全文获取类型
收费全文 | 760篇 |
免费 | 48篇 |
专业分类
化学 | 688篇 |
晶体学 | 3篇 |
力学 | 18篇 |
数学 | 52篇 |
物理学 | 47篇 |
出版年
2023年 | 7篇 |
2022年 | 14篇 |
2021年 | 22篇 |
2020年 | 17篇 |
2019年 | 20篇 |
2018年 | 18篇 |
2017年 | 14篇 |
2016年 | 23篇 |
2015年 | 27篇 |
2014年 | 31篇 |
2013年 | 37篇 |
2012年 | 71篇 |
2011年 | 64篇 |
2010年 | 46篇 |
2009年 | 34篇 |
2008年 | 68篇 |
2007年 | 45篇 |
2006年 | 45篇 |
2005年 | 41篇 |
2004年 | 35篇 |
2003年 | 20篇 |
2002年 | 27篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 10篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1991年 | 7篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有808条查询结果,搜索用时 15 毫秒
51.
Adnan Zahirović Marina Cindrić Sandra Kraljević Pavelić Mirsada Hukić Anja Harej 《Journal of Coordination Chemistry》2017,70(24):4030-4053
Heteroleptic ruthenium(II) bioflavonoid complexes of quercetin, morin, chrysin, and 3-hydroxyflavone were prepared and their interaction with CT DNA and BSA along with antioxidant and in vitro anticancer and antimicrobial activities was investigated. The formulation and characterization of complexes were achieved through elemental and thermal analysis, mass spectrometry, 1H NMR spectroscopy along with infrared, electronic absorption, and emission spectroscopy as well as square-wave voltammetry, and magnetic and conductivity measurements. Ruthenium(II) is octahedrally coordinated in cationic complex species to two bidentate diimine ligands (2,2′-bipyridine or 1,10-phenanthroline) and one bidentate monobasic flavonoid ligand through 3,4-site of quercetin, morin, and 3-hydroxyflavone or 4,5-site of chrysin. Complexes bind CT DNA by intercalation and binding constants comparable to ethidium bromide or 10 times higher. Binding constants of complexes to BSA were several times higher compared to ibuprofen and diazepam, and suggest that the complexes have a strong affinity to BSA. Antioxidant activity tests showed that the complexes are more potent in terms of radical inhibition compared to the parent flavonoids. Cytotoxic testing revealed that the Ru(II) complex of quercetin with 2,2′-bipyridine co-ligand has good selectivity to breast adenocarcinoma, while the complex of 3-hydroxyflavone with 2,2′-bipyridine co-ligand showed strong cytotoxicity toward all tested cell lines with IC50 ~ 1 μM. All complexes showed moderate activity toward Acinetobacter baumannii, while the Ru(II) complex of 3-hydroxyflavone with 2,2′-bipyridine showed excellent activity toward MRSA and Candida albicans. 相似文献
52.
Patrick J. M. Stals Jeffrey C. Everts Robin de Bruijn Ivo A. W. Filot Maarten M. J. Smulders Rafael Martín‐Rapún Dr. Evgeny A. Pidko Dr. Tom F. A. de Greef Dr. Anja R. A. Palmans Dr. E. W. Meijer Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(3):810-821
N‐Centred benzene‐1,3,5‐tricarboxamides (N‐BTAs) composed of chiral and achiral alkyl substituents were synthesised and their solid‐state behaviour and self‐assembly in dilute alkane solutions were investigated. A combination of differential scanning calorimetry (DSC), polarisation optical microscopy (POM) and X‐ray diffraction revealed that the chiral N‐BTA derivatives with branched 3,7‐dimethyloctanoyl chains were liquid crystalline and the mesophase was assigned as Colho. In contrast, N‐BTA derivatives with linear tetradecanoyl or octanoyl chains lacked a mesophase and were obtained as crystalline compounds. Variable‐temperature infrared spectroscopy showed the presence of threefold, intermolecular hydrogen bonding between neighbouring molecules in the mesophase of the chiral N‐BTAs. In the crystalline state at room temperature a more complicated packing between the molecules was observed. Ultraviolet and circular dichroism spectroscopy on dilute solutions of N‐BTAs revealed a cooperative self‐assembly behaviour of the N‐BTA molecules into supramolecular polymers with preferred helicity when chiral alkyl chains were present. Both the sergeants‐and‐soldiers as well as the majority‐rules principles were operative in stacks of N‐BTAs. In fact, the self‐assembly of N‐BTAs resembles closely that of their carbonyl (C?O)‐centred counterparts, with the exception that aggregation is weaker and amplification of chirality is less pronounced. The differences in the self‐assembly of N‐ and C?O‐BTAs were analysed by density functional theory (DFT) calculations. These reveal a substantially lower interaction energy between the monomeric units in the supramolecular polymers of N‐BTAs. The lower interaction energy is due to the higher energy penalty for rotation around the Ph? NH bond compared to the Ph? CO bond and the diminished magnitude of dipole–dipole interactions. Finally, we observed that mixed stacks are formed in dilute solution when mixing N‐BTAs and C?O BTAs. 相似文献
53.
54.
Kauffmann-Weiss S Gruner ME Backen A Schultz L Entel P Fähler S 《Physical review letters》2011,107(20):206105
We exploit the intrinsic structural instability of the Fe(70)Pd(30) magnetic shape memory alloy to obtain functional epitaxial films exhibiting a self-organized nanostructure. We demonstrate that coherent epitaxial straining by 54% is possible. The combination of thin film experiments and large-scale first-principles calculations enables us to establish a lattice relaxation mechanism, which is not expected for stable materials. We identify a low twin boundary energy compared to a high elastic energy as key prerequisite for the adaptive nanotwinning. Our approach is versatile as it allows to control both, nanostructure and intrinsic properties for ferromagnetic, ferroelastic, and ferroelectric materials. 相似文献
55.
We report on an analytical study of a quasicontinuum method in the context of fracture mechanics in a one-dimensional setting. To this end, we compare the asymptotic behaviour of a discrete model with nearest and next-to-nearest neighbour interactions of Lennard-Jones type and its quasicontinuum approximation via Γ-convergence. In case of fracture it turns out that one has to coarse grain in the continuum region and at the atomistic/continuum interface in order to capture the same behavior as the atomistic model, while this is not needed if the boundary conditions are such that the system behaves elastically. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
56.
57.
58.
59.
60.
Nikola Popović Dirk Praetorius Anja Schlömerkemper 《Continuum Mechanics and Thermodynamics》2007,19(1-2):67-80
The mathematical and physical analysis of magnetoelastic phenomena is a topic of ongoing research. Different formulae have
been proposed to describe the magnetic forces in macroscopic systems. We discuss several of these formulae in the context
of rigid magnetized bodies. In case the bodies are in contact, we consider formulae both in the framework of macroscopic electrodynamics
and via a multiscale approach, i.e., in a discrete setting of magnetic dipole moments. We give mathematically rigorous proofs
for domains of polygonal shape (as well as for more general geometries) in two and three space dimensions. In an accompanying
second article, we investigate the formulae in a number of numerical experiments, where we focus on the dependence of the
magnetic force on the distance between the bodies and on the case when the two bodies are in contact. The aim of the analysis
as well as of the numerical simulation is to contribute to the ongoing debate about which formula describes the magnetic force
between macroscopic bodies best and to stimulate corresponding real-life experiments.
相似文献