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141.
The modified imbedded disc retraction method for measurement of interfacial tension in polymer melts
The imbedded disc retraction method is used to estimate interfacial tension in LLDPE/PS system with PS as the imbedded disc.
Shape evolution of a disc of one material (PS) imbedded into the matrix of another material is observed (LLDPE). Three to
five repetitions at three different temperature levels are observed. The Newtonian model of Rundqvist et al. (1996) for the
imbedded disc retraction is modified to include elastic effects. The modified model is derived assuming uniaxial extension,
starting with the lower convected Maxwell model. Both the original model and modified imbedded disc retraction model are used
in data analysis. The mean values of interfacial tension at 190 °C, 200 °C, and 210 °C are 6.8 ± 0.7 mN/m, 3.9 ± 0.3 mN/m,
and 3.7 ± 0.2 mN/m, respectively. A method of estimating whether elastic effects will significantly affect the estimated interfacial
tension value during retraction for the given polymer pair is provided.
Received: 6 August 1999 Accepted: 2 January 2001 相似文献
142.
Savic S Lukic M Jaksic I Reichl S Tamburic S Müller-Goymann C 《Journal of colloid and interface science》2011,358(1):182-191
To be considered as a suitable vehicle for drugs/cosmetic actives, an emulsion system should have a number of desirable properties mainly dependent on surfactant used for its stabilization. In the current study, C(12-14) alkyl polyglucoside (APG)-mixed emulsifier of natural origin has been investigated in a series of binary (emulsifier concentration 10-25% (w/w)) and ternary systems with fixed emulsifier content (15% (w/w)) with or without glycerol. To elucidate the systems' colloidal structure the following physicochemical techniques were employed: polarization and transmission electron microscopy, X-ray diffraction (WAXD and SAXD), thermal analysis (DSC and TGA), complex rheological, pH, and conductivity measurements. Additionally, the emulsion vehicles' skin hydration potential was tested in vivo, on human skin under occlusion. In a series of binary systems with fixed emulsifier/water ratios ranging from 10/90 to 25/75 the predominance of a lamellar mesophase was found, changing its character from a liquid crystalline to a gel crystalline type. The same was observed in gel emulsions containing equal amounts of emulsifier and oil (15% (w/w)), but varying in glycerol content (0-25%). Different emulsion samples exhibited different water distribution modes in the structure, reflecting their rheological behavior and also their skin hydration capacity. 相似文献
143.
Shahed Al‐Haque Jason W. Miklas Nicole Feric Loraine L. Y. Chiu Wen Li Kelly Chen Craig A. Simmons Milica Radisic 《Macromolecular bioscience》2012,12(10):1342-1353
Previous studies demonstrated the importance of substrate stiffness and topography on the phenotype of many different cell types including fibroblasts. Yet the interaction of these two physical parameters remains insufficiently characterized, in particular for cardiac fibroblasts. Most studies focusing on contact guidance use rigid patterned substrates. It is not known how the ability of cardiac fibroblasts to follow grooves and ridges changes as the substrate stiffness is decreased to match the range of stiffness found in native heart tissues. This report demonstrates a significant interactive effect of substrate stiffness and topography on cardiac fibroblast elongation and orientation using polyacrylamide substrates of different stiffness and topography.
144.
Vasić M Šljukić B Wildgoose GG Compton RG 《Physical chemistry chemical physics : PCCP》2012,14(28):10027-10031
Graphite modified with gallic acid to form 'gallic acid-carbon' is demonstrated to be efficient for the removal of bismuth(III) ions from aqueous solutions. The uptake is demonstrated to be rapid but not to follow standard adsorption isotherm models. Instead, the uptake was found to be further promoted by the presence of the adsorbed metal. Additionally, the bismuth uptake showed linear dependence on the square of its concentration suggesting the possible formation of polymeric bismuth species. The gallic acid-carbon shows great promise as a relatively inexpensive material for solid-phase extraction and water purification with extraction efficiency close to 98%. 相似文献
145.
Mirjana Stojanovic 《PAMM》2013,13(1):367-368
Fractional differential equations have received increasing attention during recent years since the behavior of many physical systems can be properly described using the fractional order system theory. By fractional analog for Duhamel principle we give the existence-uniqueness result for linear and nonlinear time fractional evolution equations with singularities in corresponding norm in extended Colombeau algebra of generalized functions. In order to find the explicit solutions we use integral representation of the solution obtained via Laplace and Fourier transforms in succession and their inverses. We deal with some nonlinear models with singularities appearing in viscoelasticity and in anomalous processes, extending the results in viscoelasticity, continuum random walk, seismology, continuum mechanics and many other branches of life and science. The main task is finding existence-uniqueness results like in the case of evolution equations with entire derivatives. By examining the fractional evolution equations it turns out that they lead to till now known results from the evolution equations with entire derivatives in limiting case. They give more, behavior of the solution when order of derivatives are inside the intervals of entire points. In this way we can follow the influence of the operators generated by entire derivative in many fractional time evolution PDEs especially with singular initial data, and non-Lipschitz's nonlinear term. Apart from evolution equations we prove also an existence-uniqueness result for an initial value problem with singularities for linear and nonlinear fractional elliptic equation of Helmholtz type and fractional order α, where 1 < Re(α) ≤ 2, with respect to the one variable from R +. As a framework, we employ also Colombeau algebra of generalized functions containing fractional derivatives and operations among them in order to deal with the fractional equations with singularities. We apply the same techniques to the fractional Laplace and Poisson equation linear and nonlinear ones. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
146.
Ivica Vujčić Tamara Gavrilović Milica Sekulić Slobodan Mašić Bojana Milićević Miroslav D. Dramićanin 《辐射效应与固体损伤》2013,168(11-12):1054-1067
ABSTRACTYPO4 phosphors doped with trivalent ion Pr3+ were prepared by sol–gel method and treated with different doses of gamma radiation, from 0.25 MGy to 4 MGy. Effects of radiation on morphology, structure and luminescent properties were analyzed. Also, the influence of radiation on the change in the color of the samples was examined. The color efficiency of powders was evaluated by colorimetric analysis (CIE and L * a * b system). It has been observed that powders change color under the influence of radiation, i.e. they pass from white to pinkish red. Also, it has been determined that the radiation affects morphology change, as the particle size increases with increasing of the radiation dose. With the increase in the radiation dose, the emission intensity of samples decreases. The structure remains almost unchanged after irradiation, and the intensity constantly decreases with increasing of dose. 相似文献
147.
The theorem of Wick, which provides a systematic scheme for calculation of matrix elements in quantum many-body theories, is generalized to cover problems in which non-orthogonal Slater determinants appear The power of the present theorem is demonstrated by an example in the framework of the complex molecular orbital method. 相似文献
148.
Violeta D. Mitic Marija D. Ilic Vesna P. Stankov-Jovanovic Gordana S. Stojanovic Marija V. Dimitrijevic 《Natural product research》2018,32(2):222-224
The essential oil isolated from Erica spiculifolia Salisb. by hydrodistillation was analysed by GC-MS. One hundred compounds representing 92.6% of total oil were identified. Among the detected compounds 38 were monoterpenoids (46.2%), 30 were sesquiterpenoids (31.7%), 2 diterpene (0.4%) and 30 compounds (14.3%) were with various non-terpenoid structures. Oxygenated monoerpenes were by far the main class (45.3%) with α-terpineol (7.5%) endo-borneol (7.2%), pinocarveol (5.9%) and thymol (3.7%) as the major compounds. The predominant components of sesquiterpenes were caryophyllene oxide (5.0%), caryophyllene (4.2%), τ –murrolol (3.5%), spathulenol (2.9) and α-cadinol (2.3%). 相似文献
149.
Rozalija Ninković Jelena Miladinović Milica Todorović Snežana Grujić Joseph A. Rard 《Journal of solution chemistry》2007,36(4):405-435
Isopiestic vapor pressure measurements were made for {xZnCl2+(1−x)ZnSO4}(aq) solutions with ZnCl2 molality fractions of x=(0,0.3062,0.5730,0.7969, and 1) at the temperature 298.15 K, using KCl(aq) as the reference standard. These measurements
cover the water activity range 0.901–0.919≤a
w≤0.978. The experimental osmotic coefficients were used to evaluate the parameters of an extended ion-interaction (Pitzer)
model for these mixed electrolyte solutions. A similar analysis was made of the available activity data for ZnCl2(aq) at 298.15 K, while assuming the presence of equilibrium amounts of ZnCl+(aq) ion-pairs, to derive the ion-interaction parameters for the hypothetical pure binary electrolytes (Zn2+,2Cl−) and (ZnCl+,Cl−). These parameters are required for the analysis of the mixture results. Although significant concentrations of higher-order
zinc chloride complexes may also be present in these solutions, it was possible to represent the osmotic coefficients accurately
by explicitly including only the predominant complex ZnCl+(aq) and the completely dissociated ions. The ionic activity coefficients and osmotic coefficients were calculated over the
investigated molality range using the evaluated extended Pitzer model parameters. 相似文献
150.
Zoran D. Matovi Vesna D. Mileti Miorad M. Vasojevi Milica Cvijovi Svetlana uri Svetlana K. Beloevi 《Monatshefte für Chemie / Chemical Monthly》2007,138(9):823-832
Summary. An iron(III) complex with the hexadentate ligand 1,3-propanediamine-N,N′-diacetate-N,N′-di-3-propionate (1,3-pddadp) was prepared, chromatographically isolated as its isomer trans(O5O6)-Cs[Fe(1,3-pddadp)] · 2H2O, and characterized. The trans(O5O6) configuration of the iron(III) compound was found to dominate and this geometry was established by means of IR spectroscopy
and Density Functional Theory (DFT). Structural data correlating the octahedral geometry of the [Fe(1,3-pddadp)]− unit and an extensive strain analysis are discussed in relation to the information obtained for similar complexes. Antibacterial
activities of the free ligand and its corresponding iron(III) complex towards common Gram-negative and Gram-positive bacteria are reported as well. 相似文献