全文获取类型
收费全文 | 1663篇 |
免费 | 20篇 |
国内免费 | 22篇 |
专业分类
化学 | 1075篇 |
晶体学 | 15篇 |
力学 | 51篇 |
数学 | 311篇 |
物理学 | 253篇 |
出版年
2022年 | 17篇 |
2021年 | 23篇 |
2020年 | 16篇 |
2019年 | 20篇 |
2018年 | 19篇 |
2017年 | 21篇 |
2016年 | 38篇 |
2015年 | 20篇 |
2014年 | 44篇 |
2013年 | 81篇 |
2012年 | 81篇 |
2011年 | 76篇 |
2010年 | 59篇 |
2009年 | 68篇 |
2008年 | 87篇 |
2007年 | 112篇 |
2006年 | 102篇 |
2005年 | 86篇 |
2004年 | 78篇 |
2003年 | 59篇 |
2002年 | 48篇 |
2001年 | 33篇 |
2000年 | 23篇 |
1999年 | 20篇 |
1998年 | 20篇 |
1997年 | 22篇 |
1996年 | 33篇 |
1995年 | 24篇 |
1994年 | 22篇 |
1993年 | 23篇 |
1992年 | 19篇 |
1991年 | 16篇 |
1990年 | 21篇 |
1989年 | 15篇 |
1988年 | 17篇 |
1987年 | 14篇 |
1986年 | 16篇 |
1985年 | 23篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1982年 | 24篇 |
1981年 | 12篇 |
1980年 | 15篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1977年 | 18篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1965年 | 8篇 |
排序方式: 共有1705条查询结果,搜索用时 0 毫秒
81.
For wide classes of locally convex spaces, in particular, for the space of continuous real‐valued functions on a Tychonoff space X equipped with the pointwise topology, we characterize the existence of a fundamental bounded resolution (i.e., an increasing family of bounded sets indexed by the irrationals which swallows the bounded sets). These facts together with some results from Grothendieck's theory of ‐spaces have led us to introduce quasi‐ ‐spaces, a class of locally convex spaces containing ‐spaces that preserves subspaces, countable direct sums and countable products. Regular ‐spaces as well as their strong duals are quasi‐ ‐spaces. Hence the space of distributions provides a concrete example of a quasi‐ ‐space not being a ‐space. We show that has a fundamental bounded resolution if and only if is a quasi‐ ‐space if and only if the strong dual of is a quasi‐ ‐space if and only if X is countable. If X is metrizable, then is a quasi‐ ‐space if and only if X is a σ‐compact Polish space. 相似文献
82.
Litak Grzegorz Margielewicz Jerzy Gąska Damian Yurchenko Daniil Dąbek Krzysztof 《Nonlinear dynamics》2020,102(4):2125-2142
Nonlinear Dynamics - This paper examines the oscillations of a spherical pendulum with horizontal Lissajous excitation. The pendulum has two degrees of freedom: a rotational angle defined in the... 相似文献
83.
84.
85.
86.
87.
88.
Maria Kucharska-Zon Jerzy Zon 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Many complexes of 1-aminoakylphosphonic acids have been obtained and their structures have been studied [1–3]. On the other hand, 2-aminoindan-2-phosphonic acid (2-AIP), the phosphonic conformationally restricted cyclic analogue of phenylalanine, has been recently obtained [4]. We undertook a study of interaction of cobalt(II), nickel(II), and copper(II) with 2-AIP, to learn how the rigid Iigand structure influences the complexes structure. 相似文献
89.
Jerzy Zakrzewski Maria Krawczyk 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1880-1903
Thio and seleno analogs of fenuron, isoproturon, chlorotoluron, metoxuron, monuron, and diuron were synthesized from the corresponding aryl amines. Their reaction with thiophosgene leads to isothiocyanates. Aryl amines were also converted (via isocyanides) to isoselenocyanates. The reaction of both isothio- and isoselenocyanates with dimethylamine affords the corresponding thio and seleno analogs of the above-mentioned urea herbicides. Herbicidal activity of the synthesized compounds was slightly lower than the activity of the parent urea herbicides. The thio and seleno analogs as well as the parent ureas showed good fungicidal activity at a concentration of 200 ppm against selected fungi. 相似文献
90.
Roza Trzcinska Piotr Suder Anna Bodzon-Kulakowska Magdalena Skalska Andrzej Marcinkowski Jerzy Kubacki Roman Pedrys Jerzy Silberring Andrzej Dworak Barbara Trzebicka 《Analytical and bioanalytical chemistry》2013,405(28):9049-9059
Peptide surfaces were obtained by the covalent immobilisation of fluorescently labelled pentapeptides carboxyfluorescein–glycine–arginine–methionine–leucine–glycine, either directly or through a poly(ethylene glycol) (PEG) linker on modified silicon wafers. Each step during the preparation of the peptide surfaces was confirmed by several surface characterisation techniques. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy were used to determine the surface composition, the wafers philicity was measured by contact angle and atomic force microscopy was used to investigate the surface morphology. Exposure of the peptide surfaces to trypsin resulted in the release of a fluorescently labelled peptide product, which allowed the kinetics of the enzymatic reaction to be followed with the aid of fluorescence spectroscopy. The electrospray ionisation mass spectrometry analysis of the post-digestion solution confirmed that the pentapeptides attached to the solid support undergo specific trypsin hydrolysis at the C-terminus of the arginine residues. Detailed surface analyses before and after the enzyme action was performed using ToF-SIMS. Because of the limited accessibility of the short peptide directly attached to the surface, a quantitative yield of enzymatic hydrolysis was observed only in case when the peptide was bound through the PEG linker. The insertion of the PEG linker increased the number of immobilised peptides and the rate of enzymatic digestion which consequently improved the quality of the enzyme assays. The described approach may be used for different peptide sequences designed for other proteases. Figure
Monitoring of trypsin hydrolysis on PEG-peptide surface 相似文献