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41.
Alaa A.-M. Abdel-Aziz 《Tetrahedron letters》2007,48(16):2861-2865
2-Methoxy-3-cyano-4,6-diarylpyridines were subjected to Lewis acid-promoted nucleophilic displacement reactions with various organo cuprates to afford the corresponding 2,4,6-trisubstituted nicotinonitriles. Subsequent hydrolysis of compounds 10 and 11 afforded the corresponding 2,4,6-trisubstituted nicotinic acid 22 and nicotinamide 23 derivatives, respectively. The mechanism of the displacement reaction has been studied experimentally and by molecular modeling calculations. 相似文献
42.
Khedr A 《Journal of chromatographic science》2007,45(6):305-310
The purpose of this work is to develop a sensitive, selective, and validated stability-indicating HPLC assay of tianeptine (TIA) in bulk drug and tablet form. TIA is subjected to different stress conditions, including UV-light, oxidation, acid base-base hydrolysis, and temperature. TIA and its possible degradation products are analyzed on Agilent-Zorbax-XDB-C18 column using gradient elution with acetonitrile and 0.02M sodium acetate (pH 4.2). The samples are monitored simultaneously with photo-diode array at 254 nm and fluoroscence detector set to 350 nm (ex) and 425 nm (em). TIA is integrated from its UV-chromatogram, and the photodecomposition products are integrated from the fluoroscence-chromatogram. TIA and its photodecomposition products are separated by TLC using ethyl acetate-n-hexane-glacial acetic acid-methanol (10.0:14.0:0.2:1.0, v/v) as developing system. One potential photodegradation product is detected by fluoroscence in TIA-tablet form and separated by TLC. The linear range of TIA is between 0.5 to 50 microg/injection with limits of quantitation and detection values of 30 and 8 ng/injection, respectively. The inter-assay percentage of deviation is not more than 0.03%, and the day-to-day variation is not more than 0.1%. 相似文献
43.
Alaa S. Abd‐El‐Aziz Erin K. Todd Tarek H. Afifi 《Macromolecular rapid communications》2002,23(2):113-117
This communication is focused on the controlled design of star‐shaped aromatic ethers with pendent cyclopentadienyliron moieties. A trimetallic core was prepared, which was then reacted with a number of oligomeric ether complexes to give star‐shaped polymers with six, nine, twelve and fifteen pendent cationic cyclopentadienyliron moieties. Cyclic voltammetric studies showed reduction of the iron centers between –0.99 and –1.41 V. Thermogravimetric analysis showed that loss of the metallic moieties occurred between 225 and 284°C. 相似文献
44.
Alaa S. Abd‐El‐Aziz Leslie J. May Andrea L. Edel 《Macromolecular rapid communications》2000,21(9):598-602
Synthesis and characterization of new thermally stable polynorbornenes functionalized with pendent flexible side‐chains are reported. The flexible side‐chains with terminal hydroxy groups were synthesized via SNAr reactions of cyclopentadienyliron‐complexed chlorobenzenes with aliphatic diols. Condensation of these side‐chains with exo,endo‐5‐norbornene‐2‐carboxylic acid led to the formation of substituted monomers which were characterized using one‐ and two‐dimensional NMR techniques. Ring‐opening metathesis polymerization of these monomers yielded polynorbornenes with pendent side‐chains. 相似文献
45.
Christine R. de Denus Philip Baker Jaclyn Toner Sheila McKevitt Erin K. Todd Alaa S. Abd-El-Aziz 《Macromolecular Symposia》2003,196(1):113-123
Cyclic voltammetry was employed to investigate the electrochemical behavior of numerous cyclopentadienyliron (CpFe+) and pentamethyl-cyclopentadienylruthenium (Cp*Ru+) coordinated oligomers and polymers. The electrochemical behavior of the iron systems indicated the cyclopentadienyliron complexes had isolated redox centers and that changes in the reversibility of the redox couple occurred with changes in solvent and temperature. In contrast, the monometallic ruthenium systems showed large peak separations that suggested slow kinetics on the CV timescale. The cyclic voltammograms of the larger ruthenium-containing oligomers and polymers showed multiple redox steps indicating complex electrochemical behavior. 相似文献
46.
Alaa S. Amin 《Chemical Papers》2009,63(6):625-634
A simple, selective, highly sensitive and accurate procedure for the determination of trace amounts of copper has been developed
based on solid-phase spectrophotometry. Copper reacts with 5-(2-benzothiazolylazo)-8-hydroxyquinoline (BTAHQ) to give a complex
with high molar absorptivity (3.17 × 107 L mol−1 cm−1, 3.07 × 108 L mol−1 cm−1, 1.22 × 109 L mol−1 cm−1, and 1.80 × 109 L mol−1 cm−1), fixed on a Dowex 1-X8 type anion-exchange resin for 10 mL, 100 mL, 500 mL, and 1000 mL, respectively. The absorbance at
667 nm and 800 nm packed in a 1.0 mm cell was measured directly. Calibration is linear over the range 0.2–3.7 μg L−1 with RSD of < 1.28 % (n = 10). The detection and quantification limits of the 500 mL sample method are 79 ng L−1 and 260 ng L−1 when using 60 mg of Dowex 1-X8. For a 1000 mL sample, the detection and quantification limits are 67 ng L−1 and 220 ng L−1 using 60 mg of the exchanger. Increasing the sample volume can enhance the sensitivity. The proposed method was applied to
the determination of copper in different environmental water samples (tap, pit, spring, and river), food products (rice, corn
flour, and tea), and mushrooms, using the standard addition technique. 相似文献
47.
In a multistep reaction, 3,3′-(2-aryl-2H-isoindol-1,3-ylene)-di-(1,4-naphthoquinone-2-carbonitriles) 13a-f have been formed in 25-61% yield from a series of N-arylisoindolines 8a-f with (1,3-dioxo-2,3-dihydro-1H-inden-2-ylidene)propanedinitrile (1) in aerated pyridine. The structure of one of these products (13f) has been unambiguously confirmed by a single crystal X-ray structure analysis. Under otherwise the same conditions, 2-(3-methoxyphenyl)-isoindoline (8g) and 1 gave 38% of [4-(2,3-dihydro-1H-isoindol-2-yl)-2-methoxyphenyl]-1,3-dioxoindan-2-ylidene)acetonitrile (15). Rationales for these conversions involving the known rearrangement of the radical anion of 1 into the radical anion of 1,4-naphthoquinone-2,3-dicarbonitrile (3) are presented. 相似文献
48.
For the first time, polyaniline-coated cerium oxide nanoparticles were synthesized in alkaline media and applied for preconcentration of ultra-trace levels of cadmium (??) in different real samples followed by electrothermal atomic absorption spectrometry. Cerium oxide nanoparticles were synthesized by a microwave method and modified by polyaniline to produce polyaniline-coated cerium oxide nanoparticles. Fourier-transform infrared spectroscopy and scanning electron microscopy were used to characterize the synthesized adsorbent. To optimize the critical experimental conditions; surface response methodology—Box–Behnken experimental design was used. On the basis of the results, pH 8.4, 10?mg of polyaniline-coated cerium oxide nanoparticles, 14.4?min extraction time, and 4.3?min desorption time were selected as the optimum conditions. Under the optimum conditions the calibration curve of cadmium (??) was linear in the range of 0.02–0.4?ng?mL?1 with a correlation coefficient of 0.9976. The relative standard deviation based on seven replicate analysis of 0.1?ng?mL?1 cadmium (??) was 4.2% and limit of detection was 0.005?ng?mL?1 cadmium (??). The analysis of certified reference material shows very good agreement with the certified value. Finally, the proposed method was applied for the determination of ultra-trace levels of cadmium (??) in different water, rice, and tea samples. 相似文献
49.
Alaa A. Hassan Fathy F. Abdel‐Latif Mohamed Abdel‐Aziz Sara M. Mostafa Stefan Bräse Martin Nieger 《Journal of heterocyclic chemistry》2016,53(2):633-636
New series of substituted aminothiadiazolylhydrazonoindolin‐2‐ones were prepared in high yields (89–94%) via the cyclocondensation of thiocarbonohydrazides ( 1a , 1b , 1c , 1d ) with 3‐(dicyanomethylene)‐2‐indolone in (ethanol/piperidine) at room temperature. Explanations of these conversations involve the nucleophilic addition on the dicyanomethylene carbon atom. The structures were established by spectroscopic data and single crystal X‐ray crystallography. 相似文献
50.
Alaa S. Abd‐El‐Aziz Christian Agatemor Nola Etkin 《Macromolecular rapid communications》2014,35(5):513-559
Sandwich complexes feature unique properties as the physical and electronic properties of a hydrocarbon ligand or its derivative are integrated into the physical, electronic, magnetic, and optical properties of a metal. Incorporation of these complexes into macromolecules results in intriguing physical, electrical, and optical properties that were hitherto unknown in organic‐based macromolecules. These properties are tunable through well‐designed synthetic strategies. This review surveys many of the synthetic approaches that have resulted in tuning the properties of sandwich complex‐containing macromolecules. While the past two decades have seen an ever‐growing number of research publications in this field, gaps remain to be filled. Thus, we expect this review to stimulate research interest towards bridging these gaps, which include the insolubility of some of these macromolecules as well as expanding the scope of the sandwich complexes.