全文获取类型
收费全文 | 2601篇 |
免费 | 54篇 |
国内免费 | 11篇 |
专业分类
化学 | 1565篇 |
晶体学 | 14篇 |
力学 | 84篇 |
数学 | 589篇 |
物理学 | 414篇 |
出版年
2021年 | 31篇 |
2020年 | 23篇 |
2019年 | 30篇 |
2016年 | 42篇 |
2015年 | 54篇 |
2014年 | 42篇 |
2013年 | 108篇 |
2012年 | 86篇 |
2011年 | 101篇 |
2010年 | 60篇 |
2009年 | 56篇 |
2008年 | 99篇 |
2007年 | 75篇 |
2006年 | 63篇 |
2005年 | 56篇 |
2004年 | 51篇 |
2003年 | 35篇 |
2002年 | 50篇 |
2001年 | 26篇 |
2000年 | 41篇 |
1999年 | 45篇 |
1998年 | 33篇 |
1997年 | 39篇 |
1996年 | 29篇 |
1995年 | 40篇 |
1994年 | 27篇 |
1993年 | 28篇 |
1992年 | 36篇 |
1991年 | 23篇 |
1990年 | 22篇 |
1989年 | 20篇 |
1988年 | 25篇 |
1987年 | 30篇 |
1986年 | 27篇 |
1985年 | 47篇 |
1984年 | 33篇 |
1983年 | 22篇 |
1982年 | 24篇 |
1981年 | 34篇 |
1980年 | 40篇 |
1979年 | 35篇 |
1978年 | 24篇 |
1977年 | 40篇 |
1976年 | 32篇 |
1975年 | 23篇 |
1974年 | 21篇 |
1971年 | 20篇 |
1967年 | 17篇 |
1933年 | 20篇 |
1930年 | 21篇 |
排序方式: 共有2666条查询结果,搜索用时 31 毫秒
1.
2.
3.
Kinetics and Catalysis - Boron and barium were employed as dopants for the VMgO system. The catalysts were characterized by ICP-OES, BET, IR, powder XRD, EDX, TPR-H2, TPD-NH3, XPS, and 51V MAS NMR.... 相似文献
4.
To investigate local ordering and segregation phenomenon in a Ni91Pt9-alloy after sputtering and annealing a 3D optical atom probe (OAP) has been used. The specimen tips have been prepared from polycrystalline samples. To sputter the samples a separate preparation chamber with a scannable Ar-sputter-gun is connected to the OAP vessel. When necessary, the sample can be electrically heated to induce segregation and cure the altered layer. After a heat treatment of a Ni91 at. %Pt 9 at.% specimen at 1100 K the surface of a (111)-oriented specimen is enriched in platinum by a factor of two in relation to the bulk. The phenomenon of short-range ordering has been investigated on the surface and in the subsurface volume. A 3D reconstruction of this annealed NiPt specimen shows regions with high concentration of platinum that gives an indication at short-range ordering. Uniform sputtering of the tip without a heat treatment induces a decisive depletion of Pt on the surface and the following subatomic layers. The atom-probe results of specimens in thermal equilibrium are in close agreement to further surface sensitive results obtained from Ion Scattering Spectroscopy (ISS) and Auger Electron Spectroscopy (AES). 相似文献
5.
We relate the Schramm–Loewner Evolution processes (SLE) to highest-weight representations of the Virasoro Algebra. The restriction properties of SLE that have been recently derived in [19] play a crucial role. In this setup, various considerations from conformal field theory can be interpreted and reformulated via SLE. This enables one to make a concrete link between the two-dimensional discrete critical systems from statistical physics and conformal field theory. To cite this article: R. Friedrich, W. Werner, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 947–952. 相似文献
6.
7.
Ohne Zusammenfassung 相似文献
8.
Christian J. -F. Dupraz Patrick Nickels Udo Beierlein Wendy U. Huynh Friedrich C. Simmel 《Superlattices and Microstructures》2003,33(5-6):369
This paper provides an overview of recent research developments in the field of nanoelectronics with organic materials such as carbon nanotubes and DNA-templated nanowires. Carbon nanotubes and gold electrodes are chemically functionalized in order to contact carbon nanotubes by self-assembly. The transport properties of these nanotubes are dominated by charging effects and display clear Coulomb blockade behaviour. A different approach towards nanoscale electronics is based on the molecular recognition properties of biomolecules such as DNA. As an example, DNA is stretched between electrodes using a molecular combing technique. A two-step metallization procedure leads to the formation of highly conductive gold nanowires. 相似文献
9.
Holger Poths Erik Wischerhoff Rudolf Zentel Axel Sch nfeld Guido Henn Friedrich Kremer 《Liquid crystals》1995,18(5):811-818
Two new ferroelectric oligosiloxanes, a cyclic tetramer and a twin, have been synthesized. By a comparative study with their corresponding monomer and side chain polysiloxanes, the influence of oligo- and polymerization on the liquid crystalline and ferroelectric properties have been investigated. Polymerization leads to a stabilization of LC phases through increase of the clearing temperatures and suppression of crystallization. Oligomerization also leads to mesophase broadening, but, due to the low degree of polymerization, the effect is inferior to the linear polysiloxanes. The low viscosity of the oligosiloxanes ensures response times in the microsecond region, thus being comparable with their monomer and conventional LMWFLCs. It is found that polymerization increases the spontaneous polarization Ps. This is attributed to the density increase after polymerization, enhancing the inter-mesogenic interactions. The collective and local dynamics of the OFLCs are influenced differently with respect to their molecular structures. Each oligomer is already a good model for its corresponding polymer concerning the soft mode dynamics. For the local β-relaxation a similar temperature dependence of the relaxation times τ for the cyclic tetramer and for the side chain polysiloxanes is observed. The long axial rotation of the twin, having a very efficient decoupling, is significantly faster, thus resembling the monomer. 相似文献
10.