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111.
Ahmed A. Abdel-Khalek Said M. Sayyah Fadia F. Abdel-Hameed 《Transition Metal Chemistry》1994,19(1):108-110
A novel chromium(III) complex of tetraoxalylurea was prepared. In aqueous solutions, [CrIII(H2L)(H2O)]+ (H2L = diprotonated tetraoxalylurea) is oxidized by IO
4
–
according to the rate law
相似文献
112.
Samples of orthoferrites La1−xCaxFeO3 (0.15≤x≤0.45) were synthesized by double sintering ceramic technique. X-ray diffraction and infrared spectroscopy experiments were carried out and discussed for the investigated samples. The data showed the formation of single-phase orthorhombic structure of space group Pbnm. The FTIR spectra were performed in the region (1200–200 cm−1). Four main absorption bands were present with some side bands and shoulders in the range (1200–400 cm−1). Another four bands were appeared in the range (400–200 cm−1). The positions, intensities and values of the absorptions bands vary depending on the Ca content in the samples. The first absorption band appeared at about 920 cm−1 was assigned to the La–O stretching vibration. 相似文献
113.
The syntheses and the X-ray structures of the tetranuclear gold(I) benzamidinate, Au4[PhNC(Ph)NPh]4, and the tetranuclear gold(I) acetamidinate, Au4[PhNC(CH3)NPh]4, clusters are reported. The clusters are produced by the reaction of the sodium salt of an amidine ligand with the gold precursor
Au(THT)Cl in a (1:1) stoichiometry. The average Au...Au distance between adjacent Au(I) atoms is ∼2.9 ?, typical of compounds
having an aurophilic interaction. The four gold atoms are arranged in a square (Au...Au...Au... = 88–91°) in the acetamidinate
and in a distorted square (Au...Au...Au... = 82–97°) in the benzamidinate derivative. Electrochemical oxidation of the tetranuclear
complex Au4[PhNC(Ph)NPh]4 show three reversible waves at 0.87, 1.19, 1.42 V vs. Ag/AgCl at a scan rate of 100 mV/s in CH2Cl2 similar to the three reversible waves seen before from the tetranuclear complexes Au4[ArNC(H)NAr]4, Ar = C6H4-4-OMe, Ar = C6H4-4-Me, and Ar = C6H3-3,5-Cl. A summary of the chemistry of the tetranuclear Au(I) amidinate complexes Au4[ArNC(H)NAr]4, Ar = C6H4-4-OMe, C6H3-3,5-Cl, C6H4-4-Me, C6H4-3-CF3, C6F5, C10H7 also is presented. The tetranuclear clusters Au4[ArNC(H)NAr]4, Ar = C6H4-4-OMe, Ar = C6H4-3-CF3, Ar = C6H4-4-Me and Ar = C6H4-3,5-Cl are the first tetranuclear gold(I) cluster species from group 11 elements to show fluorescence at room temperature.
The lifetimes of the naphthyl and trifluoromethylphenyl complexes are in the millisecond range indicating phosphorescent processes.
Recently it has been shown that Au4[ArNC(H)NAr]4 are very effective catalysts upon calcination for room temperature CO oxidation.
Congratulations to Dieter Fenske, a superb synthetic chemist with exceptional talents in cluster chemistry, on the occasion
of his 65th birthday. 相似文献
114.
Ahmed El Nemr Eman Serag Azza El-Maghraby Shadia A. Fathy Fatma F. Abdel Hamid 《高分子科学杂志,A辑:纯化学与应用化学》2019,56(8):781-793
The purpose of this paper is studying the effect of incorporation of Multiwall Carbon Nanotubes (MWCNT) into two different nanocomposites in poly vinyl alcohol (PVA)/polyvinylpyrrolidone (PVP), and PVA/Polyethylene glycol (PEG). MWCNT were synthesized by chemical vapor deposition (CVD) method using acetylene and Fe/Co/Al2O3 as carbon precursor and catalyst, respectively. Nitric acid and sulfuric acid were used for purification and functionalization of MWCNT. Afterward, highly pure and functionalized MWCNT (0, 0.02, and 0.05% w/w) were incorporated in PVA/PVP and PVA/PEG to synthesize PVA/PVP/MWCNT and PVA/PEG/MWCNT nanocomposites hydrogel membranes that cross-linked by freezing–thawing. PEG and PVP were selected in these nanocomposites as dispersion matrix for MWCNT as well as for increasing the elasticity of the nanocomposites membranes. The morphology of the hydrogels was characterized by SEM, FTIR, XRD, TGA, and the mechanical properties of the hydrogel membranes were investigated. The swelling behavior in different pH-buffer solutions was studied as well as studying weight loss percentage and swelling kinetic. The drug releasing process of the hydrogel membranes was investigated using salicylic acid as a model drug. It was found that MWCNT are dispersed well into the polymers and crystallinity, mechanical properties and thermal stability of the hydrogels contain MWCNT are better than that without MWCNT. Maximum degree of swelling was observed at pH 7 and swelling degree increases with increasing the ratio of MWCNT in the hydrogels from 0.02 to 0.05%. All hydrogel membranes followed non-Fickian mechanism and drug releasing were controlled by varying the pH and amount of MWCNT. 相似文献
115.
Ahmed Akelah 《European Polymer Journal》1982,18(7):559-561
Insoluble polystyryldiphenyl-methoxymethyl- and methylthiomethyl-phosphonium chlorides have been prepared by treating polystyryldiphenylphosphine with chloromethylmethyl-ether and thioether respectively. These reagents were used for the conversion under mild conditions of carbonyl compounds into vinyl-ethers and thioethers, otherwise difficult to obtain; yields are high and work-up is easy. Moreover, methyl and ethyl β-styryl ethers were also prepared from the polymeric phosphorane by treatment with formate esters. 相似文献
116.
3-[1′(1′H)-Substituent-pyrazol-5′-yl]benzo[5,6]coumarins and 3-(1′,2′-oxazol-5′-yl)benzo[5,6]coumarin were prepared via condensation of 3-(2′-formyl-1′-chlorovinyl)benzo[5,6] coumarin with hydrazine derivatives or hydroxylamine.Reaction of 3-[1′(1′H)-pyrazol-5′-yl]benzo[5,6]coumarin with alkyl halides,olefinic compunds or acid chlorides are described. 相似文献
117.
Cycloheptyne-dicobalt hexacarbonyl complexes, substituted by propargylic ether functions, undergo 2 + 2 + 2 cycloaddition reactions with alkynes to give tricyclic benzocycloheptanes; an all-intramolecular version of this transformation is also possible. 相似文献
118.
Mohamed GG Omar MM Hindy AM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(4-5):1140-1150
Metal complexes of Schiff base derived from 2-thiophene carboxaldehyde and 2-aminobenzoic acid (HL) are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The ligand dissociation as well as the metal-ligand stability constants were calculated pH metrically at 25 degrees C and ionic strength mu=0.1 (1M NaCl). The complexes are found to have the formulae [M(HL)2](X)n.yH2O (where M=Fe(III) (X=Cl, n=3, y=3), Co(II) (X=Cl, n=2, y=1.5), Ni(II) (X=Cl, n=2, y=1) and UO2(II) (X=NO3, n=2, y=0)) and [M(L)2] (where M=Cu(II) (X=Cl) and Zn(II) (X=AcO)). The molar conductance data reveal that Fe(III) and Co(II), Ni(II) and UO2(II) chelates are ionic in nature and are of the type 3:1 and 2:1 electrolytes, respectively, while Cu(II) and Zn(II) complexes are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a terdentate manner with ONS donor sites of the carboxylate O, azomethine N and thiophene S. From the magnetic and solid reflectance spectra, it is found that the geometrical structure of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species. 相似文献
119.
A summary of the chemistry of the tetranuclear Au(I) amidinate complexes is presented. Tetranuclear Au(I) amidinate clusters are produced by the reaction of the sodium salt of a amidine ligand with the gold precursor Au(THT)Cl in a (1:1) stoichiometry. The structures of the tetranuclear Au4[ArNC(H)NAr]4, Ar = C6H4‐4‐OMe, C6H3‐3,5‐Cl, C6H4‐4‐Me, C6H4‐3‐CF3, C6F5, C10H7 and the tetranuclear Au4[(PhNC(Ph)NPh]4 and Au4[PhNC(CH3)NPh]4 have been characterized by X‐ray crystallography. The average Au···Au distance between adjacent Au(I) atoms is ?3.0 Å, typical of compounds having an aurophilic interaction. The four gold atoms are located at the corner of a rhomboid with the amidinate ligands bridged above and below the near plane of the four Au(I) atoms. The angles at Au···Au···Au in the cyclic units are between 70° and 116°. The tetranuclear gold(I) amidinate clusters each show different luminescence behavior. The tetranuclear clusters Au4[(ArNC(H)NAr]4, Ar = C6H4‐4‐OMe, Ar = C6H4‐3‐CF3, Ar = C6H4‐4‐Me and Ar = C6H4‐3,5‐Cl are the first tetranuclear gold(I) cluster species from group 11 elements that show fluorescence at room temperature. The tetranuclear naphthyl derivative Ar = C10H7 is luminescent only at 77 K. The pentafluorophenyl derivative Ar = C6F5 does not show any photoluminescence in the solid state nor in the solution. The lifetimes of the naphthyl and trifluoromethylphenyl complexes are in the millisecond range indicating phosphorescent processes. Electrochemical and chemical oxidation studies of the tetranuclear Au(I) amidinate clusters are presented. The tetranuclear complexes Au4[ArNC(H)NAr]4, Ar = C6H4‐4‐OMe, Ar = C6H4‐4‐Me, and Ar = C6H3‐3,5‐Cl, show three reversible waves at 0.75, 0.95, 1.09 V vs. Ag/AgCl at a scan rate of 500 mV/s in 0.1 M Bu4NPF6/CH2Cl2 at a Pt working electrode in CH2Cl2. Three reversible waves at 0.87, 1.19, 1.42 V vs. Ag/AgCl at a scan rate of 100 mV/s are also observed for the tetranuclear complex Au4[PhNC(Ph)NPh]4 in CH2Cl2. The pentafluorophenyl amidinate derivative, Au4[ArNC(H)NAr]4, Ar = C6F5 shows no oxidation wave below 1.8 V. Recently it has been shown that Au4[ArNC(H)NAr]4 is a very effective catalyst precursor for room temperature CO oxidation. 相似文献
120.
El-Hendawy Ahmed M. Alqaradawi Siham Y. Al-Madfa Homaid A. 《Transition Metal Chemistry》2000,25(5):572-578
The new complexes [RuIIIbpyL2](PF6) and [RuIIIbpyLCl2] [bpy = 2,2-bipyridine; HL = acetylacetone, trifluoroacetylacetone, benzoylacetone (Hbac), tropolone or maltol; HL = Hbac or dibenzoylmethane) have been prepared and characterized by spectroscopy. Their redox behaviour was studied by cyclic voltammetry. They effectively catalyze the oxidation of alcohols, alkanes and primary aromatic amines. 相似文献
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