全文获取类型
收费全文 | 1089篇 |
免费 | 93篇 |
国内免费 | 4篇 |
专业分类
化学 | 903篇 |
晶体学 | 9篇 |
力学 | 7篇 |
数学 | 80篇 |
物理学 | 187篇 |
出版年
2023年 | 10篇 |
2022年 | 9篇 |
2021年 | 26篇 |
2020年 | 37篇 |
2019年 | 51篇 |
2018年 | 33篇 |
2017年 | 24篇 |
2016年 | 50篇 |
2015年 | 41篇 |
2014年 | 64篇 |
2013年 | 65篇 |
2012年 | 90篇 |
2011年 | 102篇 |
2010年 | 40篇 |
2009年 | 36篇 |
2008年 | 78篇 |
2007年 | 63篇 |
2006年 | 71篇 |
2005年 | 71篇 |
2004年 | 60篇 |
2003年 | 36篇 |
2002年 | 37篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 14篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1186条查询结果,搜索用时 218 毫秒
81.
82.
83.
Yoshida R Sakai T Ito S Yamaguchi T 《Journal of the American Chemical Society》2002,124(27):8095-8098
Self-oscillation of polymer chains in an aqueous solution has been achieved. The ruthenium catalyst for the Belousov-Zhabotinsky reaction was polymerized by using N-isopropylacrylamide and dissolved into the solution containing the BZ substrates. Periodical soluble-insoluble changes of the polymer chain were spontaneously induced by the BZ reaction. The conformational oscillations of the polymer were measured as the optical transmittance changes of the solution. This is the first report that rhythmical and reversible soluble-insoluble changes of polymer chains are realized under constant and homogeneous conditions. The transducing system from chemical energy of the BZ reaction to optical information has been constructed. 相似文献
84.
We report the results of in situ AFM measurements examining the phase transition of bilayers formed from the zwitterionic phospholipid, DMPC, 1,2-dimyristoyl-sn-glycero-3-phosphocholine, supported on mica. The images show that the fluid to gel phase transition process features substantial tearing of the bilayer due to the density change between the two phases. The gel to fluid transition is strongly affected by the resultant stress introduced into the gel phase, which changes the degree of cooperativity, the shape of developing fluid phase regions, and the course of the transition. 相似文献
85.
Doping transition metal cation is known to enhance the electronic conduction of solid electrolytes, however, the ionic conduction
can also be improved by those dopants. In this investigation, the oxide ion conductivity of LaGaO3 based oxide doped with transition metal cations such as Fe, Co, Ni, Mn, and Cu for the Ga site was studied. It was found
that doping Co or Fe is effective for enhancing the oxide ion conductivity. The improved oxide ion conductivity may be induced
by the improved mobility of oxide ion. Among examined transition metal cations, cobalt is the most adequate cation as a dopant
for the Ga site of LSGM. Considering the conductivity and the transport number, the optimized composition is found to be La0.8Sr0.2Ga0.8Mg0.115Co0.085O3. In this work, application of Co2+ doped LSGM as the electrolyte of internally reformed fuel cells was also investigated. Improvement in oxide ion conductivity
is effective for enhancing the power generation characteristics.
Paper presented at the 4th Euroconference on Solid State Ionics, Renvyle, Galway, Ireland, Sept. 13–19, 1997 相似文献
86.
We report the first experimental demonstration of an optical quantum controlled-NOT gate without any path interference, where the two interacting path interferometers of the original proposals have been replaced by three partially polarizing beam splitters with suitable polarization dependent transmittance and reflectance. The performance of the device is evaluated using a recently proposed method, by which the quantum process fidelity and the entanglement capability can be estimated from the 32 measurement results of two classical truth tables, significantly less than the 256 measurement results required for full quantum tomography. 相似文献
87.
We present a mode locking (ML) phenomenon of vortex matter observed around the peak effect regime of 2H-NbSe2 pure single crystals. The ML features allow us not only to trace how the shear rigidity of driven vortices persists on approaching the second critical field, but also to demonstrate a dynamic melting transition of driven vortices at a given velocity. We observe the velocity dependent melting signatures in the peak effect regime, which reveal a crossover between the disorder-induced transition at small velocity and the thermally induced transition at large velocity. This uncovers the relationship between the peak effect and the thermal melting. 相似文献
88.
Functional porous coordination polymers 总被引:18,自引:0,他引:18
The chemistry of the coordination polymers has in recent years advanced extensively, affording various architectures, which are constructed from a variety of molecular building blocks with different interactions between them. The next challenge is the chemical and physical functionalization of these architectures, through the porous properties of the frameworks. This review concentrates on three aspects of coordination polymers: 1). the use of crystal engineering to construct porous frameworks from connectors and linkers ("nanospace engineering"), 2). characterizing and cataloging the porous properties by functions for storage, exchange, separation, etc., and 3). the next generation of porous functions based on dynamic crystal transformations caused by guest molecules or physical stimuli. Our aim is to present the state of the art chemistry and physics of and in the micropores of porous coordination polymers. 相似文献
89.
90.
The synthesis, crystal structures, inclusion ability, and structural robustness of novel crystalline inclusion compounds of [Ni(SCN)2(isoH)2].xG (isoH = isonicotinic acid; G = aromatic guest) are described. The inclusion compounds are constructed by stacking identical 2D host layers that consist of SCN-, isoH, and Ni2+ with van der Waals contact separation. In the layer, two types of rectangular cavities (A-type and B-type) are formed, and the guests are included in the former cavity. The inclusion compounds were categorized into four stacking modes according to the difference in the stacking mode of the layers. A systematic investigation of the crystal structures of the 21 inclusion compounds clarified the close relationship between the molecular structure of the guest and the resultant stacking mode of the layers. 相似文献