全文获取类型
收费全文 | 559篇 |
免费 | 9篇 |
专业分类
化学 | 382篇 |
晶体学 | 6篇 |
力学 | 11篇 |
数学 | 35篇 |
物理学 | 134篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 4篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 17篇 |
2015年 | 7篇 |
2014年 | 13篇 |
2013年 | 21篇 |
2012年 | 20篇 |
2011年 | 29篇 |
2010年 | 16篇 |
2009年 | 17篇 |
2008年 | 33篇 |
2007年 | 29篇 |
2006年 | 42篇 |
2005年 | 40篇 |
2004年 | 21篇 |
2003年 | 23篇 |
2002年 | 20篇 |
2001年 | 16篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 10篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 5篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1971年 | 3篇 |
1969年 | 3篇 |
1967年 | 2篇 |
1958年 | 2篇 |
1956年 | 2篇 |
排序方式: 共有568条查询结果,搜索用时 15 毫秒
1.
2.
3.
Holographic interferometry is proposed to detect the change in the mechanical responses of reed stems growing in eutrophic, as compared with those in healthy, water bodies. The detection of the difference in behaviour could be a sensitive way to index the degree of eutrophication. An interferometric method based on holomicroscopic moiré is developed and preliminary results obtained are presented. 相似文献
4.
We present a theoretical analysis of corrugated long-period gratings in planar waveguides. In particular, we calculate the transmission spectra for both the TE and TM polarizations and highlight the polarization-independence conditions. 相似文献
5.
R. M. Sawant R. K. Rastogi N. K. Chaudhuri 《Journal of Radioanalytical and Nuclear Chemistry》1998,238(1-2):203-206
The paper presents a radiokinetic study on the appearance and growth of*Fe2S3,*Fe(OH)3,*Fe2(C2O4)3,*Fe(IO3)3 crystals in a colloidal medium of agar and gelatine. The values of the diffusion constants through gels of55+59Fe3+ radioactive cations and of the rate of global growth process of these crystals in agar or gelatine were calculated using
the experimental data. A new method for the determination of the starting time for the complex nucleation process was proposed.
The formation rate of crystals under study decreases in the order:*Fe(OH)3>*Fe(IO3)3>*Fe2S3>*Fe2(C2O4)3, in agar medium and*Fe(OH)3>*Fe(IO3)3>*FeC2O4)3>*FeS3, in gelatine medium. 相似文献
6.
High-frequency sinusoidal oscillations of a coarse-grained polymer model are used to calculate the local dynamic mechanical properties (DMPs) of free-standing polymer thin films. The storage modulus G(') and loss modulus G(") are examined as a function of position normal to the free surfaces. It is found that mechanically soft layers arise near the free surfaces of glassy thin films, and that their thickness becomes comparable to the entire film thickness as the temperature approaches the glass transition T(g). As a result, the overall stiffness of glassy thin films decreases with film thickness. It is also shown that two regions coexist in thin films just at the bulk T(g); a melt-like region (G(')G(")) in the middle of the film. Our findings on the existence of a heterogeneous distribution of DMPs in free-standing polymer thin films provide insights into recent experimental measurements of the mechanical properties of glassy polymer thin films. 相似文献
7.
R. P. Rastogi Kehar Singh Ram Shabd B. M. Upadhyay 《Journal of colloid and interface science》1981,80(2):402-411
Electrical properties of cholesterol interfaces have been investigated. For this purpose electroosmotic and hydrodynamic permeation of water, sodium chloride, barium chloride, aluminum chloride, and urea solutions across a cholesterol plug have been investigated. Dependence of electroosmotic permeability on concentration of electrolytes has also been studied. Electrophoretic mobility of cholesterol particles of known size distribution and dispersed in solutions of varying concentrations of electrolytes and urea has also been studied. The data have been used to estimate ζ potentials in order to have a plausible picture of the electrical double layer at the cholesterol/ solution interfaces. 相似文献
8.
Subphase conditions have been optimized to obtain stable organophosphorous hydrolase (OPH-EC 3.1.8.1) as Langmuir films. The Langmuir film was characterized by surface pressure and surface potential-area isotherms and UV-Vis spectroscopy in situ. The interaction of an organophosphorous compound, namely Paraoxon, with the OPH film was investigated for various surface pressures. The stability of the monolayer and the evidence of the enzyme activity at air-water interface support the use of enzyme LB films as biosensor. 相似文献
9.
An interesting transformation during the oxidation of 3,4-epoxy alcohols 1a-d, derived from the corresponding homoallylic alcohols, led to the formation of 4-hydroxy-2,3-unsaturated carbonyls 2a-d in very good yields. One of these products 2c was transformed into the functionalised carboxylic acid 5, an advanced stage intermediate from which the total synthesis of macrosphelide A has been reported. 相似文献
10.
Dimers of the pyrrole amino acid (Paa), 5-(aminomethyl)pyrrole-2-carboxylic acid, and its derivatives having Lys anchored on N- and C-termini bind in the minor groove of DNA with considerable apparent binding affinities. When the Lys unit is attached to the C-terminus, the resulting ligand binds to ds-DNA with twice the affinity, of the order of 105, than the one carrying two positive charges at the same end. 相似文献