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31.
Densities and speeds of sound of three ionic liquids (ILs), 1-ethyl-3-methyl imidazoliumtetrafluoroborate (C2mimBF4), 1-butyl-3-methylimidazoliumtetrafluoroborate (C4mimBF4) and 1-hexyl-3-methylimidazoliumtetrafluoroborate (C6mimBF4) were measured in aqueous solutions at (288.15, 293.15, 298.15, 303.15 and 308.15) K. These data were used to calculate the volumetric properties apparent molar volume and apparent molar isentropic compression as a function of molality. Infinite dilution values for these properties were evaluated by an extrapolation procedure based on Redlich–Meyer type equations. Apparent molar isobaric expansions at infinite dilution were also obtained from the slopes of the apparent molar volume at infinite dilution versus temperature. All these properties are interpreted in terms of IL–water interactions. The hydrolysis of the \( {\text{BF}}_{4}^{ - } \) anion of the ILs and its effects on the results is discussed. 相似文献
32.
Tan S Erol M Sukhishvili S Du H 《Langmuir : the ACS journal of surfaces and colloids》2008,24(9):4765-4771
Positively charged silver nanoparticles, Ag [+], obtained by UV-assisted reduction of silver nitrate using branched poly(ethyleneimine) (BPEI) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) solutions as reducing agents, were immobilized on glass surfaces to produce substrates active in surface-enhanced Raman scattering (SERS). Negatively charged silver nanoparticles, Ag [-], synthesized via a modified citrate reduction method, were also investigated for comparison. At a sparse surface coverage of 30 nanoparticles/microm(2), substrates with immobilized Ag [+] showed increasing SERS sensitivity to a variety of anions in water in the order SO(4)(2-) < CN(-) < SCN(-) approximately ClO(4)(-), with corresponding binding constants of 10(5), 3.3 x 10(5), and 10(7) (for both SCN- and ClO(4)(-)) M(-1), respectively. This order followed the Hofmeister series of anion binding in water. Significantly, substrates with Ag [+] allowed limit of detection values of 8.0 x 10(-8) M (8 ppb) and 2.7 x 10(-7) M (7 ppb) for environmentally relevant perchlorate (ClO(4)(-)) and cyanide (CN(-)) anions, respectively. In contrast, substrates with immobilized Ag [-], even upon subsequent modification by a monolayer of BPEI for positive surface charge of the nanoparticles, showed a drastically lower sensitivity to these anions. The high sensitivity of substrates with Ag [+] for anion detection can be attributed to the presence of two types of functional groups, amino and amide, on the nanoparticle surface resulting from UV-assisted fragmentation of BPEI chains. Both amino and amide provide strong binding of anions with Ag [+] nanoparticles due to the synergistic effect through a combination of electrostatic, hydrogen bonding, and dispersive interactions. 相似文献
33.
Bayrakçeken F Karaaslan IS Erol B 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(1):139-142
Infrared, Fourier transform infrared, Raman, UV absorption and emission spectra of cresylviolet perchlorate (CV) in polyvinylbutyral (PVB) were recorded in the region 1250-4000 cm(-1) at room temperature and assignments have been made for the observed absorption emission and Raman scattered lines. 相似文献
34.
35.
A 2-D computer simulation of a coaxial plasma device depending on the conservation equations of electrons, ions and excited
atoms together with the Poisson equation for a plasma gun is carried out. Some characteristics of the plasma focus device
(PF) such as critical wave numbers a
c and voltages U
c in the cases of various pressures Pare estimated in order to satisfy the necessary conditions of traveling particle densities (i.e. plasma patterns) via a linear analysis. Oscillatory solutions are characterized by a nonzero imaginary part of the growth
rate (σ) for all cases. The model also predicts the minimal voltage ranges of the system for certain pressure intervals.
相似文献
36.
Asker E Masnovi J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,71(5):1973-1978
1,n-Di(9-ethylcarbazol-3-yl)alkanes, where n=1-5, as the dichromophoric model compounds of poly-3-vinylcarbazoles were synthesized to examine their complexation behaviors with the electron acceptors tetracyanoethylene (TCNE) and tetranitromethane (TNM). 9,9'-Diethyl-3,3'-dicarbazolyl, di(3-ethylcarbazol-9-yl)methane, and three monomeric analogues were also included for comparison. In dichloromethane solution, the dicarbazoles formed stable 1:1 electron donor-acceptor complexes with TCNE having formation enthalpies around -3.5kcal/mol. With TNM they formed more weakly bound complexes that showed little dependence on concentration and almost zero dependence on temperature changes having nearly 0kcal/mol enthalpies of formation. The smaller gap between the two carbazole groups in 1,n-di(9-ethylcarbazol-3-yl)alkanes with nor=3. 相似文献
37.
38.
A CFD simulation usually requires extensive computer storage and lengthy computational time. The application of artificial
neural network models to thermal management of chips is still limited. In this study, the main objective is to find a neural
network solution for obtaining suitable thickness levels and material for a chip subjected to a constant heat power. To achieve
this aim a neural network is trained and tested using the results of the CFD program package Fluent. The back-propagation
learning algorithm with three different variants, single layer and logistic sigmoid transfer function is employed in the network.
By using the weights of the network, various formulations are designed for the output. The network has resulted in R
2 values of 0.999, and the mean% errors smaller than 0.8 and 0.7 for the training and test data, respectively. The analysis
is extended for different thickness and input power values. Comparison of some randomly selected results obtained by the neural
network model and the CFD program has yielded a maximum error of 1.8%, mean absolute percentage error of 0.55% and R
2 of 0.99994. 相似文献
39.
Niftaliyeva Aysel Karaduman Ali Kalwar Nazar Hussain Avci Ahmet Pehlivan Erol 《Research on Chemical Intermediates》2022,48(1):145-165
Research on Chemical Intermediates - Synthesis of Ag, Ni, Cu metallic and Ag/Ni, Ag/Cu bimetallic nanoparticles (NPs) was carried out by using metal nitrate salts as precursors via an easy and... 相似文献
40.
Eda Cagli Erol Yildirim Shuo‐Wang Yang Irem Erel‐Goktepe 《Journal of Polymer Science.Polymer Physics》2019,57(4):210-221
Besides temperature, self‐aggregation of poly(2‐isopropyl‐2‐oxazoline) (PIPOX) can also be triggered via pH in aqueous solution (25 °C, pH > 5). Lowest energy structures and interaction energies of PIPOX with H3O+, OH?, and H2O were calculated by DFT methods showed that, in addition to their ability to protonate PIPOX, H3O+ ions had strong interaction with both water and PIPOX in acidic conditions. H3O+ ions acted as compatibilizer between PIPOX and water and increased the solubility of PIPOX. OH? ions were found to have stronger interaction with water compared to PIPOX resulting in desorption of water molecules from PIPOX phase and decreased solubility, leading to enhanced hydrophobic interactions among isopropyl groups of PIPOX and formation of aggregates at high pH. Results concerning the effect of end‐groups on aggregate size were in good agreement with statistical mechanics calculations. Moreover, the effect of polymer concentration on the aggregate size was examined. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 210–221 相似文献