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排序方式: 共有138条查询结果,搜索用时 328 毫秒
81.
I Hoffmann M Theile S Grätz J Scholz P Barreleiro W von Rybinski M Gradzielski 《Langmuir : the ACS journal of surfaces and colloids》2012,28(31):11400-11409
In this study, we examined the influence of surfactants on the adsorption of polymers on cotton fibers. The extent of polymer adsorption on cotton was determined directly by means of fluorescence spectroscopy using fluorescently labeled polymers. The investigation of polymer adsorption in the presence of different types of surfactants and for a large range of differently structured polymers allows us to obtain a rather general picture of this important issue. Systematic relationships between the presence of surfactant and the type of polymer can be deduced but cannot be cast in simple terms such as electrostatic interaction but instead depend on the detailed interaction between the surfactant and polymer both in solution and adsorbed on the cotton surface. A particularly complex situation arises for the case of oppositely charged surfactant and polymer because of the possibility of precipitate formation. The study of such complex systems not only is of scientific interest but also is of great commercial interest because both polymers and surfactants are parts of detergent formulations and cotton is one of the most abundantly used materials for fabrics. 相似文献
82.
83.
Olof Heden Juliane Lehmann Esmeralda N?stase Papa Sissokho 《Designs, Codes and Cryptography》2012,64(3):265-274
A subspace partition Π of V?= V(n, q) is a collection of subspaces of V such that each 1-dimensional subspace of V is in exactly one subspace of Π. The size of Π is the number of its subspaces. Let σ q (n, t) denote the minimum size of a subspace partition of V in which the largest subspace has dimension t, and let ρ q (n, t) denote the maximum size of a subspace partition of V in which the smallest subspace has dimension t. In this article, we determine the values of σ q (n, t) and ρ q (n, t) for all positive integers n and t. Furthermore, we prove that if n ≥?2t, then the minimum size of a maximal partial t-spread in V(n +?t ?1, q) is σ q (n, t). 相似文献
84.
Microchip electrophoresis has become a powerful tool for DNA separation, offering all of the advantages typically associated with miniaturized techniques: high speed, high resolution, ease of automation, and great versatility for both routine and research applications. Various substrate materials have been used to produce microchips for DNA separations, including conventional (glass, silicon, and quartz) and alternative (polymers) platforms. In this study, we perform DNA separation in a simple and low-cost polyester-toner (PeT)-based electrophoresis microchip. PeT devices were fabricated by a direct-printing process using a 600 dpi-resolution laser printer. DNA separations were performed on PeT chip with channels filled with polymer solutions (0.5% m/v hydroxyethylcellulose or hydroxypropylcellulose) at electric fields ranging from 100 to 300 V cm(-1). Separation of DNA fragments between 100 and 1000 bp, with good correlation of the size of DNA fragments and mobility, was achieved in this system. Although the mobility increased with increasing electric field, separations showed the same profile regardless of the electric field. The system provided good separation efficiency (215,000 plates per m for the 500 bp fragment) and the separation was completed in 4 min for 1000 bp fragment ladder. The cost of a given chip is approximately $0.15 and it takes less than 10 minutes to prepare a single device. 相似文献
85.
Barbier J Wegner J Benson S Gentzsch J Pietschmann T Kirschning A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(29):9083-9090
The total synthesis of 16 new ion channel inhibitors derived from noricumazole?A, a secondary metabolite from the myxobacterium Sorangium cellulosum, is reported. Particular focus of library design is put on stereochemical permutations in the central region (C9 and C11), the oxazole moiety and the side chain at C4 of the isochromanone moiety. Noricumazole?A and all new noricumazole derivatives were tested in an assay system with inhibitory effect on the hepatitis?C virus (HCV) life cycle. Most of them are moderate to strong HCV inhibitors (350?nM-6?nM) but also exert pronounced cytotoxicity. In contrast, the thiazole analogue of noricumazole?A is a strong HCV inhibitor with only moderate cytotoxic property. It may become a lead structure with a good therapeutic index (CC(50)/IC(50)) of greater than 10. 相似文献
86.
We report the synthesis and biophysical characterization of a novel class of zwitterionic lipids (ZL) with head groups containing a 3° or 4° amine and carboxylate. ZL form stable liposomes that exhibit head group dependent, pH-responsive biophysical characteristics. These lipids may be suitable components for drug delivery applications due to their ease of synthesis and unique pH-dependent properties. 相似文献
87.
M de Torres J Dimroth IW Arends J Keilitz F Hollmann 《Molecules (Basel, Switzerland)》2012,17(8):9835-9841
Rh(III)-TsDPEN, an immobilized analog of the well-known [Cp*Rh(bpy)(H2O)]2+ was evaluated as a heterogeneous, recyclable regeneration catalyst for reduced oxidoreductase cofactors [NAD(P)H]. Repeated use of this catalyst was established and the catalytic properties were initially investigated. Apparently, Rh(III)-TsDPEN is prone to severe diffusion limitations, necessitating further developments. Overall, a promising concept for chemoenzymatic redox catalysis is proposed, which may overcome some of the current limitations such as catalyst cost and incompatibility of Rh with some biocatalysts. 相似文献
88.
89.
Mixture surrogate models based on Dempster-Shafer theory for global optimization problems 总被引:2,自引:0,他引:2
Recent research in algorithms for solving global optimization problems using response surface methodology has shown that it
is in general not possible to use one surrogate model for solving different kinds of problems. In this paper the approach
of applying Dempster-Shafer theory to surrogate model selection and their combination is described. Various conflict redistribution
rules have been examined with respect to their influence on the results. Furthermore, the implications of the surrogate model
type, i.e. using combined, single or a hybrid of both, have been studied. The suggested algorithms were applied to several
well-known global optimization test problems. The results indicate that the used approach leads for all problems to a thorough
exploration of the variable domain, i.e. the vicinities of global optima could be detected, and that the global minima could
in most cases be approximated with high accuracy. 相似文献
90.