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941.
Harry Cárdenas 《Molecular physics》2016,114(18):2627-2640
ABSTRACTThis work illustrates the application of a three-party approach based on theoretical modelling, molecular dynamic (MD) simulations and available experimental data for describing the phase equilibrium and interfacial properties for the ternary system: carbon dioxide + n-butane + n-decane and its corresponding binary sub-systems at 344.3 K. Specifically, a coarse-grained force field is employed for both theoretical predictions and MD. The interfacial region is described by the square gradient theory where the homogenous Helmholtz energy density contribution is provided by the Statistical Associated Fluid Theory equation of state for potentials of variable range for molecules conformed of segments interacting through the Mie potential (SAFT-VR Mie) and MD simulations in the canonical ensemble where the molecules are represented by a coarse-grained Mie force field. The novelty here is that both the theory and the simulations uniquely share the same underlying intermolecular potentials; hence, the experimental data are employed to verify both the theory and simulations. In this schema, the ternary mixture is full predictive as its parameters are only based on pure fluids parameters and binary interactions. It is observed that the phase equilibria and the interfacial properties are equally well represented by the used approach. 相似文献
942.
Martin G. Bjørner 《Molecular physics》2016,114(18):2641-2654
ABSTRACTIn this work, a quadrupolar cubic plus association (qCPA) equation of state is evaluated for its ability to predict the phase equilibria of multicomponent mixtures containing CO2 and alkanes, alcohols, and/or water. A single binary interaction parameter is employed in qCPA for all binary combinations. All parameters are based solely on pure fluid or binary mixture data and multicomponent data are used only to evaluate the predictions. The performance of qCPA is, for all mixtures, compared to CPA where CO2 is considered to be either non-associating (inert), solvating or self-associating. In the latter two approaches, an additional adjustable parameter is employed for binary pairs of CO2 and an associating compound. The results show that the predictions with qCPA are very similar to the best performing CPA approaches, even though the model uses fewer adjustable binary parameters. The predictions with qCPA and the best CPA approaches are typically satisfactory and predict the general behaviour of the systems. As expected, qCPA and CPA with solvation or association typically performs better than inert CPA for two- and three phase vapour–liquid and vapour–liquid–liquid equilibria. However, inert CPA yields the best results of all the models for the prediction of dew point pressures. 相似文献
943.
Effect of Confinement on the Properties of Sequestered Mixed Polar Solvents: Enzymatic Catalysis in Nonaqueous 1,4‐Bis‐2‐ethylhexylsulfosuccinate Reverse Micelles 下载免费PDF全文
Dr. Andres M. Durantini Dr. R. Dario Falcone Dr. Juana J. Silber Dr. N. Mariano Correa 《Chemphyschem》2016,17(11):1678-1685
The influence of different glycerol, N,N‐dimethylformamide (DMF) and water mixtures encapsulated in 1,4‐bis‐2‐ethylhexylsulfosuccinate (AOT)/n‐heptane reverse micelles (RMs) on the enzymatic hydrolysis of 2‐naphthyl acetate by α‐chymotrypsin is demonstrated. In the case of the mixtures with DMF and protic solvents it has been previously shown, using absorption, emission and dynamic light‐scattering techniques, that solvents are segregated inside the polar core of the RMs. Protic solvents anchor to the AOT, whereas DMF locates to the polar core of the aggregate. Thus, DMF not only helps to solubilize the hydrophobic substrate, increasing its effective concentrations but surprisingly, it does not affect the enzyme activity. The importance of ensuring the presence of RMs, encapsulation of the polar solvents and the corrections by substrate partitioning in order to obtain reliable conclusions is highlighted. Moreover, the effect of a constrained environment on solvent–solvent interactions in homogenous media and its impact on the use of RMs as nanoreactors is stressed. 相似文献
944.
基于HPLC/Q-TOF MS的4种农药联合暴露人群的代谢组学研究 总被引:1,自引:0,他引:1
采用基于高效液相色谱-飞行时间质谱联用(HPLC-TOF MS)的代谢组学方法,研究了啶虫脒、高效氯氟氰菊酯、联苯菊酯、甲氨基阿维菌素苯甲酸盐4种农药联合暴露所致的施药人群尿液中内源性代谢物的变化。采集30位农民喷洒4种复合农药前和喷洒农药期1,3,5,7 d的尿液进行检测。提取正常尿液中常见代谢物并通过质控样品评价手段进行分析,结果表明该方法具有良好的稳定性和精密度,可用于尿液中代谢物分析。多变量分析结果表明,暴露人群施药前后尿液的代谢物含量存在较大差异。对选取的36个差异离子进行鉴定,确定了8个生物标志物的结构。结果显示联合暴露组人群尿液中多巴胺、5-羟色胺、酪氨酸、色氨酸、牛磺酸和马尿酸的含量显著下降;犬尿素和肌酸的含量显著上升。4种农药联合暴露导致接触人群尿液中色氨酸代谢途径的中间产物含量降低,肝代谢和能量代谢相关的代谢物蓄积,可能与神经系统和肝脏功能的受损有关。 相似文献
945.
P. V. Verdes M. M. Mato J. L. Legido M. I. Paz Andrade 《Journal of Thermal Analysis and Calorimetry》2008,92(1):179-183
Densities at 298.15 K and atmospheric pressure have been measured, using a DMA 4500 Anton Paar densimeter, for the ternary
mixture methyl tert-butyl ether (MTBE)+1-pentanol+nonane and for the involved binary mixture 1-pentanol+nonane. In addition, excess molar volumes
were determined from the densities of the pure liquids and mixtures. Suitable fitting equations have been used in order to
correlate adequately the excess molar volumes.
Experimental data were also used to test several empirical expressions for estimating ternary properties from experimental
binary results. 相似文献
946.
Nina Lorenz Jianing Liu Thomas Palberg 《Colloids and surfaces. A, Physicochemical and engineering aspects》2008,319(1-3):109-115
As a step towards the modelling of binary metal alloys we here report on the shape of the phase boundary of two deionized charged sphere colloidal suspensions as a function of mixing ratio and particle density. Their size ratios are r = 0.68 and r = 0.56. Both aqueous suspensions of polystyrene copolymer spheres crystallize in a body-centred cubic structure. Interesting differences in the shape of the phase boundary are observed. In the first case a peaked increase of crystal stability was observed for a mixing ratio of p = 0.2–0.3, which gives the fraction of small spheres. Also in the second case the stability of the crystalline phase is larger than expected for an ideal solid solution but over a more extended range of small p. In addition at p = 0.7–0.8 we find a pronounced suppression of crystallization and furthermore some indications of a precipitation of one species at p = 0.9. While the first phase diagram resembles that of a solid solution with possibly the onset of compound formation, the second more resembles a eutectic. 相似文献
947.
In order to study the intrinsic characteristics and to evaluate the structural variations determined by the addition of a co-solvent to 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) we examined the behaviour of some probes in [bmim][BF4]/co-solvent binary mixtures. The rate constants of the piperidino-catalyzed rearrangement of the Z-phenylhydrazone of the 3-benzoyl-5-phenyl-1,2,4-oxadiazole into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole as well as the spectrometric properties of pyrene and Nile Red were evaluated. With the same purpose also 1H NMR and conductivity measurements were carried out. By comparison the behaviour of 1-butyl-3-methylimidazolium bis-(trifluoromethylsulfonylimide)/1,4-dioxane mixtures has been analyzed. The whole of data confirms the presence of weak interactions that determine a partially preorganized structure for [bmim][X]. This is perturbed at some degrees by quantity and nature of guest molecules. For example conductivity measurements support the idea that different charged aggregates are present in the [bmim][X]/co-solvent binary mixtures. 相似文献
948.
The liquid structures of water-tetrahydrofuran (THF) and water-acetone binary mixtures were investigated by the X-ray scattering
method. Comparison of the X-ray scattering data revealed that only one kind of intermolecular water-organic molecule interaction
is commonly involved throughout all mole fractions of these liquid mixtures, in addition to the intermolecular water-water
and organic molecule-organic molecule interactions, which are present in neat water and organic liquids, respectively. On
the basis of this finding, we proposed a new analytical method for studying liquid mixtures. By this method the structural
information on the intermolecular water-organic molecule interaction as well as the concentrations of the intermolecular water-water,
water-organic molecules, and organic molecule-organic molecule interactions were obtained. Combining the concentrations of
the intermolecular water-water interaction with the concentrations of water in the liquid mixtures, the number of water-water
hydrogen bonds at various mole fractions was experimentally determined for the first time. From the dependence of the number
of water-water hydrogen bonds on the composition of the liquid mixtures, the change of the size of the self-associated water-water
clusters was deduced. 相似文献
949.
Petr Křenek 《Plasma Chemistry and Plasma Processing》2008,28(1):107-122
The article presents the calculation of thermophysical properties of the mixture water steam–argon which has been used to
further enhance the characteristics of plasma torches stabilized by the water wortex. The calculations were performed at the
temperatures 400–50,000 K and at 0.1 MPa. First, the composition and thermodynamic properties are determined by classical
methods. Further the calculations of viscosity, electrical conductivity and thermal conductivity of the mixture are computed
in the 4th approximation of the Chapman–Enskog method. The computation of collision integrals is described with special respect
to the interactions of charged particles where the necessary calculations for the Coulomb potential screened at the Debye
length were enlarged to cover the 4th approximation. Then the formulae describing the method based on the variational principle
of solving the system of Boltzmann integrodifferential equations are shortly introduced and the transport coefficients are
presented. 相似文献
950.
Oger L Ammi M Valance A Beladjine D 《The European physical journal. E, Soft matter》2005,17(4):467-476
We performed numerical simulations of one-bead collision on the surface of a static granular medium. The simulations have been done for two- and three-dimensional packings of beads. The effect of the incident bead velocity, the shot angle, the mechanical parameters and the packing structure are analyzed for ordered and disordered 2D packings and only disordered 3D packings. The 2D results are in good agreement with experimental available data. The 3D simulations give good preliminaries results about the shock-wave propagation through the stacking and provides new insights in the ejection process (“splash function”). 相似文献