全文获取类型
收费全文 | 6256篇 |
免费 | 218篇 |
国内免费 | 22篇 |
专业分类
化学 | 3934篇 |
晶体学 | 40篇 |
力学 | 165篇 |
数学 | 1118篇 |
物理学 | 1239篇 |
出版年
2023年 | 41篇 |
2022年 | 77篇 |
2021年 | 132篇 |
2020年 | 106篇 |
2019年 | 127篇 |
2018年 | 129篇 |
2017年 | 118篇 |
2016年 | 217篇 |
2015年 | 201篇 |
2014年 | 228篇 |
2013年 | 325篇 |
2012年 | 465篇 |
2011年 | 412篇 |
2010年 | 258篇 |
2009年 | 226篇 |
2008年 | 350篇 |
2007年 | 355篇 |
2006年 | 294篇 |
2005年 | 473篇 |
2004年 | 419篇 |
2003年 | 312篇 |
2002年 | 202篇 |
2001年 | 117篇 |
2000年 | 96篇 |
1999年 | 59篇 |
1998年 | 61篇 |
1997年 | 49篇 |
1996年 | 56篇 |
1995年 | 48篇 |
1994年 | 54篇 |
1993年 | 56篇 |
1992年 | 45篇 |
1991年 | 48篇 |
1990年 | 36篇 |
1989年 | 31篇 |
1988年 | 21篇 |
1987年 | 29篇 |
1986年 | 16篇 |
1985年 | 37篇 |
1984年 | 36篇 |
1983年 | 17篇 |
1982年 | 14篇 |
1981年 | 9篇 |
1980年 | 16篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1976年 | 7篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1968年 | 5篇 |
排序方式: 共有6496条查询结果,搜索用时 15 毫秒
1.
Antonio R. Montoro Bustos Marta Garcia-Cortes Hector González-Iglesias Jorge Ruiz Encinar José M. Costa-Fernández Miguel Coca-Prados Alfredo Sanz-Medel 《Analytica chimica acta》2015
A generic strategy based on the use of CdSe/ZnS Quantum Dots (QDs) as elemental labels for protein quantification, using immunoassays with elemental mass spectrometry (ICP-MS), detection is presented. In this strategy, streptavidin modified QDs (QDs-SA) are bioconjugated to a biotinylated secondary antibody (b-Ab2). After a multi-technique characterization of the synthesized generic platform (QDs-SA-b-Ab2) it was applied to the sequential quantification of five proteins (transferrin, complement C3, apolipoprotein A1, transthyretin and apolipoprotein A4) at different concentration levels in human serum samples. It is shown how this generic strategy does only require the appropriate unlabeled primary antibody for each protein to be detected. Therefore, it introduces a way out to the need for the cumbersome and specific bioconjugation of the QDs to the corresponding specific recognition antibody for every target analyte (protein). Results obtained were validated with those obtained using UV–vis spectrophotometry and commercial ELISA Kits. 相似文献
2.
3.
4.
Marius Lupu Adnana Zaulet Prof. Dr. Francesc Teixidor Prof. Dr. Eliseo Ruiz Prof. Dr. Clara Viñas 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6888-6897
The metallacarborane [3,3′‐Co(1,2‐closo‐C2B9H11)2]? has been synthesized. This species allows the formation of redox couples in which both partners are negatively charged. The E1/2 potential can be tuned by adjusting the nature and number of substituents on B and C. The octaiodinated species [3,3′‐Co(1,2‐closo‐C2B9H7I4)2]? is the most favorable, as it is isolatable and stable in air. A DFT study on stability and redox potentials of complexes has been performed. 相似文献
5.
Fabio Fagnani Sandro Zampieri 《Transactions of the American Mathematical Society》1997,349(5):1993-2006
In this paper we study symbolic dynamics over alphabets which are modules over a principal ideal domain, considering topological shifts which are also submodules. Our main result is the classification, up to algebraic and topological conjugacy, of the torsion-free, transitive, finite memory shifts.
6.
Filippo Bracci Roberto Tauraso Fabio Vlacci 《Journal of Mathematical Analysis and Applications》2002,270(2):1131-473
Let f,g be two commuting holomorphic self-maps of the unit disc. If f and g agree at the common Wolff point up to a certain order of derivatives (no more than 3 if the Wolff point is on the unit circle), then f≡g. 相似文献
7.
We study a site analogue of directed percolation. Random trajectories are generated and their critical behavior is studied. The critical behavior corresponds to that of simple percolation in some of the parameter space, but elsewhere the exponents reveal new universality classes. As a byproduct, we use the model to make an improved estimate of the percolation hull exponents and to calculate the site percolation probability for the square lattice. 相似文献
8.
Fabio Schoen 《Journal of Global Optimization》1991,1(3):207-228
In this paper stochastic algorithms for global optimization are reviewed. After a brief introduction on random-search techniques, a more detailed analysis is carried out on the application of simulated annealing to continuous global optimization. The aim of such an analysis is mainly that of presenting recent papers on the subject, which have received only scarce attention in the most recent published surveys. Finally a very brief presentation of clustering techniques is given. 相似文献
9.
In this paper we introduce the notion of symplectically asystatic Hamiltonian action on a Kahler manifold. In the algebraic
setting we prove that if a complex linear group G acts on a Kahler manifold in a symplectically asystatic fashion, then the
G-orbits are spherical. Finally, we give the complete classification of symplectically asystatic irreducible representations. 相似文献
10.
G.P. Romanelli D. Bennardi D.M. Ruiz G. Baronetti H.J. Thomas 《Tetrahedron letters》2004,45(48):8935-8939
Substituted coumarins are synthesized from phenols and β-ketoesters by the Pechmann reaction, using a Wells-Dawson heteropolyacid (H6P2W18O62·24H2O) as catalyst by a solvent-free procedure. This one requires low reaction times, 130 °C temperature and as little as 1 mol % of Wells-Dawson acid, obtaining good to excellent yields of coumarins. The catalyst showed to be reusable with no differences in the yields. The results are compared with those of the reactions performed in toluene solution. The presented synthetic procedure is a convenient, clean and fast alternative for synthesizing 4-substituted coumarins (17 examples). 相似文献