全文获取类型
收费全文 | 1384篇 |
免费 | 57篇 |
国内免费 | 12篇 |
专业分类
化学 | 766篇 |
晶体学 | 10篇 |
力学 | 46篇 |
数学 | 388篇 |
物理学 | 243篇 |
出版年
2023年 | 6篇 |
2022年 | 24篇 |
2021年 | 24篇 |
2020年 | 33篇 |
2019年 | 33篇 |
2018年 | 31篇 |
2017年 | 30篇 |
2016年 | 36篇 |
2015年 | 47篇 |
2014年 | 46篇 |
2013年 | 76篇 |
2012年 | 87篇 |
2011年 | 69篇 |
2010年 | 72篇 |
2009年 | 40篇 |
2008年 | 57篇 |
2007年 | 57篇 |
2006年 | 55篇 |
2005年 | 53篇 |
2004年 | 70篇 |
2003年 | 42篇 |
2002年 | 36篇 |
2001年 | 29篇 |
2000年 | 25篇 |
1999年 | 29篇 |
1998年 | 20篇 |
1997年 | 25篇 |
1996年 | 35篇 |
1995年 | 26篇 |
1994年 | 20篇 |
1993年 | 25篇 |
1992年 | 23篇 |
1991年 | 22篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1976年 | 5篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 3篇 |
排序方式: 共有1453条查询结果,搜索用时 15 毫秒
101.
A simple and robust method for determining the relative orientations of covalently linked protein domains using conjoined rigid body/torsion angle dynamics simulated annealing on the basis of residual dipolar couplings is presented. In this approach each domain is treated as a rigid body and the relevant degrees of conformational freedom are restricted to the backbone torsion angles (phi, psi) of the linker between the domains. By this means translational information afforded by the presence of an intact linker is preserved. We illustrate this approach using the domain-swapped dimer of the HIV-inactivating protein cyanovirin-N as an example. 相似文献
102.
Two simple proofs of the result that a relativistic summational invariant is a linear combination of the momentum four-vector p
are given by assuming that is a continuous and differentiable function of class C
2. The results can be extended to the case when is just assumed to be a generalized function. 相似文献
103.
We study limit distribution of partial sums SN,k(t) =
s = 1
[N t]
Ak(Xs) of Appell polynomials of the long-range dependent moving average process Xt> = i t bt - i i, where {i} is a strictly stationary and weakly dependent martingale difference sequence, and bi id - 1 (0 < d < 1/2). We show that if k(1-2 d)<1, then suitably normalized partial sums SN,k(t) converge in distribution to the kth order Hermite process. This result generalizes the corresponding results of Surgailis, and Avram and Taqqu obtained in the case of the i.i.d. sequence { i}. 相似文献
104.
Marius Crainic 《K-Theory》1999,17(4):319-362
We give a general method for computing the cyclic cohomology of crossed products by étale groupoids, extending the Feigin–Tsygan–Nistor spectral sequences. In particular we extend the computations performed by Brylinski, Burghelea, Connes, Feigin, Karoubi, Nistor, and Tsygan for the convolution algebra C
c
(G) of an étale groupoid, removing the Hausdorffness condition and including the computation of hyperbolic components. Examples like group actions on manifolds and foliations are considered. 相似文献
105.
106.
107.
108.
J.L. Osborne C.A. Barnes R.W. Kavanagh R.M. Kremer G.J. Mathews J.L. Zyskind P.D. Parker A.J. Howard 《Nuclear Physics A》1984,419(1):115-132
Cross sections for the 3He(α, γ)7Be reaction have been measured at several energies from Ec.m. = 165 to 1169 keV by counting prompt γ-rays from a windowless, differentially pumped, recirculating, 3He gas target. The cross-section factor S34(Ec.m.) and branching ratio γ1/γ0 were determined at each energy. Cross sections were also measured at Ec.m. = 947 and 1255 keV by counting the γ-rays from the 7Be produced in a 3He gas cell with a Ni entrance foil. Combining the results of these two independent experiments yields a zero-energy intercept for the cross-section factor of S34(0) = 0.53 ± 0.03 keV · b. The relationship between these measurements and several theoretical calculations, and the import of the extrapolated cross section for the solar-neutrino problem are discussed. 相似文献
109.
Li J Tammer M Kremer F Komp A Finkelmann H 《The European physical journal. E, Soft matter》2005,17(4):423-428
Polarized Fourier transform infrared (FTIR) spectroscopy is employed to study the segmental orientation and mobility of liquid-crystalline elastomers (LCEs) with a monodomain structure in response to external mechanical fields parallel and perpendicular to the initial nematic director. The mean orientation and the molecular order parameter of the different molecular moieties referring to the mesogen, the spacer and the network are analyzed in detail. Parallel stretch leaves the mean orientation of the different molecular moieties and its molecular order parameter nearly uninfluenced. Perpendicular stretch results in a threshold-like dependence: for elongation ratios λ ⩽ λc = 1.3 (10 mol% crosslinker density), respectively λ ⩽ λc = 1.6 (5 mol% crosslinker density) no change of the mean orientation and the molecular order parameters is observed, while for λ ≥ λc all molecular units reorient and their molecular order parameters are strongly decreased. The present studies give no indications that the reorientational dynamics of the network and the mesogens differ as long as the elongation ratio is smaller than λc. 相似文献
110.
Martin?Dindo? Marius?MitreaEmail author 《Archive for Rational Mechanics and Analysis》2004,174(1):1-47
We consider the linearized version of the stationary Navier-Stokes equations on a subdomain of a smooth, compact Riemannian manifold M. The emphasis is on regularity: the boundary of is assumed to be only C1 and even Lipschitz, and the data are selected from appropriate Sobolev-Besov scales. Our approach relies on the method of boundary integral equations, suitably adapted to the variable-coefficient setting we are considering here. Applications to the stationary, nonlinear Navier-Stokes equations in this context are also discussed. 相似文献