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101.
Lorena Martínez Livia Arizaga Donatella Armentano Francesc Lloret Ricardo González Carlos Kremer 《Journal of Coordination Chemistry》2018,71(6):748-762
AbstractTwo new mixed-valence iron complexes with 2-pyridyl oximes, [Fe(mpko)3Fe(H2O)2(NO3)](NO3)·2H2O (1) (mpko? = methyl(2-pyridyl)ketone oximate) and [{Fe(dpko)3}2Fe](ClO4)·4H2O (2) (dpko? = bis(2-pyridyl)ketone oximate), have been prepared by reaction of FeIII with mpkoH in methanol (1) and FeII with dpkoH in methanol/water (2). Dinuclear FeII(low-spin)FeIII(high-spin) and trinuclear FeII(low-spin)FeIII(high-spin)FeII(low-spin) cations are present in the crystal structure of 1 and 2, respectively. Intermolecular hydrogen bonds in 1 lead to weak antiferromagnetic interactions between pairs of neighboring FeIII centers, which allows observation of single-ion zero-field splitting effects. 相似文献
102.
Synthesis of Densely Packaged,Ultrasmall Pt02 Clusters within a Thioether‐Functionalized MOF: Catalytic Activity in Industrial Reactions at Low Temperature 下载免费PDF全文
Marta Mon Miguel A. Rivero‐Crespo Dr. Jesús Ferrando‐Soria Alejandro Vidal‐Moya Dr. Mercedes Boronat Dr. Antonio Leyva‐Pérez Prof. Dr. Avelino Corma Dr. Juan C. Hernández‐Garrido Dr. Miguel López‐Haro Prof. Dr. José J. Calvino Giulio Ragazzon Prof. Dr. Alberto Credi Dr. Donatella Armentano Dr. Emilio Pardo 《Angewandte Chemie (International ed. in English)》2018,57(21):6186-6191
The gram‐scale synthesis, stabilization, and characterization of well‐defined ultrasmall subnanometric catalytic clusters on solids is a challenge. The chemical synthesis and X‐ray snapshots of Pt02 clusters, homogenously distributed and densely packaged within the channels of a metal–organic framework, is presented. This hybrid material catalyzes efficiently, and even more importantly from an economic and environmental viewpoint, at low temperature (25 to 140 °C), energetically costly industrial reactions in the gas phase such as HCN production, CO2 methanation, and alkene hydrogenations. These results open the way for the design of precisely defined catalytically active ultrasmall metal clusters in solids for technically easier, cheaper, and dramatically less‐dangerous industrial reactions. 相似文献
103.
Donatella Banti 《Tetrahedron》2004,60(37):8043-8052
Norbornene derivatives bearing endo-substituents in the 5- and 6-positions were studied as substrates for ene-yne metathesis cascades. Substrates which contained an internal alkyne and a terminal alkene or alkyne in each sidechain were found to undergo a metathesis cascade leading to pentacyclic bis-dienes and bis-trienes. Attempts to extend the chemistry further to sidechains containing two internal alkynes or two internal alkynes and a terminal alkene were not successful with the first generation Grubbs' catalyst. However, the substrate containing two internal alkynes did react with the second generation Grubbs' catalyst to give a tetra-diene containing product. 相似文献
104.
Fabbrizzi L Licchelli M Mascheroni S Poggi A Sacchi D Zema M 《Inorganic chemistry》2002,41(23):6129-6136
The water soluble Ni(II) complexes of the cyclam derivatives with 1,3-benzodioxole and 1,2,3-trimethoxybenzene display the fluorescent emission typical of the covalently linked fluorophores, which results from a charge transfer excited state. On oxidation to Ni(III), the fluorescence is completely quenched due to the occurrence of an electron transfer (eT) process from the excited fluorogenic fragment Fl to the oxidized metal. Thus, fluorescence can be switched off/on at will, for several cycles, by consecutively oxidizing and reducing the metal center, in controlled potential electrolysis experiments both in acetonitrile and in aqueous 0.1 M HClO4. Occurrence of an eT process from Fl to Ni(III) ultimately depends upon the easy oxidation of Fl to Fl+, whereas failure of the occurrence of an eT process from Ni(II) to Fl has to be ascribed to the particular resistance of Fl fragments to the reduction. 相似文献
105.
Presciutti F Capitani D Sgamellotti A Brunetti BG Costantino F Viel S Segre A 《The journal of physical chemistry. B》2005,109(47):22147-22158
The aim of this study is to clarify the structure of an iron-rich clay and the structural changes involved in the firing process as a preliminary step to get information on ancient ceramic technology. To this purpose, illite-rich clay samples fired at different temperatures were characterized using a multitechnique approach, i.e., by electron paramagnetic resonance, scanning electron microscopy with electron dispersion X-ray spectrometry, X-ray powder diffraction, magic angle spinning and multiple quantum magic angle spinning NMR. During firing, four main reaction processes occur: dehydration, dehydroxylation, structural breakdown, and recrystallization. When the results are combined from all characterization methods, the following conclusions could be obtained. Interlayer H2O is located close to aluminum in octahedral sites and is driven off at temperatures lower than 600 degrees C. Between 600 and 700 degrees C dehydroxylation occurs whereas, between 800 and 900 degrees C, the aluminum in octahedral sites disappears, due to the breakdown of the illite structure, and all iron present is oxidized to Fe3+. In samples fired at 1000 and 1100 degrees C iron clustering was observed as well as large single crystals of iron with the occurrence of ferro- or ferrimagnetic effects. Below 900 degrees C the aluminum in octahedral sites presents a continuous distribution of chemical shift, suggesting the presence of slightly distorted sites. Finally, over the whole temperature range, the presence of at least two tetrahedral aluminum sites was revealed, characterized by different values of the quadrupolar coupling constant. 相似文献
106.
Paolo Ganis Donatella Furlani Daniele Marton Giuseppe Tagliavini Giovanni Valle 《Journal of organometallic chemistry》1985,293(2):207-212
The crystal structure of (C6H5)3SnCH2CHCH2 has been determined. The asymmetric unit consists of two molecules of triphenylallyltin having virtually the same conformation. Their geometrical parameters exclude pπ-dπ bonding between the metal and the allyl double bond, and seem to be in a better agreement with a σ-π conjugation effect. 相似文献
107.
β-(2-Aminophenyl)-α,β-ynones readily react with nitrogen nucleophiles to give three major types of products, depending on reaction conditions and variation in the nucleophiles. The reaction may lead to simple 1,2-nucleophilic adducts or, at higher temperatures, to a divergent sequential cyclisation giving rise to 2-aryl-4-aminoquinolines by reaction with amines, or to substituted 2-aryl or 2-alkyl-4-alkylidene quinazolines by reaction with amidines. The latter could also be synthesised by reaction of β-(2-aminophenyl)-α,β-ynones with iminochlorides. 相似文献
108.
Dr. Marta Viciano-Chumillas Dr. Geneviève Blondin Dr. Martin Clémancey Dr. Jurek Krzystek Dr. Mykhaylo Ozerov Prof. Dr. Donatella Armentano Dr. Alexander Schnegg Dr. Thomas Lohmiller Prof. Dr. Joshua Telser Prof. Francesc Lloret Dr. Joan Cano 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(62):14242-14251
A mononuclear iron(III) porphyrin compound exhibiting unexpectedly slow magnetic relaxation, which is a characteristic of single-ion magnet behaviour, is reported. This behaviour originates from the close proximity (≈550 cm−1) of the intermediate-spin S=3/2 excited states to the high-spin S=5/2 ground state. More quantitatively, although the ground state is mostly S=5/2, a spin-admixture model evidences a sizable contribution (≈15 %) of S=3/2 to the ground state, which as a consequence experiences large and positive axial anisotropy (D=+19.2 cm−1). Frequency-domain EPR spectroscopy allowed the mS= |±1/2⟩→|±3/2⟩ transitions to be directly accessed, and thus the very large zero-field splitting in this 3d5 system to be unambiguously measured. Other experimental results including magnetisation, Mössbauer, and field-domain EPR studies are consistent with this model, which is also supported by theoretical calculations. 相似文献
109.
New stereorandom syntheses of juvabione and dehydrojuvabione using kinetic e-nolates as synthons are described. 相似文献
110.
The synthesis and crystal structural characterization of the compound of formula {[FeII(phen)3]2[Fe2IIIox5]}·11H2O (1) has been reported. The most interesting feature of the solid state structure of 1 consists in the occurrence of decanuclear water clusters made up of self-assembled cyclic hexameric water clusters with a quasi-planar conformation, unclosed trinuclear clusters and individual water molecules. The decanuclear water clusters are connected to the host lattices via an extensive net of strong hydrogen bonds that finally lead to an extended 3D supramolecular organization, wherein hexameric water clusters interconnected with dodecameric hybrid water–Ooxalate clusters can be identified. The comparison of this supramolecular architecture with that found in the already known compound of formula [Fe(bpm)3]2[Fe2(ox)5]·8H2O (2) allows some preliminary observations on the design and control of water cluster nuclearity and conformation. 相似文献