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31.
Alban A. Letailleur Sergey Yu Grachev Elin Søndergård Christophe Couteau Gilles Lérondel Emmanuelle Peter 《Journal of luminescence》2011,131(12):2646-2651
The application of alumina-doped ZnO (AZO) films as luminescent material for large area lighting sources has been evaluated. Thin films were grown on quartz using magnetron sputtering and subsequently annealed under argon atmosphere in a rapid thermal annealing experiment. Below 550 °C, red-shift of the optical band gap and increase of the visible emission are observed in agreement with Al diffusion and formation of interstitial oxygen atoms. At temperatures higher than 800 °C, diffusion is activated and Ostwald ripening leads to the formation of larger grains and an increase of the crystalline phase. The photoluminescence (PL) intensity is enhanced, specifically in the UV range. As a result the emission spectrum of AZO thin films can be adjusted by the annealing conditions, with equal contributions from the UV and orange parts of the PL spectrum resulting in an efficient white emission as quantified using the color space map of the Commission Internationale de l'Éclairage. 相似文献
32.
Florent Lafay Emmanuelle Vulliet Marie-Magdeleine Flament-Waton 《Analytical and bioanalytical chemistry》2010,396(2):937-941
A simple, rapid, sensitive, and non-consuming solvent method for the determination of cotinine in urine was developed, based
on sample preparation by the relatively new technique microextraction in packed sorbent (MEPS) and analysis by GC–MS. This
optimized method was compared with conventional solid-phase extraction/liquid–liquid extraction method used as reference.
The wide linear range (5–5,000 ng/mL) and high sensitivity of the MEPS method (limit of detection 0.8 ng/mL) allow application
to analysis of urine from smokers as well as non-smokers susceptible to passive smoking. 相似文献
33.
34.
We study quantum automorphism groups of vertex-transitive graphs having less than 11 vertices. With one possible exception,
these can be obtained from cyclic groups , symmetric groups S
n
and quantum symmetric groups , by using various product operations. The exceptional case is that of the Petersen graph, and we present some questions about
it. 相似文献
35.
Cristina Díez Davy Guillarme Aline Staub Spörri Emmanuelle Cognard Didier Ortelli Patrick Edder Serge Rudaz 《Analytica chimica acta》2015
In this study, fourteen highly polar aminoglycoside (AGs) antibiotics were selected. Various stationary phases were tested, including Obelisc R, ZIC-HILIC, BEH amide and aminopropyl. The nature of the stationary phase, mobile phase (water or buffer solutions and acetonitrile), pH (percentage of formic acid), gradient conditions and injection solvents were systematically studied as relevant parameters for tuning retention selectivity and detectability of AGs in liquid chromatography electrospray tandem mass spectrometry (LC–(ESI)–MS/MS). Only the two zwitterionic phases (Obelisc R and ZIC-HILIC) achieved a proper chromatographic separation considering interferences due to the crosstalk effect in low resolution mass spectrometers. The water/acetonitrile mobile phase containing 1% formic acid used with Obelisc R provided more sensitivity than the highly concentrated buffered mobile phases required for ZIC-HILIC. A solid phase extraction (SPE) clean-up procedure with polymeric weak cation exchange (WCX) cartridges was optimized for honey, milk and liver samples. Different brands of cartridges and elution solvents were tested, and the Taurus WCX offered the best recovery rate with a buffer elution at pH 3. The final optimized method was validated in these matrices according to Decision 2002/657/EC. A monitoring campaign for sixty honey, milk and liver samples was carried out at the Food Authority Control in Geneva. The concentration of dihydrostreptomycin (DSTP) found in one ovine liver exceeded the established maximum residue levels (MRLs) within the European and Swiss legislations but it was compliant taking into account the validation data. 相似文献
36.
Julien Camilleri Robert Baudot Laure Wiest Emmanuelle Vulliet Cécile Cren-Olivé 《International journal of environmental analytical chemistry》2015,95(1):67-81
The present work describes the development and validation of a sensitive method for the determination of traces of diverse groups of pharmaceuticals and endocrine disruptors in surface water. Thirty-seven substances have been selected, including 10 pesticides, 6 hormonal steroids and assimilates, 12 pharmaceuticals, 5 alkylphenols, 1 chlorophenol and 3 other well-known human contaminants, 1 UV filter and 2 plasticisers. An automated online solid-phase extraction (SPE) is directly coupled to liquid chromatography–tandem mass spectrometry. Different SPE columns have been tested, and the injection volume has been optimised. The developed analytical methodology is based on the direct injection of 2.5 mL of water sample acidified at pH 1.6 on an Oasis HLB loading column (20 × 2.1 mm) with 5-µm particles. Then, the chromatographic separation is achieved on a Kinetex XB C18 (100 × 2.1 mm; 1.7 µm) column, and the quantification is realised in multiple-reaction monitoring mode. The online SPE step warrants minimal sample handling, low solvent consumption, high sample throughput, saving time and costs. This method allows the quantification of the target analytes in the lower ng/L concentration range, with limits of quantification (LQs) between 100 pg/L and 10 ng/L, 26 compounds having LQ lower than 1 ng/L. The monitoring of two selected MS/MS transitions for each compound allows the reliable confirmation of positive findings even at the LQ level. The developed and validated methodology has been applied to the analysis of various real samples from two French rivers. Twelve target compounds have been detected in the environmental samples, and the major pollutants are pharmaceuticals usually used by humans (paracetamol, carbamazepine, oxazepam, ketoprofen, trimethoprim). The pesticides atrazine and carbendazim have been ubiquitously detected in real samples too. Metronidazole, sulfamethoxazole and diuron were also frequently quantified in the water samples. 相似文献
37.
Optimization of Experimental Parameters to Explore Small‐Ligand/Aptamer Interactions through Use of 1H NMR Spectroscopy and Molecular Modeling
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Dr. Florence Souard Dr. Sandrine Perrier Dr. Vincent Noël Dr. Claire Fave Emmanuelle Fiore Prof. Eric Peyrin Prof. Julian Garcia Dr. Cécile Vanhaverbeke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(44):15740-15748
Aptamers constitute an emerging class of molecules designed and selected to recognize any given target that ranges from small compounds to large biomolecules, and even cells. However, the underlying physicochemical principles that govern the ligand‐binding process still have to be clarified. A major issue when dealing with short oligonucleotides is their intrinsic flexibility that renders their active conformation highly sensitive to experimental conditions. To overcome this problem and determine the best experimental parameters, an approach based on the design‐of‐experiments methodology has been developed. Here, the focus is on DNA aptamers that possess high specificity and affinity for small molecules, L ‐tyrosinamide, and adenosine monophosphate. Factors such as buffer, pH value, ionic strength, Mg2+‐ion concentration, and ligand/aptamer ratio have been considered to find the optimal experimental conditions. It was then possible to gain new insight into the conformational features of the two ligands by using ligand‐observed NMR spectroscopic techniques and molecular mechanics. 相似文献
38.
Emmanuelle Augeraud-Veron Mauro Bambi Fausto Gozzi 《Journal of Optimization Theory and Applications》2017,173(2):584-611
In this paper, we study an economic model, where internal habits play a role. Their formation is described by a more general functional form than is usually assumed in the literature, because a finite memory effect is allowed. Indeed, the problem becomes the optimal control of a standard ordinary differential equation, with the past of the control entering both the objective function and an inequality constraint. Therefore, the problem is intrinsically infinite dimensional. To solve this model, we apply the dynamic programming approach and we find an explicit solution for the associated Hamilton–Jacobi–Bellman equation, which lets us write the optimal strategies in feedback form. Therefore, we contribute to the existing literature in two ways. Firstly, we fully develop the dynamic programming approach to a type of problem not studied in previous contributions. Secondly, we use this result to unveil the global dynamics of an economy characterized by generic internal habits. 相似文献
39.
Martha V. Escárcega-Bobadilla Emmanuelle TeumaAnna M. Masdeu-Bultó Montserrat Gómez 《Tetrahedron》2011,67(2):421-428
New azadioxaphosphabicyclo[3.3.0]octane ligands showing a trans arrangement with regard to the two five-membered heterocycles, were obtained as a mixture of three conformers, in agreement with molecular modelling studies. The stability of oxaphosphane ligands was studied under basic catalytic conditions, monitored by NMR spectroscopy. Palladium catalytic systems containing these ligands were active in Suzuki C-C cross-coupling reactions between phenylboronic acid and aryl halides (bromide and chloride derivatives) bearing electron-donor or electron-withdrawing substituents, in both organic and ionic liquid solvents. The catalytic systems showed a high stability even under the most severe reaction conditions used in this work. The ionic liquid catalytic phase could be recycled up to ten times without significant activity loss. 相似文献
40.
The synthesis of a series of novel indazole-5,6-diamine derivatives is described. This indazole ring system was incorporated in an octahydropyrrolo[3,4-b]phenazine scaffold and was diversely and regioselectively substituted on the nitrogen atoms at the 5- and 10-positions. Thus, the nitrogen atom at the 5-position was found to be more reactive toward electrophiles than the one at the 10-position. This difference of reactivity could be attributed to the electronic effect of the pyrazole moiety. Moreover, an unexpected tetrahydropyran protecting group migration was observed from the N-1 atom to the C-11 position of the octahydropyrrolo[3,4-b]phenazine scaffold. 相似文献