全文获取类型
收费全文 | 41860篇 |
免费 | 788篇 |
国内免费 | 314篇 |
专业分类
化学 | 20010篇 |
晶体学 | 308篇 |
力学 | 1616篇 |
综合类 | 12篇 |
数学 | 10907篇 |
物理学 | 10109篇 |
出版年
2023年 | 105篇 |
2022年 | 122篇 |
2021年 | 200篇 |
2020年 | 293篇 |
2019年 | 240篇 |
2018年 | 1391篇 |
2017年 | 1586篇 |
2016年 | 1190篇 |
2015年 | 1001篇 |
2014年 | 956篇 |
2013年 | 1288篇 |
2012年 | 3976篇 |
2011年 | 3242篇 |
2010年 | 2399篇 |
2009年 | 2024篇 |
2008年 | 1378篇 |
2007年 | 1375篇 |
2006年 | 1298篇 |
2005年 | 5094篇 |
2004年 | 4481篇 |
2003年 | 2720篇 |
2002年 | 896篇 |
2001年 | 498篇 |
2000年 | 253篇 |
1999年 | 345篇 |
1998年 | 250篇 |
1997年 | 255篇 |
1996年 | 176篇 |
1995年 | 175篇 |
1994年 | 175篇 |
1993年 | 137篇 |
1992年 | 272篇 |
1991年 | 226篇 |
1990年 | 193篇 |
1989年 | 188篇 |
1988年 | 170篇 |
1987年 | 99篇 |
1986年 | 85篇 |
1985年 | 102篇 |
1984年 | 80篇 |
1983年 | 72篇 |
1982年 | 79篇 |
1981年 | 75篇 |
1980年 | 58篇 |
1979年 | 65篇 |
1976年 | 105篇 |
1975年 | 72篇 |
1974年 | 68篇 |
1973年 | 79篇 |
1972年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
191.
Cross ratios constitute an important tool in classical projective geometry. Using the theory of Tutte groups as discussed in [6] it will be shown in this note that the concept of cross ratios extends naturally to combinatorial geometries or matroids. From a thorough study of these cross ratios which, among other observations, includes a new matroid theoretic version and proof of the Pappos theorem, it will be deduced that for any projective space M=
n
(K) of dimension n2 of M over some skewfield K the inner Tutte group is isomorphic to the commutator factor group K
*/[K
*, K
*] of K
*K{0}. This shows not only that in case M=
n
(K) our matroidal cross ratios are nothing but the classical ones. It can also be used to correlate orientations of the matroid M=
n
(K) with the orderings of K. And it implies that Dieudonné's (non-commutative) determinants which, by Dieudonné's definition, take their values in K
*/[K
*, K
*] as well, can be viewed as a special case of a determinant construction which works for just every combinatorial geometry.Research supported by the DFG (Deutsche Forschungsgemeinschaft). 相似文献
192.
Andreas Blass 《Archive for Mathematical Logic》1990,30(1):1-11
We prove several theorems about the cardinal
associated with groupwise density. With respect to a natural ordering of families of nond-ecreasing maps from to, all families of size
are below all unbounded families. With respect to a natural ordering of filters on, all filters generated by
sets are below all non-feeble filters. If
then
and
. (The definitions of these cardinals are recalled in the introduction.) Finally, some consequences deduced from
by Laflamme are shown to be equivalent to
. 相似文献
193.
194.
Book Review
Functional analysis and boundary-value problems: An introductory treatmentB. Dayanand Reddy: Pitman Monographs and Survey in Pure and Applied Mathematics, Longman Scientific and Technical, 1986, 333 pp., £45.00 net 相似文献195.
We develop the quantization of topological solitons (vortices) in three-dimensional quantum field theory, in terms of the Euclidean region functional integral. We analyze in some detail the vortices of the abelian Higgs model. If a Chern-Simons term is added to the action, the vortices turn out to be anyons, i.e. particles with arbitrary real spin and intermediate () statistics. Localization properties of the interpolating field, scattering theory and spin-statistics connection of anyons are discussed. Such analysis might be relevant in connection with the fractional quantum Hall effect and two-dimensional models of HighT
csuperconductors. 相似文献
196.
Andreas Floer 《Communications in Mathematical Physics》1988,118(2):215-240
To an oriented closed 3-dimensional manifoldM withH
1(M, )=0, we assign a 8-graded homology groupI
*(M) whose Euler characteristic is twice Casson's invariant. The definition uses a construction on the space of instantons onM×. 相似文献
197.
It is shown that the time-dependent WKB expansion highlights some of the hidden properties of the Schrödinger equation and forms a natural bridge between that equation and the functional integral formulation of quantum mechanics. In particular it is shown that the leading (zero- and first-order in ) terms in the WKB expansion are essentially classical, and the relationship of this result to the classical nature of the WKB partition function, and of the anomalies in quantum field theory, is discussed. 相似文献
198.
199.
Claudio Albanese Jürg Fröhlich Thomas Spencer 《Communications in Mathematical Physics》1988,119(4):677-699
This is our second paper devoted to the study of some non-linear Schrödinger equations with random potential. We study the non-linear eigenvalue problems corresponding to these equations. We exhibit a countable family of eigenfunctions corresponding to simple eigenvalues densely embedded in the band tails. Contrary to our results in the first paper, the results established in the present paper hold for an arbitrary strength of the non-linear (cubic) term in the non-linear Schrödinger equation. 相似文献
200.
R. E. Ansorge B. ?sman C. N. Booth L. Burow P. Carlson R. S. De Wolf B. Eckart G. Ekspong C. Fuglesang J. Gaudaen C. Geich-Gimbel B. Holl R. Hospes K. Jon-And D. P. Johnson F. Lotse N. Manthos D. J. Munday J. E. V. Ovens W. Pelzer J. G. Rushbrooke F. Triantis L. Van hamme C. Walck C. P. Ward D. R. Ward C. J. S. Webber T. O. White G. Wilquet N. Yamdagni UA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,41(2):179-190
A detailed analysis ofK s 0 production in \(\bar pp\) |<2.5 the average transverse momentum is found to be 0.53±0.07 GeV/c at 200 GeV and 0.62±0.08 GeV/c at 900 GeV, which is an increase with respect to data at c.m. energies below 60 GeV. TheK s 0 production cross sections in inelastic collisions are 29±4 mb at 200 GeV and 63±6 mb at 900 GeV, showing an increase compared to lower energy data. The central kaon density is found to increase as a logarithmic function of energy. At 900 GeV, where statistics are sufficient to allow one to draw conclusions, the average transverse momentum is higher in events with large charged multiplicity than in events with low multiplicity. 相似文献