全文获取类型
收费全文 | 408篇 |
免费 | 29篇 |
专业分类
化学 | 320篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 31篇 |
物理学 | 80篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 13篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 15篇 |
2014年 | 14篇 |
2013年 | 30篇 |
2012年 | 26篇 |
2011年 | 19篇 |
2010年 | 17篇 |
2009年 | 19篇 |
2008年 | 29篇 |
2007年 | 21篇 |
2006年 | 27篇 |
2005年 | 20篇 |
2004年 | 23篇 |
2003年 | 27篇 |
2002年 | 23篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1943年 | 1篇 |
1912年 | 1篇 |
排序方式: 共有437条查询结果,搜索用时 15 毫秒
51.
We consider the two-dimensional motion of a rigid structure immersed in an incompressible fluid governed by Navier–Stokes equations. The control force acts on a fixed subset of the fluid domain. We prove that our system is null controllable; that is, for small initial data, the system can be driven at rest and the structure can be driven to the origin at a given . The result holds for a structure symmetric with respect to the center of mass and for initial conditions satisfying strong compatibility conditions. To cite this article: M. Boulakia, A. Osses, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
52.
53.
An efficient method for the synthesis of N-acyl-benzotriazoles from a wide variety of protected amino acids, as well as from compounds frequently used in drug discovery such as biotin and N-Fmoc polyethylene glycol, has been developed. The reaction of carboxylic acid derivatives with benzotriazole in the presence of T3P® yielded the corresponding N-acyl-benzotriazoles, which were obtained in high purity following a simple work-up procedure, in most cases via precipitation of the desired product in water. 相似文献
54.
Anca‐Elena Dascalu Alina Ghinet Muriel Billamboz Emmanuelle Lipka 《Electrophoresis》2019,40(15):1986-1991
CD‐CZE methods were developed for complete stereoisomeric separations of a series of six γ‐lactam analogues, of which some were neutral, or cationic depending on the background electrolyte nature. The tested cyclodextrin was the versatile sulfobutylether‐ β‐CD, used either in a phosphate buffer using capillaries dynamically coated with polyethylene oxide or in a borate buffer using uncoated capillaries. Long‐end and short‐end modes and concentration variations of chiral selectors allowed finding conditions of complete separation of four out of the six derivatives (i.e., 1 , 2 , 3, and 4 ) in short run times, confirming their broad range of applications. To separate the two last compounds, the highly sulfated‐ γ‐CD was examined as chiral selector in acidic phosphate conditions. The enantiomers of the γ‐lactam analogues 5 and 6 were baseline resolved with 5.5 and 4%, respectively as concentration in the buffer. 相似文献
55.
We demonstrate a simple technique for the implementation of an all-optical integrator based on a uniform-period fiber Bragg grating (FBG) in reflection that is designed to present a decreasing exponential impulse response. The proposed FBG integrator is readily feasible and can perform close to ideal integration of few-picosecond and subpicosecond pulses. 相似文献
56.
57.
Romain Bénéteau Anne Boussonnière Jean‐Christophe Rouaud Prof. Dr. Jacques Lebreton Dr. Jérôme Graton Prof. Dr. Denis Jacquemin Dr. Muriel Sebban Prof. Dr. Hassan Oulyadi Ghanem Hamdoun Dr. Amber N. Hancock Prof. Dr. Carl H. Schiesser Dr. Fabrice Dénès 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4809-4824
α‐Bromo aluminium acetals are suitable substrates for Ueno–Stork‐like radical cyclisations affording γ‐lactols and acid‐sensitive methylene‐γ‐lactols in high yields. The mechanistic study herein sets the scope and limitation of this reaction. The influence of the halide (or chalcogenide) atom X (X=Cl, Br, I, SPh, SePh) in the precursors α‐haloesters, as well as influence of the solvent and temperature was studied. The structure of the aluminium acetal intermediates resulting from the reduction of the corresponding α‐haloesters has been investigated by low‐temperature 13C‐INEPT diffusion‐ordered NMR spectroscopy (DOSY) experiments and quantum calculations, providing new insights into the structures of these thermally labile intermediates. Oxygen‐bridged dimeric structures with a planar Al2O2 ring are proposed for the least hindered aluminium acetals, while monomeric structures seem to prevail for the most hindered species. A comparison against the radical cyclisation of aluminium acetals derived from allyl and propargyl alcohols with the parent Ueno–Stork has been made at the BHandHLYP/6‐311++G(d,p) level of theory, highlighting mechanistic similarities and differences. 相似文献
58.
59.
Vivares D Soussan E Blanzat M Rico-Lattes I 《Langmuir : the ACS journal of surfaces and colloids》2008,24(17):9260-9267
The aggregation behavior of the cationic-rich side of a sugar-based tricatenar catanionic mixture was investigated in water, and it was shown that the excess of cationic sugar-based surfactant enhanced vesicle stability as well as encapsulation properties. Moreover, when the system was diluted, the vesicular solution collapsed into a lamellar phase, whereas, when it was concentrated, no major impact on the shape and stability of the aggregates was observed. We also showed that both an increase in temperature and the addition of salt induced reversible vesicle aggregation, which appeared to be salt-specific, following the direct order of the Hofmeister series. A proper adjustment of these parameters should then enable better control of the shape, stability, and even encapsulation ability of the aggregates formed by these tricatenar cationic/anionic mixtures. 相似文献
60.
Dr. Serhii Krykun Dr. Muriel Durandetti 《European journal of organic chemistry》2023,26(4):e202201393
A convenient and efficient approach for the construction of aryl trifluoromethyl selenoethers from aryl iodides under mild conditions is reported. Electrochemical activation of stable and inexpensive NiBr2bipy (bipy – bipyridine) complex instead of labile Ni(COD)2 (COD – cyclooctadiene) catalyst. [NMe4][SeCF3] is employed as shelf-stable source of SeCF3 fragment. The reaction tolerates a wide range of substrates, including modification of drug-like molecules. Cyclic voltammetry studies allow insight into the reaction mechanism. 相似文献