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101.
Popa I Cahill BP Maroni P Papastavrou G Borkovec M 《Journal of colloid and interface science》2007,309(1):28-35
The adsorption of poly(diallyldimethyl ammonium chloride) (DADMAC) on planar silica substrates was examined as a function of ionic strength and pH. The study was carried out with reflectometry in an impinging-jet cell and complemented by atomic force microscopy (AFM) and ellipsometry investigations. The adsorption process is initially transport limited, whereby the adsorption rate increases somewhat with increasing ionic strength. This effect is caused by a simultaneous decrease of the hydrodynamic radius of the polymer. After a transient period, the adsorption process saturates and leads to an adsorption plateau. The plateau value increases strongly with increasing ionic strength. This increase can be explained by progressive screening of the electrostatic repulsion between the adsorbing polyelectrolyte chains, as can be rationalized by a random sequential adsorption (RSA) model. The adsorbed amount further increases with increasing pH, and this effect is probably caused by the corresponding increase of the surface charge of the silica substrate. 相似文献
102.
A strategy for obtaining stable concentrated silver dispersions without dedicated stabilizing agents is presented. This approach consists of rapidly mixing aqueous solutions of silver salicylate and ascorbic acid. By using salicylate as Ag(+) counterion, it is possible to prepare stable sols with metal concentrations up to two orders of magnitude higher than with silver nitrate. The stabilizing effect of the counterion is the result of a decreased ionic strength due to salicylate protonation and its adsorption on the surface of silver. Both effects increase the range of the electrostatic repulsive forces by expanding the electrical double layer. 相似文献
103.
Vladimir?Iancu Mihai?Razvan?Mitroi Ana-Maria?Lepadatu Ionel?Stavarache Magdalena?Lidia?CiureaEmail author 《Journal of nanoparticle research》2011,13(4):1605-1612
The quantum efficiency of the absorption on quantum confinement levels is investigated. This is achieved by modeling the electron
confinement in a spherical quantum dot (QD). The confinement levels are calculated using both infinite and finite rectangular
quantum wells. The spectral internal quantum efficiency is evaluated within both the models, by computing Einstein’s coefficients
for the transitions between confinement levels. The size of QDs (1–3 nm radius) leads to negligible many body effects. The
nature of the QD material and of the matrix embedding is taken into account in the finite rectangular quantum well approximation
and introduces only a small correction. The temperature dependence of the efficiency is also taken into account. A numerical
application is performed for a silicon QD of 2.5 nm radius, embedded in amorphous silica. It is proved that the absorption
threshold shifts toward the far infrared limit and that the spectral internal quantum efficiency reaches 4–5% at the threshold. 相似文献
104.
Adriana Valentina Busuioc Ionel Sorin Ciuperca Dragoş Iftimie Liviu Iulian Palade 《Journal of Dynamics and Differential Equations》2014,26(2):217-241
We consider the FENE dumbbell polymer model which is the coupling of the incompressible Navier-Stokes equations with the corresponding Fokker–Planck–Smoluchowski diffusion equation. We show global well-posedness in the case of a 2D bounded domain. We assume in the general case that the initial velocity is sufficiently small and the initial probability density is sufficiently close to the equilibrium solution; moreover an additional condition on the coefficients is imposed. In the corotational case, we only assume that the initial probability density is sufficiently close to the equilibrium solution. 相似文献
105.
Daniela Dirtu Lucia Odochian Aurel Pui Ionel Humelnicu 《Central European Journal of Chemistry》2006,4(4):666-673
The paper reports the thermal decomposition of ammonia under dynamic conditions at 800°C in a quartz reactor. Its purpose
is to confirm the homogeneous-heterogeneous degenerated branched chain mechanism established in previous studies, which assume
the formation of N2H4 as a molecular intermediate; this paper identifies hydrazine as a product of thermal decomposition using FT-IR and UV-VIS
spectroscopies. 相似文献
106.
This study investigates the conformity to Benford’s Law of the information disclosed in financial statements. Using the first digit test of Benford’s Law, the study analyses the reliability of financial information provided by listed companies on an emerging capital market before and after the implementation of International Financial Reporting Standards (IFRS). The results of the study confirm the increase of reliability on the information disclosed in the financial statements after IFRS implementation. The study contributes to the existing literature by bringing new insights into the types of financial information that do not comply with Benford’s Law such as the amounts determined by estimates or by applying professional judgment. 相似文献
107.
Madalina Tudorache George Ghemes Andreea Nae Elena Matei Ionel Mercioniu Erhard Kemnitz Benjamin Ritter Simona Coman Vasile I. Parvulescu 《Central European Journal of Chemistry》2014,12(12):1262-1270
A comparative study of two different biocatalytic models, e.g. enzyme immobilized on magnetic particles (EIMP) and cross-linking enzyme aggregates onto magnetic particles (CLEMPA) was performed. The first model was designed as enzyme-immobilized on the magnetic particles surface (EIMP). The second model was constructed as a network structure with the enzyme aggregates and magnetic particles placed into the nodes and polyglutaraldehyde cross-linker as the network ledges. The design was called cross-linking enzyme aggregates onto magnetic particles (CLEMPA). The biocatalysts were prepared using lipase enzyme from Aspergillus niger for catalyzing the glycerol (Gly) conversion to glycerol carbonate (GlyC). The biocatalyst characteristics for both designs (EIMP and CLEMPA) were evaluated using scanning electron microscopy (SEM), laser light scattering (LLS) and UV-Vis techniques. The EIMP model was strongly influenced by the composition of the polymeric layer covering the particles surface, while the size of the magnetic particles affected mostly the CLEMPA design. Also, the biocatalytic capacity of the tested models was evaluated as maximum 52% Gly conversion with 90% GlyC selectivity for EIMP, and 73% Gly conversion with 77% GlyC selectivity for CLEMPA. Both biocatalytic models were successfully used to prepare GlyC from “crude” glycerol collected directly from the biodiesel process (e.g. 49% Gly conversion with 91% GlyC selectivity for EIMP and 70% Gly conversion with 80% GlyC selectivity for CLEMPA). 相似文献
108.
Ionel Rovenţa 《Mediterranean Journal of Mathematics》2016,13(2):573-583
In this paper, we study some weak majorization properties with applications for the trees. A strongly notion of majorization is introduced and Hardy–Littlewood–Polya’s inequality is generalized. 相似文献
109.
John Peter Coats Rémy Cochereau Ionel Adrian Dinu Daniel Messmer Flavien Sciortino Cornelia. G. Palivan 《Macromolecular bioscience》2023,23(8):2200474
Polymeric nano- and microscale materials bear significant potential in manifold applications related to biomedicine. This is owed not only to the large chemical diversity of the constituent polymers, but also to the various morphologies these materials can achieve, ranging from simple particles to intricate self-assembled structures. Modern synthetic polymer chemistry permits the tuning of many physicochemical parameters affecting the behavior of polymeric nano- and microscale materials in the biological context. In this Perspective, an overview of the synthetic principles underlying the modern preparation of these materials is provided, aiming to demonstrate how advances in and ingenious implementations of polymer chemistry fuel a range of applications, both present and prospective. 相似文献
110.
This paper presents the results obtained by numerical simulations, the magnetic relaxation time simulation for a fine particle system with dipolar magnetic interaction. We used a 3D simulation model for fine magnetic particles with spherical shape and lognormal distribution for their diameters. Starting from Dormann–Bessais–Fiorani model, the 3D model we used is more realistic if we consider that the particles are randomly arranged into a preset volume, following a Gaussian distribution generated with the Box–Mueller transformation. 相似文献