全文获取类型
收费全文 | 5968篇 |
免费 | 135篇 |
国内免费 | 46篇 |
专业分类
化学 | 3717篇 |
晶体学 | 35篇 |
力学 | 208篇 |
数学 | 1275篇 |
物理学 | 914篇 |
出版年
2022年 | 54篇 |
2021年 | 57篇 |
2020年 | 65篇 |
2019年 | 67篇 |
2018年 | 58篇 |
2017年 | 49篇 |
2016年 | 96篇 |
2015年 | 116篇 |
2014年 | 135篇 |
2013年 | 310篇 |
2012年 | 294篇 |
2011年 | 325篇 |
2010年 | 222篇 |
2009年 | 207篇 |
2008年 | 305篇 |
2007年 | 315篇 |
2006年 | 305篇 |
2005年 | 272篇 |
2004年 | 267篇 |
2003年 | 216篇 |
2002年 | 209篇 |
2001年 | 99篇 |
2000年 | 91篇 |
1999年 | 98篇 |
1998年 | 73篇 |
1997年 | 66篇 |
1996年 | 90篇 |
1995年 | 66篇 |
1994年 | 73篇 |
1993年 | 81篇 |
1992年 | 65篇 |
1991年 | 43篇 |
1990年 | 75篇 |
1989年 | 59篇 |
1988年 | 47篇 |
1987年 | 53篇 |
1986年 | 47篇 |
1985年 | 68篇 |
1984年 | 81篇 |
1983年 | 51篇 |
1982年 | 79篇 |
1981年 | 79篇 |
1980年 | 94篇 |
1979年 | 75篇 |
1978年 | 80篇 |
1977年 | 76篇 |
1976年 | 71篇 |
1975年 | 51篇 |
1974年 | 38篇 |
1973年 | 58篇 |
排序方式: 共有6149条查询结果,搜索用时 15 毫秒
991.
Michel Bara 《Journal of Electroanalytical Chemistry》1982,141(4):517-525
The transfer of solutes and water across the amniotic membrane, in vivo, is controlled by hydraulic, osmotic and electrochemical factors. In this study the electrochemical component is specified in vitro, and the mechanism of ion transport across the amnion is characterized by comparison with artificial membranes (bilayers and Teflon millipore filters). The electrochemical study shows that the amniotic conductance depends on time and salt concentration; the cationic transference number is comprised between 0.75 and 0.85; the electro-osmotic potentials are negative; the I(V) curves are linear; the activation conductance energy ranges between 4 and 8 kcal degree?1 mole?1 and the cation selectivity sequence is: RbCsK>Na>Li. The pharmacological agents (ouabain, amiloride, dinitrophenol) decrease gNa. These results suggest: (1) that the amnion has fixed neutral sites in external epithelial cell membranes and on intercellular channels with, under certain conditions, negative sites in greater number than positive sites; (2) that the amnion is comparable to negative artificial membranes; (3) that the paracellular pathway is more important than the transcellular pathway; (4) that there are specific sites on the external membranes and in intercellular channels. 相似文献
992.
Jean-Claude Richer Martine Beljean Michel Pays 《Journal of mass spectrometry : JMS》1977,12(11):689-694
The synthesis and the spectral properties of 2-alkylidenehydrazono-3-methyl-2,3-dihydrobenzothiazoles are reported. In the mass spectra of each of these compounds, the main fragmentation implies the breaking of the ?N? -N?bond of the azine. 相似文献
993.
994.
995.
996.
Michel Lassalle 《Inventiones Mathematicae》1984,77(1):129-161
Sans résumé 相似文献
997.
Roger Spitz Jean-Loup Lacombe Michel Primet 《Journal of polymer science. Part A, Polymer chemistry》1984,22(10):2611-2624
In this article we describe a study of the reaction between triethylaluminium (TEA) and ethylbenzoate (BE) in a heptane solution by Fourier transform, infrared (IR), and ultraviolet (UV) spectroscopy. These compounds were chosen as a model of the cocatalytic solution used with a Ziegler-Natta catalyst supported on MgCl2 for the stereospecific polymerization of propene. In the polymerization concentration range a 2 TEA:1 BE yellow complex was added to the solution and no free BE could be detected at a AI/BE molar ratio above 2: the solution contained only free and complexed TEA. The complex decomposed spontaneously to a colorless aluminium alcoholate. The rate of decomposition remained slow at room temperature and the reaction was enhanced by heating or by a high AI/BE ratio or high AI concentration. The decomposition was inhibited in the presence of an olefin. 相似文献
998.
Mireille Bourhis René Golse Michel Goursolle Philippe Picard 《Tetrahedron letters》1985,26(29):3445-3448
Amino norbornenonecarboxylates were synthesized from methyl acrylate and amino butadienecarboxylates. This result is equivalent of amino cyclopentadienones Diels-Alder reaction. Amino butadienecarboxylates were prepared by prototropic transposition of the β-allenic aminoesters. 相似文献
999.
Michel André 《manuscripta mathematica》1988,60(2):171-183
For a J-ring A, each deviation is bounded on Spec A and the morphism of A into the infinite product IIA has almost the contangent complex of a smooth morphism. 相似文献
1000.