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71.
Amit Dahiya Markus D. Schoetz Prof. Dr. Franziska Schoenebeck 《Angewandte Chemie (International ed. in English)》2023,62(43):e202310380
Reported herein is a fully orthogonal olefination, which involves the site- and E-selective coupling of aryl germanes with alkenes, tolerating otherwise widely employed coupling handles such as aromatic (pseudo)halogens (C−I, C−Br, C−Cl, C−F, C−OTf, C−OSO2F), silanes and boronic acid derivatives as well as alternative functionalities. This unprecedented [Ge]-based oxidative Heck coupling proceeds at room temperature with high speed (10 min to 2 hours) and operational simplicity owing to its base-free and air-tolerant features. 相似文献
72.
Dr. Franziska Kreuzer Dr. Elena Mena-Osteritz Prof. Peter Bäuerle 《European journal of organic chemistry》2023,26(27):e202300358
Dithienopyrazines are only scarcely used as building blocks in organic electronic materials. Here, we report efficient preparation and investigation of syn- and anti-dithienopyrazines, which were functionalized with triaraylamine units to provide different series of donor-acceptor-donor-type materials. The characterization of the optoelectronic properties resulted in valuable structure-property relationships and allowed for the elucidation of the influence of structural effects such as core structure (syn vs anti), type of substituents (directly arylated vs ethynylated aryl), and substitution pattern (α,α’- vs β,β’- vs fourfold substitution). Finally, first application of a dithienopyrazine derivative as model for hole-transport materials tailored for organic electronic devices has been realized. 相似文献
73.
Franziska Fischer Sebastian Greiser Dr. Dietmar Pfeifer Prof. Dr. Christian Jäger Prof. Dr. Klaus Rademann Dr. Franziska Emmerling 《Angewandte Chemie (International ed. in English)》2016,55(46):14281-14285
Benzamide has been known for its polymorphism for almost 200 years. Three polymorphic forms are described. To date, it was only possible to crystallize a metastable form in a mixture together with the thermodynamically most stable form I. A complete transformation of form I into the metastable form III by mechanochemical treatment has been achieved. Catalytic amounts of nicotinamide seeds were used to activate the conversion by mechanochemical seeding. NMR experiments indicated that the nicotinamide molecules were incorporated statistically in the crystal lattice of benzamide form III during the conversion. The transformation pathway was evaluated using in situ powder X‐ray diffraction. 相似文献
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Martin Gawron Franziska Gilch Daniel Schmidhuber Dr. John A. Kelly Dr. Thomas M. Horsley Downie Prof. Dr. Axel Jacobi von Wangelin Prof. Dr. Julia Rehbein Prof. Dr. Robert Wolf 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(6):e202315381
We show that countercations exert a remarkable influence on the ability of anionic cobaltate salts to catalyze challenging alkene hydrogenations. An evaluation of the catalytic properties of [Cat][Co(η4-cod)2] (Cat=K ( 1 ), Na ( 2 ), Li ( 3 ), (Depnacnac)Mg ( 4 ), and N(nBu)4 ( 5 ); cod=1,5-cyclooctadiene, Depnacnac={2,6-Et2C6H3NC(CH3)}2CH)]) demonstrated that the lithium salt 3 and magnesium salt 4 drastically outperform the other catalysts. Complex 4 was the most active catalyst, which readily promotes the hydrogenation of highly congested alkenes under mild conditions. A plausible catalytic mechanism is proposed based on density functional theory (DFT) investigations. Furthermore, combined molecular dynamics (MD) simulation and DFT studies were used to examine the turnover-limiting migratory insertion step. The results of these studies suggest an active co-catalytic role of the counterion in the hydrogenation reaction through the coordination to cobalt hydride intermediates. 相似文献
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77.
Cationic,Methylene‐Bridged,Intramolecular Donor‐Acceptor Systems Based on Zirconium and Hafnium and Phosphino‐methanides 下载免费PDF全文
Martin Pieper Pauline Auer Sabrina Schwarzbich Franziska Kühn Beate Neumann Hans‐Georg Stammler Norbert W. Mitzel 《无机化学与普通化学杂志》2017,643(14):909-915
A new access to cationic zirconium and hafnium compounds [L2MCH2PR2][MeB(C6F5)3] (L = Cp, Ind; R = iso‐Pr, tert‐Bu; M = Zr, Hf) exhibiting an intramolecular donor‐acceptor system was established by treating the precursors L2M(Me)CH2PR2 with B(C6F5)3 (BCF). Precursors 1 – 6 [L2M(Me)CH2PR2 with L = Cp, Ind; R = iso‐Pr, tert‐Bu; M = Zr, Hf] were fully characterized. The crystal structures of these compounds revealed large M–CH2–P bond angles with values of about 134° indicating the absence of interactions between the Lewis‐acid and Lewis‐base. The cationic compounds [L2MCH2PR2][MeB(C6F5)3] ( 7 – 12 ) were obtained by treatment of 1 – 6 with BCF. They were characterized by NMR spectroscopy, mass spectrometry, and elemental analyses; in H/D‐scrambling experiments with H2/D2 mixtures 7 – 12 disclosed their reactivity towards cleavage of hydrogen. 相似文献
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Franziska A. Klapper Dr. Christine Kiel Dr. Peter Bellstedt Prof. Dr. Wim Vyverman Prof. Dr. Georg Pohnert 《Angewandte Chemie (International ed. in English)》2023,62(43):e202307165
Diatoms are abundant unicellular microalgae, responsible for ≈20 % of global photosynthetic CO2 fixation. Nevertheless, we know little about fundamental aspects of their biology, such as their sexual reproduction. Pheromone-mediated chemical communication is crucial for successful mating. An attraction pheromone was identified in the diatom Seminavis robusta, but metabolites priming cells for sex and synchronizing search and mating behavior remained elusive. These sex-inducing pheromones (SIP) induce cell cycle arrest and trigger the production of the attraction pheromone. Here we describe the challenging structure elucidation of an S. robusta SIP. Guided by metabolomics, a candidate metabolite was identified and elucidated by labeling experiments, NMR, ESI MSn analyses, and chemical transformations. The use of negative ion mode MS was essential to decipher the unprecedented hydroxyproline and β-sulfated aspartate-containing cyclic heptapeptide that acts in femtomolar concentrations. 相似文献
80.
Franziska Pecho Dr. You-Quan Zou Johannes Gramüller Prof. Dr. Tadashi Mori Prof. Dr. Stefan M. Huber Dr. Andreas Bauer Prof. Dr. Ruth M. Gschwind Prof. Dr. Thorsten Bach 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(23):5190-5194
A chiral phosphoric acid with a 2,2’-binaphthol core was prepared that displays two thioxanthone moieties at the 3,3’-position as light-harvesting antennas. Despite its relatively low triplet energy, the phosphoric acid was found to be an efficient catalyst for the enantioselective intermolecular [2+2] photocycloaddition of β-carboxyl-substituted cyclic enones (e.r. up to 93:7). Binding of the carboxylic acid to the sensitizer is suggested by NMR studies and by DFT calculations to occur by means of two hydrogen bonds. The binding event not only enables an enantioface differentiation but also modulates the triplet energy of the substrates. 相似文献