全文获取类型
收费全文 | 343篇 |
免费 | 23篇 |
专业分类
化学 | 301篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 34篇 |
物理学 | 26篇 |
出版年
2023年 | 9篇 |
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 13篇 |
2019年 | 7篇 |
2018年 | 1篇 |
2017年 | 7篇 |
2016年 | 18篇 |
2015年 | 16篇 |
2014年 | 16篇 |
2013年 | 20篇 |
2012年 | 39篇 |
2011年 | 33篇 |
2010年 | 21篇 |
2009年 | 17篇 |
2008年 | 30篇 |
2007年 | 20篇 |
2006年 | 16篇 |
2005年 | 25篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有366条查询结果,搜索用时 62 毫秒
91.
92.
Balz M Barriau E Istratov V Frey H Tremel W 《Langmuir : the ACS journal of surfaces and colloids》2005,21(9):3987-3991
The formation of biominerals by living organisms is governed by the cooperation of soluble and insoluble macromolecules with peculiar interfacial properties. To date, most of the studies on mineralization processes involve model systems that only account for the existence of one organic matrix and thus disregard the interaction between the soluble and insoluble organic components that is crucial for a better understanding of the processes taking place at the inorganic-organic interface. We have set up a model system composed of a matrix surface, namely, a self-assembled monolayer (SAM), and a soluble component, hyperbranched polyglycerol. The model mineral calcium carbonate displays diverse polymorphism. It could be demonstrated that the phase selection of calcium carbonate is controlled by the cooperative interaction of the SAM and hyperbranched polyglycerol of different molecular weights (M(n) = 500-6000 g/mol) adsorbed to the SAM. Our studies showed that hyperbranched polyglycerol is adsorbed to polar as well as to nonpolar SAMs. This effect can be related to its highly flexible structure and its amphiphilic character. The adsorption of hyperbranched polyglycerol to the SAMs with different surface polarities resulted in the formation of aragonite for alkyl-terminated SAMs and no phase selection for carboxylate-terminated SAMs. 相似文献
93.
Bourles E Alves de Sousa R Galardon E Giorgi M Artaud I 《Angewandte Chemie (International ed. in English)》2005,44(38):6162-6165
94.
Emilie Barriau Alejandra García Marcos Holger Kautz Holger Frey 《Macromolecular rapid communications》2005,26(11):862-867
Summary: A convenient three‐step strategy has been developed for the preparation of well‐defined amphiphilic, linear‐hyperbranched block copolymers by hypergrafting. The synthetic procedure is based on a combination of carbanionic polymerization with the alkoxide‐based, controlled ring‐opening multibranching polymerization of glycidol. A linear AB diblock copolymer polystyrene‐block‐polybutadiene (PS‐b‐PB) with narrow polydispersity was obtained by anionic copolymerization. Subsequent hydroxylation by hydroboration led to PS508‐b‐(PB‐OH)56, used as macroinitiator for the polymerization of glycidol under slow monomer addition conditions.
95.
Coraline Sester Fabrice Ofridam Noureddine Lebaz Emilie Gagnire Denis Mangin Abdelhamid Elaissari 《先进技术聚合物》2020,31(3):440-450
Poly (methyl methacrylate) derivatives such as Eudragit are largely used for drug encapsulation and in controlled oral drug delivery. With special focusing on those applications, solubilization and precipitation conditions of two pH‐sensitive Eudragit polymers, namely, L100 and E100, were investigated via systematic studies. Effects of various physicochemical parameters such as pH, polymer concentration, salinity, buffer concentration, and incubation time on the solubilization and precipitation of these polymers were investigated. In addition, pH titration of both polymers was reported. Considering both macroscopic and quantitative aspects such as the final mean particle size, size distribution, morphology, and the zeta potential, it was established that the different precited parameters could not be dissociated and exert a synergic action on the solubilization and precipitation of both polymers. Titration curves revealed two equivalences that helped estimating carboxylic content of Eudragit L100 (6 mmol/g) and ammonium content of Eudragit E100 (4 mmol/g). In this study, the solubilization and the precipitation domains were for the first time clearly established by considering the above‐mentioned parameters. Moreover, it was found that Eudragit L100 and E100 cannot be considered as classic polyelectrolytes; in fact, solubilization and precipitation domains were not affected by ionic strength. 相似文献
96.
Thermal Behavior of d‐Ribose Adsorbed on Silica: Effect of Inorganic Salt Coadsorption and Significance for Prebiotic Chemistry 下载免费PDF全文
Mariame Akouche Maguy Jaber Emilie‐Laure Zins Marie‐Christine Maurel Jean‐Francois Lambert Thomas Georgelin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15834-15846
Understanding ribose reactivity is a crucial step in the “RNA world” scenario because this molecule is a component of all extant nucleotides that make up RNA. In solution, ribose is unstable and susceptible to thermal destruction. We examined how ribose behaves upon thermal activation when adsorbed on silica, either alone or with the coadsorption of inorganic salts (MgCl2, CaCl2, SrCl2, CuCl2, FeCl2, FeCl3, ZnCl2). A combination of 13C NMR, in situ IR, and TGA analyses revealed a variety of phenomena. When adsorbed alone, ribose remains stable up to 150 °C, at which point ring opening is observed, together with minor oxidation to a lactone. All the metal salts studied showed specific interactions with ribose after dehydration, resulting in the formation of polydentate metal ion complexes. Anomeric equilibria were affected, generally favoring ribofuranoses. Zn2+ stabilized ribose up to higher temperatures than bare silica (180 to 200 °C). Most other cations had an adverse effect on ribose stability, with ring opening already upon drying at 70 °C. In addition, alkaline earth cations catalyzed the dehydration of ribose to furfural and, to variable degrees, its further decarbonylation to furan. Transition‐metal ions with open d‐shells took part in redox reactions with ribose, either as reagents or as catalysts. These results allow the likelihood of prebiotic chemistry scenarios to be evaluated, and may also be of interest for the valorization of biomass‐derived carbohydrates by heterogeneous catalysis. 相似文献
97.
98.
Estelle Gérard Emilie Bessy Gregory Hénard Laurent Ducoroy Thierry Verpoort Jacqueline Marchand‐Brynaert 《Journal of polymer science. Part A, Polymer chemistry》2011,49(23):5087-5099
The surface of meltblown poly(butylene terephthalate) (PBT) nonwoven was modified by photochemistry using the photolinker O‐succinimidyl 4‐azido‐2,3,5,6‐tetrafluorobenzoate for the introduction of activated ester functions and then coupling of molecular probes or biomolecules. Approximately 4000 pmol of (L )‐4,5‐[3H]‐lysine was fixed per PBT sample (1.13 cm2) and measured by liquid scintillation counting. The method consisted in a two‐step process: (a) coating of the clip (0.05 mg/sample) on the fibrous surface of the PBT followed by UV irradiation (30 min, 254 nm) and (b) coupling of amine‐terminated molecules (10?3 M in phosphate buffer–CH3CN [1/1, v/v], 20 h). Moreover, about 2000 pmol of 3H‐lysine can be immobilized on the PBT surface after UV irradiation (without clip) by aminolysis reactions with the created oxygenated functions. The derivatizations (via the clip and UV irradiation only) were stable after long‐term heating at 100 °C in water or under steam‐sterilization conditions. They induce neither modifications of the nonwoven morphology nor cytotoxicity. This method was applied for the grafting of peptides Gly‐Arg‐Gly‐Asp‐Ser and Gly‐Gly‐Gly‐Gly‐Gly to perform blood filtration experiments and to retain the leukocytes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
99.
100.
Dorian Sonet Mattéo Cayla Dr. Raphaël Méreau Estelle Morvan Aline Lacoudre Dr. Nicolas Vanthuyne Muriel Albalat Dr. Dario M. Bassani Dr. Antoine Scalabre Dr. Emilie Pouget Prof. Dr. Brigitte Bibal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(72):e202202695
Chiral trifluoromethyl alcohol groups were introduced at the hindered ortho positions of 9,10-diphenylanthracenes to investigate their effects on the physical properties and reactivity towards oxidative dearomatization. In such compact structures, the position in different quadrants and the preferred orientation of the −CH(OH)CF3 groups were determined by the relative and absolute configurations of each stereoisomer, respectively. As a consequence, the stereochemistry governs the organization of the H-bonded molecules in single crystals (homochiral dimers vs ribbon), whereas in chlorinated solvents, they all behave as discrete compounds. Concerning their reactivity, the stereospecific dearomative oxidation of these molecules leads to 9,10-bis-spiro-isobenzofuran-anthracenes, when using organic single-electron transfer oxidants. The chiroptical properties of the alcohols and the corresponding dearomatized products were compared and showed an important modulation of the intensity. 相似文献