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91.
Al-Hazmi GA El-Metwally NM El-Gammal OA El-Asmy AA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(1):56-61
The condensation products of acetophenone (or its derivatives), salicylaldehyde and o-hydroxy-p-methoxybenzophenone with thiosemicarbazide and ethyl- or phenyl-thiosemicarbazide are the investigated thiosemicarbazones. Their reactions with H(2)PtCl(6) produced Pt(IV) complexes characterized by elemental, thermal, mass, IR and electronic spectral studies. The coordination modes were found mononegative bidentate in the acetophenone derivatives and binegative tridentate in the salicylaldehyde derivatives. The complexes were analyzed thermogravimetrically and found highly stable. Some ligands and their complexes were screened against Sarcina sp. and E. coli using the cup-diffusion technique. [Pt(oHAT)(OH)Cl] shows higher activity against E. coli than the other compounds. The degradation power of the tested compounds on the calf thymus DNA supports their selectivity against bacteria and not against the human or related eukaryotic organisms. 相似文献
92.
93.
Abdullah S. Babaqi Mohamed T. Mohamed Salah S. Massoud Mohamed F. Amira 《Transition Metal Chemistry》1988,13(3):201-204
Summary The aquation of chloropentamminecobalt(III) ion has been studied in ethylene glycol-water mixtures up to 80% by weight at five temperatures from 35 to 55°C. Specific solvent effects on the reaction rate and mechanism have been investigated and discussed. The validity of our previously proposed equations, correlating the specific reaction rate with the dielectric constant of the medium has been examined. The thermodynamic parameters of activation have been calculated and presented as evidence for the solvation effects and in support of the proposed reaction mechanism. 相似文献
94.
《Solid State Ionics》2006,177(3-4):269-274
Alkaline earth substituted UO2 (U1 − xMxO2 ± δ; M = Mg, Ca, Sr; 0.1 ≤ x ≤ 0.525) with fluorite structure was synthesized in reducing atmosphere. Structure and conductivity properties of U1 − xMxO2 ± δ fluorites were investigated for possible application in solid oxide fuel cells (SOFC). At room temperature and ambient atmosphere the materials are stable; however they decompose at an oxygen partial pressure pO2 > 10− 4 atm and temperatures higher than 600 °C. The total conductivity measured for the best conducting U1 − xMxO2 ± δ material with M = Ca and x = 0.177 is as high as 3 S/cm at pO2 < 10− 4 atm at 600 °C. The relatively low ionic transference number (ti∼0.02) is disadvantageous for potential use as electrolyte material for SOFC applications. The high conductivity and possible depolarization effects suggest potential use as anode materials in SOFC. 相似文献
95.
A series of W-type hexagonal ferrites with the composition BaCoZn1−xMgxFe16O27 (0?x?0.6) were prepared by the conventional ceramic method to study their structural and magnetic properties as a function of temperature and composition. The characterization using X-ray diffraction indicated that a hexagonal W-type single-phase structure and the effect of composition on the unit cell parameters, density and porosity was studied. The variation of the magnetic susceptibility (χM) with temperature for all the investigated samples in the temperature range (300–800 K) shows three regions of behavior that was explained on the basis of the distribution of Zn2+ and Mg2+ ions in the lattice and leads to the anomalous behavior of the effective magnetic moment μeff. The Curie temperature indicated that the critical concentration is at x=0.5. Paramagnetic nature of the samples above the Curie temperature is observed. The Curie Weiss constant θ calculated from the plot of 1/χM vs. T (K) is in agreement with the expected value. The effective magnetic moment μeff decreases with increasing the intensity of magnetic field. The possible mechanisms contributing to these properties are discussed in the text. 相似文献
96.
Taleb T. Al-Nahary Mohamed Abdel Nabi El-Ries Gehad G. Mohamed Ali Kamal Attia Yahia Nasser Mabkhot Michelyne Haroun Assem Barakat 《Arabian Journal of Chemistry》2013,6(1):131-144
The drugs under study; repaglinide (Repag), flubendazole (Flu), robenidine hydrochloride (Roben) and danofloxacin (Dano) are antidiabetic, anthelmintic, anticoccidial, and antibiotic drugs. In the present study, they are investigated using electron impact mass spectral (EI-MS) fragmentation at 70 eV, in comparison with thermal analyses measurements (TGA/DrTGA and DTA) and molecular orbital calculation (MO). Semi-empirical MO calculation, AM1 procedure, has been carried out on Repag, Flu, Roben and Dano both as neutral molecules (in TA) and the corresponding positively charged species (in MS). The calculated MO parameters include bond length, bond order, charge distribution on different atoms and heat of formation. The fragmentation pathways of Repag, Flu, Roben and Dano in EI-MS led to the formation of important primary and secondary fragment ions. The mechanism of formation of some important daughter ions can be illuminated from comparing with that obtained using mass spectrometer through the accurate mass measurement determination. The MO provides a base for fine distinction among sites of initial bond cleavage and subsequent fragmentation of drug molecules in both thermal analysis and MS techniques. The activation thermodynamic parameters, such as, (activation energy E1), (enthalpy ΔH1), (entropy ΔS1) and (Gibbs free energy ΔG1) are calculated from the DrTGA curves using Coats–Redfern and Horowitz–Mitzger methods. 相似文献
97.
Comparative analysis of the oil and supercritical CO(2) extract of Schinus molle L. growing in Yemen
Ali NA Marongiu B Piras A Porcedda S Falconieri D Al-Othman AH 《Natural product research》2011,25(14):1366-1369
In this study, we report the preliminary data on the chemical composition of Yemeni Schinus molle L. volatile oil obtained by supercritical extraction with carbon dioxide (40°C and 90?bar), SFE, and by hydrodistillation (HD). The composition of the volatile oil has been analysed by GC and GC-MS. The content of the major constituents in the oils from leaves varied in the following ranges: germacrene D 3.7% in SFE and 16.7% in HD; β-caryophyllene 19.1% in SFE and 13.5% in HD. The amount of monoterpenes constituted 4%, in all the analysed samples, while the number of sesquiterpenes was 44% in supercritical and 67% in HD oil. Some compounds were not identified by GC-MS and it will require further analysis using other analytical techniques. 相似文献
98.
Summary Poly(5-vinylsalicylidene-2-benzothiazoline) homopolymer (PVSBH2) and polymer complexes of 5-vinylsalicylidene-2-benzothiazoline with a number of divalent transition metals have been prepared and characterized using spectral (1H NMR and13C-NMR, IR, UV-VIS) and magnetic measurements. The data suggest that the Co(II), Ni(II), Fe(II) and Mn(II) polymer complexes are octahedral dimers, while the rest are monomeric with square planar tetrahedral geometries.
Polymere Komplexe, 21. Mitt.: Stereochemische Änderungen in Metallchelaten von Poly(5-vinylsalicyliden-2-benzothiazolinen)
Zusammenfassung Es wurden homopolymere Poly(5-vinylsalicyliden-2-benzothiazolin)-(PVSBH2) und polymere 5-Vinylsalicyliden-2-benzothiazolin-Komplexe mit einer Reihe von zweiwertigen Metallen hergestellt und mittels spektroskopischer (1H- und13C-NMR, IR, UV-VIS) und magnetischer Messungen charakterisiert. Die Daten erlauben den Schluß, daß es sich bei den Co(II)-, Ni(II)-, Fe(II)- und Mn(II)-Polymerkomplexen um oktahedrale Dimere handelt, während der Rest monomere Strukturen mit planar-tetrahedraler Geometrie zeigt.相似文献
99.
A E Almeida A G Ferreira M S Crespi Z A Andrade M C Chung 《Journal of Thermal Analysis and Calorimetry》2006,83(2):277-281
Oxamniquine polymeric prodrug with potential antischistosomal
activity was prepared using dextran T-70 as a carrier, which was analysed
by 1HNMR, 13C NMR and
IR spectroscopy. The formation of the oxamniquine salt was confirmed by thermogravimetric
analysis (TG) and differential scanning calorimetry (DSC) which showed a different
thermal behaviour when compared to the physical mixture. 相似文献
100.
Summary CoII, NiII, CuII, ZnII, CdII and UVIO2 complexes of 5, 5-dimethyl-1, 3-cyclohexanone bis(4-phenylthiosemicarbazone), H2CPT, have been characterized by elemental analysis, i.r. and reflectance spectral studies, and magnetic moment measurements. I.r. spectra show that H2CPT gives rise to dibasic quadridentate SNNS donor. A square-planar structure is proposed for the copper(II) complex and octahedral for cobalt(II) and nickel(II) complexes according to the magnetic and electronic spectral data. The electrical conductivities of H2CPT and its COII, NiII, CuII and CdII complexes were measured. The positive temperature coefficient (d/dT) and the higher activation energies of H2CPT and its CdII and CuII complexes is evidence of their semiconducting character. 相似文献