全文获取类型
收费全文 | 158篇 |
免费 | 3篇 |
专业分类
化学 | 122篇 |
力学 | 4篇 |
数学 | 19篇 |
物理学 | 16篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 10篇 |
2011年 | 5篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 11篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1992年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1970年 | 3篇 |
1969年 | 4篇 |
1968年 | 4篇 |
1955年 | 1篇 |
1954年 | 4篇 |
1924年 | 1篇 |
1882年 | 2篇 |
排序方式: 共有161条查询结果,搜索用时 31 毫秒
1.
Mathilde Kammerer-Colin de Verdière 《Comptes Rendus Mathematique》2004,339(9):625-629
For generic families of vector fields or transformations, normally hyperbolic invariant products of spheres appear near partially elliptic rest points. To cite this article: M. Kammerer-Colin de Verdière, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
2.
3.
Marc Chaperon Mathilde Kammerer-Colin De Verdière Santiago López De Medrano 《Comptes Rendus Mathematique》2006,342(5):301-305
Near partially elliptic rest points of generic families of vector fields or transformations, many types of normally hyperbolic invariant compact manifolds can appear, diffeomorphic to intersections of quadrics. To cite this article: M. Chaperon et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
4.
Résumé Les auteurs décrivent une méthode efficate et les conditions (faibles valeurs de pH, milieu dioxane/eau (1∶2), carbodiimide
hydrosoluble) de formation de peptides colorés par réaction de leur groupe carboxylique avec un colorant aminé (par exemple:
1(4-diméthylamino-1 phénylazo)-4-aminobenzène=p,p′-dimapa-aniline), sans polymérisation du peptide non-protégé. Quelques méthodes
chromatographiques, faciles à mettre en oeuvre, pour l'isolement de peptide-p,p′-dimapa-anilides et quelques propriétés de
ces nouveaux composés (peptides-C-colorés) sont présentées.
相似文献
Method for labelling carboxylic groups in peptides. Chromatographic and other properties of peptide-p,p′-dimapa-anilides
Summary The authors describe an effective method and the conditions (low pH values, dioxane/water (1∶2) media, watersoluble carbodiimide) for making coloured carboxylic peptides from amino-dye (i.e.: 1(4-dimethylamino-1 phenylazo)-4-aminobenzene=p,p′-dimapa-aniline), without polymerisation of unprotected peptide. Some easy chromatographic methods for isolation of peptide-p,p′-dimapa-anilides and some properties of these new compounds (C-dyed-peptides) are given.
相似文献
5.
6.
Summary New separation procedures for alkaloids of similar polarity and structure or of very different polarity and structure, based upon two-dimensional thin-layer chromatography on unmodified silica gel under mild conditions are described. Separation factors and separation mechanisms based on the structure of the bases and mobile phase composition are discussed for some examples of very efficient procedures.Proportions in solvent mixtures are v/v except where otherwise indicated. 相似文献
7.
Résumé De nouveaux solvants mobiles contenant un acide volatil sont proposés pour la séparation des acides aliphatiques non volatils du métabolisme et des fermentations et des diacides aliphatiques à chaîne droite. Les solvants les plus efficaces du point de vue séparation, sont ceux qui contiennent des éthers. Les meilleurs chromatogrammes sont ceux pour lesquels les frontières d'autochromatographie des produits issus des liants de la couche et des composants du solvant ont une très faible mobilitè. D'excellentes séparations sont obtenues par chromatographie sur couche mince de poudre de cellulose. Les solvants mobiles les plus intéressants sont:Eucalyptol/acide formique 98%/eau (65025075) Ether di-n-butylique/acide formique 98%/eau (65025022)Ether di-isopropylique/acide formique 98%/eau (650250100) Ether di-isoamylique/acide formique 98%/eau (6502505,5)Benzène/acide propionique/eau (47047057) Toluène/acide propionique/eau (47047049)Par suite des propriétés adsorbantes et échangeuses d'ions du gel de silice, les résultats obtenus sur ces couches minces sont décevants pour la plupart des acides aliphatiques lorsqu'on les chromatographie dans un solvant mobile alcalin. Il en est de même pour les acides oxalique et malonique, les hydroxyacides et les acides aliphatiques du métabolisme et des fermentations lorsqu'on les chromatographie dans un solvant mobile acide.
Thin-layer chromatography of non-volatile aliphatic acids. Part I. New mobile phases containing a volatile acid. Preliminary observations
Summary New mobile phases containing a volatile acid are proposed for the separation of non-volatile aliphatic acids (metabolic acids or acids produced in fermentation) and of straight-chain aliphatic diacids. From the point of view of separations, solvents containing ethers are the most efficient. Best results are obtained when impurities in the binder and the components of the solvent are of very low mobility. Excellent separations are obtained by chromatography on cellulose powder thin layers.The most interesting mobile solvents are: Eucalyptol/98% formic acid/water (65025075) n-Dibutyl-ether/98% formic acid/water (65025022). Diisopropyl-ether/98% formic acid/water (650250100). Diisoamyl-ether/98% formic acid/water (6502505.5). Benzene/propionic acid/water (47047057). Toluene/propionic acid/water (47047049).Because of its adsorbent and ion-exchange properties, results obtained with thin layers of silica gel are disappointing for most aliphatic acids when chromatographed using an alkaline mobile phase, and for oxalic and malonic acids, hydroxyacids, aliphatic metabolic acids and aliphatic acids produced during fermentation when chromatographed using an acid mobile phase.相似文献
8.
Yingyongnarongkul BE How SE Díaz-Mochón JJ Muzerelle M Bradley M 《Combinatorial chemistry & high throughput screening》2003,6(7):577-587
Advances in high throughput screening (HTS), together with the rapid progress in combinatorial chemistry, genomic and proteomic sciences have dramatically stimulated the development of a variety tools to enable the drug discovery process to become more efficient. Major future challenges in HTS include obtaining high density and good quality data based on assays that are rapid, reliable, inexpensive, sensitive, simple and miniaturised. This paper reviews the development and role of bead-based assays for HTS including DNA and single nucleotide polymorphism (SNP) assays, particularly from a multiplex perspective and evaluating the recent advances in bead-based arrays. The encoding strategies that are commonly used in bead-based assays are highlighted, while the importance of magnetic beads in genomic and proteomic purifications is discussed. In conclusion, bead-based assays offer a powerful promising approach for many aspects of drug discovery. 相似文献
9.
A convenient method for the conjugation of ruthenium complex on oligonucleotides and peptides through chemoselective oxime linkage is reported. Novel Ru(II) complexes sustaining an aminooxy containing ligand were prepared and efficiently coupled with the oligonucleotides and peptides functionalized with the complementary reactive aldehyde group. The method described herein could be a useful tool for preparing a broad range of metal complex-oligonucleotide and peptide conjugates. 相似文献
10.
Laura Febvay Erwann Hamon Raphaël Recht Nicolas Andres Mathilde Vincent Dalal Aoudé-Werner Hervé This 《Magnetic resonance in chemistry : MRC》2019,57(9):589-602
Roasting of Coffea arabica L. seeds gives rise to chemical reactions that produce more than 800 compounds, some being responsible for the desired organoleptic properties for which the beverage called “coffee” is known. In the industry, the “roasting profile,” that is, the times and temperatures applied, is key to influence the composition of roasted coffee beans and the flavour of the beverage made from them. The impact of roasting on the chemical composition of coffee has been the subject of numerous studies, including by nuclear magnetic resonance (NMR) spectroscopy. However, the roasting equipment and profiles applied in these studies are often far from real industrial conditions. In this work, the effects of two critical technological parameters of the roasting process, namely, the “development time” (the period of time after the “first crack,” a characteristic noise due to seed disruption) and the final roasting temperature on coffee extracts, were investigated. Seeds were roasted at pilot scale according to 13 industrial roasting profiles and extracted in D2O. The extracts were analysed by 1H NMR experiments. The NMR spectra were compared using (a) quantitative analysis of main signals by successive orders of magnitude and (b) chemometric tools (principal component analysis, partial least squares and sparse-orthogonal partial least squares analysis). This allowed to identify compounds, which may serve as markers of roasting and showed that changes in chemical composition can be detected even for slight change in final temperature (~1°C) or in total roasting time (~25 s). 相似文献