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951.
We establish the fundamental results of genus theory for finite (non necessary Galois) extensions of global fields by using
narrow S-class groups, when S is an arbitrary finite set of places. This exposition, which involves both the number fields and the functions fields cases,
generalizes most classical results on this subject.
Received: 8 February 1999 / Revised version: 17 December 1999 相似文献
952.
Pierre Thuéry Martine Nierlich Éronique Lamare Jean-François Dozol Zouhair Asfari Jacques Vicens 《Journal of inclusion phenomena and macrocyclic chemistry》2000,36(4):375-408
The association within one molecule ofcalix[4]arene and crown ether moieties leads toligands with new complexing properties. In particular,calix[4]arene bis(crown-6) and some of itsderivatives have been shown to be highly selectiveextractants for caesium ions. This review presents thebackground of the study and the results of crystalstructure determinations and molecular modellingcalculations performed during the investigation of twomolecular families, the bis(crown ether) and theazobenzocrown derivatives of calix[4]arene. 相似文献
953.
Bernard Refouvelet Nadia Pellegrini Jean‐Franois Robert Gregorio Crini Olivier Blacque Marek M. Kubicki 《Journal of heterocyclic chemistry》2000,37(6):1425-1430
A series of new 2‐substituted thiazolidine‐4‐carboxamide derivatives which have potentially useful immunological properties, have been synthesized in a stereoselective manner by coupling 2‐subsituted thiazolidine‐4‐carboxylic acids with amines or amino esters. The structure of these compounds was established by combination of NMR methods and by X‐ray analysis. 相似文献
954.
The daily returns of financial market indices of nineteen Eastern European countries are modelled, linear trend or ARMA(p, q) for the levels and GARCH(p ′, q ′) for the residuals. For the non Gaussian residuals -stable distributions are proposed. Then, risk measures, like the STARR and the R-ratio are used to analyse the risk in the cases of Gaussian and -stable distribution models of the residuals. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
955.
Abderramane Amgoune Christophe M. Thomas Jean‐Franois Carpentier 《Macromolecular rapid communications》2007,28(6):693-697
Amino‐alkoxy‐bis(phenolate) yttrium complexes act in the presence of an excess of alcohol (up to 50 equiv. vs. Y) as highly active and stereoselective catalysts for rac‐lactide and rac‐β‐butyrolactone polymerizations. These versatile systems enable the production of large quantities of polymer with small amounts of catalyst, optimizing productivity, and also allow the preparation of polymers with functional end groups, which may be employed as intermediates for macromolecular engineering applications.
956.
957.
Eric Osei-Agyemang Jean-Franois Paul Romain Lucas Sylvie Foucaud Sylvain Cristol Anne-Sophie Mamede Nicolas Nuns Ahmed Addad 《Molecules (Basel, Switzerland)》2022,27(9)
The mechanical and physical properties of zirconium carbide (ZrC) are limited to its ability to deteriorate in oxidizing environments. Low refractory oxides are typically formed as layers on ZrC surfaces when exposed to the slightest concentrations of oxygen. However, this carbide has a wide range of applications in nuclear reactor lines and nozzle flaps in the aerospace industry, just to name a few. To develop mechanically strong and oxygen-resistant ZrC materials, the need for studying and characterizing the oxidized layers, with emphasis on the interfacial structure between ZrC and the oxidized phases, cannot be understated. In this paper, the ZrC(111)//c-ZrO2 (111) interface was studied by both finite temperature molecular dynamic simulation and DFT. The interfacial mechanical properties were characterized by the work of adhesion which revealed a Zr|OO|Zr|OO//ZrC(111) interface model as the most stable with an oxygen layer from ZrO2 being deposited on the ZrC(111) surface. Further structural analysis at the interface showed a crack in the first ZrO2 layer at the interfacial region. Investigations of the electronic structure using the density of state calculations and Bader charge analysis revealed the interfacial properties as local effects with no significant impacts in the bulk regions of the interface slab. 相似文献
958.
Ganjehi L Marchiano R Coulouvrat F Thomas JL 《The Journal of the Acoustical Society of America》2008,124(1):57-71
The influence of the planetary boundary layer on the sonic boom received at the ground level is known since the 1960s to be of major importance. Sonic boom propagation in a turbulent medium is characterized by an increase of the mean rise time and a huge variability. An experiment is conducted at a 1:100,000 scale in water to investigate ultrasonic shock wave interaction with a single heterogeneity. The experiment shows a very good scaling with sonic boom, concerning the size of the heterogeneities, the wave amplitude, and the rise time of the incident wave. The wave front folding associated with local focusing, and its link to the increase of the rise time, are evidenced by the experiment. The observed amplification of the peak pressure (by a factor up to 2), and increase of the rise time (by up to about one magnitude order), are in qualitative agreement with sonic boom observations. A nonlinear parabolic model is compared favorably to the experiment on axis, though the paraxial approximation turns out less precise off axis. Simulations are finally used to discriminate between nonlinear and linear propagations, showing nonlinearities affect mostly the higher harmonics that are in the audible range for sonic booms. 相似文献
959.
Mathilde Briday Franois Hall Lauriane Lecoq Sylvie Radix Juliette Martin Roland Montserret Marie Dujardin Marie-Laure Fogeron Michael Nassal Beat H. Meier Thierry Lomberget Anja Bckmann 《Chemical science》2022,13(30):8840
Hepatitis B virus (HBV) is a small enveloped retrotranscribing DNA virus and an important human pathogen. Its capsid-forming core protein (Cp) features a hydrophobic pocket proposed to be central notably in capsid envelopment. Indeed, mutations in and around this pocket can profoundly modulate, and even abolish, secretion of enveloped virions. We have recently shown that Triton X-100, a detergent used during Cp purification, binds to the hydrophobic pocket with micromolar affinity. We here performed pharmacomodulation of pocket binders through systematic modifications of the three distinct chemical moieties composing the Triton X-100 molecule. Using NMR and ITC, we found that the flat aromatic moiety is essential for binding, while the number of atoms of the aliphatic chain modulates binding affinity. The hydrophilic tail, in contrast, is highly tolerant to changes in both length and type. Our data provide essential information for designing a new class of HBV antivirals targeting capsid–envelope interactions.Small-molecule binding to the Hepatitis B virus core protein hydrophobic pocket, a possible strategy for targeting viral particle assembly. 相似文献
960.
Bastien Cochereau Laurence Meslet-Cladire Yves Franois Pouchus Olivier Grovel Catherine Roullier 《Molecules (Basel, Switzerland)》2022,27(10)
In nature, living organisms produce a wide variety of specialized metabolites to perform many biological functions. Among these specialized metabolites, some carry halogen atoms on their structure, which can modify their chemical characteristics. Research into this type of molecule has focused on how organisms incorporate these atoms into specialized metabolites. Several families of enzymes have been described gathering metalloenzymes, flavoproteins, or S-adenosyl-L-methionine (SAM) enzymes that can incorporate these atoms into different types of chemical structures. However, even though the first halogenation enzyme was discovered in a fungus, this clade is still lagging behind other clades such as bacteria, where many enzymes have been discovered. This review will therefore focus on all halogenation enzymes that have been described in fungi and their associated metabolites by searching for proteins available in databases, but also by using all the available fungal genomes. In the second part of the review, the chemical diversity of halogenated molecules found in fungi will be discussed. This will allow the highlighting of halogenation mechanisms that are still unknown today, therefore, highlighting potentially new unknown halogenation enzymes. 相似文献