全文获取类型
收费全文 | 547篇 |
免费 | 191篇 |
国内免费 | 142篇 |
专业分类
化学 | 476篇 |
晶体学 | 12篇 |
力学 | 2篇 |
综合类 | 3篇 |
数学 | 6篇 |
物理学 | 381篇 |
出版年
2024年 | 4篇 |
2023年 | 6篇 |
2022年 | 19篇 |
2021年 | 36篇 |
2020年 | 36篇 |
2019年 | 27篇 |
2018年 | 23篇 |
2017年 | 18篇 |
2016年 | 46篇 |
2015年 | 27篇 |
2014年 | 41篇 |
2013年 | 67篇 |
2012年 | 51篇 |
2011年 | 39篇 |
2010年 | 27篇 |
2009年 | 46篇 |
2008年 | 34篇 |
2007年 | 38篇 |
2006年 | 28篇 |
2005年 | 33篇 |
2004年 | 28篇 |
2003年 | 30篇 |
2002年 | 46篇 |
2001年 | 24篇 |
2000年 | 18篇 |
1999年 | 21篇 |
1998年 | 10篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 13篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1982年 | 2篇 |
1978年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有880条查询结果,搜索用时 15 毫秒
141.
《Journal of Coordination Chemistry》2012,65(21):3534-3553
AbstractA family of copper(II) compounds has been prepared with the general formula (2-chloro-3-fluoro-pyridine)2CuX2·n(Y), where X?=?Cl, Br, n?=?0,1, and Y?=?methanol or water. For the copper chloride complexes, only solvated structures were obtained (1, X?=?Cl, Y?=?H2O; 2, X?=?Cl, Y?=?CH3OH) while for the copper bromide compounds, both a desolvated structure and the methanol solvate were prepared (3, X?=?Br, Y?=?none; 4, X?=?Br, Y?=?CH3OH). Each compound has been characterized by IR, powder X-ray diffraction, single-crystal X-ray diffraction, and temperature-dependent magnetic susceptibility measurement. Compounds 1 and 4 are isostructural, in the space group Cm, and neither exhibits significant magnetic exchange although superexchange pathways are present. Compound 2 also crystallizes in the Cm space group and exhibits weak ferromagnetic interactions (J/kB?=?1.72(2) K from the 1D-ferromagnetic chain model) which are likely propagated by hydrogen bonding. Compound 3 crystallizes in the space group P21/n with the Cu(II) ion sitting on a crystallographic inversion center. Compound 3 exhibits weak antiferromagnetic exchange via two-halide superexchange typical for similar complexes. The magnetic data for 3 were fit to the 1D-antiferromagnetic chain model resulting in J/kB?=??1.21(1). 相似文献
142.
《Physics and Chemistry of Liquids》2012,50(1):151-154
Abstract A recent paper of Wu et al., discusses thermodynamic observables in a fractional quantum Hall (FQH) liquid. In particular the de Haas-van Alphen effect is considered theoretically. Here, it is pointed out that laboratory experiments on GaAs/AlGaAs heterojunctions, plus the analogue of the Clausius-Clapeyron equation in an applied magnetic field, allow schematic analysis of the orbital magnetism of the FQH liquid. There is general agreement with the theoretical results of Wu et al. 相似文献
143.
Krishnamurthy V. V. Watanabe I. Nagamine K. Kitagawa J. Ishikawa M. Komatsubara T. 《Hyperfine Interactions》2001,136(3-8):385-389
Magnetic and quadrupolar ordering phenomena in a Ce3Pd20Ge6 single crystal have been investigated by muon spin rotation/relaxation (μ+SR) spectroscopy. We have observed spontaneous precession of muons in zero-field below T
N
=0.7 K in the antiferromagnetic state. The precession frequency follows the power law: ν(T)=ν(0)(1−T/T
N
)
n
. The exponent n=0.43(2) is close to the mean-field value of 0.5. The muon longitudinal spin relaxation rate 1/T
1 is found to be nearly independent of temperature in the range of 0.3 to 2 K, i.e., across either T
N
or T
Q
=1.2 K, the quadrupolar ordering temperature. Two likely mechanisms for the temperature independent behavior of 1/T
1 are suggested.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
144.
145.
Three new binudear cobalt (II) complexes with extended te-tracarboxylato- bridge have been synthesized and characterized, namely [Co2 (PMTA) (bpy)4] (1), [Co2(PMTA)-(phen)4] (2) and [Co2(PMTA) (NO2phen)4] (3), where PMTA represents the tetraanion of pyroniellitic acid, and bpy, phen, NO2-phen denote 2,2'-bipyridine, 1,10-phenan-throline; 5-nirto-1, 10-plienanthroline, respectively. Based on elemental analyses, molar conductivity measurements, IR and electronic spectra studies, it is proposed that these complexes have PMTA-bridged structures and consist of two cobalt (II) ions, each in a distorted octahedral environment. These complexes were further characterized by variable temperature magnetic susceptibility measurements (4-300 K) and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, giving the exchange integral J = - 1.02 cm-1 for 1, J = -1.21 cm-1 for 2 and J = - 1.18 cm-1 for 3, respectively. These results revealed the operation of antiferromagneti 相似文献
146.
CHEN Hong ZHANG Jun-Feng YUAN Hong-Kuan 《理论物理通讯》2007,48(4):749-753
To understand the electronic and magnetic properties, we have studied Cr-doped zinc-blende AlN system in detail by applying a first-principle plane wave pseudopotential method based on the density functional theory within the local spin density approximation. The analyses of the band structures, density of states, exchange interactions, and magnetic moments show that Al1-xCrxN alloys may exhibit a half-metallic ferromagnetism character, that Cr in the diluted doping limit forms near-midgap deep levels, and that the total magnetization of the cell is 3μB per Cr atom, which does not change with Cr concentration. Moreover, we have succeeded in predicting that Al1-xCrzN alloys in x = 0.0625 has a very high Curie temperature, and lind that ferromagnetic exchange interaction between magnetic dopants is short-ranged. 相似文献
147.
148.
A scanning superconducting quantum interference device microscope for room temperature samples
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We have constructed a scanning low-Tc superconducting quantum interference device (SQUID) microscope, in which the SQUID is mounted on the lower end of a copper rod and cooled to liquid helium temperature. There is a 65μm thick sapphire window under the SQUID. The sample at room temperature underneath the window can be scanned to produce magnetic images. The microscope has a spatial resolution of 100-150μm and a magnetic field sensitivity of 3-60pT/$\sqrt{Hz}$ in a magnetically unshielded environment. We have used this scanning SQUID microscope to measure various room temperature samples. 相似文献
149.
150.
The study of dilute Sc impurities in either heavier d-transition metals or in alkali metal hosts is difficult due to their limited solubility; however, the large host-impurity mismatch in these systems makes them particularly interesting in terms of local electronic structure. One way to overcome the solubility problem is implantation into the desired host; in particular, using recoil implantation following heavy-ion nuclear reactions, deep implantation into practically any host can be achieved. Here, we compare the implantation of 43Sc into Cs, studied in situ by the in-beam TDPAD method [1], with the implantation of 44m
Sc into Fe, studied by low-temperature nuclear orientation (LTNO) and related techniques (NMRON, thermal cycling) [2]. 相似文献