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91.
Lenka Malinová Michaela Stolínová Daniela Lubasová Lenka Martinová Jiří Brožek 《European Polymer Journal》2013
The paper is focused on the preparation of nanofiber layers of polyesteramides with various ratios of ε-caprolactam/ε-caprolactone structural units. We have studied the effect of the system parameters, i.e., the composition of the copolymer, its molar mass and the concentration of the solution on morphology of fiber layers being formed during the electrostatic wet spinning. The process parameters were constant during the processing. Morphology of the fiber layers is given by the composition of the copolymer, i.e., by its polarity, the content of the crystalline phase and thus its separation in the process of evaporating the solvent. Fibers with diameters ranging from 100 to 160 nm were obtained for polyesteramides containing 20 or 40 mol% lactone units during optimizing the system parameters, i.e., the concentration of the solution and molar mass of polyesteramide. 相似文献
92.
93.
We analyse the size of an independent set in a random graph on n vertices with specified vertex degrees, constructed via a simple greedy algorithm: order the vertices arbitrarily, and, for each vertex in turn, place it in the independent set unless it is adjacent to some vertex already chosen. We find the limit of the expected proportion of vertices in the greedy independent set as (the jamming constant), expressed as an integral whose upper limit is defined implicitly, valid whenever the second moment of a random vertex degree is uniformly bounded. We further show that the random proportion of vertices in the independent set converges in probability to the jamming constant as . The results hold under weaker assumptions in a random multigraph with given degrees constructed via the configuration model. © 2017 Wiley Periodicals, Inc. Random Struct. Alg., 51, 565–586, 2017 相似文献
94.
95.
Zusammenfassung An gesinterten Proben von ScO wurden die elektrochemischen Eigenschaften im sauren und alkalischen Milieu festgestellt. In Gegenwart von H2SO4 wird ScO zu Scandium(III)-sulfat oxidiert, in Gegenwart von NaOH ist ScO beständig bis zum Gebiet der Entwicklung von Sauerstoff. Der Verlauf dieser Reaktionen wurde mittels einerTafel-Gleichung ausgedrückt.
Mit 1 Abbildung
Herrn Prof. Dr.H. Nowotny gewidmet. 相似文献
Electrochemical properties of scandium monoxide
Electrochemical properties of sintered ScO both in the acid and alkaline medium were investigated. Scandium monoxide dissolved in H2SO4 is oxidized to Scandium(III) sulphate, while in alkaline solution (NaOH) ScO is stable up to the region of oxygen evolution. The reaction course was explained by theTafel equation.
Mit 1 Abbildung
Herrn Prof. Dr.H. Nowotny gewidmet. 相似文献
96.
Jeroen J. Jansen Rasmus Bro Huub C. J. Hoefsloot Frans W. J. van den Berg Johan A. Westerhuis Age K. Smilde 《Journal of Chemometrics》2008,22(2):114-121
Novel post‐genomics experiments such as metabolomics provide datasets that are highly multivariate and often reflect an underlying experimental design, developed with a specific experimental question in mind. ANOVA‐simultaneous component analysis (ASCA) can be used for the analysis of multivariate data obtained from an experimental design instead of the widely used principal component analysis (PCA). This increases the interpretability of the model in terms of the experimental question. Aside from the levels of individual factors, variation that can be described by the experimental design may also depend on levels of multiple (crossed) factors simultaneously, e.g. the interactions. ASCA describes each contribution with a PCA model, but a contribution depending on crossed factors may be described more parsimoniously by multiway models like parallel factor analysis (PARAFAC). The combination of PARAFAC and ASCA, named PARAFASCA, provides a view on the data that is both parsimonious and focused on the experimental question. The novel method is used to analyze a dataset in which the effect of two doses of hydrazine on the urinary chemical composition of rats is investigated by time‐resolved metabolic fingerprinting with nuclear magnetic resonance (NMR) spectroscopy. This experiment has been conducted to monitor the dose‐specific urine composition changes in time upon hydrazine administration. Comparison of the PCA, the ASCA and the PARAFASCA models shows that ASCA and PARAFASCA describe the data more dedicated to the experimental question than PCA, but that PARAFASCA is more parsimonious than ASCA, and separates the variation underlying different effects better. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
97.
Polyamide 6/12 copolymers were prepared by employing two different initiation systems containing activator N-benzoyl-ε-caprolactam (BzCL) and initiator either sodium salt of ε-caprolactam (CLNa) or ε-caprolactam magnesium bromide (CLMgBr). Materials prepared by initiation with CLNa show one melting endotherm and are random copolymers. Materials prepared by initiation with CLMgBr show two melting endotherms and are probably composed from random copolymer and block copolymer containing blocks of random copolymer and blocks of copolymer with ε-caprolactam rich segments. The character of copolymers and fractionalized materials was evaluated by means of DSC and NMR. 相似文献
98.
Pedersen HT Bro R Engelsen SB 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,157(1):141-155
In this work an alternative method, named SLICING, for two-dimensional and noniterative T(2) decomposition of low-field pulsed NMR data (LF-NMR) is proposed and examined. The method is based on the Direct Exponential Curve Resolution Algorithm (DECRA) proposed by W. Windig and A. Antalek (1997, Chemom. Intell. Lab. Syst.37, 241-254) and takes advantage of the fact that exponential decay functions, when translated in time, retain their characteristic relaxation times while only their relative amounts or concentrations change. By such simple translations (slicing) it is possible to create a new "pseudo" direction in the relaxation data and thus facilitate application of trilinear (multiway) data-analytical methods. For the application on LF-NMR relaxation data, the method has two basic requirements in practice: (1) two or more samples must be analyzed simultaneously and (2) all samples must contain the same qualities (i.e., identical sets of distinct T(2) values). In return, if these requirements are fulfilled, the SLICING (trilinear decomposition) method provides very fast and unique curve-resolution of multiexponential LF-NMR relaxation curves and, as a spin-off, calibrations to reference data referring to individual proton components require only scaling of the resulting unique concentrations. In this work the performance of the SLICING method (including multiple slicing schemes) is compared to a traditional two-dimensional curve fitting algorithm named MATRIXFIT through application to simulated data in a large-scale exhaustive experimental design and the results validated by application to two small real data sets. Finally a new algorithm, Principal Phase Correction (PPC) based on principal component analysis, is proposed for phase rotation of CPMG quadrature data, an important prerequisite to optimal SLICING analysis. 相似文献
99.
100.
Jan Bednář Jaromír Brož Karel Šmirous Zdeněk Trousil 《Czechoslovak Journal of Physics》1954,4(3):345-349
Pure iron has been prepared by electrolysis of ferrous chloride as well as by reduction of ferric oxide. The material thus obtained was refined in solid state by moist hydrogen. Its magnetic and electrical properties were measured and its thermal conductivity determined. By comparing the data gained in this way with the data obtained by other authors conclusions about the purity of this iron were drawn.See. tables and figures preceding Russian article. 相似文献