全文获取类型
收费全文 | 1195篇 |
免费 | 23篇 |
国内免费 | 5篇 |
专业分类
化学 | 609篇 |
晶体学 | 5篇 |
力学 | 19篇 |
数学 | 133篇 |
物理学 | 457篇 |
出版年
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2016年 | 31篇 |
2015年 | 16篇 |
2014年 | 20篇 |
2013年 | 50篇 |
2012年 | 44篇 |
2011年 | 57篇 |
2010年 | 24篇 |
2009年 | 33篇 |
2008年 | 68篇 |
2007年 | 54篇 |
2006年 | 35篇 |
2005年 | 32篇 |
2004年 | 38篇 |
2003年 | 31篇 |
2002年 | 33篇 |
2001年 | 29篇 |
2000年 | 30篇 |
1999年 | 14篇 |
1998年 | 15篇 |
1997年 | 10篇 |
1996年 | 17篇 |
1995年 | 24篇 |
1994年 | 10篇 |
1993年 | 21篇 |
1992年 | 23篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 21篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1985年 | 19篇 |
1984年 | 24篇 |
1983年 | 18篇 |
1982年 | 19篇 |
1981年 | 21篇 |
1980年 | 16篇 |
1979年 | 24篇 |
1978年 | 19篇 |
1977年 | 20篇 |
1976年 | 23篇 |
1975年 | 18篇 |
1974年 | 20篇 |
1973年 | 14篇 |
1972年 | 12篇 |
1971年 | 12篇 |
1970年 | 10篇 |
1969年 | 9篇 |
排序方式: 共有1223条查询结果,搜索用时 0 毫秒
141.
Gemma L. Ellis V. Elena Ramos S. Barret Kalindjian David J. Tapolczay 《Tetrahedron letters》2007,48(10):1683-1686
Functionalised hydroxylamine derivatives of (S)-proline and (R)-pipecolic acid have been prepared using a Cope elimination. These undergo reverse Cope elimination onto a pendant double bond to give bicyclic lactam and lactone N-oxides containing three contiguous chiral centres, this extends the scope and applicability of the reverse Cope elimination in the synthesis of heterocyclic systems by incorporation of the lactone and lactam structural motifs. 相似文献
142.
D. M. Ellis 《The Journal of the Operational Research Society》1966,17(4):413-424
A mathematical model is proposed for finding the response to an advertising campaign. Although, hypothetically, there is no restriction on the media involved, the assumptions made are more suited to a campaign in newspapers or magazines, rather than, for example, on television. The deficiencies in the model are discussed, and the use of such a model is compared with the use of simulation techniques. Two previous attempts to optimize similar models are discussed, and a technique for building up a sequence of optimum schedules with an example and a proof of the optimum properties are presented. 相似文献
143.
144.
Recent experimental data on correlations in large transverse momentum reactions are analyzed in a two-jet picture. Scaling in jet fragmentation is shown to account well for the existing data. The formulae that are given can be used as a basis for a more detailed analysis of the dynamics. A particular result is that we predict that a two-jet structure can also be produced in events where it is not required that any single hadron has large pT, with a cross section as large as mb or more (at ISR energies with the total transverse momentum of each jet ?2.5 GeV/c). 相似文献
145.
146.
147.
LEED patterns characteristic of an ordered array of equally spaced steps of minimum height resulted from pulsing disordered Bi(~ 0001) vicinal surfaces. Ten XeCl eximer laser pulses at λ = 308 nm, of 10 ns duration and each and at 0.5 s intervals optimized ordering on the Bi(101̄16) surface, but additional exposure degraded the surface crystallinity as did a twentyfold increase in power density. 相似文献
148.
Using a Hartree-Fock basis the diagrams of the Tamm-Dancoff and random-phase approximations have been summed to calculate the effective charge in the (1s0d) shell. The enhancement of the effective charge found by this summation is much less than in an oscillator basis, in fact in most cases the HF RPA result is smaller than the value obtained from the lowest order core polarization diagram in an oscillator basis. The HF neutron effective charges are thus too small. For protons the enhancement of the bare effective charge in a HF basis must also be taken into account, but for cases involving the 0d5/2 orbital the final result appears rather small. 相似文献
149.
We study a recently proposed lattice version of the reggeon field theory. First a simple one-dimensional system possessing many of the features of the reggeon calculus (Ising model in an imaginary magnetic field) is solved. Surprisingly, the system is found to undergo a phase transition at a non-zero critical temperature, which, although of first order obeys the universality and scaling laws previously postulated for the reggeon calculus. Returning to the full lattice theory, the machinery for performing a high temperature expansion is set up, and initial calculations carried out to order T?3. In this order, best estimates for the critical indices η and v in the asymptotic elastic amplitude A(s,t) ~ is (ln s)ηf(t(lns)v) yield . Check on the method, including comparisons with known Ising model results, are also discussed. 相似文献
150.