全文获取类型
收费全文 | 73556篇 |
免费 | 2422篇 |
国内免费 | 62篇 |
专业分类
化学 | 45421篇 |
晶体学 | 540篇 |
力学 | 1349篇 |
综合类 | 1篇 |
数学 | 13203篇 |
物理学 | 15526篇 |
出版年
2023年 | 507篇 |
2022年 | 485篇 |
2021年 | 790篇 |
2020年 | 1042篇 |
2019年 | 1029篇 |
2018年 | 1491篇 |
2017年 | 1330篇 |
2016年 | 2578篇 |
2015年 | 2134篇 |
2014年 | 2161篇 |
2013年 | 4743篇 |
2012年 | 4590篇 |
2011年 | 4556篇 |
2010年 | 2961篇 |
2009年 | 2474篇 |
2008年 | 4011篇 |
2007年 | 3791篇 |
2006年 | 3417篇 |
2005年 | 3228篇 |
2004年 | 2753篇 |
2003年 | 2194篇 |
2002年 | 1958篇 |
2001年 | 1494篇 |
2000年 | 1446篇 |
1999年 | 1027篇 |
1998年 | 800篇 |
1997年 | 668篇 |
1996年 | 907篇 |
1995年 | 660篇 |
1994年 | 732篇 |
1993年 | 715篇 |
1992年 | 700篇 |
1991年 | 574篇 |
1990年 | 607篇 |
1989年 | 507篇 |
1988年 | 501篇 |
1987年 | 462篇 |
1986年 | 450篇 |
1985年 | 633篇 |
1984年 | 598篇 |
1983年 | 467篇 |
1982年 | 449篇 |
1981年 | 454篇 |
1980年 | 392篇 |
1979年 | 399篇 |
1978年 | 400篇 |
1977年 | 399篇 |
1976年 | 408篇 |
1974年 | 364篇 |
1973年 | 364篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
The capability of gated saturable absorbers for single-pulse selection is studied theoretically using the classical space-time-dependent rate-equation model. The dynamics of operation is followed experimentally by the well-known pump—probe technique. Comparing the theoretical and experimental results, it is found that gated saturable absorbers can efficiently be used for pulse forming and pulse selection of pulses longer than picosecond. 相似文献
32.
33.
34.
Balázs Szendröi 《Mathematische Zeitschrift》2002,240(2):233-241
This note shows that a certain toric quotient of the quintic Calabi-Yau threefold in provides a counterexample to a recent conjecture of Cox and Katz concerning nef cones of toric hypersurfaces.
Received: 8 February 2001; in final form: 17 September 2001 / Published online: 1 February 2002 相似文献
35.
36.
Lubomír Kubáček 《Applications of Mathematics》2006,51(6):565-582
Some remarks to problems of point and interval estimation, testing and problems of outliers are presented in the case of multivariate
regression model.
This work was supported by the Council of Czech Government J14/98:153100011. 相似文献
37.
Ricardo Celorrio Vı́ctor Domínguez Francisco-Javier Sayas 《Comptes Rendus Mathematique》2002,334(10):923-926
In this work we study the solution of Laplace's equation in a domain with holes by an iteration consisting of splitting the problem in an exterior one, around the holes, plus an interior problem in the unholed domain. We show the existence of a decomposition of the solution when the exterior problem is represented by means of a single-layer protential. Also, for the three-dimensional case and with some adjustments for the two-dimensional case, we prove convergence of the method by writing the iteration as a Jacobi iteration for an operator equation and studying the spectrum of the iteration operator. To cite this article: R. Celorrio et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 923–926. 相似文献
38.
Possible Loss and Recovery of Gibbsianness¶During the Stochastic Evolution of Gibbs Measures 总被引:1,自引:1,他引:0
A.C.D. van Enter R. Fernández F. den Hollander F. Redig 《Communications in Mathematical Physics》2002,226(1):101-130
We consider Ising-spin systems starting from an initial Gibbs measure ν and evolving under a spin-flip dynamics towards a
reversible Gibbs measure μ≠ν. Both ν and μ are assumed to have a translation-invariant finite-range interaction. We study
the Gibbsian character of the measure νS(t) at time t and show the following:
(1) For all ν and μ, νS(t) is Gibbs for small t.
(2) If both ν and μ have a high or infinite temperature, then νS(t) is Gibbs for all t > 0.
(3) If ν has a low non-zero temperature and a zero magnetic field and μ has a high or infinite temperature, then νS(t) is Gibbs for small t and non-Gibbs for large t.
(4) If ν has a low non-zero temperature and a non-zero magnetic field and μ has a high or infinite temperature, then νS(t) is Gibbs for small t, non-Gibbs for intermediate t, and Gibbs for large t.
The regime where μ has a low or zero temperature and t is not small remains open. This regime presumably allows for many different scenarios.
Received: 26 April 2001 / Accepted: 10 October 2001 相似文献
39.
Lithium (10–150 ng ml?1) in wine is determined by atomic absorption spectrometry by direct nebulization and after digestion with mixed acids. The results of methods are similar. Thirty-four wines from various Spanish provinces are analysed. 相似文献
40.
Capillary Electrophoresis Chiral Separation for Enantiomeric Purity Determination of a Basic Drug in Pharmaceutical Formulations 总被引:1,自引:0,他引:1
Capillary electrophoresis using a running buffer composed of β-cyclodextrin as the chiral selector and ethanolamine mesylate at pH 9.6 is being used to monitor the stereochemical stability of a hydrophobic drug, containing two chiral centers, in two different formulated self-emulsifying drug delivery system (SEDDS) products. The separation takes place in less than 25 min. Strategies for enhancing the method reproducibility and detection sensitivity in the lower potency formulation are presented. The results demonstrating the specificity, assay precision, recovery, linearity and range achieved during the method validation experiments are presented in this paper.Presented at: CE in the Biotechnology and Pharmaceutical Industries: 7th Symposium on the Practical Applications for the Analysis of Proteins, Nucleotides and Small Molecules, Montreal, Canada, August 12–16, 2005. 相似文献