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31.
Access to New Endoperoxide Derivatives by Electrochemical Oxidation of Substituted 3‐Azabicyclo[4.1.0]hept‐4‐enes
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Dr. Frédérick Nuter Dr. Abdou Khadre Djily Dimé Dr. Cheng Chen Dr. Lotfi Bounaadja Dr. Elisabeth Mouray Dr. Isabelle Florent Dr. Yvan Six Dr. Olivier Buriez Dr. Angela Marinetti Dr. Arnaud Voituriez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5584-5593
A series of substituted 3‐azabicyclo[4.1.0]hept‐4‐ene derivatives were prepared and analysed by cyclic voltammetry. Preparative aerobic electrochemical oxidation reactions were then carried out. Three original endoperoxides were isolated, characterised and subjected to antimalarial and cytotoxicity activity assays. 相似文献
32.
Michael K. Pitt Sheheryar Malik Arnaud Doucet 《Annals of the Institute of Statistical Mathematics》2014,66(3):527-552
Discrete-time stochastic volatility (SV) models have generated a considerable literature in financial econometrics. However, carrying out inference for these models is a difficult task and often relies on carefully customized Markov chain Monte Carlo techniques. Our contribution here is twofold. First, we propose a new SV model, namely SV–GARCH, which bridges the gap between SV and GARCH models: it has the attractive feature of inheriting unconditional properties similar to the standard GARCH model but being conditionally heavier tailed. Second, we propose a likelihood-based inference technique for a large class of SV models relying on the recently introduced continuous particle filter. The approach is robust and simple to implement. The technique is applied to daily returns data for S&P 500 and Dow Jones stock price indices for various spans. 相似文献
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34.
Arnaud Heibig 《偏微分方程通讯》2013,38(1-2):281-304
This paper deals with oscillatory solutions of one dimensional syterns of conservation laws endowed with one linearly degenerate characteristic field. Recently, Weinan E (cf. [3]) and D. Sene (cf. [11]) derived a system of homogenized equations, by using a multiple scale analysis. Our goal is to prove rigourous error estimates in order to justify the validity of these equations, at least when initial data are smooth. 相似文献
35.
Pablo López-Tarifa Marie-Anne Hervé du Penhoat Rodophe Vuilleumier Marie-Pierre Gaigeot Ursula Rothlisberger Ivano Tavernelli Arnaud Le Padellec Jean-Philippe Champeaux Manuel Alcamí Patrick Moretto-Capelle Fernando Martín Marie-Françoise Politis 《Central European Journal of Physics》2014,12(2):97-102
We use time-dependent density functional theory and Born-Oppenheimer molecular dynamics methods to investigate the fragmentation of doubly ionized uracil in gas phase. Different initial electronic excited states of the dication are obtained by removing electrons from different inner-shell orbitals of the neutral species. We show that shape-equivalent orbitals lead to very different fragmentation patterns revealing the importance of the intramolecular chemical environment. The results are in good agreement with ionion coincidence measurements of uracil collision with 100 keV protons. 相似文献
36.
37.
Dr. Sylvain Achelle Dr. Jean‐Pierre Malval Dr. Stéphane Aloïse Dr. Alberto Barsella Dr. Arnaud Spangenberg Dr. Loic Mager Dr. Huriye Akdas‐Kilig Dr. Jean‐Luc Fillaut Prof. Bertrand Caro Prof. Françoise Robin‐le Guen 《Chemphyschem》2013,14(12):2725-2736
The nonlinear properties and the photophysical behavior of two π‐conjugated chromophores that incorporate an electron‐deficient pyrimidine core (A) and γ‐methylenepyrans as terminal donor (D) groups have been thoroughly investigated. Both dipolar and quadrupolar branching strategies are explored and rationalized on the basis of the Frenkel exciton model. Even though a cooperative effect is clearly observed if the dimensionality is increased, the nonlinear optical (NLO) response of this series is moderate if one considers the nature of the D/A couple and the size of the chromophores (as measured by the number of π electrons). This effect was attributed to a disruption in the electronic conjugation within the dyes’ scaffold for which the geometry deviates from planarity owing to a noticeable twisting of the pyranylidene end‐groups. This latter structural parameter also has a strong influence on the excited‐state dynamics, which leads to a very efficient fluorescence quenching. 相似文献
38.
Toshiyuki Fujii Frédéric Moynier Arnaud Agranier Emmanuel Ponzevera Minori Abe Akihiro Uehara Hajimu Yamana 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(1):261-265
Environmental transport of Tl is affected by redox reaction between Tl(I) and Tl(III) and ligand exchange reactions of them. In order to deepen the knowledge of Tl chemistry, we investigated fractionation of Tl stable isotopes (203Tl and 205Tl) in a chemical exchange system. Tl isotopes were fractionated in a liquid–liquid extraction system, in which aqueous and organic phases are hydrochloric acid solution and dichloroethane including a crown ether, respectively. After purification by ion-exchange chemistry, the isotope ratio of 205Tl/203Tl in equilibrated aqueous phase was measured precisely by multiple-collector–inductively-coupled-plasma–mass-spectrometry. A large isotope fractionation >1 ‰ was found. Electronic structures of possible Tl species (hydrated Tl+, Tl3+, and Tl chlorides) were calculated by ab initio methods, and the isotope fractionation factor was theoretically obtained. The isotope fractionation via intramolecular vibrations was calculated to be much smaller than the experimental result. The isotope fractionation via isotopic change in nuclear volume, named the nuclear field shift effect, was calculated to be >1 ‰ in Tl(I)–Tl(III) redox systems and/or ligand exchange systems of Tl(III). The nuclear field shift effect was found to be the major origin of Tl isotope fractionation. 相似文献
39.
Yves Blériotc Arnaud Genre-Grandpierre Anne Imberty Charles Tellier 《Journal of carbohydrate chemistry》2013,32(8):985-1000
ABSTRACT The conformation of two mannose-based amidines, the N-benzylmannoamidine and a pseudo (1→6) dimannoside, has been evaluated using semi-empirical AMI calculations and 1H NMR studies. The most stable conformations of the mannoamidine ring correspond to the half-chair forms 3H4 and 4H3. The conformations (Z) or (E) about the exocyclic C-N bond depend on the substituents and it was shown that, in solution, the N-benzylmannoamidine was (E)-configured whilst the pseudo (1→6) dimannoside was (Z)-configured. Using the grid-search approach, the potential energy maps of both mannoamidines were calculated as a function of the torsion angles which define the orientation of the amidine substituent. Three stable conformers were identified for the N-benzylmannoamidine and seven for the pseudo (1→6) dimannoside. Inter-glycosidic NOE have provided evidence for a preferred conformation of the pseudo (1→6) dimannoside in solution. The transition state structure of the α-phenylmannose hydrolysis was optimized using the AMI method and compared to the N-benzylmannoamidine. The developing oxocarbenium ion is well matched by the mannoamidine ring but the orientation of the phenyl group in the inhibitor differs significantly from the position of the leaving group in the transition state. The use of sugar type amidines as haptens to obtain catalytic antibodies is then discussed. 相似文献
40.
Arnaud Tatibouët Patrick Rollin Olivier R. Martin 《Journal of carbohydrate chemistry》2013,32(4-5):641-645
Within the frame of an ongoing project on glycosidase inhibitors, we have been interested in the synthesis of “heteroglycals”, namely, glycal analogues with sulfur or nitrogen in the ring. Glycals2 are well known for their applications in sugar chemistry in particular for glycosyl transfer.3 They are also known as glycosidase inhibitors through a slow chemical reaction with the enzyme. Recently exo-glycals emerged as a new class of glycals4 which showed interesting features as glycosidase inhibitors but also as precursors of glycomimetics such as C-glycosides.5 We have undertaken investigations on related heteroglycals: such compounds are of interest because they combine a planar geometry at the anomeric center and a possible charge site - both elements known to be important to mimic the transition state of the enzymatic glycoside hydrolysis process.6 相似文献