全文获取类型
收费全文 | 711篇 |
免费 | 45篇 |
国内免费 | 3篇 |
专业分类
化学 | 509篇 |
晶体学 | 8篇 |
力学 | 17篇 |
数学 | 108篇 |
物理学 | 117篇 |
出版年
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 13篇 |
2020年 | 25篇 |
2019年 | 13篇 |
2018年 | 6篇 |
2017年 | 11篇 |
2016年 | 20篇 |
2015年 | 22篇 |
2014年 | 20篇 |
2013年 | 31篇 |
2012年 | 60篇 |
2011年 | 58篇 |
2010年 | 44篇 |
2009年 | 21篇 |
2008年 | 59篇 |
2007年 | 44篇 |
2006年 | 38篇 |
2005年 | 34篇 |
2004年 | 23篇 |
2003年 | 18篇 |
2002年 | 18篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 3篇 |
1980年 | 4篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 7篇 |
1939年 | 3篇 |
1924年 | 2篇 |
排序方式: 共有759条查询结果,搜索用时 15 毫秒
71.
Morgan Tizzotti Marie‐Pierre Labeau Thierry Hamaide Eric Drockenmuller Aurélia Charlot Etienne Fleury 《Journal of polymer science. Part A, Polymer chemistry》2010,48(13):2733-2742
Thermosensitive guar‐based hydrogels are obtained in water solutions by copper‐catalyzed 1,3‐dipolar cycloaddition between alkyne‐functionalized guars and α,ω‐diazido‐poly[(ethylene glycol)‐co‐(propylene glycol)]. Characterization by TGA, HR‐MAS 1H NMR, and rheology have shown that hydrogels with tunable physico‐chemical properties, such as crosslinking density, viscoelasticity, swelling ratio, and so forth, could be obtained by varying the guar molar mass, the degree of alkyne functionality, the guar/crosslinker weight ratio, and the reaction temperature. Based on swelling measurements, it has been shown that the thermal sensitiveness of guar‐based hydrogels is fast, reversible, and intimately related to the weight fraction of the thermosensitive crosslinker in the network. Finally, the monitoring of doxorubicin hydrochloride release has demonstrated the potential of these hydrogels as temperature‐dependent drug release devices. The robust, efficient, and orthogonal approach described herein represents a general approach towards the development of well‐controlled guar‐based hydrogels using α,ω‐diazido crosslinkers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2733–2742, 2010 相似文献
72.
73.
74.
75.
Franck Pastor Malorie Trillat Joseph Pastor Etienne Loute 《Comptes Rendus Mecanique》2006,334(4):213-219
A nonlinear interior point method associated with the kinematic theorem of limit analysis is proposed. Associating these two tools enables one to determine an upper bound of the limit loading of a Gurson material structure from the knowledge of the sole yield criterion. We present the main features of the interior point algorithm and an original method providing a rigorous kinematic bound from a stress formulation of the problem. This method is tested by solving in plane strain the problem of a Gurson infinite bar compressed between rough rigid plates. To cite this article: F. Pastor et al., C. R. Mecanique 334 (2006). 相似文献
76.
Charles Moureu und Etienne Boismenu 《Fresenius' Journal of Analytical Chemistry》1924,65(3-4):157-158
Ohne Zusammenfassung 相似文献
77.
The oscillating flow field in a thermoacoustic stack is visualized experimentally using PIV measurements, and computationally using results of low-Mach-number simulations. The experiments and computations are performed under similar conditions. Results are obtained for two distinct configurations, involving thin and thick stack plates. In the first case, the flow field around the edge of the stack exhibits elongated vorticity layers, while in the latter it is dominated by the shedding and impingement of concentrated vortices. A close agreement between experimental and computational results is found, thus providing strong support for both approaches and further predictions. To cite this article: P. Blanc-Benon et al., C. R. Mecanique 331 (2003). 相似文献
78.
A Bioinspired Molybdenum Complex as a Catalyst for the Photo‐ and Electroreduction of Protons 下载免费PDF全文
Jean‐Philippe Porcher Thibault Fogeron Dr. Maria Gomez‐Mingot Dr. Etienne Derat Lise‐Marie Chamoreau Dr. Yun Li Prof. Marc Fontecave 《Angewandte Chemie (International ed. in English)》2015,54(47):14090-14093
A molybdenum–dithiolene–oxo complex was prepared as a model of some active sites of Mo/W‐dependent enzymes. The ligand, a quinoxaline–pyran‐fused dithiolene, mimics molybdopterin present in these active sites. For the first time, this type of complex was shown to be active as a catalyst for the photoreduction of protons with excellent turnover numbers (500) and good stability in aqueous/organic media and for the electroreduction of protons in acetonitrile with remarkable rate constants (1030 s?1 at ?1.3 V versus Ag/AgCl). DFT calculations provided insight into the catalytic cycle of the reaction, suggesting that the oxo ligand plays a key role in proton exchange. These results provide a basis to optimize this new class of H2‐evolving catalysts. 相似文献
79.
A Highly Effective Ruthenium System for the Catalyzed Dehydrogenative Cyclization of Amine–Boranes to Cyclic Boranes under Mild Conditions 下载免费PDF全文
Dr. Christopher J. Wallis Dr. Gilles Alcaraz Dr. Alban S. Petit Dr. Amalia I. Poblador‐Bahamonde Dr. Eric Clot Dr. Christian Bijani Dr. Laure Vendier Dr. Sylviane Sabo‐Etienne 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):13080-13090
We recently disclosed a new ruthenium‐catalyzed dehydrogenative cyclization process (CDC) of diamine–monoboranes leading to cyclic diaminoboranes. In the present study, the CDC reaction has been successfully extended to a larger number of diamine–monoboranes ( 4 – 7 ) and to one amine–borane alcohol precursor ( 8 ). The corresponding NB(H)N‐ and NB(H)O‐containing cyclic diaminoboranes ( 12 – 15 ) and oxazaborolidine ( 16 ) were obtained in good to high yields. Multiple substitution patterns on the starting amine–borane substrates were evaluated and the reaction was also performed with chiral substrates. Efforts have been spent to understand the mechanism of the ruthenium CDC process. In addition to a computational approach, a strategy enabling the kinetic discrimination on successive events of the catalytic process leading to the formation of the NB(H)N linkage was performed on the six‐carbon chain diamine–monoborane 21 and completed with a 15N NMR study. The long‐life bis‐σ‐borane ruthenium intermediate 23 possessing a reactive NHMe ending was characterized in situ and proved to catalyze the dehydrogenative cyclization of 1 , ascertaining that bis σ‐borane ruthenium complexes are key intermediates in the CDC process. 相似文献
80.
Audrey Llevot Etienne Grau Stphane Carlotti Stphane Grelier Henri Cramail 《Macromolecular rapid communications》2016,37(1):9-28
Nowadays, the synthesis of (semi)aromatic polymers from lignin derivatives is of major interest, as aromatic compounds are key intermediates in the manufacture of polymers and lignin is the main source of aromatic biobased substrates. Phenols with a variety of chemical structures can be obtained from lignin deconstruction; among them, vanillin and ferulic acid are the main ones. Depending on the phenol substrates, different chemical modifications and polymerization pathways are developed, leading to (semi)aromatic polymers covering a wide range of thermomechanical properties. This review discusses the synthesis and properties of thermosets (vinyl ester resins, cyanate ester, epoxy, and benzoxazine resins) and thermoplastic polymers (polyesters, polyanhydrides, Schiff base polymers, polyacetals, polyoxalates, polycarbonates, acrylate polymers) prepared from vanillin, ferulic acid, guaiacol, syringaldehyde, or 4‐hydroxybenzoic acid.