全文获取类型
收费全文 | 150篇 |
免费 | 5篇 |
专业分类
化学 | 124篇 |
力学 | 4篇 |
数学 | 14篇 |
物理学 | 13篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2019年 | 3篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2003年 | 9篇 |
2002年 | 5篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1957年 | 2篇 |
1940年 | 1篇 |
1916年 | 1篇 |
1914年 | 1篇 |
1913年 | 1篇 |
1909年 | 7篇 |
1904年 | 1篇 |
1903年 | 6篇 |
1902年 | 3篇 |
1900年 | 4篇 |
1898年 | 3篇 |
1895年 | 3篇 |
1890年 | 1篇 |
1887年 | 5篇 |
1886年 | 1篇 |
1885年 | 5篇 |
1884年 | 4篇 |
1882年 | 1篇 |
1881年 | 2篇 |
1879年 | 1篇 |
1878年 | 1篇 |
1870年 | 1篇 |
1865年 | 1篇 |
排序方式: 共有155条查询结果,搜索用时 31 毫秒
91.
Marta Pascoal M. Eugénia Captivo João Clímaco Ana Laranjeira 《4OR: A Quarterly Journal of Operations Research》2013,11(3):275-294
We address a bicriterion path problem where each arc is assigned with a cost value and a label (such as a color). The first criterion intends to minimize the total cost of the path (the summation of its arc costs), while the second intends to get the solution with a minimal number of different labels. Since these criteria, in general, are conflicting criteria we develop an algorithm to generate the set of non-dominated paths. Computational experiments are presented and results are discussed. 相似文献
92.
Roe‐type Riemann solver for gas–liquid flows using drift‐flux model with an approximate form of the Jacobian matrix
下载免费PDF全文
![点击此处可从《国际流体数值方法杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This work presents an approximate Riemann solver to the transient isothermal drift ‐ flux model. The set of equations constitutes a non‐linear hyperbolic system of conservation laws in one space dimension. The elements of the Jacobian matrix A are expressed through exact analytical expressions. It is also proposed a simplified form of A considering the square of the gas to liquid sound velocity ratio much lower than one. This approximation aims to express the eigenvalues through simpler algebraic expressions. A numerical method based on the Gudunov's fluxes is proposed employing an upwind and a high order scheme. The Roe linearization is applied to the simplified form of A . The proposed solver is validated against three benchmark solutions and two experimental pipe flow data. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
93.
94.
Rodríguez O Cristóvão RO Tavares AP Macedo EA 《Applied biochemistry and biotechnology》2011,164(4):524-533
The activity and stability of laccase and their kinetic mechanisms in water soluble ionic liquids (ILs): 1-butyl-3-methyl
imidazolium chloride [C4mim][Cl], 1-octyl-3-methyl imidazolium chloride [C8mim][Cl], and 1-decyl-3-methyl imidazolium chloride [C10mim][Cl] were investigated. The results show that an IL concentration up to 10% is satisfactory for initial laccase activity
at pH 9.0. The laccase stability was well maintained in [C4mim][Cl] IL when compared to the control. The inactivation of laccase increases with the length of the alkyl chain in the
IL: [C10mim][Cl] > [C8mim][Cl] > [C4mim][Cl]. The kinetic studies in the presence of ABTS as substrate allowed calculating the Michaelis–Menten parameters. Among
the ILs, [C4mim][Cl] was the suitable choice attending to laccase activity and stability. Alkyl chains in the ions of ILs have a deactivating
effect on laccase, which increases strongly with the length of the alkyl chain. 相似文献
95.
Noelia Calvar Elena Gómez Ángeles Domínguez Eugénia A. Macedo 《The Journal of chemical thermodynamics》2011,43(8):1256-1262
The osmotic and activity coefficients and vapour pressures of binary mixtures containing 1-propanol, or 2-propanol and imidazolium-based ionic liquids with bis(trifluoromethylsulfonyl)imide as anion (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, C2MimNTf2, 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide, C3MimNTf2, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, C4MimNTf2) were determined at T = 323.15 K using the vapour pressure osmometry technique. The experimental osmotic coefficients were correlated using the extended Pitzer model modified by Archer and the MNRTL model, obtaining standard deviations lower than 0.033 and 0.064, respectively. The mean molal activity coefficients and the excess Gibbs free energy for the mixtures studied were calculated from the parameters of the extended Pitzer model modified by Archer. Besides the effect of the alkyl-chain of the cation, the effect of the anion can be assessed comparing the experimental results with those previously obtained for imidazolium ionic liquids with sulphate anions. 相似文献
96.
Eugénie Hunsicker Hengguang Li Victor Nistor Ville Uski 《Numerical Methods for Partial Differential Equations》2014,30(4):1130-1151
In this article, we consider the problem of optimal approximation of eigenfunctions of Schrödinger operators with isolated inverse square potentials and of solutions to equations involving such operators. It is known in this situation that the finite element method performs poorly with standard meshes. We construct an alternative class of graded meshes, and prove and numerically test optimal approximation results for the finite element method using these meshes. Our numerical tests are in good agreement with our theoretical results.Copyright © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 1130–1151, 2014 相似文献
97.
Dr. Eugénie Fournier Dr. Sybille Tachon Dr. Nicholas J. Fowler Dr. Guillaume Gerbaud Dr. Pascal Mansuelle Dr. Pierre Dorlet Dr. Sam P. de Visser Prof. Valérie Belle Dr. A. Jalila Simaan Dr. Marlène Martinho 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(60):13766-13776
1-Aminocyclopropane-1-carboxylic oxidase (ACCO) is a non-heme iron(II)-containing enzyme involved in the biosynthesis of the phytohormone ethylene, which regulates fruit ripening and flowering in plants. The active conformation of ACCO, and in particular that of the C-terminal part, remains unclear and open and closed conformations have been proposed. In this work, a combined experimental and computational study to understand the conformation and dynamics of the C-terminal part is reported. Site-directed spin-labeling coupled to electron paramagnetic resonance (SDSL-EPR) spectroscopy was used. Mutagenesis experiments were performed to generate active enzymes bearing two paramagnetic labels (nitroxide radicals) anchored on cysteine residues, one in the main core and one in the C-terminal part. Inter-spin distance distributions were measured by pulsed EPR spectroscopy and compared with the results of molecular dynamics simulations. The results reveal the existence of a flexibility of the C-terminal part. This flexibility generates several conformations of the C-terminal part of ACCO that correspond neither to the existing crystal structures nor to the modelled structures. This highly dynamic region of ACCO raises questions on its exact function during enzymatic activity. 相似文献
98.
Ana P. M. Tavares Rui P. Silva António L. Amaral Eugénio C. Ferreira Ana M. R. B. Xavier 《Applied biochemistry and biotechnology》2014,172(4):2132-2142
Image analysis technique was applied to identify morphological changes of pellets from white-rot fungus Trametes versicolor on agitated submerged cultures during the production of exopolysaccharide (EPS) or ligninolytic enzymes. Batch tests with four different experimental conditions were carried out. Two different culture media were used, namely yeast medium or Trametes defined medium and the addition of lignolytic inducers as xylidine or pulp and paper industrial effluent were evaluated. Laccase activity, EPS production, and final biomass contents were determined for batch assays and the pellets morphology was assessed by image analysis techniques. The obtained data allowed establishing the choice of the metabolic pathways according to the experimental conditions, either for laccase enzymatic production in the Trametes defined medium, or for EPS production in the rich Yeast Medium experiments. Furthermore, the image processing and analysis methodology allowed for a better comprehension of the physiological phenomena with respect to the corresponding pellets morphological stages. 相似文献
99.
100.