全文获取类型
收费全文 | 7147篇 |
免费 | 196篇 |
国内免费 | 4篇 |
专业分类
化学 | 4587篇 |
晶体学 | 39篇 |
力学 | 232篇 |
数学 | 873篇 |
物理学 | 1616篇 |
出版年
2022年 | 46篇 |
2021年 | 59篇 |
2020年 | 84篇 |
2019年 | 83篇 |
2018年 | 107篇 |
2017年 | 72篇 |
2016年 | 146篇 |
2015年 | 191篇 |
2014年 | 170篇 |
2013年 | 378篇 |
2012年 | 436篇 |
2011年 | 437篇 |
2010年 | 283篇 |
2009年 | 197篇 |
2008年 | 428篇 |
2007年 | 383篇 |
2006年 | 372篇 |
2005年 | 353篇 |
2004年 | 324篇 |
2003年 | 294篇 |
2002年 | 231篇 |
2001年 | 149篇 |
2000年 | 165篇 |
1999年 | 82篇 |
1998年 | 104篇 |
1997年 | 77篇 |
1996年 | 103篇 |
1995年 | 53篇 |
1994年 | 69篇 |
1993年 | 68篇 |
1992年 | 69篇 |
1991年 | 42篇 |
1990年 | 50篇 |
1989年 | 43篇 |
1988年 | 50篇 |
1987年 | 32篇 |
1986年 | 40篇 |
1985年 | 73篇 |
1984年 | 79篇 |
1983年 | 46篇 |
1982年 | 45篇 |
1981年 | 63篇 |
1980年 | 62篇 |
1979年 | 50篇 |
1978年 | 55篇 |
1977年 | 50篇 |
1976年 | 69篇 |
1975年 | 41篇 |
1974年 | 34篇 |
1973年 | 37篇 |
排序方式: 共有7347条查询结果,搜索用时 31 毫秒
41.
Hermann Grabert Gert-Ludwig Ingold Michel H. Devoret Daniel Estève Hugues Pothier Cristian Urbina 《Zeitschrift für Physik B Condensed Matter》1991,84(1):143-155
The rate of electron tunneling through normal metal tunnel junctions is calculated for the case of ultrasmall junction capacitances. The so-called Coulomb blockade of electron tunneling at low temperatures is shown to be strongly affected by the external electrical circuit. Under the common experimental condition of a low impedance environment the Coulomb blockade is suppressed for single tunnel junctions. However, a Coulomb gap structure emerges for junctions embedded in a high impedance environment. For a double junction setup a Coulomb blockade of tunneling arises even for low impedance environments due to the charge quantization on the metallic island between the junctions. An approach using circuit analysis is presented which allows to reduce the calculation of tunneling rates in multijunction circuits to those of a single junction in series with an effective capacitance. The range of validity of the socalled local rule and global rule rates is clarified. It is found that the tunneling rate tends towards the global rule rate as the number of junctions is increased. Some specific results are given for a one-dimensional array of tunnel junctions. 相似文献
42.
G. Meillère 《Analytical and bioanalytical chemistry》1899,38(9-10):674-675
43.
44.
Quantization consists in studying the L
r
-error induced by the approximation of a random vector X by a vector (quantized version) taking a finite number n of values. We investigate this problem for Gaussian random vectors in an infinite dimensional Banach space and in particular, for Gaussian processes. A precise link proved by Fehringer(4) and Dereich et al.
(3) relates lower and upper bounds for small ball probabilities with upper and lower bounds for the quantization error, respectively. We establish a complete relationship by showing that the same holds for the direction from the quantization error to small ball probabilities. This allows us to compute the exact rate of convergence to zero of the minimal L
r
-quantization error from logarithmic small ball asymptotics and vice versa. 相似文献
45.
46.
47.
E. Manova C. Estournès D. Paneva J.-L. Rehspringer T. Tsoncheva B. Kunev I. Mitov 《Hyperfine Interactions》2005,165(1-4):215-220
Iron–nickel spinel oxide NiFe2O4 nanoparticles have been prepared by the combination of chemical precipitation and subsequent mechanical milling. For comparison, their analogue obtained by thermal synthesis is also studied. Phase composition and structural properties of iron–nickel oxides are investigated by X-ray diffraction and Mössbauer spectroscopy. Their catalytic behavior in methanol decomposition to CO and methane is tested. An influence of the preparation method on the reduction and catalytic properties of iron–nickel samples is established. 相似文献
48.
49.
50.
Philippe Boyer Gilles Renversez Evgeny Popov Michel Nevière 《Optical and Quantum Electronics》2006,38(1-3):217-230
The present work adapts a recent grating theory called “Fast Fourier factorization” to cylindrical coordinates in order to study microstructured optical fibers (MOFs). Compared with the classical differential method, this new differential method takes into account the truncation of Fourier series and the discontinuities of the fields across the diffracting surface with the help of new factorization rules. The main advantage of this method is that the directrix of the diffracting cylindrical surface is arbitrary and permits anisotropic and inhomogeneous media although its numerical application needs longer computation time, compared with other well-known numerical methods. The S-propagation algorithm is used to avoid numerical contaminations. The numerical results are validated and compared with the well-established Multipole method in the case of a MOF with six circular cylinders. Further, a new cross-sectional profile (with sectorial inclusions) that the Multipole method cannot consider is studied. 相似文献