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111.
Slawomir Pitula Dr. Anja‐Verena Mudring Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(11):3355-3365
Several ionic liquids (ILs) based on complex manganate(II) anions with chloro, bromo, and bis(trifluoromethanesulfonyl)amido (Tf2N) ligands have been synthesized. As counterions, n‐alkyl‐methylimidazolium (Cnmim) cations of different chain length (alkyl=ethyl (C2), propyl (C3), butyl (C4), hexyl (C6)) were chosen. Except for the 1‐hexyl‐3‐methylimidazolium ILs, all of the prepared compounds could be obtained in a crystalline state at room temperature. However, each of the compounds displayed a strong tendency to form a supercooled liquid. Generally, solidification via a glass transition took place below ?40 °C. Consequently, all of these compounds can be regarded as ionic liquids. Depending on the local coordination environment of Mn2+, green (tetrahedrally coordinated Mn2+) or red (octahedrally coordinated Mn2+) luminescence emission from the 4T(G) level is observed. 1 The local coordination of the luminescent Mn2+ centre has been unequivocally established by UV/Vis as well as Raman and IR vibrational spectroscopies. Emission decay times measured at room temperature in the solid state (crystalline or powder) were generally a few ms, although, depending on the ligand, values of up to 25 ms were obtained. For the bromo compounds, the luminescence decay times proved to be almost independent of the physical state and the temperature. However, for the chloro‐ and bis(trifluoromethanesulfonyl)amido ILs, the emission decay times were found to be dependent on the temperature even in the solid state, indicating that the measured values are strongly influenced by nuclear motion and the vibration of the atoms. In the liquid state, the luminescence of tetrahedrally coordinated Mn2+ could only be observed when the tetrachloromanganate ILs were diluted with the respective halide ILs. However, for [C3mim][Mn(Tf2N)3], in which Mn2+ is in an octahedral coordination environment, a weak red emission from the pure compound was found even in the liquid state at elevated temperatures. 相似文献
112.
Fanny Chaux Slawomir Frynas Hugo Laureano Christine Salomon Gérald Morata Marie-Laure Auclair Michel Stephan Rachid Merdès Philippe Richard Marie-Jo Ondel-Eymin Jean-Christophe Henry Jér?me Bayardon Christophe Darcel Sylvain Jugé 《Comptes Rendus Chimie》2010,13(8-9):1213-1226
Several approaches for the enantiodivergent synthesis of P-chirogenic mono- and diphosphines are described, using ephedrine methodology and phosphine borane chemistry. Firstly, both enantiomers of a tertiary phosphine can be obtained starting from the same oxazaphospholidine borane complex, prepared from (+)-ephedrine, when changing the order of addition of the organolithium reagents during the synthetic pathway. The second approach is based on the chlorophosphine boranes, which react with an organolithium reagent, to afford the corresponding phosphines with inversion of configuration. In the case where the chlorophosphine borane reacts with the t-butyl lithium reagent, a metal-halogen exchange occurs to afford the corresponding phosphide borane with retention of the configuration. The reaction of the phosphide borane with an alkyl halide leads to the same phosphine, but with the opposite configuration. Another approach depends on the diastereoselective preparation of the starting oxazaphospholidine borane complex from (?)-ephedrine, which leads according the case, to either one or the other enantiomer of a phosphine. Finally, the synthesis of (R,R)- and (S,S)-1,2-bis(methylphenylphosphino)ethane is also demonstrated using both enantiomers of the P-chirogenic diphosphinite diborane, which simultaneously allows the introduction of alkyl- or aryl substituents on the phosphorus atoms. In summary, these approaches show the great efficiency of the “ephedrine methodology” for the enantiodivergent synthesis of P-chirogenic mono- and diphosphines, and bearing alkyl or aryl substituents. 相似文献
113.
Slawomir Zolkiewski 《PAMM》2012,12(1):163-164
In this paper the research results of hybrid composite materials made of a steel plate and laminates are presented. The tested composites were made of a metal sheet plate and a laminate plate connected by means of barbed studs. The laminates were made of three different types of fabrics with: fibreglass, carbon fibres and aramid fibres. As a warp, epoxide resin and polyester resin were used. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
114.
Anna Jasik Marek Berkowski Slawomir M. Kaczmarek Andrzej Suchocki Agata Kaminska Grzegorz Leniec Piotr Nowakowski Viktor Domukhovski 《Central European Journal of Physics》2012,10(2):506-513
Single crystals of lithium-sodium-tetragermanate, a member of the solid solution series Li2−xNa
x
Ge4O9 with x=0.28, pure and slightly doped with Cr3+ ions (0.03 mol.% and 0.1 mol.%), were grown in ambient atmosphere by the Czochralski technique from stoichiometric melt.
The crystals with dimensions up to 20 mm in diameter and 50 mm in length were obtained. The crystal structure has been determined
by means of X-ray diffraction. Phase analysis and structural refinement of the Li1.72Na0.28Ge4O9 crystals were performed by X-ray powder diffraction using Ni-filtered Cu Kα radiation with a Siemens D5000 diffractometer. The absorption, excitation and photoluminescence spectra of the crystals were
measured in the UV-VIS and IR range at low temperatures. EPR investigations were performed using a conventional X-band Bruker
ELEXSYS E 500 CW-spectrometer operating at 9.5 GHz with 100 kHz magnetic field modulation. Temperature and angular dependences
of the EPR spectra of the crystal samples were recorded in the 3–300 K temperature range. 相似文献
115.
116.
Teresa Basinska Stanislaw Slomkowski Slawomir Kazmierski Andrzej Dworak Mohamed M. Chehimi 《Journal of polymer science. Part A, Polymer chemistry》2004,42(3):615-623
The composition and properties of the surface layers of poly(styrene/α-t-butoxy-ω-polyglycidol) [poly(styrene/VB-polyGL)] microspheres synthesized by the radical copolymerization of styrene and α-t-butoxy-ω-vinylbenzyl-polyglycidol (VB-polyGL) macromonomers [number-average molecular weight (Mn) = 950 or 2700] were investigated with X-ray photoelectron spectroscopy, 13C NMR, and the adsorption of human serum albumin and γ-globulins. The number-average diameter of the synthesized microspheres was 220 nm. Their surface layers were rich in polyglycidol, with polyglycidol-to-polystyrene unit ratios of 0.443 (VB-polyGL with Mn = 950) and 0.427 (VB-polyGL with Mn = 2700). In suspensions of poly(styrene/VB-polyGL) particles in D2O, the polymer chains in the polyglycidol-rich surface layers were highly mobile, allowing the registration of polyglycidol 13C NMR spectra with standard procedures for polymer solutions. In these spectra, the signals of the relatively immobile polystyrene segments were absent. The spin–lattice relaxation times (T1) measured for polyglycidol in the microsphere surface layers and for VB-polyGL macromonomers in solution were very close, indicating similar degrees of motion in bound (in particle surface layers) and free (in solution) polyglycidol macromolecules. Studies of protein adsorption revealed that hydrophilic polyglycidol layers were protein-repellent. It was found that longer polyglycidol chains in particle surface layers were more mobile (higher T1 values) and provided better protection against protein adsorption. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 615–623, 2004 相似文献
117.
Ireneusz Winnicki Janusz Jasinski Slawomir Pietrek 《Numerical Methods for Partial Differential Equations》2019,35(6):2275-2304
The paper presents an enhanced analysis of the Lax‐Wendroff difference scheme—up to the eighth‐order with respect to time and space derivatives—of the modified‐partial differential equation (MDE) of the constant‐wind‐speed advection equation. The modified equation has been so far derived mainly as a fourth‐order equation. The Π ‐form of the first differential approximation (differential approximation or equivalent equation) derived by expressing the time derivatives in terms of the space derivatives is used for presenting the MDE. The obtained coefficients at higher order derivatives are analyzed for indications of the character of the dissipative and dispersive errors. The authors included a part of the stencil applied for determining the modified differential equation up to the eighth‐order of the analyzed modified differential equation for the second‐order Lax‐Wendroff scheme. Neither the derived coefficients at the space derivatives of order p ∈ (7 – 8) in the modified differential equation for the Lax‐Wendroff difference scheme nor the results of analyses on the basis of these coefficients of the group velocity, phase shift errors, or dispersive and dissipative features of the scheme have been published. The MDEs for 2 two‐step variants of the Lax‐Wendroff type difference schemes and the MacCormack predictor–corrector scheme (see MacCormack's study) constructed for the scalar hyperbolic conservation laws are also presented in this paper. The analysis of the inviscid Burgers equation solution with the initial condition in a form of a shock wave has been discussed on their basis. The inviscid Burgers equation with the source is also presented. The theory of MDE started to develop after the paper of C. W. Hirt was published in 1968. 相似文献
118.
119.
Ignacio Viciano Slawomir Berski Sergio Martí Juan Andrés 《Journal of computational chemistry》2013,34(9):780-789
The electronic structure of iron‐oxo porphyrin π‐cation radical complex Por·+FeIV?O (S? H) has been studied for doublet and quartet electronic states by means of two methods of the quantum chemical topology analysis: electron localization function (ELF) η(r) and electron density ρ(r). The formation of this complex leads to essential perturbation of the topological structure of the carbon–carbon bonds in porphyrin moiety. The double C?C bonds in the pyrrole anion subunits, represented by pair of bonding disynaptic basins Vi=1,2(C,C) in isolated porphyrin, are replaced by single attractor V(C,C)i=1–20 after complexation with the Fe cation. The iron–nitrogen bonds are covalent dative bonds, N→Fe, described by the disynaptic bonding basins V(Fe,N)i=1–4, where electron density is almost formed by the lone pairs of the N atoms. The nature of the iron–oxygen bond predicted by the ELF topological analysis, shows a main contribution of the electrostatic interaction, Feδ+···Oδ?, as long as no attractors between the C(Fe) and C(O) core basins were found, although there are common surfaces between the iron and oxygen basines and coupling between iron and oxygen lone pairs, that could be interpreted as a charge‐shift bond. The Fe? S bond, characterized by the disynaptic bonding basin V(Fe,S), is partially a dative bond with the lone pair donated from sulfur atom. The change of electronic state from the doublet (M = 2) to quartet (M = 4) leads to reorganization of spin polarization, which is observed only for the porphyrin skeleton (?0.43e to 0.50e) and S? H bond (?0.55e to 0.52e). © 2012 Wiley Periodicals, Inc. 相似文献
120.
Krzywoszynska K Rowinska-Zyrek M Witkowska D Potocki S Luczkowski M Kozlowski H 《Dalton transactions (Cambridge, England : 2003)》2011,40(40):10434-10439
The coordination properties of three peptides with CXXC motif: Ac-GCASCDNCRACKK-NH(2), Ac-GCASCDNCRAAKK-NH(2) and Ac-GCASCDNARAAKK-NH(2) as donors of four, three and two thiol ligands for Ni(2+),Cd(2+), Zn(2+) and Bi(3+) were studied by potentiometric titrations, UV-Vis and CD spectra measurements. Since the stability of the complexes is closely connected with the amount of the metal-bound cysteine sulfurs, competition plots of the complexes of peptides with 2, 3 and 4 cysteines further prove the involvement of all thiols in the metal ion binding. Furthermore, the sulfur-bound zinc complexes appear to be much more stable than the sulfur-bound nickel ones. The stabilities of the studied complexes decreases in the series Bi(3+) ? Cd(2+) > Zn(2+) > Ni(2+). 相似文献