)3] as the starting compound. The samples were characterised for phase composition (X-ray diffraction) and surface area (BET). Electrochemical determinations of the double layer reactivity of the pure and doped oxides were performed both by surface charge and by electrokinetic sonic amplitude (ESA) determinations. The interfacial electrostatic response is discussed and analysed also with reference to the sample surface state obtained by X-ray photoelectron spectroscopy (XPS). 相似文献
567.