全文获取类型
收费全文 | 1060篇 |
免费 | 21篇 |
国内免费 | 2篇 |
专业分类
化学 | 632篇 |
晶体学 | 3篇 |
力学 | 43篇 |
数学 | 118篇 |
物理学 | 287篇 |
出版年
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 28篇 |
2015年 | 16篇 |
2014年 | 16篇 |
2013年 | 39篇 |
2012年 | 49篇 |
2011年 | 69篇 |
2010年 | 37篇 |
2009年 | 27篇 |
2008年 | 48篇 |
2007年 | 63篇 |
2006年 | 56篇 |
2005年 | 49篇 |
2004年 | 57篇 |
2003年 | 34篇 |
2002年 | 42篇 |
2001年 | 24篇 |
2000年 | 16篇 |
1999年 | 16篇 |
1998年 | 24篇 |
1997年 | 20篇 |
1996年 | 22篇 |
1995年 | 12篇 |
1994年 | 20篇 |
1993年 | 28篇 |
1992年 | 29篇 |
1991年 | 14篇 |
1990年 | 6篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 15篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 13篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1973年 | 6篇 |
1971年 | 4篇 |
排序方式: 共有1083条查询结果,搜索用时 156 毫秒
1.
The development of a tool for calculating resonances and bound states in three-body systems described by a single-potential
energy surface is reported. The method has been applied to the antiprotonic helium, doubly excited states in helium, the 11Li nuclear halo, the NeICl van der Waals molecule, and the recently found FHD reaction complex.
Received November 26, 2001; accepted for publication November 28, 2001 相似文献
2.
A highly selective solid phase extraction sorbent for pre-concentration of sameridine made by molecular imprinting 总被引:5,自引:0,他引:5
Summary A novel approach to solid phase extraction, based on the use of a highly selective molecularly imprinted polymer, is presented.
The versatility of this type of sorbent for solid phase extraction was demonstrated in a model batch-wise pre-concentration
of sameridine prior to gas chromatography. Problems associated with leakage of remaining imprint molecules during the desorption
phase could be eliminated by the use of a close structural analogue of sameridine as the imprint species. It was found that
a major benefit of the imprinted polymer was its specificity, which lead to distinctly cleaner chromatographic traces and
ability to improve sensitivity by extracting sameridine from larger sample volumes. 相似文献
3.
4.
In this paper, the development of decision support tools for dynamic ambulance relocation and automatic ambulance dispatching is described. The ambulance dispatch problem is to choose which ambulance to send to a patient. The dynamic ambulance relocation problem occurs in the operational control of ambulances. The objective is to find new locations for some of the ambulances, to increase the preparedness in the area of responsibility. Preparedness is a way of evaluating the ability to serve potential patients with ambulances now and in the future. Computational tests using a simulation model show that the tools are beneficial in reducing the waiting periods for the patients. 相似文献
5.
C. G. Andersson 《Zeitschrift für Physik A Hadrons and Nuclei》1980,295(4):349-354
Different ways of treating the pairing interaction in the particle-rotor model are discussed and compared in a model which can be solved exactly. Special attention is paid to the interaction between the yrast and yrare bands as function of the shell filling. 相似文献
6.
Among the salient features of shear-driven plane Couette flow is the constancy of the total shear stress (viscous and turbulent) across the flow. This constancy gives rise to a quasi-homogenous core region, which makes the bulk of the flow substantially different from pressure-driven Poiseuille flow. The present second-moment closure study addresses the conflicting hypotheses relating to turbulent Couette flow. The inclusion of a new wall-proximity function in the wall-reflection part of the pressure-strain model seems mandatory, and the greement with recent experimental and direct numerical simulation (DNS) results is encouraging. Analysis of model computations in the range 750 ≤ Re ≤ 35,000 and comparisons with low-Re DNS data suggest that plane Couette flow exhibits a local-equilibrium core region, in which anisotropic, homogeneous turbulence prevails. However, the associated variation of the mean velocity in the core, as obtained by the model, conflicts with the intuitively appealing assumption of homogeneous mean shear. The constancy of the velocity gradient exhibited by the DNS therefore signals a deficiency in the modeled transport equation for the energy dissipation rate. 相似文献
7.
The soft mode dielectric response of three ferroelectric chiral smectic C* substances is studied in the vicinity of the smectic C*-smectic A* phase transition. For some substances the soft mode dielectric strength exhibits a pronounced anomaly in the C* phase just below the phase transition. We show how this anomaly can be systematically correlated with a corresponding anomaly in the experimentally determined ratio of spontaneous polarization over tilt. By comparing the experimental results with the theoretical predictions of an extended Landau model, we demonstrate how the crossover behaviour of the system can be interpreted as being the consequence of the presence of a biquadratic coupling between tilt and polarization in the Landau free-energy of the system. 相似文献
8.
9.
We define a smooth functional calculus for a non-commuting tuple of (unbounded) operators Aj on a Banach space with real spectra and resolvents with temperate growth, by means of an iterated Cauchy formula. The construction is also extended to tuples of more general operators allowing smooth functional calculii. We also discuss the relation to the case with commuting operators. 相似文献
10.
L. Feenstra L. M. Andersson J. Schmiedmayer 《General Relativity and Gravitation》2004,36(10):2317-2329
Magnetic microtraps and Atom Chips are safe, small-scale, reliable and flexible tools to prepare ultra-cold and degenerate atom clouds as sources for various atom-optical experiments. We present an overview of the possibilities of the devices and indicate how a microtrap can be used to prepare and launch a Bose-Einstein condensate for use in an atom clock or an interferometer. 相似文献