全文获取类型
收费全文 | 226篇 |
免费 | 10篇 |
专业分类
化学 | 219篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 5篇 |
物理学 | 7篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 9篇 |
2014年 | 5篇 |
2013年 | 14篇 |
2012年 | 14篇 |
2011年 | 28篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 19篇 |
2007年 | 18篇 |
2006年 | 18篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 12篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999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 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有236条查询结果,搜索用时 0 毫秒
101.
Siebe Vanlommel Alexander E. J. Hoffman Dr. Sam Smet Dr. Sambhu Radhakrishnan Karel Asselman Dr. C. Vinod Chandran Dr. Eric Breynaert Prof. Dr. Christine E. A. Kirschhock Prof. Dr. Johan A. Martens Prof. Dr. Veronique Van Speybroeck 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(68):e202202621
An important aspect within zeolite synthesis is to make fully tunable framework materials with controlled aluminium distribution. A major challenge in characterising these zeolites at operating conditions is the presence of water. In this work, we investigate the effect of hydration on the 27Al NMR parameters of the ultracrystalline K,Na-compensated aluminosilicate JBW zeolite using experimental and computational techniques. The JBW framework, with Si/Al ratio of 1, is an ideal benchmark system as a stepping stone towards more complicated zeolites. The presence and mobility of water and extraframework species directly affect NMR fingerprints. Excellent agreement between theoretical and experimental spectra is obtained provided dynamic methods are employed with hydrated structural models. This work shows how NMR is instrumental in characterising aluminium distributions in zeolites at operating conditions. 相似文献
102.
Celine Marie Leroy Thierry Cardinal Veronique Jubera Dr. Mona Treguer‐Delapierre Dr. Jerome Majimel Jean Pierre Manaud Renal Backov Dr. Cedric Boissière Dr. David Grosso Prof. Clement Sanchez Dr. Bruno Viana Dr. Fabienne Pellé 《Chemphyschem》2008,9(14):2077-2084
Herein, EuIII‐doped 3D mesoscopically ordered arrays of mesoporous and nanocrystalline titania are prepared and studied. The rare‐earth‐doped titania thin films—synthesized via evaporation‐induced self‐assembly (EISA)—are characterized by using environmental ellipsoporosimetry, electronic microscopy (i.e. high‐resolution scanning electron microscopy, HR‐SEM, and transmission electron microscopy, HR‐TEM), X‐ray diffraction, and luminescence spectroscopy. Structural characterizations show that high europium‐ion loadings can be incorporated into the titanium‐dioxide walls without destroying the mesoporous arrangement. The luminescence properties of EuIII are investigated by using steady‐state and time‐resolved spectroscopy via excitation of the EuIII ions through the titania host. Using EuIII luminescence as a probe, the europium‐ion sites can be addressed with at least two different environments within the mesoporous framework, namely, a nanocrystalline environment and a glasslike one. Emission fluctuations (5D0→7F2) are observed upon continuous UV excitation in the host matrix. These fluctuations are attributed to charge trapping and appear to be strongly dependent on the amount of europium and the level of crystallinity. 相似文献
103.
Dr. David Lebœuf Dr. Marc Presset Bastien Michelet Dr. Christophe Bour Dr. Sophie Bezzenine‐Lafollée Prof. Dr. Vincent Gandon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11001-11005
Direct alkenylation of a variety of alcohols with vinylboronic acids has been accomplished using the air‐stable calcium(II) complex Ca(NTf2)2 under mild conditions with short reaction times. For reluctant transformations, an ammonium salt was used as an additive to circumvent the reactivity issue. 相似文献
104.
Combinatorial Approach to Chiral Tris‐ligated Carbophilic Platinum Complexes: Application to Asymmetric Catalysis 下载免费PDF全文
Dr. Alexandre Pradal Prof. Serafino Gladiali Dr. Veronique Michelet Dr. Patrick Y. Toullec 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(23):7128-7135
A straightforward methodology for the synthesis of libraries of chiral tris‐ligated cationic platinum complexes and their in situ evaluation as asymmetric carbophilic catalysts in a model domino hydroarylation/cyclization reaction of a 1,6‐enyne was developed. A catalyst‐generation process based on a combination of a monodentate and a bidentate phosphorus ligand allowed the formation of 108 chiral complexes. One‐pot screening of the stereoinduction obtained with this library in a test domino addition/cyclization reaction validated this approach and stressed the key role played by the monodentate ligand partner in obtaining high enantioselectivities. In the case of two challenging substrate/nucleophile combinations, the combinatorial approach resulted in a significant gain in enantioselectivity. 相似文献
105.
Rodolphe Beaud Bastien Michelet Yasmin Reviriot Agns Martin‐Mingot Jean Rodriguez Damien Bonne Sbastien Thibaudeau 《Angewandte Chemie (International ed. in English)》2020,59(3):1279-1285
Achieving in a straightforward way the synthesis of enantioenriched elaborated three‐dimensional molecules related to bioactive natural products remains a long‐standing quest in organic synthesis. Enantioselective organocatalysis potentially offers a unique opportunity to solve this problem, especially when combined with complementary modes of activation. Here, we report the sequential association of organocatalytic and superacid activations of simple linear achiral readily available precursors to promote the formation of unique highly elaborated chiral methylene‐bridged benzazocanes exhibiting three to five fully‐controlled stereocenters. This peculiar backbone, difficult to assemble by standard synthetic approaches, is closely related to bioactive natural and synthetic morphinans and benzomorphans. The formation of a highly reactive chiral 7‐membered ring N‐acyl iminium superelectrophilic ion, evidenced by low‐temperature in situ NMR experiments, triggers a challenging stereoselective Friedel–Crafts‐type cyclization. 相似文献
106.
Julien Bonnet Veronique Bounor‐Legaré Fernande Boisson Flavien Mélis Philippe Cassagnau 《Journal of polymer science. Part A, Polymer chemistry》2011,49(13):2899-2907
In this article, the hydrosilylation reaction of carbonyl groups of acetate derivatives and SiH groups of hydride‐terminated polydimethylsiloxane at high temperature (100–130 °C) are described. Triruthenium dodecacarbonyl, Ru3(CO)12, was used as effective catalyst for hydrosilylation reaction. The hydrosilylation reactions with octyl acetate and 4‐heptyl acetate were investigated by multinuclear NMR spectroscopy (1H, 13C, and 29Si). This work provides evidence of the addition reaction of SiH groups onto carbonyl groups. The influence of the nature of the acetate structure on the reaction kinetics was shown and the slight contribution of side reactions at high temperature highlighted. Hydrosilylation reaction was extent to the crosslinking of ethylene‐vinyl acetate (EVA) copolymer in the same range of temperature. The formation of EVA chemical network was demonstrated by HR‐MAS NMR spectroscopy and by measuring the gel fraction of EVA chains in hot toluene. From Flory theory, the crosslinking density of elastic strand was calculated to be 80 mol m?3 in agreement with the measurements from swelling ratio (VA/SiH molar ratio: 11.8). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
107.
108.
109.