全文获取类型
收费全文 | 2018篇 |
免费 | 33篇 |
国内免费 | 8篇 |
专业分类
化学 | 1306篇 |
晶体学 | 23篇 |
力学 | 21篇 |
数学 | 209篇 |
物理学 | 500篇 |
出版年
2020年 | 20篇 |
2019年 | 18篇 |
2018年 | 19篇 |
2017年 | 20篇 |
2016年 | 30篇 |
2015年 | 16篇 |
2014年 | 26篇 |
2013年 | 98篇 |
2012年 | 45篇 |
2011年 | 73篇 |
2010年 | 45篇 |
2009年 | 37篇 |
2008年 | 58篇 |
2007年 | 66篇 |
2006年 | 75篇 |
2005年 | 77篇 |
2004年 | 64篇 |
2003年 | 70篇 |
2002年 | 44篇 |
2001年 | 44篇 |
2000年 | 43篇 |
1999年 | 24篇 |
1998年 | 16篇 |
1997年 | 28篇 |
1996年 | 28篇 |
1995年 | 18篇 |
1994年 | 26篇 |
1993年 | 36篇 |
1991年 | 25篇 |
1990年 | 23篇 |
1989年 | 29篇 |
1988年 | 25篇 |
1987年 | 32篇 |
1986年 | 29篇 |
1985年 | 28篇 |
1984年 | 35篇 |
1983年 | 26篇 |
1982年 | 38篇 |
1981年 | 23篇 |
1980年 | 37篇 |
1979年 | 22篇 |
1978年 | 21篇 |
1977年 | 31篇 |
1976年 | 22篇 |
1975年 | 20篇 |
1974年 | 29篇 |
1973年 | 19篇 |
1972年 | 19篇 |
1970年 | 19篇 |
1966年 | 13篇 |
排序方式: 共有2059条查询结果,搜索用时 729 毫秒
11.
Silvia Vogel 《Annals of Operations Research》2006,142(1):269-282
The paper considers upper semicontinuous behavior in distribution of sequences of random closed sets. Semiconvergence in distribution
will be described via convergence in distribution of random variables with values in a suitable topological space. Convergence
statements for suitable functions of random sets are proved and the results are employed to derive stability statements for
random optimization problems where the objective function and the constraint set are approximated simultaneously.
The author is grateful to two anonymous referees for helpful suggestions. 相似文献
12.
13.
14.
15.
16.
In this article we focus on the multiplicities of resonances, ratios of resonant over non-resonant states and rescattering processes in heavy ion collisions. Therefore we utilize a hadron transport model (UrQMD v1.3). We find that rescattering of decay particles is of great importance when studying resonances in a hadronic medium. 相似文献
17.
We report on calculations of the electric field gradient at the site of the Al nucleus in the Si-H-Al complex in silicon. As a model for the surroundings of the complex we used a cluster consisting of 43 silicon and one aluminum atoms. The geometry of this cluster was fully optimized at the Hartree-Fock level. To discuss the dependence of our results on the level of theory, we studied a subcluster of four silicon and one aluminum atoms at the Hartree-Fock and CASSCF level. 相似文献
18.
Mixtures composed of amides and electrolytes exhibit interesting properties such as viscoelastic behaviour and a megavalue of the dielectric constant. In order to improve the dielectric properties, the authors are investigating a large number of molten mixtures of CF3COONa with different types of amides, including the ternary system sodium trifluoroacetate-chloroacetamide-acetamide. The experimental measurements showed that the ternary mixtures are thermally unstable. A yellow oily product is formed; this was purified and tested by means of IR and NMR techniques. The formula and the kinetic mechanism are proposed. 相似文献
19.
Urine transport is made from the kidney to the bladder through the ureter by isolated pockets called bolus. To determine the urine flow in a bolus, we use an adherence condition on the interface urine/wall. It gives us an infinite linear system verified by a set of parameters. An iterative and convergent algorithm allows us to solve this system and to determine analytically the components of the velocity vector in the bolus. To cite this article: A. Vogel et al., C. R. Mecanique 332 (2004). 相似文献
20.
Vitali Vogel Jean‐Franois Gohy Bas G. G. Lohmeijer Jacomina A. Van Den Broek Winfried Haase Ulrich S. Schubert Dieter Schubert 《Journal of polymer science. Part A, Polymer chemistry》2003,41(20):3159-3168
In aqueous solutions, amphiphilic block copolymers in which a polystyrene (PS) segment is connected to a poly(ethylene oxide) (PEO) block via a bis(2,2′:6′,2″‐ terpyridine ruthenium) complex can form micelles. Such micelles of the protomer type PS20‐[Ru]‐PEO70, according to the preparation procedure representing frozen micelles, were studied by sedimentation velocity and sedimentation equilibrium analysis in an analytical ultracentrifuge and by transmission electron microscopy, with different techniques applied for the sample preparation. The particles obtained were surprisingly multifarious in size. In ultracentrifugation experiments performed at relatively low salt concentrations, the distributions of the sedimentation coefficient s20,w showed a pronounced peak at 9.6 S and a broad, only partly separated second peak around 14 S. The molar mass of the particles at the peak was around 430,000 g/mol, corresponding to an aggregation number of approximately 85. The average hydrodynamic diameter of the particles in the peak fraction was approximately 13 nm. In electron micrographs of negatively stained samples, spheres of diameters between 10 and 25 nm were the most abundant particles, but larger ones with a wide size range were also visible. The latter particles apparently were composed of smaller ones. The data from both sedimentation analysis and electron microscopy showed that (1) the studied compound formed primary micelles of diameters around 20 nm and (2) the primary micelles had a tendency toward aggregation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3159–3168, 2003 相似文献