全文获取类型
收费全文 | 423篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
化学 | 322篇 |
晶体学 | 22篇 |
力学 | 5篇 |
数学 | 24篇 |
物理学 | 61篇 |
出版年
2023年 | 1篇 |
2021年 | 6篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 21篇 |
2012年 | 20篇 |
2011年 | 22篇 |
2010年 | 11篇 |
2009年 | 20篇 |
2008年 | 29篇 |
2007年 | 26篇 |
2006年 | 19篇 |
2005年 | 21篇 |
2004年 | 15篇 |
2003年 | 21篇 |
2002年 | 17篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 12篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有434条查询结果,搜索用时 15 毫秒
101.
M. F. Braa J. M. Castellano M. C. Redondo J. Esplugues 《Journal of heterocyclic chemistry》1987,24(3):741-743
Reaction of 4-acylaminomethylpyridine N-oxides with phenylbutazone in the presence of acetic anhydride is described. In the pharmacological screening one compound shows an interesting anticonvulsant activity. 相似文献
102.
A. Benavente J. A. de Morán O. E. Piro E. E. Castellano P. J. Aymonino 《Journal of chemical crystallography》1997,27(6):343-352
The single crystal and anion structure of Mn[Fe(CN)5NO·2H2O, obtained by slow interdiffusion of reactant solutions through a TMS gel, was solved by X-ray diffraction methods and refined toR1=0.036. Spatial group: orthorhombic,Pnma,a=14.069(2),b=7.538(1),c=10.543(1)Å,Z=4. The Mn(II) ion and the water molecules are sited on mirror planes, which bisect the nitroprusside ions. One of the water molecules is coordinated to Mn(II) and the other, strongly hydrogen (as acceptor) bonded to the first molecule. The IR spectrum confirms the bonding of the water molecules and TGA results are in accordance with the dihydrate character of the substance and its dehydration in two successive steps. DTA results and the Raman spectrum agree with other results and the comparison between IR and RamanvNO wavenumbers confirms the expected strong vibrational interaction between the closely packed antiparallel (eclipsed) NO groups. There is a topotactic relationship between the dihydrate and the trihydrate, which crystallizes in the space subgroupP2 1/n. 相似文献
103.
Transition rates were obtained from spectra for pure metallic samples of atomic number ranging from 22 to 27, measured with monochromatic incident X-ray beams from a synchrotron source. The experimental setup for this consisted of an energy dispersive spectrometer in a conventional 45–45° geometry, mounted in an evacuated chamber. Absorption, detector efficiency and multiple scattering were taken into account. The results obtained are compared with recent theoretical and experimental data as well as with the well-known theoretical predictions from Scofield. 相似文献
104.
We consider a smooth perturbation δε( x , y , z ) of a constant background permittivity ε=ε0 that varies periodically with x , does not depend on y , and is supported on a finite-length interval in z . We investigate the theoretical and numerical determination of such perturbation from (several) fixed frequency y -invariant electromagnetic waves.
By varying the direction and frequency of the probing radiation a scattering matrix is defined. By using an invariant-imbedding technique we derive an operator Riccati equation for such scattering matrix. We obtain a theoretical uniqueness result for the problem of determining the perturbation from the scattering matrix.
We also investigate a numerical method for performing such reconstruction using multi-frequency information of the truncated scattering matrix. This relies on ideas of regularization and recursive linearization. Numerical experiments are presented validating such approach. 相似文献
By varying the direction and frequency of the probing radiation a scattering matrix is defined. By using an invariant-imbedding technique we derive an operator Riccati equation for such scattering matrix. We obtain a theoretical uniqueness result for the problem of determining the perturbation from the scattering matrix.
We also investigate a numerical method for performing such reconstruction using multi-frequency information of the truncated scattering matrix. This relies on ideas of regularization and recursive linearization. Numerical experiments are presented validating such approach. 相似文献
105.
106.
107.
108.
Henryk Malak Ignacy Gryczynski Joseph R. Lakowicz Gerald J. Meyers Felix N. Castellano 《Journal of fluorescence》1997,7(2):107-112
We examined the intensity and anisotropy decays of DNA labeled with two ruthenium metalligand complexes, [Ru(bpy)2(dppz)]2+ and [Ru(phe)2(dppz)]2+. Both complexes display high emission anisotropies in the absence of rotational diffusion, making them suitable probes for
rotational motions. When bound to DNA, these complexes display decay times as long as 294 ns, providing long-lived probes
of DNA dynamics. The decay times of both complexes were rather insensitive to dissolved oxygen. We examined anisotropy decays
of these complexes bound to B-form DNA. The anisotropy decays revealed correlation times near 10, 50, and several hundred
nanoseconds, suggesting that these probes are sensitive to a wide range of DNA motions. The use of metalligand complexes should
allow resolution of both the torsional and bending motions of DNA, the latter of which has been mostly inaccessible using
shorter-lived fluorescent probes bound to DNA.
Dedicated to Professor Robert F. Steiner upon his retirement 相似文献
109.
110.
M. G. Castellano M. Bassan P. Carelli E. Coccia C. Cosmelli V. Fafone I. Modena 《Il Nuovo Cimento C》1992,15(2):219-225
Summary We present noise measurements made at temperatures down to 200 mK on a tunnel junction d.c. SQUID, to be used as amplifier
for the gravitational-wave experiment Nautilus of the Rome group. We find that the flux noise decreases with temperature,
as expected, with a best measured value of
at 0.2 K. The presence of an excess noise term independent of temperature is discussed. 相似文献