全文获取类型
收费全文 | 366篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
化学 | 248篇 |
晶体学 | 5篇 |
力学 | 36篇 |
数学 | 61篇 |
物理学 | 32篇 |
出版年
2023年 | 2篇 |
2022年 | 12篇 |
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 20篇 |
2015年 | 6篇 |
2014年 | 18篇 |
2013年 | 34篇 |
2012年 | 28篇 |
2011年 | 23篇 |
2010年 | 13篇 |
2009年 | 18篇 |
2008年 | 20篇 |
2007年 | 20篇 |
2006年 | 15篇 |
2005年 | 8篇 |
2004年 | 17篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1989年 | 3篇 |
1985年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1938年 | 1篇 |
1921年 | 1篇 |
排序方式: 共有382条查询结果,搜索用时 562 毫秒
51.
Copper (I) complexes of phosphorus ligands react with 3-cyano 3-bromo pyrrolidine 2,5-diones give phosphoranes and complexes of copper (I)-halogens. 相似文献
52.
53.
Hisao Fujita Yashima Rachid Benabidallah 《Rendiconti del Circolo Matematico di Palermo》1993,42(2):195-218
In questo articolo dimostriamo l'unicità della soluzione (globale in tempo) dell'equazione monodimensionale o a simmetria
sferica di un gas viscoso e termoconduttore con la superficie libera. In questo risultato il limite inferiore della densità
ρ può essere uguale a 0. Assieme al teorema di esistenza dimostrato nei lavori precedenti, costituisce il teorema di esistenza
e di unicità (globale in tempo) per questa equazione. 相似文献
54.
Rachid Ait-Haddou Marie-Laurence Mazure 《Foundations of Computational Mathematics》2018,18(1):135-158
A classical theorem by Chebyshev says how to obtain the minimum and maximum values of a symmetric multiaffine function of n variables with a prescribed sum. We show that, given two functions in an Extended Chebyshev space good for design, a similar result can be stated for the minimum and maximum values of the blossom of the first function with a prescribed value for the blossom of the second one. We give a simple geometric condition on the control polygon of the planar parametric curve defined by the pair of functions ensuring the uniqueness of the solution to the corresponding optimization problem. This provides us with a fundamental blossoming inequality associated with each Extended Chebyshev space good for design. This inequality proves to be a very powerful tool to derive many classical or new interesting inequalities. For instance, applied to Müntz spaces and to rational Müntz spaces, it provides us with new inequalities involving Schur functions which generalize the classical MacLaurin’s and Newton’s inequalities. This work definitely demonstrates that, via blossoms, CAGD techniques can have important implications in other mathematical domains, e.g., combinatorics. 相似文献
55.
Rachid Tribak 《代数通讯》2013,41(8):3190-3206
We introduce and study the notion of wd-Rickart modules (i.e. modules M such that for every nonzero endomorphism ? of M, the image of ? contains a nonzero direct summand of M). We show that the class of rings R for which every right R-module is wd-Rickart is exactly that of right semi-artinian right V-rings. We prove that a module M is dual Baer if and only if M is wd-Rickart and M has the strong summand sum property. Several structure results for some classes of wd-Rickart modules and dual Baer modules are provided. Some relevant counterexamples are indicated. 相似文献
56.
The aim of this work is the phytochemical study of the butanolic extract of the aerial parts of Veronica rosea. Four compounds 1–4 have been isolated using different chromatographic methods. The structures of these compounds were determined by NMR spectral analysis and mass spectroscopy. The adsorption and anticorrosion effects of this extract were investigated towards the corrosion of copper in 1 M HNO3 aqueous by the weight loss technique and potentiodynamic polarization. The results showed that the butanolic extract is a good inhibitor and the inhibition efficiency increases with increasing of concentration of the inhibitor. The adsorption of this extract on the copper specimen surface was spontaneous and obeyed the Langmuir’s adsorption isotherm. Large value of adsorption equilibrium Constant (K ads = 35 L g?1) was obtained. The polarization experiments confirmed the data obtained by gravimetric weight-loss. Tafel plot of polarization curves indicates that the extract acts as a mixed type inhibitor. 相似文献
57.
58.
Wakif Abderrahim Chamkha Ali Thumma Thirupathi Animasaun I. L. Sehaqui Rachid 《Journal of Thermal Analysis and Calorimetry》2021,143(2):1201-1220
Journal of Thermal Analysis and Calorimetry - Sequel to the fact that hybrid nanofluidic systems (e.g. scalable micro-/nanofluidic device) exhibit greater thermal resistance with increasing... 相似文献
59.
Yassine Benmassaoud Khaled Murtada Rachid Salghi Mohammed Zougagh ngel Ríos 《Molecules (Basel, Switzerland)》2021,26(9)
In this study, we combine magnetic solid phase extraction (MSPE), with the screen-printed carbon electrode (SPCE) modified by a molecular imprinted polymer (MIP) for sensitive and selective extraction and electrochemical determination of Rhodamine B in food samples. A magnetic solid phase extraction (MSPE) was carried out using magnetic poly(styrene-co-divinylbenzene) (PS-DVB) and magnetic nanoparticles (MNPs) synthetized on the surface of multiwalled carbon nanotubes (MWCNTs). An MIP was prepared on the surface of MWCNTs in the presence of titanium oxide nanoparticles (TiO2NPs) modifying the SPCE for the rapid electrochemical detection of Rhodamine B. The MIPs synthesis was optimized by varying the activated titanium oxide (TiO2) and multiwalled carbon nanotubes (MWCNTs) amounts. The MSPE and electrochemical detection conditions were optimized as well. The present method exhibited good selectivity, high sensitivity, and good reproducibility towards the determination of Rhodamine B, making it a suitable method for the determination of Rhodamine B in food samples. 相似文献