全文获取类型
收费全文 | 39646篇 |
免费 | 1139篇 |
国内免费 | 268篇 |
专业分类
化学 | 26922篇 |
晶体学 | 159篇 |
力学 | 832篇 |
综合类 | 2篇 |
数学 | 7571篇 |
物理学 | 5567篇 |
出版年
2022年 | 225篇 |
2021年 | 320篇 |
2020年 | 441篇 |
2019年 | 408篇 |
2018年 | 348篇 |
2017年 | 336篇 |
2016年 | 782篇 |
2015年 | 795篇 |
2014年 | 899篇 |
2013年 | 1823篇 |
2012年 | 1723篇 |
2011年 | 2067篇 |
2010年 | 1185篇 |
2009年 | 1042篇 |
2008年 | 1824篇 |
2007年 | 1806篇 |
2006年 | 1914篇 |
2005年 | 1738篇 |
2004年 | 1651篇 |
2003年 | 1424篇 |
2002年 | 1384篇 |
2001年 | 683篇 |
2000年 | 614篇 |
1999年 | 518篇 |
1998年 | 510篇 |
1997年 | 570篇 |
1996年 | 557篇 |
1995年 | 489篇 |
1994年 | 541篇 |
1993年 | 515篇 |
1992年 | 492篇 |
1991年 | 469篇 |
1990年 | 412篇 |
1989年 | 421篇 |
1988年 | 396篇 |
1987年 | 355篇 |
1986年 | 373篇 |
1985年 | 590篇 |
1984年 | 569篇 |
1983年 | 453篇 |
1982年 | 512篇 |
1981年 | 469篇 |
1980年 | 529篇 |
1979年 | 453篇 |
1978年 | 483篇 |
1977年 | 493篇 |
1976年 | 397篇 |
1975年 | 360篇 |
1974年 | 328篇 |
1973年 | 356篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Given a principal value convolution on the Heisenberg group Hn = Cn×R, we study the relation between its Laguerre expansion and the Fourier-Bessel expansion of its limit on Cn. We also calculate the Dirichlet kernel for the Laguerre expansion on the group Hn. 相似文献
42.
G. Tiana M.H. Jensen K. Sneppen 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):135-140
A feedback mechanism that involves the proteins p53 and mdm2, induces cell death as a controlled response to severe DNA damage.
A minimal model for this mechanism demonstrates that the response may be dynamic and connected with the time needed to translate
the mdm2 protein. The response takes place if the dissociation constant k between p53 and mdm2 varies from its normal value. Although it is widely believed that it is an increase in k that triggers the response, we show that the experimental behaviour is better described by a decrease in the dissociation
constant. The response is quite robust upon changes in the parameters of the system, as required by any control mechanism,
except for few weak points, which could be connected with the onset of cancer.
Received 8 May 2002 / Received in final form 9 July 2002 Published online 17 September 2002 相似文献
43.
Peter Otte 《Proceedings of the American Mathematical Society》2004,132(3):827-830
Motivated by the general approach due to Shargorodsky we derive enclosure results for the second-order relative spectrum of bounded selfadjoint operators by studying quadratic operator pencils. The quality of the results is discussed by means of a simple example.
44.
45.
The composite comprised of zinc oxide quantum dots and poly(amic acid) (PAAc) was prepared and studied by X-rays diffraction, X-ray photoelectron spectroscopy, light scattering, UV absorbance and UV fluorescence. The UV absorbance of the ZnO/PAAc composite was found to be much larger than that of its components taken separately. The fluorescence of the ZnO/PAAc composite was found to be shifted to longer wavelengthes in comparison with pure ZnO. The presence of the dopant dodecylbenzenesulfonic acid was found to affect the observed fluorescence. 相似文献
46.
47.
Daniel C. Cohen Peter Orlik 《Transactions of the American Mathematical Society》2005,357(8):3031-3050
We study the Gauss-Manin connection for the moduli space of an arrangement of complex hyperplanes in the cohomology of a complex rank one local system. We define formal Gauss-Manin connection matrices in the Aomoto complex and prove that, for all arrangements and all local systems, these formal connection matrices specialize to Gauss-Manin connection matrices.
48.
Erich Miersemann Hans D. Mittelmann W. Trnig 《Mathematical Methods in the Applied Sciences》1989,11(1):95-104
In this paper we generalize recent theoretical results on the local continuation of parameter-dependent non-linear variational inequalities. The variational inequalities are rather general and describe, for example, the buckling of beams, plates or shells subject to obstacles. Under a technical hypothesis that is satisfied by the simply supported beam, we obtain the existence of a continuation of both the solution and the eigenvalue with respect to a local parameter. A numerical continuation method is presented that easily overcomes turning points. Numerical results are presented for the non-linear beam. 相似文献
49.
Robert Jerrard Alberto Montero Peter Sternberg 《Communications in Mathematical Physics》2004,249(3):549-577
We establish the existence of locally minimizing vortex solutions to the full Ginzburg-Landau energy in three dimensional simply-connected domains with or without the presence of an applied magnetic field. The approach is based upon the theory of weak Jacobians and applies to nonconvex sample geometries for which there exists a configuration of locally shortest line segments with endpoints on the boundary.Research partially supported by NSERC grant number 261955 相似文献
50.
Mariusz Bednarz Peter Reineker Elena Mena-Osteritz Peter Buerle 《Journal of luminescence》2004,110(4):225-231
We theoretically study the size-dependent relation between absorption spectra of thiophene-based oligomers and the corresponding cyclothiophenes. In our approach based on a Frenkel exciton Hamiltonian, we demonstrate that the geometry and selection rules determine the observed relations between the spectra. 相似文献