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排序方式: 共有141条查询结果,搜索用时 15 毫秒
1.
Carl Johan Casselgren Hrant H. Khachatrian Petros A. Petrosyan 《Discrete Mathematics》2018,341(3):627-637
An interval-coloring of a multigraph is a proper edge coloring with colors such that the colors of the edges incident with every vertex of are colored by consecutive colors. A cyclic interval-coloring of a multigraph is a proper edge coloring with colors such that the colors of the edges incident with every vertex of are colored by consecutive colors, under the condition that color is considered as consecutive to color . Denote by () and () the minimum and maximum number of colors in a (cyclic) interval coloring of a multigraph , respectively. We present some new sharp bounds on and for multigraphs satisfying various conditions. In particular, we show that if is a -connected multigraph with an interval coloring, then . We also give several results towards the general conjecture that for any triangle-free graph with a cyclic interval coloring; we establish that approximate versions of this conjecture hold for several families of graphs, and we prove that the conjecture is true for graphs with maximum degree at most . 相似文献
2.
A high-performance liquid chromatographic method was applied to evaluate the effect of bicarbonate (NaHCO3) and phosphate (NaH2PO4, Na2HPO4) buffers on monomer leachability of dental resin composites. Evetric was the restorative resin composite that was investigated in current study. Forty disk-shaped resin composite specimens (n?=?40) were immersed by means of a silk string in the following solutions: Distilled water (A), phosphate buffer (B), bicarbonate buffer (C), artificial saliva (D). After seven (7) and fourteen (14) days, the eluates were analyzed by means of High Performance Liquid Chromatography (HPLC). Subsequently, new specimens were fabricated and immersed in fresh solutions in which methanol 12% (v/v) was added. After seven and fourteen days of storage, the leaching of monomers was examined by means of HPLC, which was proved to be an effective tool to buffers demonstrate the inhibiting effect of phosphate and bicarbonate ions on the leaching pattern of dental resin composites. 相似文献
3.
S. G. Giakoumatos I. D. Vrontos P. Dellaportas D. N. Politis 《Journal of computational and graphical statistics》2013,22(3):431-451
Abstract A new diagnostic procedure for assessing convergence of a Markov chain Monte Carlo (MCMC) simulation is proposed. The method is based on the use of subsampling for the construction of confidence regions from asymptotically stationary time series as developed in Politis, Romano, and Wolf. The MCMC subsampling diagnostic is capable of gauging at what point the chain has “forgotten” its starting points, as well as to indicate how many points are needed to estimate the parameters of interest according to the desired accuracy. Simulation examples are also presented showing that the diagnostic performs favorably in interesting cases. 相似文献
4.
5.
Anxiety is a chronic severe psychiatric disorder. Crocins are among the various bioactive components of the plant Crocus sativus L. (Iridaceae) and their implication in anxiety is well-documented. However, which is the mechanism of action underlying the anti-anxiety effects of crocins remains unknown. In this context, it has been suggested that these beneficial effects might be ascribed to the agonistic properties of these bioactive ingredients of saffron on the GABA type A receptor. The current experimentation was undertaken to clarify this issue in the rat. For this research project, the light/dark and the open field tests were used. A single injection of crocins (50 mg/kg, i.p., 60 min before testing) induces an anti-anxiety-like effect revealed either in the light-dark or open field tests. Acute administration of the GABAA-benzodiazepine receptor antagonist flumazenil (10 mg/kg, i.p., 30 min before testing) abolished the above mentioned anxiolytic effects of crocins. The current findings suggest a functional interaction between crocins and the GABAA receptor allosteric modulator flumazenil on anxiety. 相似文献
6.
Petros Drineas Michael W. Mahoney S. Muthukrishnan Tamás Sarlós 《Numerische Mathematik》2011,117(2):219-249
Least squares approximation is a technique to find an approximate solution to a system of linear equations that has no exact
solution. In a typical setting, one lets n be the number of constraints and d be the number of variables, with n >> d{n \gg d}. Then, existing exact methods find a solution vector in O(nd
2) time. We present two randomized algorithms that provide accurate relative-error approximations to the optimal value and
the solution vector of a least squares approximation problem more rapidly than existing exact algorithms. Both of our algorithms
preprocess the data with the Randomized Hadamard transform. One then uniformly randomly samples constraints and solves the
smaller problem on those constraints, and the other performs a sparse random projection and solves the smaller problem on
those projected coordinates. In both cases, solving the smaller problem provides relative-error approximations, and, if n is sufficiently larger than d, the approximate solution can be computed in O(nd ln d) time. 相似文献
7.
Mathematical theory of optimization has found many applications in the area of medicine over the last few decades. Several
data analysis and decision making problems in medicine can be formulated using optimization and data mining techniques. The
significance of the mathematical models is greatly realized in the recent years owing to the growing technological capabilities
and the large amounts of data available. In this paper, we attempt to give a brief overview of some of the most interesting
applications of mathematical programming and data mining in medicine. In the overview, we include applications like radiation
therapy treatment, microarray data analysis, and computational neuroscience. 相似文献
8.
Diego Rossinelli Michael Bergdorf Georges-Henri Cottet Petros Koumoutsakos 《Journal of computational physics》2010,229(9):3316-3333
We present a GPU accelerated solver for simulations of bluff body flows in 2D using a remeshed vortex particle method and the vorticity formulation of the Brinkman penalization technique to enforce boundary conditions. The efficiency of the method relies on fast and accurate particle-grid interpolations on GPUs for the remeshing of the particles and the computation of the field operators. The GPU implementation uses OpenGL so as to perform efficient particle-grid operations and a CUFFT-based solver for the Poisson equation with unbounded boundary conditions. The accuracy and performance of the GPU simulations and their relative advantages/drawbacks over CPU based computations are reported in simulations of flows past an impulsively started circular cylinder from Reynolds numbers between 40 and 9500. The results indicate up to two orders of magnitude speed up of the GPU implementation over the respective CPU implementations. The accuracy of the GPU computations depends on the Re number of the flow. For Re up to 1000 there is little difference between GPU and CPU calculations but this agreement deteriorates (albeit remaining to within 5% in drag calculations) for higher Re numbers as the single precision of the GPU adversely affects the accuracy of the simulations. 相似文献
9.
Alexander A. Kamnev Alexei G. Shchelochkov Petros A. Tarantilis Moschos G. Polissiou Yurii D. Perfiliev 《Monatshefte für Chemie / Chemical Monthly》2001,132(6):675-681
Summary. The iron(III) complex of indole-3-acetic acid (1) was prepared, and its physicochemical properties, mode of iron(III) coordination, and electronic structure were studied
using UV/Vis, diffuse reflectance infrared Fourier transform (DRIFT), and transmission 57Fe M?ssbauer spectroscopic techniques. The data obtained provide evidence that iron(III) is not only coordinated by the carboxylic O-donor
atom, but also via the conjugated π-electronic system of the pyrrole moiety involving both the non-shared electronic pair of the heteroatom
and the C(2)*C(3) double bond. Considering the well-known increased sensitivity of the pyrrole residue in indole derivatives
to oxidation as compared to the benzene ring, as well as the formation of a triple complex (peroxidase-1-O2) proposed for the enzymatic 1 oxidative degradation mechanism involving as a key step the Fe3+ → Fe2+ transition in the enzyme form as discussed in literature, it is concluded that iron(III) coordination with 1 can influence the redox properties of the pyrrole ring by affecting its π-electronic system.
Received September 17, 2000. Accepted (revised) October 31, 2000 相似文献
10.
Christian Conti Diego Rossinelli Petros Koumoutsakos 《Journal of computational physics》2012,231(5):2229-2244
We present GPU and APU accelerated computations of Finite-Time Lyapunov Exponent (FTLE) fields. The calculation of FTLEs is a computationally intensive process, as in order to obtain the sharp ridges associated with the Lagrangian Coherent Structures an extensive resampling of the flow field is required. The computational performance of this resampling is limited by the memory bandwidth of the underlying computer architecture. The present technique harnesses data-parallel execution of many-core architectures and relies on fast and accurate evaluations of moment conserving functions for the mesh to particle interpolations. We demonstrate how the computation of FTLEs can be efficiently performed on a GPU and on an APU through OpenCL and we report over one order of magnitude improvements over multi-threaded executions in FTLE computations of bluff body flows. 相似文献