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81.
Gaber A. M. Mersal 《Journal of Solid State Electrochemistry》2012,16(6):2031-2039
A novel, simple, sensitive and highly selective pseudo-carbon paste electrode modified with poly(acrylic) acid (PCPE-PAA) was described to be useful for the electrochemical determination of ephedrine substance. The PCPE-PAA electrode was characterized using scanning electron microscope (SEM) and cyclic voltammetry. Cyclic voltammogram for ephedrine shows only one anodic oxidation peak at 1.15?V (vs. SCE) using Britton–Robinson buffer (pH 9). Theoretical calculations were performed using PM3 method to be helpful in studying the electrochemical behavior of ephedrine. The highest occupied orbitals (HOMO) of ephedrine and the lowest unoccupied orbitals (LUMOs) of its oxidation product (methcathinone) are mainly localized in the side chain of benzene ring. The values of HOMOs, LUMOs and atomic charges clearly indicate that the oxidation process occurs on the hydroxyl group of ephedrine forming ketone group, supporting the proposed electrochemical mechanism. Square wave voltammetry was used for the direct electrochemical determination of ephedrine. Ephedrine gives a linear range from 6?×?10?5 to 1?×?10?3?M with a correlation coefficient of 0.998 and a relative standard deviation of 2.165?×?10?7. A lower detection limit of 3.5?×?10?7?M was obtained. The effect of some interferences such as ascorbic acid, uric acid, urea, glucose and glycine on the peak height of ephedrine was examined. The suggested method has been applied successfully for the direct electrochemical determination of ephedrine in urine and different pharmaceutical formulations. 相似文献
82.
Reham M. El‐Morshedy Mohammed M. El‐Gamil Mohamed Mahmoud Abou‐Elzahab Gaber M. Abu El‐Reash 《应用有机金属化学》2019,33(5)
The binuclear Cr (III), Mn (II) and Fe (III) complexes of N,N′‐(2,2′‐(2‐benzylmalonyl)bis (hydrazine‐1‐carbonothioyl))dibenzamide (H4BPCD), which derived from the combination of 2‐benzylmalonohydrazide suspension with benzoyl‐isothiocyanate, have been isolated and investigated by the necessary analytical and spectroscopic techniques. The IR studies show that H4BPCD dispose as a mono‐negative hexadentate ligand (NOS)2 towards Mn (II) ion and tetra‐negative hexadentate (NOS)2 towards both Cr (III) and Fe (III) ions. The values of molar conductance in DMSO suggested the non‐electrolytic nature for all complexes. The magnetic measurements and the electronic transitions data confirmed the hexa‐coordinate geometry of complexes. The DFT geometry optimization of all compounds and IR comparative study of both theoretical and experimental of H4BPCD were carried out. Moreover, the H4BPCD and its Cr (III) complex displayed intra ligand (π → π*) fluorescence emission spectra which corroborate their photoactive nature. The coordinated and crystalline water molecules have been investigated by (TG/DTG) studies. The kinetic and thermodynamic parameters were computed using Horowitz‐ Metzger, Coats‐Redfern and Broido methods. Biological studies of DNA binding, minimum inhibitory concentration, in vitro determination of SOD‐like activity and MTT‐cytotoxicity assay as well as molecular docking studies were tested for the ligand and its complexes. 相似文献
83.
84.
Abstract Charge transfer (CT) complexes of p-benzoquinone derivatives with Indolyldiene aniline derivatives have been prepared and investigated by Elemental analysis, IR, 1H-NMR and electronic absorption spectroscopy. The spectral changes revealed that acidic acceptors form complexes with π - π? electronic interaction and proton transfer while non-acidic acceptors yield complexes having π - π transition only. The formation of 1:2 (D:A) complexes is also ascertained. The ionization potential and electron affinity are determined from the electronic absorption spectra for both the donors and acceptors respectivily. 相似文献
85.
Sanaa M. Eldin Hatem M. Gaber Sami S. Ghabrial 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):803-810
Several new pyrrolopyrazoles were synthesised via the reaction of thiazolonylarylhydrazones with N-arylmaleimides followed by partial dehydrogenation using bromobenzene and complete aromatization using nitrobenzene. Structures were elucidated by elemental analyses and spectral data studies. 相似文献
86.
Solution studies of the tetradentate ligand tris(2-benzylaminoethyl)amine, BzTren with both zinc(II) and copper(II) salts were investigated in aqueous methanol (33% v/v) by means of 1H NMR, potentiometric, and UV-visible titrations as well as cyclic voltammetry. Subsequently, their zinc(II) and copper(II) complexes [BzTren-M(OH2)]2+ 1 and 2 (M2+ = Zn2+ and Cu2+) were synthesized and fully characterized by using FT-IR spectroscopy, elemental analysis, and thermal analysis. Complexes 1 and 2 are investigated kinetically for the catalytic hydrolysis of the toxic organophosphate parathion at 50 °C in aqueous methanol (33%, v/v). The kinetic results indicate that copper(II) complex 2 is more active than zinc(II) complex 1, presumably a reflection of the effective electron-withdrawing as well as the greatest electrophilicity of copper(II) ion. 相似文献
87.
C.P. Singh M. Yousuf S.B. Qadri D.C. Turner B.P. Gaber B.R. Ratna 《Applied Physics A: Materials Science & Processing》2003,77(3-4):585-589
The synthesis of transparent monolithic silica with a structure consistent with a space group Pn3m )isdemonstratedusingatemplate-directedsynthesisapproach.TheprocedureisbasedonthehydrolysisandpolymerizationofsiliconalkoxideatlowpHinthepresenceofacationicsurfactant.Thelow-pHreactionrouteischosentoobtaintransparentmonolithicmesoporoussilica.AstructureconsistentwiththePn3m) space group with unit cell lattice parameter ranging from 60–64 Å was identified using small-angle X-ray diffraction. While the lattice parameter is observed to be a monotonically increasing function of surfactant-to-silica ratio, the surfactant-to-alkoxide ratio has a weak discernible effect on the lattice parameter. The Brunauer, Emmett, and Teller (BET) surface area, total pore volume and average pore diameter of the samples are in the range of 787–845 m2/g, 0.37–0.51 cc/g and 18–24 Å respectively. This synthesis approach offers a one-step formation of monolithic mesoporous silica of diverse dimensions for potential use in a variety of technological applications such as catalysis, controlled release and adsorption phenomena . PACS 36.10.Gr; 68.65.-k; 73.21.-b; 73.23.-b 相似文献
88.
A Convenient Synthesis of 2H‐Pyran‐2‐ones,Fused Pyran‐2‐ones,and Pyridones Bearing a Thiazole Moiety
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Samir Bondock Abd El‐Gaber Tarhoni Ahmed A. Fadda 《Journal of heterocyclic chemistry》2014,51(1):249-255
The versatile enaminonitrile, 2‐cyano‐3‐(dimethylamino)‐N‐(4‐phenylthiazol‐2‐yl)‐acrylamide ( 2 ), reacts with some C,O‐binucleophiles (acetylacetone and dimedone) in refluxing acetic acid to afford the pyranone 4 , the chromene 6 derivatives, and with C,N‐binucleophiles (2‐(benzothiazol‐2‐yl)acetonitrile and 2‐(1H‐benzimidazol‐2‐yl)acetonitrile) to afford the respective 1H‐pyrido[2,1‐b]benzothiazole 8 and pyrido[1,2‐a]benzimidazole 10 derivatives. Similar treatment of 2 with phenol, resorcinol, α‐naphthol and β‐naphthol in boiling acetic acid gave the coumarin derivatives 12 , 14 , 16 , and 18 , respectively. The utility of enaminonitrile 2 for the synthesis of 6H‐pyrano[3,2‐d]isoxazole 20 , pyrano[2,3‐c]pyrazole 22 , and pyrano[2,3‐d]pyrimidine 24 derivatives was also explored via its reaction with 3‐phenylisoxazol‐5(4H)‐one, 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐one, and barbituric acid, respectively. The mechanistic aspects for the formation of the new compounds were also discussed. 相似文献
89.
Gaber Hashem Gaber Ahmed Rosana Badía Laíño Josefa Angela García Calzón Marta Elena Díaz García 《Mikrochimica acta》2014,181(9-10):941-948
We describe the synthesis of ß-cyclodextrin modified magnetic nanoparticles (CD-mNPs) as a material for solid-phase extraction of the cancer biomarker 5-hydroxy-indole-3-acetic acid (5-HIAA) from urine. The CD-mNPs were characterized by TEM, FTIR, and XRD, and the kinetics and adsorption isotherms were studied. The strong interaction between the CD-mNPs and 5-HIAA is the main driving force for recognition and extraction, while the magnetic core of the NPs allows their separation from the sample matrix. Recovery of 5-HIAA from the adsorbent using an adequate solvent regenerated the adsorbent for further use. 5-HIAA was then quantified by fluorometry of its complex with ß-CD. The method works in the 1?×?10?7 to 1?×?10?5 mol L?1 (R2 0.9982–0.9996) concentration range, and the limits of detection (3σ) and quantification (10 σ) of the method are 1.2?×?10?8 mol L?1 and 4.01?×?10?8 mol L?1 5-HIAA, respectively. The recovery of 5-HIAA from urine samples spiked with 5-HIAA in three concentrations (1.4?×?10?6, 4.50?×?10?6 and 1.0?×?10?5 mol L?1) are within 63?±?3 %. Figure
Cyclodextrin functional magnetic nanoparticles as sorbents for separation of 5-hydroxy-3-indole acetic acid and its fluorescence determination after released with methanol. 相似文献
90.
M. M. Aly A. M. Fahmy A. M. Gaber 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):253-258
Abstract Thermolysis of N-benzoyl-N′-phenylthiourea (BPTU) on heating in air at 230°C gives NH3, H2S, benzaldehyde, benzil, aniline, azobenzene, benzamide, benzanilide, phenylisothiocyanate, phenyl-cyanamide, thiocarbanilide and benzoylisothiocyanate, whereas thermolysis of N-benzoy1-N′-benzylthiourea (BBTU) affords NH3, H2S, benzaldehyde, benzil, toluene, bibenzyl, stilbene, benzamide, cyanamide, benzylisothiocyanate, benzoylthiourea and benzoylisothiocyanate. Thermolysis of N-benzoyl-N′-α-naphthylthiourea (BNTU) under the same conditions gives NH3, H2S. benzaldehyde, benzil, benzamide, α-naphthylisothiocyanate, α-naphthanilide, α-naphthylcyanamide. benzoylisothiocyanate, α-naphthylamine and N,N′-di-α,α′-naphthylthiourea. Analogous results were also obtained on photolysis of (BFTU), (BBTU) and (BNTU) with the exception of NH3, and the photodegradation products of phenylthiourea, benzylthiourea and a-naphthylthiourea respectively. The main feature of these pyrolyses is the homolysis of the amide and thioamide bonds providing free radicals that undergo different reactions involving H-abstraction, dimerization, coupling, fragmentation, rearrangement and disproportionation to yield the identified products. 相似文献