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排序方式: 共有126条查询结果,搜索用时 15 毫秒
1.
Focant JF Reiner EJ Macpherson K Kolic T Sjödin A Patterson DG Reese SL Dorman FL Cochran J 《Talanta》2004,63(5):1231-1240
Comprehensive two-dimensional gas chromatography with isotope-dilution time-of-flight mass spectrometry (GC × GC-IDTOFMS) was used to measure polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF), and coplanar polychlorinated biphenyl (cPCB) concentrations in ash, sediment, vegetation, and fish samples. The GC × GC capability was achieved by using a quad jet, dual stage, thermal modulator. Zone compression of the GC peaks from modulation resulted in a significant increase of the signal intensity over classical GC-IDTOFMS. The GC × GC column set used an Rtx-Dioxin 2 phase as the first dimension (1D) and an Rtx-500 as the second dimension (2D). The chromatographic separation of the 17 PCDD/Fs and the 4 cPCBs was attained in 1D except for 2,3,7,8-TCDD and CB126 for which deconvoluted ion currents (DIC) were required to be reported separately. The Rtx-500 phase separated the bulk matrix interfering compounds from the target analytes in 2D. The instrumental limit of detection (iLODs) was 0.5 pg for 2,3,7,8-TCDD. The calibration curves showed good correlation coefficients for all the compounds investigated in the concentration range of 0.5–200 pg. GC × GC-IDTOFMS results compared favorably to those from conventional isotope-dilution one-dimensional gas chromatography-high resolution mass spectrometry (GC-IDHRMS). The comprehensive mass analysis of the TOFMS further permitted the identification of other contaminants of concern in the samples. 相似文献
2.
Safaa El‐din H. Etaiw Hassan Marie Elsayed M. Shalaby Rabie S. Farag Fatma A. Elsharqawy 《应用有机金属化学》2019,33(9)
Orange prismatic crystals of the supramolecular coordination polymer (SCP) ∞3[Cu(CN)2(Me3Sn)(Pyz)], SCP 1 , were synthesized using a self‐assembly method under ambient conditions. Nanosized 1 was obtained using the same molar ratio in water by ultrasonic irradiation. SCP 1 was characterized using single‐crystal X‐ray diffraction, elemental analysis, thermal analysis and Fourier transform infrared spectroscopy. SCP 1 and its nanosized 1 particles were also examined using powder X‐ay diffraction and scanning electron microscopy. The luminescence emission of SCP 1 was studied as well as its use as a sensor for the detection of common organic solvents and metal ions. Also, the catalytic activities of nanosized 1 towards various organic dyes were investigated under ambient conditions, UV irradiation and ultrasonic irradiation. Nanosized 1 as a heterogeneous nanoparticle catalyst exhibits high catalytic activity for the degradation of eosin‐Y and acid blue dyes. The mechanism of degradation investigated using various scavenger techniques is proposed and discussed. The catalytic oxidation process is mainly caused by ?OH radicals. 相似文献
3.
N. N. Sibel’din M. L. Skorikov V. A. Tsvetkov 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(1):93-95
The formation of three-particle charged exciton complexes (trions) in shallow GaAs/AlGaAs quantum wells in the temperature range 1.7–15 K has been investigated by luminescence spectroscopy and resonant light scattering. The effect of the photon energy and the intensity of additional above-barrier illumination on the trion formation kinetics has been analyzed. It is established that, upon intrawell excitation, illumination leads to the formation of trions when the light photon energy corresponds to the regions of effective formation of trions in the photoluminescence excitation spectra. It is shown that, with an increase in the illumination level, the trion concentration first increases and then reaches a plateau since the quantum well acquires an electric charge whose field equalizes the electron and hole capture rates. 相似文献
4.
Three‐dimensional organotin–hexacyanoferrate polymers of the type ∞3[(R3Sn)3FeIII(CN)6] where R = Me (I), n‐butyl (II) and phenyl (III), represent members of the family of supramolecular coordination polymers (SCPs) which have zeolitic‐like structure containing micropores. The structures of I–III contain wide channels capable of encapsulating resorcinol, which undergoes in situ oxidation to 1,3,4‐trihydroxy benzene (THB) or p‐nitrophenol (PNP), which converts to 1,4‐benzoquinone (BQ) and 2‐hydroxybenzoquinone (2‐HBQ). The oxidation products were investigated by spectroscopic methods and by HPLC. The SCP III was found to be a more effective oxidizing reagent than I and II due to the presence of terminal Sn‐OH2 groups hydrogen bonded to one‐sixth of the terminal CN groups, causing more wide expandable channels. In addition, mechanisms of the oxidation processes of resorcinol and PNP have been proposed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
5.
A. S. Zhukov V. A. Arkhipov S. S. Bondarchuk V. D. Gol’din 《Russian Journal of Physical Chemistry B, Focus on Physics》2013,7(6):777-782
A physicomathematical model of thermal and diffusion processes in a drop of a dilute metal salt solution during its heating in a plasma-chemical reactor for synthesizing metal oxide powders is presented. The results of numerical calculations are analyzed to assess the possible influence of the operation parameters of the reactor and the characteristics of the initial solution (precursor) on the morphology of the particles formed. 相似文献
6.
We consider the problem of separate detection and filtration of a flow of pulsed signals. We assume that statistically independent
pulsed signals of different shape and random amplitude appear randomly against the background of noise. An algorithm for estimation
of the detection probability of each signal is obtained. Recurrent expressions for thea posteriori probability density of each signal are found. The results of numerical simulation of the proposed algorithms of signal processing
are presented.
Lobachevsky State University of Nizhny Novgorod Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 42, No. 1, pp. 92–100, January, 1999. 相似文献
7.
In the paper, the isomorphism problem for completely decomposable Abelian torsion-free groups of finite rank is treated under the assumption that the groups of homomorphisms of these groups into some Abelian group are isomorphic and, moreover, the endomorphism semigroups of the groups are isomorphic. 相似文献
8.
Design of donor–acceptor–donor (D–A–D) type small molecule donor materials with efficient photovoltaic parameters
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Muhammad Irfan Javed Iqbal Sana Sadaf Bertil Eliasson Usman Ali Rana Salah Ud‐din Khan Khurshid Ayub 《International journal of quantum chemistry》2017,117(10)
Four Donor–Acceptor–Donor (D–A–D) type of donor molecules (M1‐M4) with triphenylamine (TPA) as donor moiety, thiophene as bridge, and thiazolothiazole as acceptor unit were designed and its photovoltaic parameters were equated with reference molecule “R.” DFT functional CAM‐B3LYP/6‐31G (d,p) was found best for geometry optimization and TD‐CAM‐B3LYP/6‐31G (d,p) was found suitable for excited state calculations. Among designed donor molecules, M4 manifests suitable lowest band gap of 4.73 eV, frontier molecular orbital energy levels as well as distinctive broad absorption of 455.3 nm due to the stronger electron withdrawing group. The electron‐withdrawing substituents contribute to red shifts of absorption spectra and better stabilities for designed molecules. The theoretically determined reorganization energies of designed donor molecules suggested excellent charge mobility property. The lower λe values in comparison with λh illustrated that these four donor materials would be ideal for electron transfer and M4 would be best amongst the investigated molecules with lowest λe of 0.0177. Furthermore, the calculated Voc of M4 is 2.04 V with respect to PC60BM (phenyl‐C61‐butyric acid methyl ester). This study revealed that the designed donor materials are suitable and recommended for high performance organic solar cell devices. 相似文献
9.
D. K. Shestakov I. K. Gainullin I. F. Urazgil’din 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(1):33-37
The electron exchange under grazing scattering of a negative hydrogen ion from a thin Al disk is analyzed via the wave packet propagation method that does not use the perturbation theory. The probability of H? ion fraction formation is calculated as a function of the ion velocity component (v‖) parallel to the surface. It is shown that the yield of negative hydrogen ions has a bell-like dependence on the value of v‖ under grazing scattering from a thin disk. The negative ion yield under grazing scattering from a disk is very close to the H? ion yield under scattering from a film. The maximum of the probability of H? fraction formation calculated for a thin disk is shifted to smaller values of v‖ with respect to the maximum of the probability of H? formation for a thin film. 相似文献
10.