全文获取类型
收费全文 | 117篇 |
免费 | 2篇 |
专业分类
化学 | 76篇 |
力学 | 4篇 |
数学 | 15篇 |
物理学 | 24篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2013年 | 9篇 |
2012年 | 9篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 2篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1989年 | 1篇 |
1985年 | 2篇 |
1981年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有119条查询结果,搜索用时 15 毫秒
21.
R. Debuyst F. Dejehet B. Mahieu D. Apers 《Journal of Physics and Chemistry of Solids》1974,35(12):1615-1618
Divalent manganese ions are found in potassium chromate single crystals after heating at 600°C in the presence of iodine. These ions occupy three differently oriented sites with the same spin Hamiltonian parameters: gz = 2·000, gx = 2·008, gy = 2·015; Az = ?88·4 G, Ax = Ay = ?91 G; D = 190 and E = ?30 G.The authors suggest that Mn2+ occupies a substitutional (K+) position rather than an interstitial one. The influence of iodine is discussed. 相似文献
22.
Nguyen TH Mahieu G Berthe M Grandidier B Delerue C Stiévenard D Ebert P 《Physical review letters》2010,105(22):226404
Determination of the Coulomb energy of single point defects is essential because changing their charge state critically affects the properties of materials. Based on a novel approach that allows us to simultaneously identify a point defect and to monitor the occupation probability of its electronic state, we unambiguously measure the charging energy of a single Si dangling bond with tunneling spectroscopy. Comparing the experimental result with tight-binding calculations highlights the importance of the particular surrounding of the localized state on the effective charging energy. 相似文献
23.
Fozia A. Adem Victor Kuete Armelle T. Mbaveng Matthias Heydenreich Andreas Koch Albert Ndakala 《Natural product research》2019,33(18):2609-2617
A new isoflavone, 4′-prenyloxyvigvexin A (1) and a new pterocarpan, (6aR,11aR)-3,8-dimethoxybitucarpin B (2) were isolated from the leaves of Lonchocarpus bussei and the stem bark of Lonchocarpus eriocalyx, respectively. The extract of L. bussei also gave four known isoflavones, maximaisoflavone H, 7,2′-dimethoxy-3′,4′-methylenedioxyisoflavone, 6,7,3′-trimethoxy-4′,5′-methylenedioxyisoflavone, durmillone; a chalcone, 4-hydroxylonchocarpin; a geranylated phenylpropanol, colenemol; and two known pterocarpans, (6aR,11aR)-maackiain and (6aR,11aR)-edunol. (6aR,11aR)-Edunol was also isolated from the stem bark of L. eriocalyx. The structures of the isolated compounds were elucidated by spectroscopy. The cytotoxicity of the compounds was tested by resazurin assay using drug-sensitive and multidrug-resistant cancer cell lines. Significant antiproliferative effects with IC50 values below 10 μM were observed for the isoflavones 6,7,3′-trimethoxy-4′,5′-methylenedioxyisoflavone and durmillone against leukemia CCRF-CEM cells; for the chalcone, 4-hydroxylonchocarpin and durmillone against its resistant counterpart CEM/ADR5000 cells; as well as for durmillone against the resistant breast adenocarcinoma MDA-MB231/BCRP cells and resistant gliobastoma U87MG.ΔEGFR cells. 相似文献
24.
25.
26.
Marcel Gielen Hassan Dalil Monique Biesemans Bernard Mahieu Dick de Vos Rudolph Willem 《应用有机金属化学》1999,13(7):515-520
Di‐n‐butyl‐, triphenyl and tri‐n‐butyltin derivatives of 3 S, 4 S ‐3‐[( R )‐1‐(tert‐butyldimethyl‐<?tw=103.5%>silyloxy)ethyl‐4‐[( R )‐1‐carboxyethyl]‐2‐azetidi<?tw>‐none were synthesized and characterized. Their antitumour activity was screened against seven tumoural cell lines of human origin. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
27.
Romeo D. Tadjouate Nago Paul Nayim Armelle T. Mbaveng James D. Simo Mpetga Gabin T. Mbahbou Bitchagno Badawe Garandi Pierre Tane Bruno N. Lenta Norbert Sewald Mathieu Tene Victor Kuete Augustin Silvere Ngouela 《Molecules (Basel, Switzerland)》2021,26(16)
The local botanical Imperata cylindrica in Cameroon was investigated for its antibacterial potency. The methanol extract afforded a total of seven compounds, including five hitherto unreported compounds comprising three flavonoids (1–3) and two C-15 isoprenoid analogues (4 and 5) together with known derivatives (6 and 7). The novelty of the flavonoids was related to the presence of both methyl and prenyl groups. The potential origin of the methyl in the flavonoids is discussed, as well as the chemophenetic significance of our findings. Isolation was performed over repeated silica gel and Sephadex LH-20 column chromatography and the structures were elucidated by (NMR and MS). The crude methanol extract and isolated compounds showed considerable antibacterial potency against a panel of multi-drug resistant (MDR) bacterial strains. The best MIC values were obtained with compound (2) against S. aureus ATCC 25923 (32 µg/mL) and MRSA1 (16 µg/mL). 相似文献
28.
Markus Henn Bernard Mahieu Arnaldo Cinquantini 《Journal of organometallic chemistry》2006,691(8):1560-1572
The intramolecularly coordinated heteroleptic stannylene [4-t-Bu-2,6-{P(O)(O-i-Pr)2}2C6H2]SnCl serves as synthon for the synthesis of the ferrocenyl-bridged bis(diorganostannylene) [4-t-Bu-2,6-{P(O)(O-i-Pr)2}2C6H2SnC5H4]2Fe (1) which in turn reacts with W(CO)6 and Cr(CO)4(C7H8) to provide the corresponding transition metal complexes [4-t-Bu-2,6-{P(O)(O-i-Pr)2}2C6H2Sn{W(CO)5}C5H4]2Fe (2) and [4-t-Bu-2,6-{P(O)(O-i-Pr)2}2C6H2SnC5H4]2Fe · Cr(CO)4 (3), respectively. Reaction of compound 1 with sulphur and atmospheric moisture gave, under partial tin-carbon and oxygen-carbon bond cleavage, a tetranuclear organotin-oxothio cluster 5. All compounds were characterized by 1H, 13C, 31P, and 119Sn NMR, and IR spectroscopy, as well as by single-crystal X-ray diffraction analysis. Compounds 1 and 3 were also investigated by Mössbauer spectroscopy. Cyclovoltametric studies reveal the influence of the organostannyl moieties on the redox-behaviour of compounds 1-3 in comparison with unsubstituted ferrocene. 相似文献
29.
Davila J Chassepot A Longo J Boulmedais F Reisch A Frisch B Meyer F Voegel JC Mésini PJ Senger B Metz-Boutigue MH Hemmerlé J Lavalle P Schaaf P Jierry L 《Journal of the American Chemical Society》2012,134(1):83-86
Cell adhesion processes take place through mechanotransduction mechanisms where stretching of proteins results in biological responses. In this work, we present the first cyto-mechanoresponsive surface that mimics such behavior by becoming cell-adhesive through exhibition of arginine-glycine-aspartic acid (RGD) adhesion peptides under stretching. This mechanoresponsive surface is based on polyelectrolyte multilayer films built on a silicone sheet and where RGD-grafted polyelectrolytes are embedded under antifouling phosphorylcholine-grafted polyelectrolytes. The stretching of this film induces an increase in fibroblast cell viability and adhesion. 相似文献
30.
Armelle Anthoine 《International Journal of Solids and Structures》2010,47(11-12):1477-1489
The homogenisation theory for periodic composites is generalised to the case of quasi-periodic composites. In quasi-periodic composites, the unit cell does not repeat throughout the medium but gradually changes along one or more directions of periodicity (grading directions). Quasi-periodic composites are thus to functionally graded materials (FGMs) what periodic composites are to statistically uniform composite materials. Contrarily to most of the homogenisation methods applied to FGMs, the proposed second-order homogenisation theory takes explicitly into account the grading at the micro-level. The derived equivalent material happens to be a particular second gradient material in which few components of the strain gradient (second gradient of the displacement) should be taken into account in addition to the classical strains (first gradient of displacement). The second gradient theory therefore appears as the natural framework to appropriately handle functionally graded materials at the macro-level. It is worth mentioning that the presented second-order homogenisation procedure is somehow analogous to the one developed for periodic composite materials submitted to rapidly varying macroscopic strain fields as in regions of high gradients. In fact, both are a generalisation of the first-order homogenisation theory for periodic media and lead to a second gradient equivalent material. However, besides their different domains of application, they exhibit further substantial differences, which are highlighted in the paper. 相似文献