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91.
Particle image velocimetry measurements and time-resolved visualization are used for the reconstruction of the Kelvin–Helmholtz
vortex passing in the near field of a round jet and of a lobed jet. For the round jet, the entrainment is produced in the
braid region, where streamwise structures develop. In the Kelvin–Helmholtz ring, entrainment is dramatically affected by the
attenuation of the streamwise structures. As for the lobed jet, the special geometry introduces a transverse shear leading
to a breakdown of the Kelvin–Helmholtz structures into “ring segments.” Streamwise structures continuously develop at the
resulting discontinuity regions and control the lobed jet self-induction. In this case, the entrainment rate is less affected
by the primary structures dynamics. 相似文献
92.
Eman M. Mohi El-Deen Manal M. Anwar Amina A. Abd El-Gwaad Eman A. Karam Mohamed K. El-Ashrey Rafika R. Kassab 《Molecules (Basel, Switzerland)》2022,27(3)
The growing risk of antimicrobial resistance besides the continuous increase in the number of cancer patients represents a great threat to global health, which requires intensified efforts to discover new bioactive compounds to use as antimicrobial and anticancer agents. Thus, a new set of pyridothienopyrimidine derivatives 2a,b–9a,b was synthesized via cyclization reactions of 3-amino-thieno[2,3-b]pyridine-2-carboxamides 1a,b with different reagents. All new compounds were evaluated against five bacterial and five fungal strains. Many of the target compounds showed significant antimicrobial activity. In addition, the new derivatives were further subjected to cytotoxicity evaluation against HepG-2 and MCF-7 cancer cell lines. The most potent cytotoxic candidates (3a, 4a, 5a, 6b, 8b and 9b) were examined as EGFR kinase inhibitors. Molecular docking study was also performed to explore the binding modes of these derivatives at the active site of EGFR-PK. Compounds 3a, 5a and 9b displayed broad spectrum antimicrobial activity with MIC ranges of 4–16 µg/mL and potent cytotoxic activity with IC50 ranges of 1.17–2.79 µM. In addition, they provided suppressing activity against EGFR with IC50 ranges of 7.27–17.29 nM, higher than that of erlotinib, IC50 = 27.01 nM. 相似文献
93.
Solid-State Near-Infrared Circularly Polarized Luminescence from Chiral YbIII-Single-Molecule Magnet
Bertrand Lefeuvre Carlo Andrea Mattei Dr. Jessica Flores Gonzalez Dr. Frédéric Gendron Dr. Vincent Dorcet Dr. François Riobé Dr. Claudia Lalli Dr. Boris Le Guennic Prof. Olivier Cador Dr. Olivier Maury Prof. Stéphan Guy Dr. Amina Bensalah-Ledoux Dr. Bruno Baguenard Dr. Fabrice Pointillart 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(26):7362-7366
A field-induced chiral YbIII Single-Molecule Magnet (SMM) displayed an unprecedented near-infrared circularly polarized luminescence (NIR-CPL) in the solid-state. The bridging bis(1,10-phenantro[5,6b])tetrathiafulvalene triad ( L ) allowed an efficient sensitization of the NIR 2F5/2→2F7/2 emission while the NIR-CPL is associated to the f-f transitions of the YbIII ion bearing chiral β-diketonate derived-camphorate ancillary ligands. 相似文献
94.
The present article reports the formation of arsenic sulfide films on GaAs by the potentiodynamic polarization in acidified thiourea (TU) electrolytes under photo-illumination. Oxidation of TU competes with the oxidation of GaAs itself and leads to the formation of surface arsenic-sulfide films. Surface chemical composition is investigated by X-ray photoelectron spectroscopy (XPS), demonstrating the formation of As-sulfide as the XPS peaks at binding energies of 42.6 and 162.5 eV for As 3d and S 2p, respectively, are observed. XPS results also show diminishing of Ga species from the surface while As-sulfide is forming. Though, As-sulfide is predominantly formed on the surface, but the inductive coupling plasma-mass spectroscopy (ICP-MS) analysis still shows a preferential dissolution of As ions into electrolytes. These results indicate that Ga ions diffuse into the bulk of the electrode material. The formation of As-sulfide, initially, enhances the photocurrent generation; presumably, due to suppressing electron-hole recombination processes. Further deposition of As-sulfide deteriorates GaAs photoactivity due to retarding light absorptivity because of depositing a thick As-sulfide film. The morphology of the As-sulfide film is characterized by scanning electron microscopy (SEM) that shows the formation of smooth and nonporous films in TU electrolytes acidified by H2SO4 of concentration ≥0.2 M. Electrochemical impedance measurements show that GaAs corrosion is limited by the growth and oxidation of the sulfide layer. 相似文献
95.
Schiff bases of the type salicylidene 2-aminobenzothiazole and o-nitrobenzylidene 2-aminobenzothiazole were prepared by condensation of 2-aminobenzothiazole with salicylaldehyde and o-nitrobenzaldehyde. The bases react with cobalt(II), nickel(II) and copper(II) chlorides to give 1:1 and 1:2 complexes. Electronic spectra, magnetic susceptibility measurements and infrared data are used to infer the structures. The thermal decomposition of the complexes and evaluation of the thermodynamic parameters are also reported. 相似文献
96.
This article presents an experimental study conducted on a six-lobed rectangular jet at a very low Reynolds number of 800. The near-exit flow dynamics is compared to the reference counterpart circular jet with same initial conditions. Flow dynamics is analyzed using time-resolved flow-visualizations, hot-wire anemometry and laser Doppler velocimetry. In the round jet, flow motion is dominated by large primary Kelvin–Helmholtz (K–H) structures. In the six-lobed rectangular jet, the K–H vortices are very thin compared to the large secondary vortices generated by the high shear at the lobed nozzle lip. The inspection of mean-velocity profiles and streamwise evolutions of the spreading rates in the major and the minor planes of the lobed jet confirm the absence of the switching-over phenomenon not observed on flow images. The streamwise structures that develop in orifice troughs render the volumetric flow rate significantly higher than that of the reference circular jet. Comparison of the obtained results to available data of the literature of similar rectangular six-lobed jets investigated at very high Reynolds numbers reinforces the notion that the three-dimensional flowfields at very low and very high Reynolds numbers are similar if the geometry of the lobed nozzle is conserved. However, important variations in flow dynamics might occur if one or several geometric parameters of the lobed nozzle are modified. 相似文献
97.
Amina Benallou Baghdad Hadri Juan Martinez-Vega Nour El Islam Boukortt 《The European Physical Journal B - Condensed Matter and Complex Systems》2018,91(4):61
The effect of percolation threshold on the behaviour of electrical conductivity at high electric field of insulating polymers has been briefly investigated in literature. Sometimes the dead ends links are not taken into account in the study of the electric field effect on the electrical properties. In this work, we present a theoretical framework and Monte Carlo simulation of the behaviour of the electric conductivity at high electric field based on the percolation theory using the traps energies levels which are distributed according to distribution law (uniform, Gaussian, and power-law). When a solid insulating material is subjected to a high electric field, and during trapping mechanism the dead ends of traps affect with decreasing the electric conductivity according to the traps energies levels, the correlation length of the clusters, the length of the dead ends, and the concentration of the accessible positions for the electrons. A reasonably good agreement is obtained between simulation results and the theoretical framework. 相似文献
98.
Amassad Amina; Fabre Caroline; Sofonea Mircea 《IMA Journal of Applied Mathematics》2004,69(5):463-482
We consider a quasistatic contact problem between a viscoplasticbody and an obstacle, the so-called foundation. The contactis modelled with normal compliance and the associated versionof Coulomb's law of dry friction. We derive a variational formulationof the problem and, under a smallness assumption on the normalcompliance functions, we establish the existence of a weak solutionto the model. The proof is carried out in several steps. Itis based on a time-discretization method, arguments of monotonicityand compactness, Banach fixed point theorem and Schauder fixedpoint theorem. 相似文献
99.
Qurat-ul-ain Khalid Amina Khan Haq Nawaz Bhatti Sana Sadaf Abida Kausar Siham A. Alissa Mona K. Alghaith Munawar Iqbal 《Arabian Journal of Chemistry》2021,14(7):103227
This work was designed to synthesize and characterize biocomposites for the adsorptive elimination of insecticide (nitenpyram). Different biocomposites were synthesized of polyaniline (PAN-PH), polypyrrole (PPY-PH) and sodium alginate (Na-Al-PH) with cellulosic biomass of peanut husk (PH), which was characterized fourier-transform infrared spectroscopy (FTIR), pHpzc and scanning electron microscope (SEM). In batch mode, different variables, i.e., contact time, pH, temperature, NP (nitenpyram) concentration and adsorbent dose effects were investigated. The adsorption capacities of PH, PAN-PH, PPY-PH and Na-Al-PH were recorded to be 13.0, 14.43, 13.61 and 11.91 (mg/g), respectively at 30 °C, 60 min contact time, 0.05 g and 2.0 pH. Pseudo second order kinetic and Freundlich isotherm models best explained the NP adsorption data. An exothermic adsorption nature of NP adsorption was observed on to PH, PAN-PH, PPY-PH and Na-Al-PH. The NP desorption was efficient with NaOH and biocomposites are competent for the adsorptive removal of NP, which can utilized for NP remediation in effluents. 相似文献
100.
Journal of Russian Laser Research - Optical bistability (OB) is theoretically examined for a double quantum dot (QD) system placed in a ring cavity that is injected with a squeezed vacuum (SV)... 相似文献