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61.
Francesco Malatesta Giacomo Carrara Maria Perla Colombini Ambrogio Giacomelli 《Journal of solution chemistry》1993,22(8):733-749
The activity coefficients of Co(en)3Cl3 and K2SO4 were measured by means of a cell with ion-exchange liquid membranes following the method described in paper I. The results prove that this method is even more valuable with multicharged salts than with 1-1 electrolytes. The values obtained are precise and reliable down to dilution limits never before accessible, e.g., 4×10–5 mol-kg–1 in Co(en)3Cl3. High dilution levels are of particular importance when dealing with highly charged electrolytes since the trend at higher concentrations often leads to errors both in extrapolation to infinite dilution and in the absolute activity coefficients. As an application, the activity coefficients of [Co(en)3]2(SO4)3-suspected to be wrongly evaluated in past literature-were measured, and their values at low concentrations were actually lower than those quoted before. 相似文献
62.
In the context of the density functional theory of the local electron density the valence and differential density distribution in crystalline sulfates of M2SO4 (M is Li, Rb, and Cs) and double sulfates of MLiSO4 were calculated using the pseudopotential method in the basis set of numerical atomic pseudo-orbitals. It is shown that in lithium sulfate crystallographically inequivalent oxygen atoms are in different charge states and have a different force of chemical bonding with sulfur. Anions are bonded to each other through lithium atoms that form tetrahedral complexes with oxygen. In rubidium sulfates the electron clouds of the anions overlap and chain structures form. Chemical bonding between the anion and the cation has an ionic nature. These features of the electron structure manifest themselves in double sulfates, where LiO4 complexes that link the anionic chains also form, and heavy metals serve as cations. 相似文献
63.
The effects of sodium dodecyl sulfate on extracellular lipase produced byCandida lipolytica have been studied. The microorganism was grown in culture medium containing different sodium dodecyl sulfate concentrations
added to the culture at different intervals of growth. The extracellular lipase activity was not detected when the treated
culture supernatants were directly tested in Yeast Mold Agar-Triolein-Rhodamine plates, regardless of surfactant addition
time and concentrations. However, after ammonium sulfate precipitation and dialysis, the extracellular lipase activity could
be recovered. Therefore, the surfactant, under the experimental conditions used here, does not seem to be able to inhibit
lipase production, but it does inhibit the enzyme activity because of its presence in the mixture of the reaction. 相似文献
64.
The electrocatalytic oxidation of hydrazine at the aluminum electrode, modified by electroless deposition of nickel pentacyanonitrosylferrate
(NiPCNF) on the surface of the electrode has been studied by cyclic voltammetry, chronoamperometry and rotating disk electrode
voltammetry and the kinetics of the catalytic reaction were investigated. The results were explained using the theory of electrocatalytic
reactions at chemically modified electrodes. It was found that a one-electron charge-transfer process is rate limiting and
that the average values of the rate constant for the catalytic reaction and the diffusion coefficient, evaluated by different
approaches, are 5.2×103 M–1s–1 and 8.5×10–6 cm2s–1, respectively. Further examinations of the modified electrodes show that the modifying layers (NiPCNF) on the aluminum substrate
have reproducible behavior and a high level of stability, after exposing them in air and hydrazine solutions for a long time.
Electronic Publication 相似文献
65.
Various types of sodium cellulose sulfate (SCS), dissolved in a 1M LiCl solution, were investigated by alternating current (AC)polarography. The SCS samples differed in the degree of substitution (DS), thedistribution of substituents within the anhydroglucose unit (AGU), and alongthechain, due to the method of synthesis. The goal was to study theelectrosorptionbehavior, characterized by the shape of the desorption wave in the polarogram,as a function of the chemical structure of the SCS samples. The shape of thedesorption wave reflects domains of different substitution. A superimpositionofparameters like DS and pattern of substitution on the electrosorption behaviorwas observed. The AC polarography method described can be used as a tool todistinguish between an even or uneven distribution of substituents along thecellulose chain. 相似文献
66.
67.
Marián Kucharík František Šimko Vladimír Danielik Miroslav Boča Roman Vasiljev 《Monatshefte für Chemie / Chemical Monthly》2007,138(12):1211-1215
Summary. The phase diagram of the system Na3AlF6–NaVO3 was determined by means of thermal analysis. The system is a simple binary eutectic one. The eutectic point was estimated
at x(NaVO3) = 0.975 and t
eut = 617°C. The XRD patterns of samples after thermal analysis revealed the presence of cryolite and NaVO3 only supporting the above assumption of a simple eutectic binary system. 相似文献
68.
Methyl methacrylate and butyl methacrylate were polymerized in oil-in-water microemulsions that were stabilized by sodium dodecyl sulphate (SDS). A poly(N-acetylethylenimine) (PNAEI) macromer was also included in the recipe, as a cosurfactant and a comonomer. Polymerizations were initiated by UV-irradiation. The average diameters of latex particles, obtained by STM, were in the range of 17-200 nm. The experimental data evidenced that the particle size was mainly dependent on the SDS/PNAEI ratio. Polymerization yields were around 75-85%. The synthesized copolymers have viscosity average molecular weights in the range of 2.1-2.4×106 and glass transition temperatures of 38.0-43.5°C, lower than those obtained without using PNAEI. The investigation by means of FTIR and 1H-NMR techniques revealed that PNAEI was incorporated into the nanoparticles. 相似文献
69.
研究了烷基硫酸钠纯度,烷基碳链分布对甲基丙烯酸甲酯种子乳液聚合反应的影响。结果表明,烷基硫酸钠中乙醇不溶物含量的增加,可提高MMA乳液聚合反应速度,在采用K2S2O8-NaHSO3-Cu^2+三元氧化-还原引发体系的MMA乳液聚合中,Fe^2+降低反应速率,而Fe^3+则提高聚合反应速率; 相似文献
70.