全文获取类型
收费全文 | 319篇 |
免费 | 25篇 |
国内免费 | 8篇 |
专业分类
化学 | 209篇 |
晶体学 | 6篇 |
力学 | 21篇 |
数学 | 61篇 |
物理学 | 55篇 |
出版年
2023年 | 5篇 |
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 11篇 |
2015年 | 14篇 |
2014年 | 16篇 |
2013年 | 21篇 |
2012年 | 15篇 |
2011年 | 10篇 |
2010年 | 11篇 |
2009年 | 13篇 |
2008年 | 23篇 |
2007年 | 21篇 |
2006年 | 21篇 |
2005年 | 13篇 |
2004年 | 16篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 17篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1963年 | 1篇 |
1960年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有352条查询结果,搜索用时 406 毫秒
81.
Nonlinear Dynamics - Compared with regular-spiking (RS) neurons, the action potentials (APs) of fast-spiking (FS) neurons are characterized by narrow spike durations and unusually fast decay... 相似文献
82.
Xudong Hou Giang Truong Nguyen Tingting Xu Dr. Haipeng Wei Dr. Tun Seng Herng Dr. Guifei Huo Dr. Dingguan Wang Prof. Jun Ding Dr. Shaofei Wu Prof. Liviu Ungur Prof. Jishan Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(31):e202200687
The incorporation of organic radicals into coordination polymers was considered as a promising strategy to promote metal-ligand exchange interactions, but there are only a very limited number of stable organic radical-based ligands that can serve well such a purpose. Herein, we report two new tris(2,4,6-trichlorophenyl)methyl (TTM) radical-based ligands L1 and L2 with two and three imidazole substituents, respectively. The imidazole unit serves as a coordination site and it can also stabilize the TTM radical by intramolecular donor–acceptor interaction. Coordination of L1 and L2 with cobalt(II) ions gave the corresponding one- ( CoCP - 1 ) and two-dimensional ( CoCP - 2 ) coordination polymers, the structures of which were confirmed by X-ray crystallographic analysis. Magnetic measurements and theoretical calculations suggest antiferromagnetic coupling between the paramagnetic cobalt(II) ions and the radical ligands. Our study provides a rational design for stable organic radical-based ligands and further demonstrated the feasibility of a metal–radical approach toward magnetic materials. 相似文献
83.
Dr. Martin Valldor Dr. Bodo Böhme Dr. Yurii Prots Dr. Horst Borrmann Dr. Peter Adler Dr. Walter Schnelle Dr. Yves Watier Dr. Chang Yang Kuo Dr. Tun‐Wen Pi Dr. Zhiwei Hu Prof. Dr. Claudia Felser Prof. Dr. Liu Hao Tjeng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(13):4626-4631
The novel host–guest compound [Cs6Cl][Fe24Se26] (I4/mmm; a=11.0991(9), c=22.143(2) Å) was obtained by reacting Cs2Se, CsCl, Fe, and Se in closed ampoules. This is the first member of a family of compounds with unique Fe–Se topology, which consists of edge‐sharing, extended fused cubane [Fe8Se6Se8/3] blocks that host a guest complex ion, [Cs6Cl]5+. Thus Fe is tetrahedrally coordinated and divalent with strong exchange couplings, which results in an ordered antiferromagnetic state below TN=221 K. At low temperatures, a distribution of hyperfine fields in the Mössbauer spectra suggests a structural distortion or a complex spin structure. With its strong Fe–Se covalency, the compound is close to electronic itinerancy and is, therefore, prone to exhibit tunable properties. 相似文献
84.
Sang‐Byung Park Jung‐guk Ha Sei Kwang Hahn Wang‐Cheol Zin 《Journal of Polymer Science.Polymer Physics》2014,52(6):470-476
The phase behaviors of binary blends of poly(styrene‐b‐butadiene) block copolymers were investigated by a small‐angle X‐ray scattering technique. The blends were composed of weakly segregated one in a random micellar phase and the other in a cylindrical phase with similar molecular weights and complementary volume fractions. Morphologies, domain spacings, and order–disorder transition temperatures of the blends indicated that the junctions of the constituent block copolymers share the interface at low temperatures. The domain spacing decreased as temperature increased in a blend with a small amount of the weakly segregated block copolymer. In the cases of the blends with a large amount of the weakly segregated constituent, domain spacing increased with increasing temperature. These results implied that some of the weakly segregated block copolymer moved from the interface to one microdomain at higher temperatures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 470–476 相似文献
85.
We study two polyhedral lift-and-project operators (originally proposed by Lovász and Schrijver in 1991) applied to the fractional stable set polytopes. First, we provide characterizations of all valid inequalities generated by these operators. Then, we present some seven-node graphs on which the operator enforcing the symmetry of the matrix variable is strictly stronger on the odd-cycle polytope of these graphs than the operator without this symmetry requirement. This disproves a conjecture of Lipták and Tunçel from 2003. 相似文献
86.
Sessler JL Cho DG Stepień M Lynch V Waluk J Yoon ZS Kim D 《Journal of the American Chemical Society》2006,128(39):12640-12641
The synthesis of an inverted, methoxylated sapphyrin derivative is described. This system, wherein inversion of pyrrolic nitrogen atoms is configurationally enforced via the use of a 3,3'-bipyrrolic precursor, displays what is best described as "weak aromaticity" as judged from its spectroscopic features and supporting theoretical calculations. 相似文献
87.
88.
Ya Juan Xu Tun Hai Xu Jun Ying Yang Sheng Xu Xie Yue Liu Yun Shan Si Dong Ming Xu 《中国化学快报》2010,21(5):580-583
<正>Two new furostanol glycoside,26-O-β-D-glucopyranosyl-(25S)-5α-furost-3β,22α,26-triol-3-O-β-D-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)]-β-D-galactopyranoside(1) and 26-O-β-D-glucopyranosyl-(25S)-5α-furost-20(22)-en-2α,3β,26-triol-3-O-β-D-glucopyranosyl-(1→2)-O-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside(2) were isolated fromthe fruits of Tribulus terrestris L.The structures of two new furostanol saponins were elucidated by spectroscopic methods. 相似文献
89.
90.