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1.
In this paper we characterize the local maxima of a continuous global optimization formulation for finding the independence
number of a graph. Classical Karush-Kuhn-Tucker conditions and simple combinatorial arguments are found sufficient to deduce
several interesting properties of the local and global maxima. These properties can be utilized in developing new approaches
to the maximum independent set problem. 相似文献
2.
The conformational equilibrium of -(aminoethyl)pyridines has been studied by molecular-mechanics using the geometry optimization. It has been determined that the equilibrium is characterized by the nearly statistical distribution of the ap- and sc-conformers about the
bond. Substitution of the dimethylamino-group for the amino-group results in a slight shift of the equilibrium toward the ap-rotamers. The global minimum in -(ammoniumethyl)pyridines corresponds to the conformation with the +sc-orientation about the central C-C bond and the -sc-orientation (in the case of the dimethylammonium derivatives) about the
bond. In the latter conformation, the
bond of the ammonium group is oriented toward the pyridine cycle. For charged compounds, the regular orthogonal conformation of the aromatic-ring plate is distorted (the vicinal C-C bond becomes eclipsed).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1833–1840, August, 1991.The authors are grateful to P. P. Shagidullin and A. Kh. Plyamovatyi for their interest in this work and for fruitful discussions. 相似文献
3.
I. A. Litvinov O. N. Kataeva V. E. Kataev O. Yu. Butenko 《Russian Chemical Bulletin》1991,40(8):1607-1609
It was established by x-ray crystallographic analysis that the molecular o-nitrobenzyltriethylammonium cation has an orthogonal orientation of the benzene ring and the vicinal C-N+ bond (=93.8°). The nitro group deviates from the plane of the aromatic ring by an angle of 26.9°. One of the ethyl groups at the quaternary nitrogen atom is in an ap-conformation (=176.2°); the other two are in sc-conformations, characterized by torsional angles 65.1 and 69.4°.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1816–1818, August, 1991. 相似文献
4.
Russian Journal of General Chemistry - The electrochemical properties of photochromic compounds from the classes of diarylethenes, fulgides, quinones, spiropyrans, and dihydropyrenes exhibiting... 相似文献
5.
Filatov G. A. Slivin A. Syresin E. M. Butenko A. V. Chesnov A. F. Parfilo T. Tuzikov A. V. 《Physics of Particles and Nuclei Letters》2020,17(4):434-437
Physics of Particles and Nuclei Letters - A new accelerator complex with new beam lines for applied research is being constructed at the Joint Institute for Nuclear Research (Dubna, Russia) as part... 相似文献
6.
I. Shlimak D.I. Golosov A. Butenko K.‐J. Friedland S.V. Kravchenko 《Annalen der Physik》2009,18(12):913-917
We report measurements on a Si‐MOSFET sample with a slot in the upper gate, allowing for different electron densities n1,2 across the slot. The dynamic longitudinal resistance was measured by the standard lock‐in technique, while maintaining a large DC current through the source‐drain channel. We find that the conductance of the sample in a strong parallel magnetic field is asymmetric with respect to the DC current direction. This asymmetry increases with magnetic field. The results are interpreted in terms of electron spin accumulation or depletion near the slot. 相似文献
7.
It was shown that the catalytic system MoCl5/SiO2-SnMe4 has almost 100% regioselectivity with respect to olefins. The stereoselectivity of the system is not a function of the length of the -olefin chain, temperature, or addition of functional groups (COOEt, Cl). Addition of pentachlorophenoxy and 8-hydroxyquinolyl ligands significantly reduces the activity of the catalytic system with a slight increase in the stereoselectivity with respect to the cis-isomer.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 168–171, January, 1990. 相似文献
8.
Austin Buchanan Jose L. Walteros Sergiy Butenko Panos M. Pardalos 《Optimization Letters》2014,8(5):1611-1617
We describe an algorithm for the maximum clique problem that is parameterized by the graph’s degeneracy \(d\) . The algorithm runs in \(O\left( nm+n T_d \right) \) time, where \(T_d\) is the time to solve the maximum clique problem in an arbitrary graph on \(d\) vertices. The best bound as of now is \(T_d=O(2^{d/4})\) by Robson. This shows that the maximum clique problem is solvable in \(O(nm)\) time in graphs for which \(d \le 4 \log _2 m + O(1)\) . The analysis of the algorithm’s runtime is simple; the algorithm is easy to implement when given a subroutine for solving maximum clique in small graphs; it is easy to parallelize. In the case of Bianconi-Marsili power-law random graphs, it runs in \(2^{O(\sqrt{n})}\) time with high probability. We extend the approach for a graph invariant based on common neighbors, generating a second algorithm that has a smaller exponent at the cost of a larger polynomial factor. 相似文献
9.
Austin Buchanan Je Sang Sung Vladimir Boginski Sergiy Butenko 《European Journal of Operational Research》2014
A connected dominating set (CDS) is commonly used to model a virtual backbone of a wireless network. To bound the distance that information must travel through the network, we explicitly restrict the diameter of a CDS to be no more than s leading to the concept of a dominating s-club. We prove that for any fixed positive integer s it is NP-complete to determine if a graph has a dominating s -club, even when the graph has diameter s+1. As a special case it is NP-complete to determine if a graph of diameter two has a dominating clique. We then propose a compact integer programming formulation for the related minimization problem, enhance the approach with variable fixing rules and valid inequalities, and present computational results. 相似文献
10.
Increasing interest in studying community structures, or clusters in complex networks arising in various applications has led to a large and diverse body of literature introducing numerous graph-theoretic models relaxing certain characteristics of the classical clique concept. This paper analyzes the elementary clique-defining properties implicitly exploited in the available clique relaxation models and proposes a taxonomic framework that not only allows to classify the existing models in a systematic fashion, but also yields new clique relaxations of potential practical interest. Some basic structural properties of several of the considered models are identified that may facilitate the choice of methods for solving the corresponding optimization problems. In addition, bounds describing the cohesiveness properties of different clique relaxation structures are established, and practical implications of choosing one model over another are discussed. 相似文献