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131.
In this work, the geometrical and electronic properties of the mono cationic ionic liquid 1‐hexyl‐3‐methylimidazolium halides ([C6(mim)]+_X?, X=Cl, Br and I) and dicationic ionic liquid 1,3‐bis[3‐methylimidazolium‐1‐yl]hexane halides ([C6(mim)2X2], X=Cl, Br and I) were studied using the density functional theory (DFT). The most stable conformer of these two types ionic liquids (IL) are determined and compared with each other. Results show that in the most stable conformers, in both monocationic ILs and dicationic ILs, the Cl? and Br? anions prefer to locate almost in the plane of the imidazolium ring whereas the I? anion prefers nearly vertical location respect to the imidazolium ring plan. Comparison of hydrogen bonding and ionic interactions in these two types of ionic liquids reveals that these ionic liquids can be formed hydrogen bond by Cl? and Br? anion. The calculated thermodynamic functions show that the interaction of cation — anion pair in the dicationic ionic liquids are more than monocationic ionic liquids and these interactions decrease with increasing the halide anion atomic weight. 相似文献
132.
133.
Transition metal complexes of a hydrazone–oxime ligand containing the isonicotinoyl moiety: Synthesis,characterization and microbicide activities
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Complexes of VO2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Ru3+ and UO22+ with (3‐(hydroxyimino)butan‐2‐ylidene)isonicotinohydrazide were synthesized and characterized using physical and spectral methods. Analytical data revealed that the complexes formed in 1:1 or 1:2 metal–ligand ratios. Spectral studies showed that the ligand bonded to the metal ion in neutral tridentate, monobasic tridentate or monobasic bidentate fashion through azomethine nitrogen atom, protonated/deprotonated imine oxime group and/or ketonic/enolic carbonyl group. From the electronic spectral data together with magnetic susceptibility values a square planar, tetrahedral or distorted octahedral structure can be proposed for all complexes. Electron spin resonance spectra for Cu2+ complexes ( 2 – 4 ) revealed axial symmetry with g|| > g⊥ > ge, indicating distorted octahedral or square planar structures and the unpaired electron exists in a orbital with marked covalent bond feature. The prepared complexes showed good to excellent biological activity, and the most active complexes against Aspergillus niger were 4 and 9 with zone of inhibition of 25 and 23 mm, respectively. Complexes 10 and 11 showed interesting activity against Escherichia coli with zone of inhibition of 44 and 32 mm, respectively. 相似文献
134.
Saied Saeed Hosseiny Davarani Leila Masoomi Mohammad Hossein Banitaba Hamid Reza Lotfi Zadeh Zhad Omid Sadeghi Azam Samiei 《Chromatographia》2012,75(7-8):371-377
This paper presents a simple and convenient analytical method for determination of 1,4-dioxane in surfactants and detergents by using a novel SPME fiber. For the preparation of the fiber, the surface of a fused silica capillary tubing was modified by means of aluminium tri-tert-butoxide in a straightforward grafting process. The surface of our proposed fiber provides a Lewis acid–base interaction with analyte functional groups. The main factors affecting the extraction were optimized by using a central composite design method, which leads to the following optimum conditions: extraction temperature of 34?°C, extraction time of 4?min, equilibrium time of 13?min, and salt content of 25% (w/v). The optimum conditions showed a linear range from 0.005 to 60?μg?g?1. LOD and LOQ of the proposed method were estimated to be 0.0015 and 0.005?μg?g?1, respectively. This method was also applied for the analysis of some real samples including ethoxylated fatty alcohol, sodium lauryl ether sulfate, dish-washing agents, and shampoos by using the standard addition method. 相似文献
135.
Saied M. Soliman Raghdaa A. Massoud Hessa H. Al-Rasheed Ayman El-Faham 《Molecules (Basel, Switzerland)》2021,26(12)
Two penta-coordinated [Co(MorphBPT)Cl2]; 1 and [Co(PipBPT)Cl2]; 2 complexes with the bis-pyrazolyl-s-triazine pincer ligands MorphBPT and PipBPT were synthesized and characterized. Both MorphBPT and PipBPT act as NNN-tridentate pincer chelates coordinating the Co(II) center with one short Co-N(s-triazine) and two longer Co-N(pyrazole) bonds. The coordination number of Co(II) is five in both complexes, and the geometry around Co(II) ion is a distorted square pyramidal in 1, while 2 shows more distortion. In both complexes, the packing is dominated by Cl…H, C-H…π, and Cl…C (anion-π stacking) interactions in addition to O…H interactions, which are found only in 1. The UV-Vis spectral band at 564 nm was assigned to metal–ligand charge transfer transitions based on TD-DFT calculations. Complexes 1 and 2 showed higher antimicrobial activity compared to the respective free ligand MorphBPT and PipBPT, which were not active. MIC values indicated that 2 had better activity against S. aureus, B. subtilis, and P. vulgaris than 1. DPPH free radical scavenging assay revealed that all the studied compounds showed weak to moderate antioxidant activity where the nature of the substituent at the s-triazine core has a significant impact on the antioxidant activity. 相似文献
136.
Ahmed Ibrahim El-Batal Gharieb Saied El-Sayyad Abbas El-Ghamery Mohamed Gobara 《Journal of Cluster Science》2017,28(3):1083-1112
Melanin pigment is witnessed to be widely used in medicine, food, cosmetic preparations with strong hydrophobicity. Streptomyces cyaneus is utilized for the synthesis of melanin by optimizing culture conditions through screening of critical factors, by Response Surface Methodology as Plackett–Burman design (P-BD), while further statistical optimization was applied using Central Composite Design (CCD) for maximizing yield. Moreover, the impacts of gamma radiation and alternative frugal l-tyrosine, natural sources were studied as it predicted for remarkable rising in the pigment concentration. Herein unprecedented achievement was realized for melanin pigment production, (9.898 mg/ml) was obtaining by optimized culture condition. Also, 2.0% fava bean’s seed peel maximized melanin (9.953 mg/ml) and hence super-yield (11.113 mg/ml) was produced by a stimulus from gamma irradiation (2.5 kGy). The extracted melanin was confirmed chemically, UV–Vis, and FT-IR analysis. Copper oxide nanoparticles (CuONPs) were synthesized by radiolytic reactions of gamma radiation (30.0 kGy) in the presence of melanin as a capping agent. CuONPs were characterized by UV–Vis, DLS, XRD, and FT-IR. TEM analysis revealed the morphology of monodispersed CuONPs with a mean diameter 29.82 nm. CuONPs exhibited excellent antimicrobial activity against food born Gram-positive, Gram-negative bacteria, and fungi; they can find potential applications for the food packaging approach. 相似文献
137.
Some organometallic compounds, e.g. Ph3SnCl, react on the surface of the smectite clay, laponite. Other compounds, e.g. Br3TeC6H4CH=NCH2CH2N=CHC6H4TeBr3, are sorbed onto the organophilic surface of cetylpyridinium-ion-exchanged Wyoming bentonite. X-ray photoelectron spectroscopy (XPS) is an appropriate technique with which to examine the nature of the surface-sorbed species; however, it is demonstrated that decomposition of the organometallic can occur when the clay surface is exposed over a period of time to energetic X-rays. Thus, care must be taken with the interpretation of data of which some features may be the result of the XPS experiment. 相似文献
138.
Solid-phase extraction of trace amounts of copper from large volumes of aqueous solutions was studied. The extraction was carried out by means of an octadecyl silica cartridge modified with cupron. The effect of different parameters such as sample matrix, flowrates of sample solution and eluent, pH, breakthrough volume, and potentially interfering ions was examined. Cu2+ was extracted from solution in the pH range of 6–8.5 on a modified cartridge. Elution was accomplished using 2mL of 0.2M HNO3. Hence, with a typical preconcentration factor of 1000, a detection limit of 0.02ngmL–1 was obtained. The method was applied to the determination of copper in natural water samples. 相似文献
139.
We present a robust and efficient numerical method for solution of the nonlinear Poisson-Boltzmann equation arising in molecular biophysics. The equation is discretized with the box method, and solution of the discrete equations is accomplished with a global inexact-Newton method, combined with linear multilevel techniques we have described in an article appearing previously in this journal. A detailed analysis of the resulting method is presented, with comparisons to other methods that have been proposed in the literature, including the classical nonlinear multigrid method, the nonlinear conjugate gradient method, and nonlinear relaxation methods such as successive overrelaxation. Both theoretical and numerical evidence suggests that this method will converge in the case of molecules for which many of the existing methods will not. In addition, for problems which the other methods are able to solve, numerical experiments show that the new method is substantially more efficient, and the superiority of this method grows with the problem size. The method is easy to implement once a linear multilevel solver is available and can also easily be used in conjunction with linear methods other than multigrid. © 1995 by John Wiley & Sons, Inc. 相似文献
140.
Jerry P. Jasinski Jason R. Bianchani Juan Cueva Fathy A. El‐Saied Ahmed A. El‐Asmy Douglas X. West 《无机化学与普通化学杂志》2003,629(2):202-206
Copper(II) complexes of 3, 4‐hexanedione bis(piperidyl‐ and bis(hexamethyleneiminylthiosemicarbazone), H2Hxpip and H2Hxhexim, respectively, have been prepared and studied spectroscopically. The bis(thiosemicarbazones) have been characterized by their melting points, as well as IR, electronic and 1H NMR spectra. Upon formation of their copper(II) complexes, loss of the hydrazinic hydrogen atoms occurs, and the ligands coordinate as dianionic, tetradentate N2S2 ligands. The crystal structures of H2Hxpip, its 4‐coordinate copper(II) complex, [Cu(Hxpip)], and the related [Cu(Hxhexim)] have been determined by single crystal x‐ray diffraction. The nature of the four‐coordinate copper(II) complexes have also been characterized by ESR, IR, and electronic spectroscopy, as well as magnetic moments and elemental analyses. 相似文献