全文获取类型
收费全文 | 3130篇 |
免费 | 127篇 |
国内免费 | 7篇 |
专业分类
化学 | 2251篇 |
晶体学 | 13篇 |
力学 | 63篇 |
数学 | 532篇 |
物理学 | 405篇 |
出版年
2023年 | 28篇 |
2022年 | 44篇 |
2021年 | 56篇 |
2020年 | 62篇 |
2019年 | 50篇 |
2018年 | 56篇 |
2017年 | 37篇 |
2016年 | 126篇 |
2015年 | 102篇 |
2014年 | 104篇 |
2013年 | 205篇 |
2012年 | 230篇 |
2011年 | 202篇 |
2010年 | 134篇 |
2009年 | 90篇 |
2008年 | 190篇 |
2007年 | 212篇 |
2006年 | 177篇 |
2005年 | 162篇 |
2004年 | 131篇 |
2003年 | 120篇 |
2002年 | 120篇 |
2001年 | 49篇 |
2000年 | 37篇 |
1999年 | 24篇 |
1998年 | 34篇 |
1997年 | 35篇 |
1996年 | 37篇 |
1995年 | 20篇 |
1994年 | 19篇 |
1993年 | 23篇 |
1992年 | 30篇 |
1991年 | 22篇 |
1990年 | 23篇 |
1989年 | 17篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 20篇 |
1984年 | 21篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1981年 | 18篇 |
1980年 | 20篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1974年 | 8篇 |
1934年 | 11篇 |
排序方式: 共有3264条查询结果,搜索用时 0 毫秒
1.
2.
Carello Giuliana Landa Paolo Tnfani Elena Testi Angela 《Central European Journal of Operations Research》2022,30(1):159-187
Central European Journal of Operations Research - In the past years, the number of patients in need of chemotherapy treatments has been constantly increasing. Chemotherapy treatments must be... 相似文献
3.
4.
Keyang Ding Angela M. Gronenborn 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,167(2):554-258
Sensitivity-enhanced 2D IPAP experiments using the accordion principle for measuring one-bond 13C'-13Calpha and 1Halpha-13Calpha dipolar couplings in proteins are presented. The resolution of the resulting spectra is identical to that of the decoupled HSQC spectra and the sensitivity of the corresponding 1D acquisitions are only slightly lower than those obtained with 3D HNCO and 3D HN(COCA)HA pulse sequences due to an additional delay 2Delta. For cases of limited resolution in the 2D 15N-1HN HSQC spectrum the current pulse sequences can easily be modified into 3D versions by introducing a poorly digitized third dimension, if so desired. The experiments described here are a valuable addition to the suites available for determination of residual dipolar couplings in biological systems. 相似文献
5.
Pál Sohár Gábor Bernáth Géza Stájer Angela E. Szabo 《Magnetic resonance in chemistry : MRC》1989,27(9):872-876
Pentacyclic isoxazolines were obtained by the cycloaddition of benzonitrile oxide to norbornene-azetidinone-fused 3,1-oxazines. The constitutions of two of the isomers obtained, and the configurations and conformations of all products, were determined by means of 1H and 13C NMR spectroscopy and DNOE experiments. 相似文献
6.
We present a new generic problem solving approach for over-constrained problems based on Max-SAT. We first define a Boolean
clausal form formalism, called soft CNF formulas, that deals with blocks of clauses instead of individual clauses, and that allows one to declare each block either as hard (i.e., must be satisfied by any solution) or soft (i.e., can be violated by some solution). We then present two Max-SAT solvers that find a truth assignment that satisfies
all the hard blocks of clauses and the maximum number of soft blocks of clauses. Our solvers are branch and bound algorithms
equipped with original lazy data structures, powerful inference techniques, good quality lower bounds, and original variable
selection heuristics. Finally, we report an experimental investigation on a representative sample of instances (random 2-SAT,
Max-CSP, graph coloring, pigeon hole and quasigroup completion) which provides experimental evidence that our approach is
very competitive compared with the state-of-the-art approaches developed in the CSP and SAT communities.
Research partially supported by projects TIN2004-07933-C03-03 and TIC2003-00950 funded by the Ministerio de Educación y Ciencia. The second author is supported by a grant Ramón y Cajal. 相似文献
7.
8.
9.
Summary. We introduce linear semi-implicit complementary volume numerical scheme for solving level set like nonlinear degenerate diffusion
equations arising in image processing and curve evolution problems. We study discretization of image selective smoothing equation
of mean curvature flow type given by Alvarez, Lions and Morel ([3]). Solution of the level set equation of Osher and Sethian
([26], \[30]) is also included in the study. We prove and estimates for the proposed scheme and give existence of its (generalized) solution in every discrete time-scale step. Efficiency
of the scheme is given by its linearity and stability. Preconditioned iterative solvers are used for computing arising linear
systems. We present computational results related to image processing and plane curve evolution.
Received April 25, 2000 / Revised version received June 11, 2001 / Published online November 15, 2001 相似文献
10.