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51.
Ivanildo?José?Da?SilvaJr Vinícius?De?Veredas Marcos?José?Souza?Carpes Cesar?Costapinto?SantanaEmail author 《Adsorption》2005,11(2):123-129
Bupivacaine is an amide type local anesthetic widely used in surgery and obstetrics because of its sustained peripheral and central nerve blockade. R-(+)-bupivacaine is more toxic to the central nervous and the cardiovascular systems than S-(?)-bupivacaine. To obtain S-(?)-bupivacaine with high degree of purity using a continuous simulated moving bed (SMB) unity, equilibrium and mass transfer parameters under dilute conditions were obtained by pulse experiments using 0,0′-bis[4-terc-butyl-benzoyl]-N,N′-diallyl-L-tartar diamide immobilized in silica (Kromasil® CHI-TBB). The linear equilibrium constants were found to be 2.12 and 2.91 for R-(+)-and S-(?)-bupivacaine, respectively. Axial dispersion coefficients were found to be practically the same for both enantiomers. A fast kinetic of mass transfer was observed. The internal resistance to the mass transfer controls all the mass transfer process in this chiral column and the pore diffusion coefficients were of the order 10?7cm2/s. The equilibrium and mass transfer parameters will be employed in future simulation and design of operating conditions of SMB unity. 相似文献
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54.
Myung‐Jae Lee Heon‐Woo Lee Jong‐Min Kang Ji‐Hyung Seo Seong‐Kun Tak Wangseob Shim Sung‐Vin Yim Seung Jae Hong Kyung‐Tae Lee 《Biomedical chromatography : BMC》2010,24(10):1031-1037
We describe a simple, rapid and sensitive high‐performance liquid chromatography–electrospray ionization tandem mass spectrometric method that was developed for the simultaneous determination of carebastine and pseudoephedrine in human plasma using cisapride as an internal standard. Acquisition was performed in multiple‐reaction monitoring mode by monitoring the transitions: m/z 500.43 > 167.09 for carebastine and m/z 166.04 > 147.88 for pseudoephedrine. The devised method involves a simple single‐step liquid–liquid extraction with ethyl acetate. Chromatographic separation was performed on a C18 reversed‐phase chromatographic column at 0.2 mL/min by isocratic elution with 10 mM ammonium formate buffer–acetonitrile (30:70, v/v; adjusted to pH 3.3 with formic acid). The devised method was validated over 0.5–100 ng/mL of carebastine and 5–1000 ng/mL of pseudoephedrine with acceptable accuracy and precision, and was successfully applied to a bioequivalence study involving a single oral dose (10 mg of ebastine plus 120 mg of pseudoephedrine complex) to healthy Korean volunteers. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
55.
Věra Jedináková-Křížová Josef Zeman Hana Vinšová Eduard Hanslík 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):719-727
The contribution is focused on chemical, geochemical and mineralogical research of bentonite stability with the aim to determine
the effect of saturation medium composition and loading by heat on bentonite stability. The main part of the research is directed
to the experimental results of bentonite and bentonite leachate samples obtained for the bentonite interaction under laboratory
experiments. Computer-modeling methods were used to calculate equilibrium thermodynamic principles, the distributions of predominant
aqueous species, and potential solubility controls for the environmentally important oxidation states of each investigated
radioactive contaminants. The Eh–pH diagrams of individual chemical species of the tested radionuclides were calculated by
the geochemical software tool Geochemist’s Workbench that included the actual chemical compositions of the solid–liquid systems
under the given experimental conditions. It was confirmed that smectites are transformed to more stable silicate phases, such
as illite/smectite mixed layers, illite. The data obtained from the model calculations conform with experimental results.
The effect of the variable aqueous phase composition on bentonite stability using Ca–Mg and Na–Ca bentonites for the experiments
was studied. The synthetic granitic waters with the higher concentration of the K+ and Mg2+ cations were applied for the study of bentonite stability. 相似文献
56.
57.
An Application of a Multi-Objective Tabu Search Algorithm to a Bicriteria Flowshop Problem 总被引:4,自引:0,他引:4
This paper proposes a new tabu search algorithm for multi-objective combinatorial problems with the goal of obtaining a good approximation of the Pareto-optimal or efficient solutions. The algorithm works with several paths of solutions in parallel, each with its own tabu list, and the Pareto dominance concept is used to select solutions from the neighborhoods. In this way we obtain at each step a set of local nondominated points. The dispersion of points is achieved by a clustering procedure that groups together close points of this set and then selects the centroids of the clusters as search directions. A nice feature of this multi-objective algorithm is that it introduces only one additional parameter, namely, the number of paths. The algorithm is applied to the permutation flowshop scheduling problem in order to minimize the criteria of makespan and maximum tardiness. For instances involving two machines, the performance of the algorithm is tested against a Branch-and-Bound algorithm proposed in the literature, and for more than two machines it is compared with that of a tabu search algorithm and a genetic local search algorithm, both from the literature. Computational results show that the heuristic yields a better approximation than these algorithms. 相似文献
58.
Anne G. D. Santos Vinícius P. S. Caldeira Mirna F. Farias Antonio S. Araújo Luiz D. Souza Allan K. Barros 《Journal of Thermal Analysis and Calorimetry》2011,106(3):747-751
In this study, the physico-chemistry characterization and kinetic study of the thermal decomposition of sunflower oil and
its biodiesel were carried out. Sunflower biodiesel was synthesized by the methanol route and basic homogeneous catalysis.
The physicochemical characterization of the sunflower oil and biodiesel were performed according to standards set out in the
ANP resolution, and both are in accordance to the specifications. The chromatographic analysis was obtained by GC-FID. The
yield of conversion of 97.4 wt% of sunflower oil in methyl esters confirms the efficiency of the conversion of the fatty acids
into esters. The thermal analysis was performed on a thermobalance, using heating rates of 5, 10, and 20 °C min−1. In these three rates, we observed a single well-defined step of mass loss that describes the volatilization and decomposition
of the sunflower oil and the biodiesel. The kinetic study was performed using equations of approximation and integration methods
such as Coats–Redfern, Van Krevelen, and Horowitz–Metzger. The kinetic parameters reaction order (n) and apparent activation energy (E
a), obtained by applying these method were correlated. 相似文献
59.
Wiggers Vinícius Rech Paulo C. 《The European Physical Journal B - Condensed Matter and Complex Systems》2018,91(7):1-5
The European Physical Journal B - In 1961 Landauer argued that reset a bit of information requires a minimum energy expenditure of kBT ln 2. This quantity is directly related to the entropy... 相似文献
60.
Heitor Evangelista Sergio Ney Machado Cardoso Aldrey Costa Gonçalves Marcus Vinícius Licínio Elenilson Barboza Anselmo Salles Paschoa 《Radiation measurements》2012,47(3):229-235
Natural gamma-radiation flux density at Earth’s surface is modulated by soil water retention capacity and the rainout/washout of short-lived radon progenies as major parameters. In this work, 11-year absorbed dose data from 36 TLD environmental stations, installed over different geological domains, allowed a better understanding of temporal and spatial variability of natural gamma-radiation, at a tropical region of Brazil. The results show conspicuous one-year cyclicity with increases during the winter-fall (dry season), varying from 3.9 to 14.1% compared to summer (wet season). TLD stations installed at beach sand terrains presented elevated coefficient of variation compared to results at soils and rocky terrains. This difference was attributed tentatively to changes in naturally occurring radionuclides activity concentrations in accordance with coastal sedimentary dynamics. Additionally, long-term TLD databases, selected from main geological domains, allowed the modeling of regional absorbed dose rates. 相似文献