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61.
62.
Synthesis and characterization of controlled drug release carriers based on functionalized amphiphilic block copolymers and super‐paramagnetic iron oxide nanoparticles 下载免费PDF全文
In this study, synthesis and characterization of magnetic nanocarriers are reported for drug delivery based on the amphiphilic di‐block and tri‐block copolymers of poly(ethylene glycol) (PEG) and poly(ε‐caprolactone) (PCL) with surface modified super‐paramagnetite Fe3O4 nanoparticles (magnetic nanoparticles (MNPs)). The synthesized block copolymers (methoxy poly(ethylene glycol) (mPEG)–PCL and PCL–PEG–PCL) were characterized by Fourier transform infrared (FT‐IR), 1H nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC), and their properties such as critical micelle concentration, hydrophilicity to lipophilicity balance, and hydrolytic degradation were investigated. The block copolymers were functionalized with terminal azide groups (mPEG–PCL(N3) and (N3)PCL–PEG–PCL(N3)), and magnetic Fe3O4 nanoparticles were surface modified with poly(acrylic acid) (PAA) and propargyl alcohol (MNP–PAA–C≡CH). Magnetic nanocarriers were synthesized by click reaction between azide‐terminated block copolymers and MNP–PAA–C≡CH and characterized by FT‐IR, thermogravimetric analysis (TGA), dynamic light scattering (DLS), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM), and cytotoxicity was investigated by methyl thiazolyl tetrazolium assay. In vitro drug loading and release and release kinetics were investigated. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
63.
M. W. Abdel Raouf K. Farah M. Nofal A. Alian 《Journal of Radioanalytical and Nuclear Chemistry》1997,221(1-2):153-159
Sorption of124Sb(III) from benzene, toluene, o-xylene and nitrobenzene on treated fly ash, pyrolysis residue and bentonite clay was studied at room temperature using the batch method. In comparison to a former study for the sorption of124Sb(V), the results revealed relatively higher sorption of the trivalent state than the pentavalent one. According to the type of the nonpolar solvent used, the order of uptake of the radioactive isotopes was often o-xylenetoluene>benzene. The sorption tendency of the sorbents used towards the radionuclides was: bentonitepyrolysis residue>treated fly ash. Sorption from an aqueous medium on the same sorbents has also been investigated for124Sb(III) compared to124Sb(V),152Eu(III) and their mixtures. The obtained results showed that the order of uptake of the different radionuclides was: Eu(III)>>Sb(III)>Sb(V)>mixture. The investigation was extended to the desorption studies of these radionuclides in the acidic and the neutral media from the dried radioactivity loaded sorbents. 相似文献
64.
Johannes Reisch Raouf A. Hussain Bernt Krebs Mechtild Dartmann 《Monatshefte für Chemie / Chemical Monthly》1990,121(11):941-944
Summary C15H24O2,M=236.2, monoclinic, P 21,a=7.229(7),b=14.925 (9),c=6.235 (9) Å, =92.40 (9)°,V=672.1 Å3,T=–133 °C,Z=2,D
x=1.17 g cm–3. The X-ray diffraction analysis of this sesquiterpenoid fromCarissa opaca confirmed the previously proposed constitution of the isolate and, furthermore, allowed precise NMR assignment.
Naturstoffchemie, 100. Mitt.: Die Struktur des Carissons, C15H24O2
Zusammenfassung C15H24O2,M=236.2, monoklin, P 21,a=7.229 (7),b=14.925 (9),c=6.235 (9) Å, =92.40 (9)°,V=672.1 Å3,T=–133 °C,Z=2,D x=1.17 g cm–3. Die Röntgenstrukturanalyse dieses Sesquiterpenoids ausCarissa opaca bestätigte die bereits vorgeschlagene Struktur und erlaubte ferner eine genaue NMR-Zuordnung.相似文献
65.
M. W. Abdel Raouf A. M. El-Kamash 《Journal of Radioanalytical and Nuclear Chemistry》2006,267(2):389-395
Summary Kinetics and equilibrium studies on the sorption of uranium and thorium ions were carried out from nitric acid solutions by
tri-n-butyl phosphate (TBP) loaded supported sorbent, commercially known as Egy-Sorb, using batch technique. Analysis of the
rate data in accordance with three kinetic models revealed that the particle diffusion process was the rate determining mechanism
and the sorption process of the metal ions onto impregnated sorbent follows first order reversible kinetics. The values of
the first order rate constants, the rate constants of intraparticle transport, and the particle diffusion coefficients for
the uranium and thorium ions were determined from the graphical representation of the proposed models. Experimental isotherms
of both ions were successfully fit to Langmuir and Freundlich isotherm models over the entire concentration range studied.
The effect of temperature on the equilibrium distribution values has been utilized to evaluate the changes in standard thermodynamic
quantities. 相似文献
66.
A. Raouf Chouikha 《Journal of Mathematical Analysis and Applications》2007,331(1):358-376
In this work we study Eq. (E) with a center at 0 and investigate conditions of its isochronicity. When f and g are analytic (not necessary odd) a necessary and sufficient condition for the isochronicity of 0 is given. This approach allows us to present an algorithm for obtained conditions for a point of (E) to be an isochronous center. In particular, we find again by another way the isochrones of the quadratic Loud systems (LD,F). We also classify a 5-parameters family of reversible cubic systems with isochronous centers. 相似文献
67.
This paper examines the dynamic behavior of a double pendulummodel with impact interaction. One of the masses of the two pendulumsmay experience impacts against absolutely rigid container wallssupported by an elastic system forming an inverted pendulum restrainedby a torsional elastic spring. The system equations of motion arewritten in terms of a non-smooth set of coordinates proposed originallyby Zhuravlev. The advantage of non-smooth coordinates is that theyeliminate impact constraints. In terms of the new coordinates, thepotential energy field takes a cell-wise non-local structure, and theimpact events are treated geometrically as a crossing of boundariesbetween the cells. Based on a geometrical treatment of the problem,essential physical system parameters are established. It is found thatunder resonance parametric conditions of the linear normal modes thesystem's response can be either bounded or unbounded, depending on thesystem's parameters. The ability of the system to absorb energy from anexternal source essentially depends on the modal inclination angle,which is related to the principal coordinates. 相似文献
68.
Khosravi Raouf Rabiei Saeed Khaki Mohammad Safaei Mohammad Reza Goodarzi Marjan 《Journal of Thermal Analysis and Calorimetry》2021,145(4):1949-1967
Journal of Thermal Analysis and Calorimetry - Analyzing microchannel heat sinks (MCHS) in terms of the second thermodynamic law is useful, and it is necessary to examine MCHSs in terms of... 相似文献
69.
Fabrication of Al/AlN nano‐composite layers by friction stir processing of 6061 Al‐T6 substrate 下载免费PDF全文
Seyed Farshid Kashani‐Bozorg Maryam Samiee Abbas Honarbakhsh‐Raouf 《Surface and interface analysis : SIA》2015,47(2):227-238
Friction stir processing was employed for the production of Al/AlN nano‐composite layers on a 6061 Al‐T6 substrate. Nano‐sized AlN powder was inserted in a groove in the middle length of the substrate. Defect‐free layers were achieved using tool rotation and substrate advancing speeds in the range of 900–1400 rpm and 63–310 mm/s, respectively. Subsequent passes were conducted to break‐up AlN clusters that formed in a non‐uniform fashion after initial pass. The grain size of aluminum matrix was found to decrease by the introduction of AlN powder. A nano‐composite layer with near uniform dispersion of nano‐sized AlN reinforcements with a ~9.6% volume fraction was achieved in a matrix of fine dynamically restorated Al grains with a mean size of ~2.5 µm after three subsequent passes. This layer showed an average micro hardness value of ~164 HV (much greater than ~103 HV of the underlying substrate). In addition, the nano‐composite layer exhibited superior dry sliding wear performance against hardened steel compared to that of 6061‐T6 substrate. Increasing tool rotation and substrate advancing speeds were found to decrease the AlN content of the processed layer possibly due to increasing in powder scattering by the pin tool. This was associated with a decrease and increase in hardness values and wear‐loss data, respectively. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
70.
Louisa Chouguiat Raouf Boulcina Bertrand Carboni Albert Demonceau Abdelmadjid Debache 《Tetrahedron letters》2014
The secondary amines synthesized by the reaction between 2-aminophenols and aromatic aldehydes, via the reduction of the corresponding imines, were employed in the synthesis of new 2-hydroxy-2H-1,4-benzoxazine derivatives through a one-pot Petasis multicomponent reaction in good to excellent yields. 相似文献