全文获取类型
收费全文 | 1154篇 |
免费 | 63篇 |
国内免费 | 6篇 |
专业分类
化学 | 760篇 |
晶体学 | 7篇 |
力学 | 32篇 |
数学 | 190篇 |
物理学 | 234篇 |
出版年
2023年 | 9篇 |
2022年 | 20篇 |
2021年 | 26篇 |
2020年 | 33篇 |
2019年 | 37篇 |
2018年 | 25篇 |
2017年 | 14篇 |
2016年 | 37篇 |
2015年 | 46篇 |
2014年 | 45篇 |
2013年 | 65篇 |
2012年 | 94篇 |
2011年 | 111篇 |
2010年 | 57篇 |
2009年 | 52篇 |
2008年 | 88篇 |
2007年 | 72篇 |
2006年 | 57篇 |
2005年 | 49篇 |
2004年 | 40篇 |
2003年 | 28篇 |
2002年 | 22篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 12篇 |
1997年 | 6篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 3篇 |
1981年 | 5篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1969年 | 5篇 |
排序方式: 共有1223条查询结果,搜索用时 31 毫秒
101.
102.
Dr. Yuexia Wang Dr. Giovanni Barcaro Dr. Fabio R. Negreiros Dr. Thierry Visart de Bocarmé Dr. Mathieu Moors Dr. Norbert Kruse Dr. Marc Hou Dr. Alessandro Fortunelli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(1):406-413
Carbon adsorption on various Ni surfaces is investigated as a function of coverage via a combination of first‐principles simulations and field emission microscope experiments. It is found that carbon can be efficiently stored as subsurface carbides, but with different energetics on differently oriented surfaces depending on their compactness and density of adsorption sites. In the resulting morphological reshaping, {113} facets are predicted to grow at the expense of {111} and {100} facets, in excellent agreement with experimental observations. Moreover, at high coverage on the {113} surface the carbon adsorption energy passes through a maximum after which a structural crossover is realized such that carbon atoms tend to ascend to the surface to form one‐dimensional chains (which are the precursors of graphitic nanostructures). This rationalizes the experimental observation of an incubation time between carbon storage and the beginning of catalytic growth, and provides insight into the early stages (nucleation mechanism) of carbon nanotubes on Ni nanoparticles. 相似文献
103.
Mathieu Toumi 《Tetrahedron letters》2010,51(47):6126-6128
A flexible six-step synthesis of potential cyclin-dependent kinase 2 (CDK2) inhibitors is reported. The synthesis involves the condensation between 3-chloro-4,4-dimethoxy-2-butanone and amidines, which provides acetyl-imidazoles and late stage palladium-catalyzed N-arylation to give the target pyrimidine derivatives. 相似文献
104.
Mathieu Van Vyve 《Mathematical Programming》2006,108(1):53-77
Recently, several authors [8, 10] have argued for the use of extended formulations to tighten production planning models.
In this work we present two linear-programming extended formulations of the constant-capacity lot-sizing problem with backlogging.
The first one applies to the problem with a general cost function and has O(n3) variables and constraints. This improves on the more straightforward O(n4) Florian and Klein [2] type formulation. The second one applies when the costs satisfy the Wagner-Whitin property but it
has O(n2) variables and O(n3) constraints. As a by-product, we positively answer an open question of Miller and Wolsey [4] about the tightness of an extended
formulation for the continuous mixing set.
This text presents research results of the Belgian Program on Interuniversity Poles of Attraction initiated by the Belgian
State, Prime Minister's Office, Science Policy Programming. The research was carried out with financial support of the Growth
Project G1RD-1999-00034 (LISCOS) of the European Community. The scientific responsibility is assumed by the author. 相似文献
105.
Antonio Da Costa Christian Mathieu Yolande Barbaux Hilde Poelman Gisele Dalmai-Vennik Lucien Fiermans 《Surface science》1997,370(2-3):339-344
Constant force images of the V2O5(001) surface were recorded in ambient conditions with atomic force microscopy. All images exhibit the 11.5 Å × 3.5 Å. periodicity expected for a bulk terminated surface. However, images reveal differences from the ideal structure. The experimental results are interpreted in terms of preferential adsorption sites for water molecules. Because these sites are thought to influence the catalytic properties of the surface, their characterization is an important step towards understanding how the atomic-scale structure of a surface influences its properties. 相似文献
106.
107.
The magnetic properties of single crystals of LiHo(x)Y(1-x)F(4) with x = 16.5% and x = 4.5% were recorded down to 35 mK using a micro-SQUID magnetometer. While this system is considered as the archetypal quantum spin glass, the detailed analysis of our magnetization data indicates the absence of a phase transition, not only in a transverse applied magnetic field, but also without field. A zero-Kelvin phase transition is also unlikely, as the magnetization seems to follow a noncritical exponential dependence on the temperature. Our analysis thus unmasks the true, short-ranged nature of the magnetic properties of the LiHo(x)Y(1-x)F(4) system, validating recent theoretical investigations suggesting the lack of phase transition in this system. 相似文献
108.
Cover Picture: Velocity of a Molecule Evaporated from a Water Nanodroplet: Maxwell–Boltzmann Statistics versus Non‐Ergodic Events (Angew. Chem. Int. Ed. 49/2015) 下载免费PDF全文
Assist. Prof. Dr. Hassan Abdoul‐Carime Francis Berthias Dr. Linda Feketeová Dr. Mathieu Marciante Dr. Florent Calvo Dr. Valérian Forquet Prof. Dr. Henry Chermette Dr. Bernadette Farizon Prof. Dr. Michel Farizon Prof. Dr. Tilmann D. Märk 《Angewandte Chemie (International ed. in English)》2015,54(49):14587-14587
109.
M. Elaloui A. Laamouri J. Fabre C. Mathieu G. Vilarem B. Hasnaoui 《Natural product research》2015,29(1):94-97
Ziziphus jujuba pulps are very much appreciated by the inhabitants and have been recently exported. This article reports on the chemical composition (amino acids, polyphenols and sugars) of the pulps of four Z. jujuba ecotypes (Choutrana, Mahdia, Mahres and Sfax). The major amino acids identified were proline, aspartic acid and glutamic acid. Among these, proline was the most abundant amino acid (17.4 mol). Considerable differences in total phenolic contents (15.85 mg/L) were found. Predominant phenols identified by using HPLC were rutin (1.09 mg/L) and chlorogenic acid (2.57 mg/100 g). Sugars isolated from Ziziphus pulps were found at a rate of 43.52%. Using HPLC method, three sugars from the pulp extract were identified: glucose, galactose and sucrose. The Mahdia ecotype was the richest in these sugars with 0.45, 136.51 and 113.28 mg/L, respectively. 相似文献
110.
Lanthanide Complexes with Multidentate Oxime Ligands as Single‐Molecule Magnets and Atmospheric Carbon Dioxide Fixation Systems 下载免费PDF全文
Dr. Małgorzata Hołyńska Dr. Rodolphe Clérac Mathieu Rouzières 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(38):13321-13329
The synthesis, structure, and magnetic properties of five lanthanide complexes with multidentate oxime ligands are described. Complexes 1 and 2 ( 1 : [La2(pop)2(acac)4(CH3OH)], 2 : [Dy2(pop)(acac)5]) are synthesized from the 2‐hydroxyimino‐N‐[1‐(2‐pyridyl)ethylidene]propanohydrazone (Hpop) ligand, while 3 , 4 , and 5 ( 3 : [Dy2(naphthsaoH)2(acac)4H(OH)]?0.85 CH3CN?1.58 H2O; 4 : [Tb2(naphthsaoH)2(acac)4H(OH)]?0.52 CH3CN?1.71 H2O; 5 : [La6(CO3)2(naphthsao)5 (naphthsaoH)0.5(acac)8(CO3)0.5(CH3OH)2.76H5.5(H2O)1.24]?2.39 CH3CN?0.12 H2O) contain 1‐(1‐hydroxynaphthalen‐2‐yl)‐ethanone oxime (naphthsaoH2). In 1 – 4 , dinuclear [Ln2] complexes crystallize, whereas hexanuclear LaIII complex 5 is formed after fixation of atmospheric carbon dioxide. DyIII‐based complexes 2 and 3 display single‐molecule‐magnet properties with energy barriers of 27 and 98 K, respectively. The presence of a broad and unsymmetrical relaxation mode observed in the ac susceptibility data for 3 suggest two different dynamics of the magnetization which might be a consequence of independent relaxation processes of the two different Dy3+ ions. 相似文献