全文获取类型
收费全文 | 6389篇 |
免费 | 774篇 |
国内免费 | 780篇 |
专业分类
化学 | 3061篇 |
晶体学 | 51篇 |
力学 | 334篇 |
综合类 | 736篇 |
数学 | 1446篇 |
物理学 | 2315篇 |
出版年
2024年 | 9篇 |
2023年 | 148篇 |
2022年 | 236篇 |
2021年 | 256篇 |
2020年 | 296篇 |
2019年 | 267篇 |
2018年 | 275篇 |
2017年 | 295篇 |
2016年 | 307篇 |
2015年 | 333篇 |
2014年 | 537篇 |
2013年 | 642篇 |
2012年 | 685篇 |
2011年 | 560篇 |
2010年 | 468篇 |
2009年 | 460篇 |
2008年 | 280篇 |
2007年 | 369篇 |
2006年 | 375篇 |
2005年 | 194篇 |
2004年 | 95篇 |
2003年 | 83篇 |
2002年 | 82篇 |
2001年 | 113篇 |
2000年 | 86篇 |
1999年 | 102篇 |
1998年 | 79篇 |
1997年 | 59篇 |
1996年 | 43篇 |
1995年 | 40篇 |
1994年 | 30篇 |
1993年 | 18篇 |
1992年 | 24篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 19篇 |
1988年 | 47篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有7943条查询结果,搜索用时 15 毫秒
111.
Compound [Zn(phen)3][BDA] (1) (BDA=6,6′-dibromo-2,2′-dimethoxy-1,1′-binaphthylene-4,4′-disulfonate, phen= 1,10-phenanthroline) composes of the anion part (racemic-(R,S)-6,6′-dibromo-2,2′-dimethoxy-1,1′-binaphthylene-4,4′-disulfonate ) and the cation part which consists of a racemic octahedrally coordinated zinc center defined six nitrogen atoms from three phen rings to form an inorganic chirality that can be resolution by chiral organic ligand, the 3D framework was formed through the strong H-bonding interaction between sulfonate and water. CCDC: 277924. 相似文献
112.
《Electrochemistry communications》2007,9(10):2457-2462
The structure and characteristic of carbon nanotubes-ionic liquid gel biosensor were studied by voltammetry, microscopy and spectroscopy. Various biomolecules were electrochemically detected with this gel biosensor such as glucose oxidase and NADH. The excellent electrochemical behavior of this gel biosensor might be due to the following three main factors: (1) the inherently perfect electrochemical characteristic of multi-wall carbon nanotubes (MWNTs); (2) the better solvent effect and conductivity of ionic liquid as well as the proper interactions between MWNTs and ionic liquid; (3) the proper mixing ratio of MWNTs to ionic liquid. Meanwhile, the interactions between MWNTs and ionic liquid were carefully studied as well. It can be concluded that the non-covalent (π–π) interaction between the imidazole loop of ionic liquid and MWNTs side wall should play an important role. This work gives a further understanding of what results in the high sensitivity and selectivity of such a biosensor to some biomolecules, and provides a simple and easy approach to design new biosensors with various nano-particles and versatile ionic liquid. 相似文献
113.
《Fluid Phase Equilibria》2005,227(2):267-274
A stability analysis of a widely used model of the Gibbs energy of fluid mixtures is presented. In that model, the solutes and the solvent are treated differently (asymmetric normalization). For the solutes, an infinitely dilute reference state is used, the ideal solution is defined using molalities, and a virial expansion in molalities is used for describing the Gibbs excess energy GE. That model is identical with the well-known Pitzer model if only uncharged molecular species are present. An unusual stability behavior of that model is observed. Instability is predicted for a wide range of concentrations in an important range of model parameters. Despite this, for principal reasons, that model does not allow determining the concentrations in coexisting phases in a physically meaningful way. For example, for binary systems it always predicts that only the pure components are globally stable. To illustrate those findings, the system hydrogen sulfide–water is discussed, for which the Pitzer model is often used in practice. For comparison with the Pitzer model the well-known Margules GE-model is used that shows no unexpected stability behavior. Conversion rules are presented that allow finding parameters for the well-behaved Margules model from those of the Pitzer model. The application is again demonstrated using the system hydrogen sulfide–water. 相似文献
114.
《Fluid Phase Equilibria》2006,239(2):133-137
Vapour–liquid equilibria at atmospheric pressure have been determined for binary mixtures of 1,2-dibromoethane + 1,2-dichloroethane, +trichloromethane, and +1,1,2,2-tetrachloroethane. These have been shown to be thermodynamically consistent. 相似文献
115.
116.
117.
118.
A Novel Carbon Nanotube-Supported NiP Amorphous Alloy Catalyst and Its Hydrogenation Activity 下载免费PDF全文
Yan Ju Fengyi Li 《天然气化学杂志》2006,15(4):313-318
A carbon nanotube-supported NiP amorphous catalyst (NiP/CNT) was prepared by induced reduction. Benzene hydrogenation was used as a probe reaction for the study of catalytic activity. The effects of the support on the activity and thermal stability of the supported catalyst were discussed based on various characterizations, including XRD, TEM, ICP, XPS, H2-TPD, and DTA. In comparison with the NiP amorphous alloy, the benzene conversion on NiP/CNT catalyst was lower, but the specific activity of NiP/CNT was higher, which is attributed to the dispersion produced by the support, an electron-donating effect, and the hydrogen-storage ability of CNT. The NiP/CNT thermal stability was improved because of the dispersion and electronic effects and the good heat-conduction ability of the CNT support. 相似文献
119.
Summary Mesoporous TiO2-CeO2mixed oxides (m-TiO2-CeO2) were synthesized under easy-operating neutral conditions. The structure was characterized by means of FT-IR, XRD, and N2adsorption methods. For methanol decomposition to CO and H2, the catalytic activity of the Ru/ m-TiO2-CeO2 catalyst was higher than that of the Ru/ m-TiO2.</o:p> 相似文献
120.