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1.
The collisional shifts and widths of several P-branch spectral lines in the fundamental band of CO-Ar have been measured at temperatures between 214 and 324 K and pressures between 0.025 and 1 atm. The widths have been determined using a line shape model based on the solution of the transport/relaxation equation for the appropriate off-diagonal element of the density matrix. The model uses a realistic molecular potential energy surface to calculate the speed dependence of the collisional broadening, and a rigid sphere potential to calculate the translational motion. It is found that both the shifting and broadening coefficients follow a power law dependence on the temperature. Additionally, it is demonstrated that studies have tended to overestimate the accuracy of collisional widths when the line shape model used to obtain the widths involves multiple fitted line shape parameters or fails to fit the measured spectra within the experimental noise. 相似文献
2.
W.John Albery David Clark Humphrey J.J. Drummond Anthony J.M. Coombs William K. Young Clive E.W. Hahn 《Journal of Electroanalytical Chemistry》1992,340(1-2)
A novel electrochemical sensor for the determination of CO2 in expired breath is described. The sensor works by generating
from the reduction of O2 in dimethyl sulphoxide (DMSO) in a generating pulse. There is a rapid titration reaction between the
and any CO2 present. In the recovery pulse the amount of unreacted
is determined. The larger the concentration of CO2 the less
is found in the recovery pulse. The solubilities and diffusion coefficients of O2 and CO2 in DMSO have been determined using rotating disc voltammetry and rotation speed step experiments. The stoichiometry, the product, and the rate constant of the titration reaction have been determined using ring—disc voltammetry and laser Raman spectroscopy. The operation and the effect of adventitious water on the sensor are described. Results are presented which show that the sensor can indeed measure the breath-by-breath rhythm of expired CO2 from a human subject. 相似文献
3.
This paper describes the use of a thin-layered dual-band electrochemical cell operating at flow conditions to determine dipyrone (sodium salt of 1-phenil-2,3-dimethyl-4-methylaminomethanesulfonate-5-pyrazolone) by reaction with electrogenerated iodine. The electrolytic cell consisted of two closely spaced gold electrodes, the upper stream electrode serving as the generator electrode and the downstream electrode working as the collector electrode. A linear dynamic range from 2 to 15 μmol l−1 dipyrone was obtained by using a sample volume of 100 μl, with a detection limit of 1.1 μmol l−1. Standard deviation (S.D.) of 3.4% for 20 repetitive injections of a 40 μmol l−1 dipyrone solution and sampling frequency of 90 h−1 were achieved. The results obtained with the thin-layered dual-band electrochemical cell for dipyrone determination in three different pharmaceutical samples compared well with those found by iodimetry with coulometrically generated iodine. 相似文献
4.
Abstract— The absorption spectra of the un-ionized and ionized forms of 4-heptadecyl-7-hydroxycoumarin (HHC) in aqueous self-assembled surfactant solution have been investigated. From a comparison with the absorption spectra of 7-hydroxycoumarin, 7-hydroxy-4-methylcoumarin (MHC) and HHC in neat organic solvents and organic solvent/water mixtures it is shown that the 7-hydroxycoumarin chromophore of HHC in self-assembled surfactant solution resides, on average, in an interfacial microenvironment which has a lower effective dielectric constant than that of the bulk aqueous solution. The absorption spectrum of the ionized form of HHC in aggregates of self-assembled surfactant molecules with cationic quaternary ammonium headgroups is found to be consistent with there being specific molecular interaction between the anionic chromophore and the quaternary ammonium headgroup. pH titrations performed with MHC in pure water and in four molar aqueous solutions of sodium chloride and tetra-methylammonium chloride indicate that the acid-base dissociation of HHC in charged micelles and vesicles should not be substantially influenced by any interfacial salt-effects, and that the acid-base dissociation of HHC in cationic micelles and vesicles with quaternary ammonium headgroups should not be markedly affected by the specific molecular interaction that exists. Estimates of the electrostatic surface potentials of a number of self-assembled surfactant aggregates are made by utilising the acid-base dissociation of HHC and assuming that the nonionic micelles of n -dodecyl octaoxyethylene glycol monoether (C12 E8 ) can serve as a reference state of zero surface potential. The validity of this assumption in relation to both micelles and vesicles is discussed in detail. 相似文献
5.
Mauricio Gomes Constantino Kleber Thiago de OliveiraAdilson Beatriz Gil Valdo José da Silva 《Tetrahedron letters》2003,44(13):2641-2643
A synthesis of a functionalized bicyclo[6.2.1]undecane, N-(7-hydroxymethyl-bicyclo[6.2.1]undeca-3,5,9-trien-2-yl)-4-methyl-benzenesulfonamide, is described. Starting with a [6+4] cycloaddition between cyclopentadiene and cycloheptatrienone, the final product was prepared in five steps with an overall 37% yield. The remarkable resistance to hydrolysis of an intermediate lactam was overcome by tosylating the amide and reducing with LiAlH4. 相似文献
6.
Carla Marisa Brito Carvalho Marta Akemi FujitaTimothy John Brocksom Kleber Thiago de Oliveira 《Tetrahedron》2013
New β-fused uracil-porphyrin conjugates were synthesized by the tetramerization of uracil-pyrroles under acidic conditions. Two different synthetic approaches were systematically studied in order to evaluate their efficiency, as well as the possibility to obtain a single regioisomer. Metallation effects were studied for aggregation in solution, and preliminary photophysical experiments were also performed in order to evaluate the potential of these new compounds. 相似文献
7.
Naloxone 3-methyl ether was selectively oxidized by treatment with cerium ammonium nitrate in aqueous acetonitrile at ambient temperature to provide the 10-(S)-hydroxy adduct. The stereochemistry of the oxidation product was proven by single crystal X-ray structure determination. The Dess-Martin periodinane further oxidized the 10-hydroxy to the 10-keto analog. Deprotection formed 10-ketonaloxone as an analytical reference standard. 相似文献
8.
Adilson Beatriz Roberto da Silva Gomes Mauricio Gomes Constantino Gil Valdo José da Silva Kleber Thiago de Oliveira 《Tetrahedron letters》2014
A bicyclo[6.2.1]undecane model compound of the core structure of the biologically active furanoheliangolide sesquiterpene was synthesized. This new and short route was developed by using a solvent-free Diels–Alder reaction between cyclopentadiene and 3-nitro-2-cyclohexenone, followed by simple transformations. Theoretical calculations were performed in order to understand reactivity aspects of the cycloaddition. 相似文献
9.
10.
Ribeiro Sabrina Dias Meneguin Andria Bagliotti Barud Hernane da Silva Silva Jhonatan Miguel Oliveira Rafael L. Asuno Rosana Maria Nascimento de Tormin Thiago Faria Muoz Rodrigo Alejandro Abarza Filho Guimes Rodrigues Ribeiro Clovis Augusto 《Journal of Thermal Analysis and Calorimetry》2022,147(13):7265-7275
Journal of Thermal Analysis and Calorimetry - Cellophane film production generates cellulosic residues from scraps, edges, and low-quality films. In this work, cellophane was used as a raw material... 相似文献