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101.
A simple and efficient synthesis of polystyrene-supported proline and prolinamide has been carried out. Polystyrene-supported proline has been used as organocatalyst in the asymmetric aldol reaction between cyclohexanone and substituted benzaldehydes in water without any additive. High yields, diastereoselectivities and ee values have been observed. The versatility of this resin was demonstrated in the α-selenenylation of aldehydes. Both proline and prolinamide resins gave high yields. Recycling studies showed that the proline resin gave better results than prolinamide resin. 相似文献
102.
Antonio Selva Pietro Traldi Paolo Ventura Renato Pellegata 《Journal of mass spectrometry : JMS》1986,21(6):343-345
Electron impact mass spectra and collisional activation/mass-analysed ion kinetic energy spectra of some phthalamic acids and their deuterium labelled analogues suggested that the genesis of [M ? 1]+ ions is due to the loss of an aromatic hydrogen ortho to the amidic group, as for aromatic amides and thioamides. 相似文献
103.
Renato Barbieri M. Teresa Musmeci 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):103-107
Abstract The title compounds, representative of classes of diorganotin (IV) derivatives active against murine leukemia P-388. interact with rat hemoglobin (selected as a model protein) by: i) co-crystallization. with formation of microcrystalline pellets, and: ii) diffusion into hemoglobin crystals from the supernatant solution (as determined for the 2-mercaptoethanesulfonato derivative). The nature of the Me2SnIV species in hemoglobin has been investigated by 119Sn Mössbauer spectroscopy, and a C2SnS2 tetrahedral geometry has been assigned by the point-charge model rationalization of the nuclear quadrupole splitting parameter. Binding into crystalline hemoglobin has been ascribed to Coulomb interactions and to hydrogen bonding between the sulfonate and the aminoacid tails of the organotin (IV) derivatives and functional groups of the globin. 相似文献
104.
Nives Galić Nataša Burić Renato Tomaš Leo Frkanec Vladislav Tomišić 《Supramolecular chemistry》2013,25(5):389-397
The fluorescent peptidocalixarenes, 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(O-methyl-l-tryptophanylcarbonylmethoxy)calix[4]arene (1) and 5,11,17,23-tetra-tert-butyl-25,27-di(O-methyl)-26,28-bis(O-methyl-l-tryptophanylcarbonylmethoxy)calix[4]arene (2), were prepared by introducing tryptophan subunits at a lower calixarene rim. Coordination abilities of 1 and 2 towards Eu(III) and alkali metal cations were studied by spectrophotometric, spectrofluorimetric, conductometric and potentiometric titrations in acetonitrile at 25°C. Rather strong complexation was observed for smaller alkali metal cations Li+ and Na+ (log K Li1 >6, log K Li2 >6, log K Na1 = 8.25, log K Na2 = 6.94), and moderate for K+ (log K K1 = 5.09, log K K2 = 4.09). Larger Rb+ and Cs+ cations did not fit in the ion binding site of 1 so no complexation was detected, whereas the more flexible ligand 2 accommodated Rb+ cation (log K Rb2 = 3.44). The fluorescence of 1 (λex = 280 nm, λem = 340 nm) was remarkably quenched by Eu(III). Stability constant of 1:1 (Eu3+:1) complex determined spectrofluorimetrically amounted to log K Eu1 = 6.16. 相似文献
105.
de Farias Davi Marques de Faria Lucas Vinícius Lisboa Thalles Pedrosa Matos Maria Auxiliadora Costa Muñoz Rodrigo Alejandro Abarza Matos Renato Camargo 《Journal of Solid State Electrochemistry》2020,24(5):1165-1173
Journal of Solid State Electrochemistry - In this paper, we compare reduced graphene oxide (RGO) electrode with multi-walled carbon nanotubes (MWCNT) as modifiers for the sensitive detection of... 相似文献
106.
107.
Johannes Stadler Benedikt Oswald Thomas Schmid Renato Zenobi 《Journal of Raman spectroscopy : JRS》2013,44(2):227-233
In this article, the electromagnetic (EM) field in gap‐mode tip‐enhanced Raman spectroscopy (TERS) is investigated theoretically and experimentally for a range of commonly used and unusual metal and nonmetal substrates. By approaching a metal tip to a substrate, both form a coupled system that confines the EM field created at the tip apex. The influence of the substrate onto the EM field enhancement is observed in a top‐illumination gap‐mode TERS setup for different metal substrates. These include Au, the most commonly used substrate, and also a wide range of rarely or previously unused TERS substrates (Cu, Ag, Al, Pd, Pt, Ni, Ti, Mo, W, stainless steel, Al2O3, SiO2). Self‐assembled monolayers of thiols and brilliant cresyl blue thin film samples are investigated experimentally on nine metal substrates, all showing considerable TERS enhancement. With finite difference time domain and finite element simulations used, the article provides a good estimate of the EM field enhancement for a wide range of substrates for users to estimate how well a substrate of choice will perform in a gap‐mode TERS experiment. The reduction in EM field strength |E2| compared with Au is less than an order of magnitude for many metals (Calculations: Cu 92%, Ag 81%, Ni 53%). This article experimentally shows that a wide variety of conductive substrates can be used, when one is willing to trade a fraction of the EM field enhancement. TERS was seen on all metal substrates including stainless steel, yet quantification was not always possible. These qualitative results were complemented with intensities from calculations. The wider variety of substrates will increase the applicability of TERS and evolve it one step further towards use in standard analytics. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
108.
Renato Vessecchi Lourenço Marcelo Kobelnik Clóvis Augusto Ribeiro Fernando L. Fernonani 《Journal of Thermal Analysis and Calorimetry》2011,106(3):735-740
The Brazilian sugarcane industry shows a great amount of generated sludge which should be utilized adequately. Two sludge
samples, aerobic and anaerobic, were collected. Both were evaluated by thermogravimetry and differential thermal analysis
(DTA) as well as X-ray power diffraction. These compounds show variations of mass between 30 and 140 °C due to the dehydration
stage. The DTA curves show that the compounds have an exothermic reaction between 450 and 550 °C, which indicates that this
can be used as an energy source. Details concerning the kinetic parameters of the dehydration and thermal decomposition have
also been described here. The kinetic study of these stages was evaluated in open crucibles under nitrogen atmosphere. The
obtained data were evaluated with the isoconversional kinetic method. The results show that different activation energies
were obtained for thermal decomposition. 相似文献
109.
110.
Efficient crystallization induced emissive materials based on a simple push-pull molecular structure
Cariati E Lanzeni V Tordin E Ugo R Botta C Schieroni AG Sironi A Pasini D 《Physical chemistry chemical physics : PCCP》2011,13(40):18005-18014
Solid state luminescent materials are the subject of ever growing interest both from a scientific and a technological point of view. Aggregation caused quenching (ACQ) processes however represent an obstacle to the development of most luminogens in the condensed phase. This is why particularly fascinating are those materials showing higher emission intensity in the solid state than in solution. Here we report on three 4-dialkylamino-2-benzylidene malonic acid dialkyl esters, very simple push-pull molecules, which are hardly emissive in solution and in the amorphous phase but become good emitters in the crystalline phase according to what has been indicated as crystallization induced emission (CIE). Thanks to combined emission and NMR spectroscopies at different temperatures on the prototype compound 4-dimethylamino-2-benzylidene malonic acid dimethyl ester in solution, we give full evidence that a restricted intramolecular rotation (RIR) phenomenon, in particular the hindered rotation around the aryl main axis of the compound, is at the origin of this behaviour. In addition, solid state photophysical and X-ray diffraction structural characterization allow us to identify J-dimeric interactions as responsible for the particularly intense emission of two of the three compounds. Moreover, by exploiting the compounds' acidochromic properties, applications in sensors and optoelectronics are envisaged. 相似文献