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101.
Structural and IR Spectroscopic Analysis of Sol-Gel Processed CuFeMnO4 Spinel and CuFeMnO4/Silica Films for Solar Absorbers 总被引:2,自引:0,他引:2
Leon KalužA Angela Šurca-Vuk Boris Orel Goran Dražič Primož Pelicon 《Journal of Sol-Gel Science and Technology》2001,20(1):61-83
Black colored CuFeMnO4 spinel powders and films were prepared using sol-gel process from Mn-acetate and Fe- and Cu-chloride precursors. Films were deposited by dip-coating technique and heat-treated at 500°C. For CuFeMnO4/silica films 3-aminopropyl-triethoxysilane (3-APTES) or tetraethoxysilane (TEOS) were used in molar proportion (Mn : Cu : Fe) : silica = 1 : 1. Films and powders were prepared by heating at 500°C. IR spectroscopic measurements were employed to follow the hydrolysis-condensation reactions in (Mn : Cu : Fe)/3-APTES sols hydrolysed with water, and (Mn : Cu : Fe)/TEOS sols hydrolysed with (NH3)aq (Stöber processing). The resulting coatings were examined with transmission electron microscopy (TEM) combined with electron dif-fraction analyses, Rutherford back scattering (RBS) and proton induced X-ray emission (PIXE) techniques. Results revealed that (Mn : Cu : Fe)/3-APTES films had a composite structure consisting of the upper Cu1.4Mn1.6O4 spinel and the lower amorphous SiO2 layer. RBS measurements confirmed the composite structure, showing also that the composition of the film was Mn : Cu : Fe = 1 : 0.96 : 0.29, i.e. close to the precursors ratio Mn : Cu : Fe = 3 : 3 : 1. (Mn : Cu : Fe)/TEOS films prepared from sols which were catalysed with (NH3)aq consisted of amorphous monodispersed spherical SiO2 particles with a size of about 400–420 nm. Solar absorbance (a
s) and thermal emittance (e
T) values of CuFeMnO4 (500°C) and (Mn : Cu : Fe)/TEOS films (500°C) showed that CuFeMnO4 films could be used as potential selective coatings for solar absorbers in solar collector systems. 相似文献
102.
Zorica S. Stojanović Ana D. Đurović Snežana Ž. Kravić Amir M. Ashrafi Lukáš Richtera 《Electroanalysis》2023,35(6):e202200446
A simple electroanalytical procedure has been developed for the determination of polyamine spermine using the ZnONPs-MWCNTs-CPE sensor. Spermine has been irreversibly oxidized on a modified electrode at a potential of +0.92 V versus Ag/AgCl (KCl, 3.5 mol L−1). The developed sensor demonstrated a respective linear response in borate buffer pH 8.5 from 2 μmol L−1 to 100 μmol L−1, with a detection limit of 0.300 μmol L−1 and quantification limit of 0.998 μmol L−1. The proposed sensor showed high reproducibility (RSD = 2.58 %), stability, robustness, and no obvious interference effects of several inorganic ions and organic molecules. The obtained results demonstrated excellent performance during the determination of the spermine in human urine samples with satisfactory recovery results (98.41–101.34 %), offering promising opportunities for practical clinical analysis. 相似文献
103.
A sensitive square‐wave voltammetry method was developed to determine cholecalciferol (vitamin D3) in pharmaceutical products at boron‐doped diamond electrode as a working electrode. Vitamin D3 provided a well‐defined voltammetric peak at around +1.00 V (vs. Ag/AgCl, 3.5 mol dm?3) in 0.02 mol dm?3 Britton‐Robinson buffer pH 5.0 prepared in 50 % ethanol. The influence of various factors such as type and pH of the supporting electrolyte, scan rate and square‐wave parameters were studied and optimized. Under optimum conditions, the oxidation peak current increased linearly with the concentration of vitamin D3 over the range of 2 to 200 μmol dm?3. The calculated limit of detection and limit of quantitation were 0.17 μmol dm?3 and 0.51 μmol dm?3, respectively. The boron‐doped diamond electrode exhibited specific recognition capability for cholecalciferol amongst possible interferences, and the determination of vitamin D3 was possible in samples such as commercial pharmaceutical products without complicated sample pretreatments. 相似文献
104.
Santiago Gómez-Ruiz Jesús Ceballos-Torres Mariano Fajardo Zorica D. Jurani? 《Journal of organometallic chemistry》2011,696(20):3206-3213
The reaction of 2,6-dimethoxypyridine-3-carboxylic acid (DMPH) with different precursors [Ti(η5-C5H5)2Cl2], [Ti(η5-C5H4Me)2Cl2], [Ti(η5-C5H4SiMe3)(η5-C5H5)Cl2], [Ti(η5-C5Me5)Cl3], SnMe3Cl and GatBu3 yielded the complexes [Ti(η5-C5H5)2(DMP-κO)2] (1), [Ti(η5-C5H4Me)2(DMP-κO)2] (2), [Ti(η5-C5H4SiMe3)(η5-C5H5)(DMP-κO)2] (3), [Ti(η5-C5Me5)(DMP-κ2O,O′)3] (4), [SnMe3(μ-DMP-κO:κO′)]∞ (5), and [GatBu2(μ-DMP-κO:κO′)]2 (6). 1-6 have been characterized by spectroscopic methods and the molecular structure of the complexes 1, 2, 3, 5 and 6 have been determined by X-ray diffraction studies. The cytotoxic activity of 1-6 was tested against the tumour cell lines human adenocarcinoma HeLa, human myelogenous leukaemia K562, human malignant melanoma Fem-x and human breast carcinoma MDA-MB-361. The results of this study show a higher cytotoxicity of the tin(IV) and gallium(III) derivatives in comparison to their titanium(IV) counterparts. Furthermore, the different titanium compounds showed differences in their cytotoxicities with a higher activity of complex 4 (mono-(cyclopentadienyl) derivative) compared to that of 1-3 (bis-(cyclopentadienyl) complexes). A qualitative UV-vis study of the interactions of these complexes with DNA has also been carried out. 相似文献
105.
Studies on Hybrid Organic/Inorganic Nanocomposite Gels Using Photoluminescence Techniques 总被引:1,自引:0,他引:1
Vlasoula Bekiari Elias Stathatos Panagiotis Lianos Urska L. Stangar Boris Orel Patrick Judeinstein 《Monatshefte für Chemie / Chemical Monthly》2001,132(1):97-102
Summary. Transparent nanocomposite gels made of hybrid organic/inorganic polymers, synthesized through the sol-gel method, composed
of poly-(ethylene oxide) or poly-(propylene oxide) chains, and grafted on silica through urea bridges, have been studied by
steady-state and time-resolved photoluminescence techniques. These nanocomposite materials consist of two distinguished subphases,
an organic and an inorganic one. The volume fraction of the organic (polyether) subphase is larger than that of the inorganic
(silica) subphase, and it increases with increasing polyether chain size. The condensation of the silica subphase provides
luminescent entities emitting light by electron-hole recombination on delocalized states associated with the active chemical
species of the urea bridges. Materials with smaller polyether chains are more luminescent than such with longer polyether
chains. Divalent or trivalent cations introduced into these materials enhance the luminescence intensity by solubilization
close to the silica cluster surface and thus by decreasing surface defects and the ensuing quenching mechanism.
Received June 23, 2000. Accepted (revised) July 18, 2000 相似文献
106.
A general first-principles theory of dissociative recombination is developed for highly symmetric molecular ions and applied to H(3)O(+) and CH(3)(+), which play an important role in astrophysical, combustion, and laboratory plasma environments. The theoretical cross sections obtained for the dissociative recombination of the two ions are in good agreement with existing experimental data from storage ring experiments. 相似文献
107.
Zorica Milovanović 《PAMM》2013,13(1):433-434
In this paper we investigate a parabolic transmission problem in disjoint domains. An a priori estimate for its weak solution in appropriate Sobolev-like space is proved. The convergence of a finite difference scheme (FDS) approximating this problem is analyzed. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
108.
Zusammenfassung Die Synthesen von [N2H5]2TiF6, [N2H5]2TiF6 · 2 HF und N2H6TiF6 sind beschrieben, die thermischen Eigenschaften, die Infrarotspektren werden diskutiert. Eine Disproportionierung von Hydrazin in Stickstoff und Ammoniak wurde festgestellt. Die Zuordnung der Infrarotbanden (4000–250 cm–1) deutet bei den ersten zwei Verbindungen auf die Hydrazinium1+-Verbindungen hin.
Mit 2 Abbildungen 相似文献
The synthesis and some thermal and structural properties of hydrazinium fluorotitanates(IV)
The synthesis of [N2H5]2TiF6, [N2H5]2TiF6 · 2 HF and N2H6TiF6 is described. The thermal properties and infrared spectra of the obtained compounds are discussed. Disproportionation of hydrazinium into nitrogen and ammonia is observed. The assignation of the bands in infrared spectra [4000 to 250 cm–1] of the first two compounds is consistent with the presence of hydrazinium1+ ion.
Mit 2 Abbildungen 相似文献
109.
Nadezhda M. Vitkovskaya Vladimir B. Orel Vladimir B. Kobychev Alexander S. Bobkov Damir Z. Absalyamov Boris A. Trofimov 《International journal of quantum chemistry》2020,120(9):e26158
The mechanisms of fundamental base-promoted acetylene reactions, namely, nucleophilic addition to the triple C ≡ C bond (vinylation) and nucleophilic addition of acetylenic carbanion to a carbonyl group (ethynylation), are addressed using three models of different complexity—pentasolvate, monosolvate, and anionic—which describe the catalytic superbasic systems MOH(OBut)/DMSO (suspensions of alkali hydroxides or tert-butoxides in dimethyl sulfoxide). The above acetylene reactions and sequential transformations of reagents arranged by the superbasic center are modeled within the framework of the most complete pentasolvate model, in which the superbase is represented by the KOH·5DMSO (KOBut·5DMSO) complexes. We have developed approaches to the construction of simplified models (monosolvate and anionic) to describe transformations in complex systems. The mechanisms of cascade assemblies of 6,8-dioxabicyclo[3.2.1]octanes, cyclopentenones, and furan cycles from ketones and acetylenes in the superbasic environment are investigated using a uniform B2PLYP/6-311+G**//B3LYP/6-31+G* approach, and the energy profiles of these different carbo- and heterocycles are analyzed. 相似文献
110.
Jelena Vasiljević Brigita Tomšič Ivan Jerman Boris Orel Gregor Jakša Janez Kovač Barbara Simončič 《Journal of Sol-Gel Science and Technology》2014,70(3):385-399
In this research, a two-component sol–gel inorganic–organic hybrid coating was prepared on a cotton fibre surface. An equimolar sol mixture of the precursors 1H,1H,2H,2H-perfluorooctyltriethoxysilane (SiF) and P,P-diphenyl-N-(3-(trimethoxysilyl)propyl) phosphinic amide (SiP) was applied to cotton fabric samples using the pad-dry-cure method. The surfaces of the untreated and coated cotton fibres were characterised using scanning electron microscopy, Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight-secondary ion mass spectrometry. The functional properties of the coated cotton fabric samples were investigated using static contact angle measurements with water and n-hexadecane, the ice-releasing test, antibacterial testing against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, thermogravimetric analysis in an air atmosphere, and vertical flammability tests. The results reveal the formation of a nanocomposite two-component inorganic–organic hybrid polymer network that is homogenously distributed over the cotton fibre surface. The presence of the SiP component in the two-component inorganic–organic hybrid coating did not hinder the functional properties imparted by the presence of the SiF component and vice versa, illustrating their compatibility. The cooperative action of the SiF and SiP components in the two-component coating provided the cotton fabric with exceptional multifunctionality, including simultaneous superhydrophobicity and high oleophobicity, passive antibacterial activity, and improved thermo-oxidative stability. 相似文献