全文获取类型
收费全文 | 101篇 |
免费 | 10篇 |
专业分类
化学 | 67篇 |
晶体学 | 2篇 |
力学 | 4篇 |
综合类 | 1篇 |
数学 | 26篇 |
物理学 | 11篇 |
出版年
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 8篇 |
2012年 | 3篇 |
2011年 | 13篇 |
2010年 | 5篇 |
2009年 | 2篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2001年 | 2篇 |
1999年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有111条查询结果,搜索用时 0 毫秒
31.
Maher Boudabra Abderrahmane Nitaj 《Journal of Applied Mathematics and Computing》2018,57(1-2):229-245
The KMOV scheme is a public key cryptosystem based on an RSA modulus \(n=pq\) where p and q are large prime numbers with \(p\equiv q\equiv 2\pmod 3\). It uses the points of an elliptic curve with equation \(y^2\equiv x^3+b\pmod n\). In this paper, we propose a generalization of the KMOV cryptosystem with a prime power modulus of the form \(n=p^{r}q^{s}\) and study its resistance to the known attacks. 相似文献
32.
Ralitsa Chimshirova Milena Popova Amina Chakir Violeta Valcheva Simeon Dimitrov Boryana Trusheva Abderrahmane Romane Vassya Bankova 《Molecules (Basel, Switzerland)》2022,27(7)
The chemical composition and antimicrobial activity of propolis from a semi-arid region of Morocco were investigated. Fifteen compounds, including triterpenoids (1, 2, 7–12), macrocyclic diterpenes of ingol type (3–6) and aromatic derivatives (13–15), were isolated by various chromatographic methods. Their structures were elucidated by a combination of spectroscopic and chiroptical methods. Compounds 1 and 3 are new natural compounds, and 2, 4–6, and 9–11 are newly isolated from propolis. Moreover, the full nuclear magnetic resonance (NMR) assignments of three of the known compounds (2, 4 and 5) were reported for the first time. Most of the compounds tested, especially the diterpenes 3, 4, and 6, exhibited very good activity against different strains of bacteria and fungi. Compound 3 showed the strongest activity with minimum inhibitory concentrations (MICs) in the range of 4–64 µg/mL. The combination of isolated triterpenoids and ingol diterpenes was found to be characteristic for Euphorbia spp., and Euphorbia officinarum subsp. echinus could be suggested as a probable and new plant source of propolis. 相似文献
33.
Characterization of v-sufficiency from the Newton filtration 总被引:2,自引:0,他引:2
Ould M Abderrahmane 《manuscripta mathematica》2005,117(1):93-103
The aim of this paper is to study the germ mappings : (n, 0)(p, 0), more precisely, we formulate certain criteria for the v-sufficiency related to the Newton polyhedron. Our result implies in particular the criteria for v-sufficiency due to Kuo and Paunescu.This research was supported by the Japan Society for the Promotion of Science.Mathematics Subject Classification (2000): 14B05;58A35 相似文献
34.
B. Elidrissi M. Addou M. Regragui A. Mzerd A. Bougrine A. Kachouane 《Solid State Ionics》2001,140(3-4):369-374
It was demonstrated that spray pyrolysis can be used to prepare Ce1−xZrxO2 thin films with x between 0 and 1. The composition of these films was determined by electron probe microanalysis (EPMA), and the crystalline structure by X-ray diffraction (XRD) and Raman spectroscopy (RS). Cyclic voltammetry (CV) was performed in an electrolyte of propylene carbonate with 1 M LiClO4. Films with high Zr content were incapable of charge exchange of Li+ ions. In the contrast, films with high Ce content were found to be able to insert/extract large charge densities of Li+ ions. They also remained transparent during Li+ intercalation. 相似文献
35.
36.
A. Ousslim K. Bekkouch A. Chetouani E. Abbaoui B. Hammouti A. Aouniti A. Elidrissi F. Bentiss 《Research on Chemical Intermediates》2014,40(3):1201-1221
The present study describes the inhibition effect of 4-benzyl piperidine (P1), 1,6-bis(4-benzylpiperidine-1-carboxamide)hexane (P2) and bis(4-benzylpiperidine)thiuram disulfide (P3) towards the corrosion of mild steel in 5.5 M H3PO4 solution using weight loss measurements and polarization technique. The influence of inhibitor concentration and temperature on the inhibitory behavior of P2 and P3 was investigated. Meanwhile, the inhibition efficiency (IE) was found to depend on the molecule structure and the concentration of piperidine derivatives. The IE for 10?3 M P2 and P2 in 5.5 M H3PO4 is around 90 %. Polarization studies clearly revealed that all the compounds used act as mixed-type inhibitors. Adsorption isotherms were fitted by the Langmuir isotherm. Adsorption energies ( $ \Updelta {\text{G}}^\circ_{\text{ads}} $ and $ \Updelta {\text{H}}^\circ_{\text{ads}} $ ) and kinetic parameters were evaluated. Significant correlations are obtained between inhibition efficiency with the calculated chemical indexes, indicating that the variation of inhibition with structure of the inhibitor may be explained in terms of electronic properties. 相似文献
37.
38.
Dr. Maximilian Joost Dr. Abderrahmane Amgoune Dr. Didier Bourissou 《Angewandte Chemie (International ed. in English)》2015,54(50):15022-15045
For a while, the reactivity of gold complexes was largely dominated by their Lewis acid behavior. In contrast to the other transition metals, the elementary steps of organometallic chemistry—oxidative addition, reductive elimination, transmetallation, migratory insertion—have scarcely been studied in the case of gold or even remained unprecedented until recently. However, within the last few years, the ability of gold complexes to undergo these fundamental reactions has been unambiguously demonstrated, and the reactivity of gold complexes was shown to extend well beyond π‐activation. In this Review, the main achievements described in this area are presented in a historical context. Particular emphasis is set on mechanistic studies and structure determination of key intermediates. The electronic and structural parameters delineating the reactivity of gold complexes are discussed, as well as the remaining challenges. 相似文献
39.
The ability of Lewis acids to coordinate to transition metals as σ-acceptor ligands was recognized as early as in the 1970's, but so-called Z-type ligands remained curiosities until the early 2000's. Over the last decade, significant progress has been made in this area, especially via the incorporation of Lewis acid moieties into multidentate, ambiphilic ligands. Our understanding of the nature and influence of TM → Z interactions has considerably improved and the scope of Lewis acids susceptible to behave as σ-acceptor ligands has been significantly extended. This feature article summarizes these recent achievements. 相似文献
40.
Piedra-Arroni E Brignou P Amgoune A Guillaume SM Carpentier JF Bourissou D 《Chemical communications (Cambridge, England)》2011,47(35):9828-9830
A dual catalytic system combining an original cationic zinc complex and a tertiary amine is shown to promote efficiently the polymerization of lactide under mild conditions. 相似文献