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11.
G. A. M. Hussein 《Journal of Thermal Analysis and Calorimetry》1994,42(6):1091-1102
Thermogravimetry, differential thermal, X-ray diffraction and infrared spectroscopy analyses showed La(CH3COO)3·1.5H2O to decompose completely at 700°C yielding La2O3. The results revealed that the compound dehydrates in two steps at 130 and 180°C, and recrystallizes at 210°C. Water thus produced hydrolyzes surface acetates (at 310°C), releasing acetic acid into the gas phase. At 334°C, the anhydrous acetate releases gas phase CH3COCH3 to give La2(CO3)3 residue, which decomposes to La2O2(CO3) via the intermediate La2O(CO3)2. On further heating up to 700°C, La2O3 is formed. IR spectroscopy of the gaseous products indicated a chemical reactivity at gas/solid interfaces formed throughout the decomposition course. As a result, CH3COCH3 was involved in a surface-mediated, bimolecular reaction, releasing CH4 and C4H8 (isobutene) into the gas phase. Non-isothermal kinetic parameters, the rate constantk, frequency factorA, and activation energy ΔE, were calculated on the basis of temperature shifts experienced in the thermal processes encountered, at various heating rates (2–20 deg·min?1). 相似文献
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Fatehy M. Abdel‐Haleem Azza Salah Mahmoud S. Rizk Hussein Moustafa Mikhael Bechelany Ahmed Barhoum 《Electroanalysis》2019,31(4):778-789
Thiourea derivative‐based carbon paste electrode (TUD1‐CPE) was constructed as a potentiometric sensor for the determination of salicylate anion in pharmaceutical formulations, Aspocid® and Aspirin®. The optimized CPE contained 45.5 % graphite, 0.5 % reduced graphene oxide (rGO), 46.0 % nitrophenyl octyl ether (NPOE) plasticizer, 5.0 % TUD1 ionophore, and 3.0 % tridodecylmethyl ammonium chloride as additive. The incorporation of NPOE of high dielectric constant, and rGO in electrode caused better performance of the sensor; Nernstian response of 59.0 mV decade?1 in the concentration range of 10?1–10?5 mole L?1, a detection limit of 1×10?5 mole L?1 in a very short response time of 6 seconds. The prepared sensor showed high selectivity against similar anions (i. e. , benzoate, I?, SCN?). Selectivity was confirmed by calculating the formation constant (Kβ) using sandwich membrane method, where Kβ for TUD1‐salicylate is 100.43. Theoretical calculations at DFT‐B3LY/6‐31G** level of theory were performed to find interaction mechanism, Energies of HOMO and LUMO orbitals, non‐linear optical (NLO) properties (the electronic dipole moment (μ), first‐order hyperpolarizability (β), the hyper‐Rayleigh scattering (βHRS) and the depolarization ratio (DR)), and other global properties; these calculations showed lower values of β and DR, higher value of βHRS, and the shortest lengths of the four N?H bonds between TUD1 and salicylate which confirm their strong complexation and salicylate‐selectivity. Also, all the studied anion‐TUD1 exhibited relatively high NLO properties, and these results were considered as a preliminary study for investigating new types of NLO bearing materials. The sensors were applied successfully for the determination of salicylate anion in Aspocid® and Aspirin®. 相似文献
15.
N. S. Prostakov A. V. Varlamov A. Hussein A. A. Fomichev N. A. Ryabova E. E. Stashenko 《Chemistry of Heterocyclic Compounds》1990,26(4):424-430
Spiro[4-azafluorene-9,1 cyclopropanes] were obtained by the reaction of 9-diazo-4-azafluorene with various alkenes in the form of a mixture of geometrical isomers differentiated according to the position of the substituents in the cyclopropane ring and also also according to position relative to the pyridine ring. In the reaction of 9-diazo-4-azafluorene with cyclopentanone, di(4-azafluorene-9 nyl) oxide is formed, while from its reaction with cyclohexanone, 2-oxo-spiro[4-azafluorene-9,1-cycloheptane] is obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 495–501, April, 1990. 相似文献
16.
The equilibrium geometry of formhydroxamic acid has been calculated within the framework of the INDO –MO formalism. Various structural factors are analyzed and discussed in terms of the calculated force constants and charge distribution. The possibility of internal rotation around the C? N bond of formhydroxamic acid has been examined. The potential energy surface for the amide-imide tautomerism is explored by calculating the geometries and characterizing saddle points on that surface. The cyclic and open dimers of formhydroxamic acid are examined and the hydrogenbond energy and length are calculated. 相似文献
17.
The reaction between 5-amino-4-imino-1(2)-substituted-1(2)H-4,5-dihydropyrazolo[3,4-d]pyrimidines and several commercially available reactants afforded new heterocycles with a conserved pyrazolo[3,4-d]pyrimidine nucleus. The key intermediates employed proved to be suitable compounds by virtue of their two vicinal amino and imino groups that were used to obtain five, six and seven-membered rings. 相似文献
18.
Mohamed M. El-Kerdawy Ali A. El-Emam Hussein I. El-Subbagh Elie Abushanab 《Monatshefte für Chemie / Chemical Monthly》1990,121(1):45-50
Summary A new series of thiophenic isosters of thioxanthones, namely: 2-substituted-4H-thieno[2,3-b][1]benzothiopyran-4-ones and 5-substituted-2-nitro-8-methyl-4H-thieno[2,3-b][1]benzothiopyran-4-ones were synthesized as potential schistosomicidal agents. The synthesized compounds were characterized by their1H-NMR data.
Synthese von substituierten 4H-Thieno[2,3-b][1]benzothiopyran-4-onen als mögliche schistosomicide Wirkstoffe
Zusammenfassung Es wurde eine neue Serie von thiophenischen Isosteren des Thioxanthons, nämlich 2-substituierte 4H-Thieno[2,3-b][1]benzothiopyran-4-one und 5-substituierte 2-Nitro-8-methyl-4H-thieno[2,3-b][1]benzothiopyran-4-one als potentielle schistosomicide Wirkstoffe synthetisiert. Die synthetisierten Verbindungen wurden mittels ihrer1H-NMR Daten charakterisiert.相似文献
19.
Summary The copper(III)-imine-oxime complexes [CuIII(Enio)]+ and [CuIII(Pre)]+ {EnioH2 =N,N-ethylene bis(isonitrosoacetylacetoneimine) and PreH2 = N,N-propylene bis (isonitrosoacetylacetoneimine)} react very rapidly with iodide. The rate law under fixed conditions for the reaction is given by the equation: –d[CuIII]/dt = (2k2[I–] + 2k3[I–]2)[CuIII] The [CuIII(Enio)]+ reaction was pH-independent whereas the [Cu (Pre)]+ reaction rate increased with increasing pH. Both the k2 and the k3 pathways are believed to involve one-electron transfer. An inner-sphere mechanism may operate in the pathway, first-order in [I–]. 相似文献
20.
A fundamental study was made on the reduction of calcium phosphate by carbon. The mechanism of reduction was presented on applying different additions. Both silica and alumina increased the extent of reduction but with variable rates. The activation energies were calculated on the basis of first-order reactions. The phases formed during reduction were investigated by X-ray analysis. 相似文献