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281.
Highly Stable Water‐Soluble Platinum Nanoparticles Stabilized by Hydrophilic N‐Heterocyclic Carbenes
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Edwin A. Baquero Dr. Simon Tricard Dr. Juan Carlos Flores Prof. Dr. Ernesto de Jesús Prof. Dr. Bruno Chaudret 《Angewandte Chemie (International ed. in English)》2014,53(48):13220-13224
Controlling the synthesis of stable metal nanoparticles in water is a current challenge in nanochemistry. The strategy presented herein uses sulfonated N‐heterocyclic carbene (NHC) ligands to stabilize platinum nanoparticles (PtNPs) in water, under air, for an indefinite time period. The particles were prepared by thermal decomposition of a preformed molecular Pt complex containing the NHC ligand and were then purified by dialysis and characterized by TEM, high‐resolution TEM, and spectroscopic techniques. Solid‐state NMR studies showed coordination of the carbene ligands to the nanoparticle surface and allowed the determination of a 13C–195Pt coupling constant for the first time in a nanosystem (940 Hz). Additionally, in one case a novel structure was formed in which platinum(II) NHC complexes form a second coordination sphere around the nanoparticle. 相似文献
282.
Nathalie Azaroual Jamal El Bakali Delphine Le Broc Carole Deghaye Amaury Farce Philippe Chavatte Régis Millet Claude Vaccher Emmanuelle Lipka-Belloli 《Journal of inclusion phenomena and macrocyclic chemistry》2014,78(1-4):265-274
Three selective CB2 cannabinoid receptor ligands have recently been discovered to be promising anti-inflammatory agents but their low water solubility hinder their per os administration. The popularity of the cyclodextrins, from a pharmaceutical standpoint lies on their ability to interact with poorly water-soluble drugs and improve their solubility. Herein, three experimental approaches for calculating the stability constant of complexes between the selective CB2 ligands and either the β-CD or the HP-β-CD, were tested: nuclear magnetic resonance, micellar electrokinetic chromatography and high performance liquid chromatography in reversed phase. In NMR studies the calculated K values were relatively high and were between 1486 and 3571 M?1 with β-CD. With HP-β-CD they were between 1203 and 2650 M?1. Concerning the two others techniques the K values were found lower. In MECK studies with β-CD they were between 308 and 792 M?1 and with HP-β-CD between 124 and 764 M?1. Finally in RP-HPLC studies with β-CD, they were between 539 and 1144 M?1 and with HP-β-CD between 196 and 396 M?1. These calculated constants suggest that a complexation phenomenon occurs. A model for inclusion of one of the CB2 ligands in the β-CD was then proposed from molecular modeling studies. 相似文献
283.
Tuan-Anh Nguyen Øyvind Weiby Gregersen Ferdinand Männle Philippe Brachet 《Journal of Sol-Gel Science and Technology》2014,69(2):237-249
The substitution of fossil based packaging materials with materials from renewable sources is a topic of current interest. Polyhedral oligomeric silsesquioxanes with fatty acid moieties can have a renewable content of more than 90 % and are therefore called bio-POSS. In this study the bio-POSS octa-(ethyl erucamide) silsesquioxane was coated on a paperboard substrate as a liquid coating. The water resistance and the water vapour barrier properties of the paperboard were improved. Samples on which the bio-POSS coating layer was dried at 80 °C had a slightly higher water resistance and water vapour barrier than samples dried at room temperature. UV treatment of the coating layer had little effect. Solid state 1H-NMR of UV treated coatings showed no reaction of double bonds of bio-POSS in the coating layer. Multiple coating considerably enhanced the water resistance and water vapour barrier properties of the paperboard, due to an increase in the coating thickness and a reduction in number of pores on top coated surfaces. 相似文献
284.
Dr. Alberto Palazzolo Dr. Timothée Naret Dr. Marion Daniel-Bertrand David-Alexandre Buisson Dr. Simon Tricard Dr. Philippe Lesot Dr. Yannick Coppel Dr. Bruno Chaudret Dr. Sophie Feuillastre Dr. Grégory Pieters 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21065-21070
We report the dramatic impact of the addition of N-heterocyclic carbenes (NHCs) on the reactivity and selectivity of heterogeneous Ru catalysts in the context of C−H activation reactions. Using a simple and robust method, we prepared a series of new air-stable catalysts starting from commercially available Ru on carbon (Ru/C) and differently substituted NHCs. Associated with C−H deuteration processes, depending on Ru/C-NHC ratios, the chemical outcome can be controlled to a large extent. Indeed, tuning the reactivity of the Ru catalyst with NHC enabled: 1) increased chemoselectivity and the regioselectivity for the deuteration of alcohols in organic media; 2) the synthesis of fragile pharmaceutically relevant deuterated heterocycles (azine, purine) that are otherwise completely reduced using unmodified commercial catalysts; 3) the discovery of a novel reactivity for such heterogeneous Ru catalysts, namely the selective C-1 deuteration of aldehydes. 相似文献
285.
Dr. Julien Es Sayed Dr. Cédric Lorthioir Dr. Philippe Banet Prof. Patrick Perrin Dr. Nicolas Sanson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(18):7108-7114
The combination of supramolecular chemistry and soft colloids as microgels represents an ambitious way to develop multi-versatile colloidal assemblies. Hereafter, terpyridine-functionalized poly(N-isopropylacrylamide) (PNiPAM) microgel building blocks are shown to undergo an assemble–freeze–disassemble process. The microgel assemblies, which are controlled by monitoring the attractive and repulsive potentials between the soft colloidal particles, are then frozen by forming inter-particle metal–terpyridine bis-complexes upon addition of the metallic cation (such as FeII, CoII). By oxidation of the metal–terpyridine bis-complex links, the aggregates open up, which is due to the complex dissociation releasing the connected particles in the form of single microgels. We extended our work to the development of 1D filaments and 2D membranes materials made of soft particles connected via supramolecular chemistry. 相似文献
286.
Dr. Viktor Pfeifer Marie Certiat Dr. Donia Bouzouita Dr. Alberto Palazzolo Sébastien Garcia-Argote Elodie Marcon David-Alexandre Buisson Dr. Philippe Lesot Prof. Laurent Maron Dr. Bruno Chaudret Dr. Simon Tricard Dr. Iker del Rosal Prof. Romuald Poteau Dr. Sophie Feuillastre Dr. Grégory Pieters 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(22):4988-4996
Ruthenium nanocatalysis can provide effective deuteration and tritiation of oxazole, imidazole, triazole and carbazole substructures in complex molecules using D2 or T2 gas as isotopic sources. Depending on the substructure considered, this approach does not only represent a significant step forward in practice, with notably higher isotope uptakes, a broader substrate scope and a higher solvent applicability compared to existing procedures, but also the unique way to label important heterocycles using hydrogen isotope exchange. In terms of applications, the high incorporation of deuterium atoms, allows the synthesis of internal standards for LC-MS quantification. Moreover, the efficacy of the catalyst permits, even under subatmospheric pressure of T2 gas, the preparation of complex radiolabeled drugs owning high molar activities. From a fundamental point of view, a detailed DFT-based mechanistic study identifying undisclosed key intermediates, allowed a deeper understanding of C−H (and N−H) activation processes occurring at the surface of metallic nanoclusters. 相似文献
287.
Julien Es Sayed Cdric Lorthioir Philippe Banet Patrick Perrin Nicolas Sanson 《Angewandte Chemie (International ed. in English)》2020,59(18):7042-7048
The combination of supramolecular chemistry and soft colloids as microgels represents an ambitious way to develop multi‐versatile colloidal assemblies. Hereafter, terpyridine‐functionalized poly(N‐isopropylacrylamide) (PNiPAM) microgel building blocks are shown to undergo an assemble–freeze–disassemble process. The microgel assemblies, which are controlled by monitoring the attractive and repulsive potentials between the soft colloidal particles, are then frozen by forming inter‐particle metal–terpyridine bis‐complexes upon addition of the metallic cation (such as FeII, CoII). By oxidation of the metal–terpyridine bis‐complex links, the aggregates open up, which is due to the complex dissociation releasing the connected particles in the form of single microgels. We extended our work to the development of 1D filaments and 2D membranes materials made of soft particles connected via supramolecular chemistry. 相似文献
288.
IRMPD Spectra of Protonated Hydroxybenzaldehydes: Evidence of Torsional Barriers in Carboxonium Ions
Prof. Barbara Chiavarino Prof. Otto Dopfer Prof. Maria Elisa Crestoni Dr. Davide Corinti Dr. Philippe Maître Prof. Simonetta Fornarini 《Chemphyschem》2020,21(8):749-761
Protonation at the formyl oxygen atom of benzaldehydes leading to the formation of carboxonium ions yields two distinct isomers, depending on the relative orientation of the proton either cis or trans with respect to the hydrogen atom on the adjacent carbon. In this context, the IR multiple photon dissociation (IRMPD) spectra of protonated ortho, meta, and para-hydroxybenzaldehydes ( OH−BZH+ ), delivered into the gas phase by electrospray ionization of hydro-alcoholic solutions, are reported in the 3200–3700 cm−1 spectral range. This range is characteristic of O−H stretching modes and thus able to differentiate cis and trans carboxonium isomers. Comparison between IRMPD spectra and DFT calculations at the B3LYP/6-311++G(2df2p) level suggests that for both p- OH−BZH+ and m- OH−BZH+ only cis conformers are present in the ion population analyzed. For o- OH−BZH+ , IRMPD spectroscopy points to a mixture comprising one trans and more than one cis conformers. The energy barrier for cis–trans isomerization calculated for each OH−BZH+ isomer is a measure of the degree of π-electron delocalization. Furthermore, IRMPD spectra of p- OH−BZH+ , m- OH−BZH+ and protonated phenol (this last used as reference) were recorded also in the fingerprint range. Both the observed C−O and O−H stretching vibrations appear to be a measure of π-electron delocalization in the ions. 相似文献
289.
Lorne Tallet Emilie Frisch Mgane Bornerie Claire Medemblik Benoît Frisch Philippe Lavalle Gilles Guichard Cline Douat Antoine Kichler 《Molecules (Basel, Switzerland)》2022,27(5)
There is an urgent need to develop new therapeutic strategies to fight the emergence of multidrug resistant bacteria. Many antimicrobial peptides (AMPs) have been identified and characterized, but clinical translation has been limited partly due to their structural instability and degradability in physiological environments. The use of unnatural backbones leading to foldamers can generate peptidomimetics with improved properties and conformational stability. We recently reported the successful design of urea-based eukaryotic cell-penetrating foldamers (CPFs). Since cell-penetrating peptides and AMPs generally share many common features, we prepared new sequences derived from CPFs by varying the distribution of histidine- and arginine-type residues at the surface of the oligourea helix, and evaluated their activity on both Gram-positive and Gram-negative bacteria as well as on fungi. In addition, we prepared and tested new amphiphilic block cofoldamers consisting of an oligourea and a peptide segment whereby polar and charged residues are located in the peptide segment and more hydrophobic residues in the oligourea segment. Several foldamer sequences were found to display potent antibacterial activities even in the presence of 50% serum. Importantly, we show that these urea-based foldamers also possess promising antifungal properties. 相似文献
290.
Philippe M. Loiseau Kaluvu Balaraman Gillian Barratt Sbastien Pomel Rmy Durand Frdric Frzard Bruno Figadre 《Molecules (Basel, Switzerland)》2022,27(7)
There is a need for new, cost-effective drugs to treat leishmaniasis. A strategy based on traditional medicine practiced in Bolivia led to the discovery of the 2-substituted quinoline series as a source of molecules with antileishmanial activity and low toxicity. This review documents the development of the series from the first isolated natural compounds through several hundred synthetized molecules to an optimized compound exhibiting an in vitro IC50 value of 0.2 µM against Leishmania donovani, and a selectivity index value of 187, together with in vivo activity on the L. donovani/hamster model. Attempts to establish structure–activity relationships are described, as well as studies that have attempted to determine the mechanism of action. For the latter, it appears that molecules of this series act on multiple targets, possibly including the immune system, which could explain the observed lack of drug resistance after in vitro drug pressure. We also show how nanotechnology strategies could valorize these drugs through adapted formulations and how a mechanistic targeting approach could generate new compounds with increased activity. 相似文献