全文获取类型
收费全文 | 203篇 |
免费 | 6篇 |
专业分类
化学 | 93篇 |
晶体学 | 3篇 |
力学 | 18篇 |
数学 | 65篇 |
物理学 | 30篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 7篇 |
2014年 | 12篇 |
2013年 | 19篇 |
2012年 | 16篇 |
2011年 | 10篇 |
2010年 | 10篇 |
2009年 | 6篇 |
2008年 | 4篇 |
2007年 | 10篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 3篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有209条查询结果,搜索用时 218 毫秒
31.
Boumeftah Ali Belmokhtar Abdelkader Benyoucef Abdelghani 《Research on Chemical Intermediates》2022,48(4):1717-1731
Research on Chemical Intermediates - Innovative hybrid composites based on poly (4,4'-Diaminodiphenyl sulfone) (PDDS) and TiO2 nanoparticles have been synthesized. The samples have been... 相似文献
32.
Let A be a Banach algebra which does not contain any nonzero idempotent element, let γ > 0, and let
. We show that if
then
. We also show, assuming a suitable spectral condition on x, that if
, then
Received: 12 July 2006 Revised: 31 January 2007 相似文献
33.
Mohand Ouidir BOUSSOUM Abdelkader ALI-NEHARI Rachida OULDMOKHTAR Beatrice GEORGE 《Turkish Journal of Chemistry》2021,45(5):1576
The aim of our work is to study the dyeing properties of extracts from natural sources such as Papaver rhoeas by modifying the conditions of the dyeing process, choosing other substrates that could be pretreated by innovative and environmentally friendly processes. The results obtained show a fairly high fixation of the extracts on the natural and artificial fibers. The use of mordants allowed the dye to be better fixed on the dyed fibers and to give several shades to the fabric. The rate of essential oil contained in Papaver rhoeas was considered important by the Clevenger process. Screening of extractive revealed the presence of polyphenols, saponins, sterols, alkaloids and flavonoids. In this study, the extractive from Papaver rhoeas was investigated as textile dyestuff. 相似文献
34.
Afiqah Nadzirah Mohammad D. Andrew S. Rees Abdelkader Mojtabi 《Transport in Porous Media》2017,117(2):189-206
The onset of convection in a porous layer heated from below is considered, and we determine how the presence of two solid but heat-conducting bounding plates of finite thickness alters the manner in which convection ensues. Heat is generated by the lower plate (with an insulating lower boundary), but the upper one is passive with a fixed upper boundary temperature. It is shown that this composite layer may mimic in turn one of the three different types of classical single-layer onset problems which are well-known in the literature. The type which is selected (or indeed whether it corresponds to a transitional case) depends quite critically on the precise values of the relative thickness of the solid layers and their conductivity ratio. It is also shown that care needs to be taken over declaring that the solid plates are thin: extreme values of the conductivity ratio can yield a stability criterion which appears to be different from that suggested by the imposed boundary conditions. 相似文献
35.
Nadia?Benhalima Khaled?Toubal Abdelkader?ChouaihEmail author Giuseppe?Chita Sabino?Maggi Ayada?Djafri Fodil?Hamzaoui 《Journal of chemical crystallography》2011,41(11):1729-1736
Abstract
We report here the synthesis of (Z)-5-(4-nitrobenzyliden)-3-N(2-ethoxyphenyl)-2-thioxo-thiazolidin-4-one (ARNO) compound. The crystal structure has been determined by X-ray diffraction. The compound crystallizes in the triclinic system with space group P[`1] P\bar{1} and cell parameters: a = 9.1289(19), b = 9.3717(7), c = 12.136(3) ?, α = 102.133(11)°, β = 90.99(2)°, γ = 117.165(9)°, V = 895.4(3) ?3 and Z = 2. The structure has been refined to a final R = 0.05 for 2591 observed reflections. The refined structure was found to be significantly non planar. The molecule exhibits intermolecular hydrogen bond of type C–H⋯O and C–H⋯S. ab initio calculations were also were performed at Hartree–Fock and density functional theory levels. The full HF and DFT geometry optimization was carried out using LANL2DZ, 6-31G* and B3LYP/6-31+G** basis sets. The optimized geometry of the title compound was found to be consistent structure determined by X-ray diffraction. The minimum energy of geometrical structure is obtained by using level HF/LANL2DZ basis sets. 相似文献36.
First-principles plane-wave pseudopotential calculations of the adhesion, bonding and magnetism of the interface between the ferromagnetic bcc Fe and non-magnetic HfC are performed. The work of adhesion for C- and Hf-site Fe/HfC interfaces is calculated. High adhesion at C-site interface is found and Fe–C polar covalent bonds are formed across the interface. The magnetic moments of Fe atoms at interface are increased in both interfaces. The effect of the magnetism on the electronic structure of Fe/HfC interface is also investigated. It is shown that the change in band of majority-spin leads to enhance the magnetic moment of Fe. 相似文献
37.
Abdelkader Salim Catherine Colin Aleksander Grah Michael E. Dreyer 《International Journal of Multiphase Flow》2010
The study of a bubbly laminar two-phase flow in an open capillary channel under microgravity conditions was conducted aboard the sounding rocket, Texus-45. The channel consists of two parallel plates of width b = 25 mm and distance a = 10 mm. The flow along the length l = 80 mm is confined by a free surface on one side and a plate on the opposite side. The bubbles are injected at the nozzle of the capillary channel via six capillary tubes of 100 μm in inner diameter. Different liquid and gas flow rates were tested leading to different liquid free surface shape and bubble size. 相似文献
38.
The optimal control of water quality model is considered. We analyze a regularized version of the pointwise control. A numerical algorithm is presented. The solution approach is a combination of a TVD scheme for the shallow water equations and a purley deterministic particle method for the pollutant problem. We present some computational results. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
39.
We consider a simple but representative model incorporating the main behavior of the electromagnetic field near the edge of a patch antenna. Recall that this kind of antenna is obtained by a metal patch laying on a dielectric substrate covering a ground metallic plane. The functioning principle of such an electric device is based on the matching of an N-dimensional behavior of the field outside the antenna with an (N-1)-dimensional one inside the zone limited by the patch and the ground plane, N = 3 or 2 according to the considered model. In this study, we make use of the technique of matched asymptotic expansions and computation of singularities to describe this behavior for the two-dimensional case. Proved error estimates enable us to give a rigorous background to the underlying asymptotic analysis. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
40.
Nouali Fatiha Kibou Zahira Boukoussa Bouhadjar Choukchou-Braham Noureddine Bengueddach Abdelkader Villemin Didier Hamacha Rachida 《Research on Chemical Intermediates》2020,46(6):3179-3191
Research on Chemical Intermediates - An efficient and green procedure for the synthesis of 2-aminopyridines derivatives via four-component reaction of acetophenone, malononitrile, triethoxymethane... 相似文献