全文获取类型
收费全文 | 364篇 |
免费 | 10篇 |
专业分类
化学 | 267篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 74篇 |
物理学 | 27篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 16篇 |
2020年 | 14篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 11篇 |
2012年 | 15篇 |
2011年 | 30篇 |
2010年 | 14篇 |
2009年 | 10篇 |
2008年 | 26篇 |
2007年 | 37篇 |
2006年 | 20篇 |
2005年 | 16篇 |
2004年 | 17篇 |
2003年 | 17篇 |
2002年 | 18篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1989年 | 3篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1906年 | 1篇 |
1904年 | 1篇 |
排序方式: 共有374条查询结果,搜索用时 8 毫秒
111.
Grazia Iannucci Vincenzo Passarelli Alessandro Passera Anna Iuliano 《Tetrahedron: Asymmetry》2017,28(11):1618-1625
Chiral binaphthyl diamidophosphites derived from deoxycholic acid were synthesized and used as ligands for the preparation of mononuclear Pd(II) complexes, which were employed as catalysts in the asymmetric Suzuki-Miyaura cross-coupling of arylboronic acids with aryl bromides. Among the different reaction parameters, the substrate concentration emerged as being crucial for the outcome of the reaction: the reaction was faster in a concentrated reaction mixture, and could be performed at 0 °C, where the reaction promoted by the Pd-complexes was more enantioselective affording cross-coupling products with ee up to 70%. 相似文献
112.
The asymptotic behavior for solutions of the semilinear motion equation of a linear viscoelastic solid of exponential type (VSET) is studied and the existence of a global attractor is proved. These results are obtained by means of a suitable class of quadratic free energies defined on the minimal state space and making use of semigroup techniques. This is the second part of a plan which was started in a previous paper [6] by the study of state-space representation, minimality and controllability for VSET. 相似文献
113.
We study some extended Lagrange interpolation processes based on the zeros of the generalized Laguerre polynomials. We give necessary and sufficient conditions such that the convergence of these processes, in suitable L p weighted spaces on the real semiaxis, is assured for 1<p<+∞. 相似文献
114.
Numerical Algorithms - In this paper, the generalized Love integral equation has been considered. In order to approximate the solution, a Nyström method based on a mixed quadrature rule has... 相似文献
115.
Mattia Scardamaglia Giuseppe Forte Silvano Lizzit Alessandro Baraldi Paolo Lacovig Rosanna Larciprete Carlo Mariani Maria Grazia Betti 《Journal of nanoparticle research》2011,13(11):6013-6020
Iron-phthalocyanine (FePc) molecules have been adsorbed on a graphene sheet prepared on the Ir(111) surface. The FePc molecules
are flat-lying on graphene, as determined by near-edge X-ray absorption fine-structure, constituting a sub-nanometer thick
molecular array at the single-layer coverage. The flat FePc single-layer presents a weak interaction of the organic macrocycle
with the graphene surface and Ir subsurface substrate. Further FePc deposition on top of the first flat single-layer determines
a three-dimensional island growth with varying molecular orientation. 相似文献
116.
Grazia Bencivenni Dr. Diana Salazar Illera Dr. Maria Moccia Prof. K. N. Houk Dr. Joseph A. Izzo Dr. Johanna Novacek Prof. Paolo Grieco Prof. Mathew J. Vetticatt Prof. Mario Waser Prof. Mauro F. A. Adamo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(44):11352-11366
Chiral phase-transfer catalysis provides high level of enantiocontrol, however no experimental data showed the interaction of catalysts and substrates. 1H NMR titration was carried out on Cinchona and Maruoka ammonium bromides vs. nitro, carbonyl, heterocycles, and N−F containing compounds. It was found that neutral organic species and quaternary ammonium salts interacted via an ensemble of catalyst +N−C−H and (sp2)C−H, specific for each substrate studied. The correspondent BArF salts interacted with carbonyls via a diverse set of +N−C−H and (sp2)C−H compared to bromides. This data suggests that BArF ammonium salts may display a different enantioselectivity profile. Although not providing quantitative data for the affinity constants, the data reported proofs that chiral ammonium salts coordinate with substrates, prior to transition state, through specific C−H positions in their structures, providing a new rational to rationalize the origin of enantioselectivity in their catalyses. 相似文献
117.
118.
Alfredo Marzocchi Jaime E. Mutoz Rivera Maria Grazia Naso 《Mathematical Methods in the Applied Sciences》2002,25(11):955-980
We show that the solution of a semilinear transmission problem between an elastic and a thermoelastic material, decays exponentially to zero. That is, denoting by ?(t) the sum of the first, second and third order energy associated with the system, we show that there exist positive constants C and γsatisfying ?(t) ? C?(0)e?γt Moreover, the existence of absorbing sets is achieved in the non‐homogeneous case. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
119.
In questo lavoro studiamo i generatori del modulo delle derivazioni di anelli di semigruppoR=k[S], dandone una caratterizzazione sotto opportune ipotesi suS. 相似文献
120.
Giovanni Neri Giuseppe Rizzo Signorino Galvagno Andrea Donato Maria Grazia Musolino Rosario Pietropaolo 《Reaction Kinetics and Catalysis Letters》2003,78(2):243-250
A microstructural characterization by XRD, FT-IR and temperature programmed reduction (TPR) of unsupported FeV and K-FeV catalysts,
prepared by solid-state synthesis, is reported. The formation of FexVyOz mixed phases of different compositions has been evidenced
depending on the V/Fe ratio and calcination temperature. The catalytic activity of the samples in the combustion of diesel
soot has been investigated with the aim to understand the role of FexVyOz mixed phases in the title reaction.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献