全文获取类型
收费全文 | 498228篇 |
免费 | 6103篇 |
国内免费 | 2212篇 |
专业分类
化学 | 275911篇 |
晶体学 | 7468篇 |
力学 | 21145篇 |
综合类 | 70篇 |
数学 | 54525篇 |
物理学 | 147424篇 |
出版年
2018年 | 4683篇 |
2017年 | 4709篇 |
2016年 | 7439篇 |
2015年 | 5044篇 |
2014年 | 7408篇 |
2013年 | 20526篇 |
2012年 | 15476篇 |
2011年 | 19194篇 |
2010年 | 13276篇 |
2009年 | 13182篇 |
2008年 | 17762篇 |
2007年 | 18043篇 |
2006年 | 17094篇 |
2005年 | 15581篇 |
2004年 | 14064篇 |
2003年 | 12535篇 |
2002年 | 12394篇 |
2001年 | 14281篇 |
2000年 | 11014篇 |
1999年 | 8441篇 |
1998年 | 6985篇 |
1997年 | 7009篇 |
1996年 | 6798篇 |
1995年 | 6192篇 |
1994年 | 6149篇 |
1993年 | 5841篇 |
1992年 | 6671篇 |
1991年 | 6688篇 |
1990年 | 6360篇 |
1989年 | 6305篇 |
1988年 | 6153篇 |
1987年 | 6106篇 |
1986年 | 5821篇 |
1985年 | 7781篇 |
1984年 | 7947篇 |
1983年 | 6616篇 |
1982年 | 7119篇 |
1981年 | 6760篇 |
1980年 | 6470篇 |
1979年 | 6874篇 |
1978年 | 7335篇 |
1977年 | 7153篇 |
1976年 | 7168篇 |
1975年 | 6716篇 |
1974年 | 6844篇 |
1973年 | 6911篇 |
1972年 | 4955篇 |
1971年 | 4107篇 |
1968年 | 4305篇 |
1967年 | 4485篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
An effective residual interaction between particles and holes for shell model calculations around 208Pb, derived from the interaction between free nucleons, is compared with the measured properties of proton-hole neutron states
in 208Tl and the interaction between proton holes is adjusted to newly measured level energies in 206Hg. These interaction elements are particularly relevant for neutron-rich nuclei. The adjustment of two mixing elements reproduces
the known γ-decay data in 208Tl.
Received: 2 April 2002 / Accepted: 2 May 2002 相似文献
992.
W. Kockelmann M. Hofmann O. Moze S.J. Kennedy K.H.J. Buschow 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(1):25-32
The element distributions and the magnetic ordering behaviour of compounds RNi10Si2 (R
=
Tb, Dy, Ho, Er, Tm) have been studied by neutron powder diffraction down to temperatures of 1.6 K. The compounds crystallize
in an ordered variant of the ThMn12 structure type in the tetragonal space group P4/nmm. An ordered 1:1 distribution of Ni and Si on sites 4d and 4e, respectively,
corresponds to a modulation vector [0, 0, 1] with respect to the space group I4/mmm of the ThMn12 structure. TbNi10Si2 orders antiferromagnetically below T
N
= 4.5 K with a magnetic propagation vector of [0, 0, 1/2]. The magnetic Tb moments, 8.97(2) /Tb atom at 1.6 K, are aligned along the c-axis. The Ni sites in TbNi10Si2 do not carry any ordered magnetic moments. The compounds with R
=
Dy, Ho, Er, and Tm are paramagnetic down to 1.6 K and 3.0 K, respectively.
Received 10 July 2002 / Received in final form 12 September 2002 Published online 29 October 2002 相似文献
993.
R. Enberg L. Motyka G. Poludniowski 《The European Physical Journal C - Particles and Fields》2002,26(2):219-228
Diffractive heavy vector meson photoproduction accompanied by proton dissociation is studied for arbitrary momentum transfer.
The process is described by the non-forward BFKL equation, for which a complete analytical solution is found, giving the scattering
amplitude. The impact of non-leading corrections to the BFKL equation is also analysed. Results are compared to the HERA data
on production.
Received: 2 July 2002 / Revised version: 29 August 2002 / Published online: 18 October 2002 相似文献
994.
Ivonin I. V. Krasil'nikova L. M. Lavrent'eva L. G. Porokhovnichenko L. P. 《Russian Physics Journal》2002,45(5):493-497
Experimental proofs of asymmetric trapping of atoms at the growth step in vapor-phase epitaxy of gallium arsenide in the GaAs–AsCl3–H2 system are given. The data obtained confirm the important role of the surface diffusion mass transfer in the growth of epitaxial GaAs layers on vicinals in the neighborhood of (111)A. The effective diffusion length is estimated. 相似文献
995.
N. H. Al-Assady 《Journal of Optimization Theory and Applications》1997,94(3):747-755
We present a method which generates conjugate search directions and maintains the quadratic convergence property, when applied to a quadratic function, even when the line searches are not exact. The method is similar to that given by Dixon, but needs one less vector store. When the method is applied to a number of general functions of different dimensionality, results show the efficiency of the method. 相似文献
996.
997.
The energy characteristics of an XeCl exciplex lamp with planar construction pumped by a low-pressure gas discharge are investigated
experimentally. When a discharge gap of width 2 cm and a Xe-Cl2 mixture were used, average radiation powers up to 20 mW were obtained in the wavelength interval 200–380 nm at efficiencies
of ∼0.4%. In this case the total efficiency of radiation into an angle of 4π exceeded 4%. It is shown that increasing the working pressure and using low discharge currents can lead to “point” radiation
sources.
Zh. Tekh. Fiz. 67, 43–46 (December 1997) 相似文献
998.
S. Moss de Oliveira P. M. C. de Oliveira F. C. de Sá Barreto 《Journal of statistical physics》1995,78(5-6):1619-1627
Using the finite-size scaling renormalization group, we obtain the two-dimensional flow diagram of the Blume-Capel model forS=1 andS=3/2. In the first case our results are similar to those of mean-field theory, which predicts the existence of first- and second-order transitions with a tricritical point. In the second case, however, our results are different. While we obtain in theS=1 case a phase diagram presenting a multicritical point, the mean-field approach predicts only a second-order transition and a critical endpoint. 相似文献
999.
The 2D Rancieite type manganic acid was prepared by reduction of KMnO4 in acidic medium. Its ion exchange behavior allows to prepare alkali derivatives. All compounds were characterized with use of a combination of X-ray diffraction, chemical analyses, TGA, magnetic measurements and spectroscopic techniques. The evolution of their chemical composition versus temperature was studied between 180 and 400 °C. It shows that the dehydration process is partly reversible in these compounds whereas the weak reduction is irreversible. The 2D Rancieite-type manganic acid is readily different from a Birnessite-type phyllomanganate, as shown by several features: the interlayer distance, the ion exchange capacity, the thermal behavior, the interlayer cation content, the manganese average oxidation state, the magnetic behavior and the IR spectrum. 相似文献
1000.
We propose an effective method of numerical determination of the gradient vector and the Hessian matrix of a quadratic quality
criterion in parametric optimization of continuous-discrete stochastic dynamic control systems based on the application of
adjoint equations.
Translated fromDinamicheskie Sistemy, No. 13, 1994, pp. 20–25. 相似文献