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61.
Bretanha LC Teixeira VE Ritter M Siqueira GM Cunico W Pereira CM Freitag RA 《Ultrasonics sonochemistry》2011,18(3):704-707
The alternative synthesis of 12 1,2,4-oxadiazoles using ultrasound irradiation from trichloroacetoamidoxime and acyl chlorides is reported. Seven of them are novel compounds. The 3-trichloromethyl-5alkyl(aryl)-1,2,4-oxadiazoles have been synthesised in better yields and shorter reaction times compared to the conventional method. This protocol can be applicable for preparation of 1,2,4-oxadiazoles containing aryl or alkyl groups attached at their C-5 side-chain. 相似文献
62.
63.
Coltro WK da Silva JA da Silva HD Richter EM Furlan R Angnes L do Lago CL Mazo LH Carrilho E 《Electrophoresis》2004,25(21-22):3832-3839
We describe the development of an electrophoresis microchip fabricated by a direct-printing process, based on lamination of printed polyester films with end-channel amperometric detection. The channel structures are defined by polyester (base and cover) and by a toner layer (walls). The polyester-toner devices presented an electroosmotic flow (EOF) magnitude of approximately 10(-5) cm2 V(-1) s(-1), which is generated by a polymeric mixture of the toner and polyester composition. The microelectrodes used for detection were produced combining this laser-printer technology to compact discs. The performance of this device was evaluated by amperometric detection of iodide and ascorbate. The detection limits found were 500 nmol.L(-1) (135 amol) and 1.8 micromol.L(-1) (486 amol) for iodide and ascorbate, respectively. 相似文献
64.
Nathália Alexandra de Oliveira Cartaxo-Furtado Aline Rogéria Freire de Castilho Irlan Almeida Freires Cleildo Pereira Santana Thaíse Oliveira Sampaio Myllena Alves Xavier Ana Claudia Dantas de Medeiros Harley da Silva Alves Edja Maria Melo de Brito Costa Pedro Luiz Rosalen Jozinete Vieira Pereira 《Journal of Thermal Analysis and Calorimetry》2017,127(2):1137-1141
The aim of this study was to determine the physicochemical characteristics of leaves of Syzygium cumini L. Skeels plant and characterize the extract of this plant by analytical techniques. Pharmacopeial methods of physicochemical analysis were used, including morphological characterization of the particle, thermal analysis, infrared spectroscopy and X-ray diffraction. The plant drug was presented as a coarse powder, within the appropriate Brazilian Pharmacopoeia parameters. The X-ray diffraction, optical microscopy and scanning electron microscopy suggested that the extract particles are amorphous and have irregular shapes, so that clusters of different sizes and morphologies are displayed. Thermal decomposition of the organic components in the sample started in a step that occurred between 151.64 and 209.27 °C with mass loss of 9.08 %, followed by another step with more significant mass loss (28.16 %). The infrared spectrum, in turn, showed many functional groups of compounds present in the lyophilized extract in different absorption bands. The results showed that the analytical techniques allowed us to characterize the physicochemical properties of the plant leaves, which may be useful in the production of new herbal medicines. 相似文献
65.
In the present work the transient energy transfer in a nonsaturated porous medium is studied, using a mixture theory viewpoint. The porous matrix is assumed homogeneous, rigid and isotropic, while the fluid is a Newtonian incompressible one and both are assumed static. Since the homogeneous matrix is not saturated, gradients of concentration are present. The porous medium and the fluid (a liquid) will be regarded as continuous constituents of a mixture that will have also a third constituent, an inert gas, assumed with zero mass density and thermal conductivity. The problem is described by a set of two partial differential equations which represent the energy balances for the fluid and the solid constituents. Isovalues for these two constituents are plotted, considering representative time instants and selected values for the energy equations coefficients and for the saturation. 相似文献
66.
Márcio Arab Murad Rogério Martins Saldanha Da Gama Rubens Sampaio Filho 《Meccanica》1992,27(2):95-104
Non-Darcy flows in saturated porous media with significative boundary and inertia effects are modelled applying the Continuum
Theory of Mixtures approach and simulated by discretization of the governing equations by the finite volume method.
Sommario Flussi di tipo ‘Non-Darcy’ in mezzi porosi saturi, con significativi effetti di bordo ed inerziali, vengono modellati applicando l'approccio della Teoria delle Miscele per il Continuo e simulati mediante discretizzazione delle equazioni governanti con il metodo del volume finito.相似文献
67.
Manica R Connor JN Carnie SL Horn RG Chan DY 《Langmuir : the ACS journal of surfaces and colloids》2007,23(2):626-637
A model developed previously to analyze force measurements between two deformable droplets in the atomic force microscope [Langmuir 2005, 21, 2912-2922] is used to model the drainage of an aqueous film between a mica plate and a deformable mercury drop for both repulsive and attractive electrical double-layer interactions between the mica and the mercury. The predictions of the model are compared with previously published data [Faraday Discuss. 2003, 123, 193-206] on the evolution of the aqueous film whose thickness has been measured with subnanometer precision. Excellent agreement is found between theoretical results and experimental data. This supports the assumptions made in the model which include no-slip boundary conditions at both interfaces. Furthermore, the successful fit attests to the utility of the model as a tool to explore details of the drainage mechanisms of nanometer-thick films in which fluid flow, surface deformations, and colloidal forces are all involved. One interesting result is that the model can predict the time at which the aqueous film collapses when attractive mica-mercury forces are present without the need to invoke capillary waves or other local instabilities of the mercury/electrolyte interface. 相似文献
68.
de Campos-Buzzi F Padaratz P Meira AV Corrêa R Nunes RJ Cechinel-Filho V 《Molecules (Basel, Switzerland)》2007,12(4):896-906
Nine acetamidochalcones were synthesized and evaluated as antinociceptive agents using the mice writhing test. Given intraperitoneally all the compounds were more effective than the two reference analgesic drugs (acetylsalicylic acid and acetaminophen) used for comparison. N-{4-[(2E)-3-(4-nitrophenyl)prop-2-enoyl]phenyl}acetamide (6) was the most effective compound and was therefore selected for more detailed studies. It caused dose-related inhibition in the writhing test, being about 32 to 34-fold more potent than the standard drugs. It was also effective in the second phase of the formalin test and the capsaicin test. These acetamidochalcones, especially compound 6, might be further used as models to obtain new and more potent analgesic drugs. 相似文献
69.
Cindy?Elena?Bustamante-VargasEmail author Débora?de?Oliveira Eunice?Valduga Luciana?Dornelles?Venquiaruto Natalia?Paroul Geciane?Toniazzo?Backes Rogério?Marcos?DallagoEmail author 《Applied biochemistry and biotechnology》2016,179(6):1060-1072
Pectinases catalyze the degradation of pectic substances and are used in several processes, mainly in food and textile industries. In this study, a biomimetic matrix of alginate/gelatin/calcium oxalate (AGOCa) was synthesized for the in situ immobilization via encapsulation of crude pectinase from Aspergillus niger ATCC 9642, obtaining an immobilization efficiency of about 61.7 %. To determine the performance of AGOCa matrix, this was compared to control matrices of alginate/calcium oxalate (AOxal) and alginate/water (ACa). By the evaluation of pH and temperature effects on the enzyme activity, it was observed an increase on pectinolytic activity for both three tested matrices with an increase on pH and temperature. The kinetic parameters for pectinase immobilized in the three matrices were determined using citric pectin as substrate. Values of K m of 0.003, 0.0013, and 0.0022 g mL?1 and V max of 3.85, 4.32, and 3.17 μmol min?1 g?1 for AGOCa, AOxal, and ACa matrices were obtained, respectively. After 33 days of storage, the pectinase immobilized in the three different matrices kept its initial activity, but that immobilized in AGOCa presented high stability to the storage with a relative activity of about 160 %. The enzyme immobilized in AGOCa, AOxal, and ACa could be used in 10, 8, and 7 cycles, respectively, keeping 40 % of its initial activity. 相似文献
70.
Ribeiro Rogério Pinto Kobelnik Marcelo Parizotto João Candido Valenga 《Journal of Thermal Analysis and Calorimetry》2019,136(2):483-492
Journal of Thermal Analysis and Calorimetry - In this study, the main purpose was the mineralogical and thermal characterization of clayey siltites sampled in a quarry located near Viracopos... 相似文献