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531.
Maxim A. Shmelev Ruslan A. Polunin Natalia V. Gogoleva Igor S. Evstifeev Pavel N. Vasilyev Alexey A. Dmitriev Evgenia A. Varaksina Nikolay N. Efimov Ilya V. Taydakov Aleksey A. Sidorov Mikhail A. Kiskin Nina P. Gritsan Sergey V. Kolotilov Igor L. Eremenko 《Molecules (Basel, Switzerland)》2021,26(14)
A series of heterometallic carboxylate 1D polymers of the general formula [LnIIICd2(piv)7(H2O)2]n·nMeCN (LnIII = Sm (1), Eu (2), Tb (3), Dy (4), Ho (5), Er (6), Yb (7); piv = anion of trimethylacetic acid) was synthesized and structurally characterized. The use of CdII instead of ZnII under similar synthetic conditions resulted in the formation of 1D polymers, in contrast to molecular trinuclear complexes with LnIIIZn2 cores. All complexes 1–7 are isostructural. The luminescent emission and excitation spectra for 2–4 have been studied, the luminescence decay kinetics for 2 and 3 was measured. Magnetic properties of the complexes 3–5 and 7 have been studied; 4 and 7 exhibited the properties of field-induced single-molecule magnets in an applied external magnetic field. Magnetic properties of 4 and 7 were modelled using results of SA-CASSCF/SO-RASSI calculations and SINGLE_ANISO procedure. Based on the analysis of the magnetization relaxation and the results of ab initio calculations, it was found that relaxation in 4 predominantly occurred by the sum of the Raman and QTM mechanisms, and by the sum of the direct and Raman mechanisms in the case of 7. 相似文献
532.
McCullough DH Grygorash R Regen SL 《Langmuir : the ACS journal of surfaces and colloids》2007,23(19):9606-9610
Langmuir-Blodgett deposition of a single monolayer of 1,2,4,5-tetrakis[(N-(perfluoroundecanoamidoethyl)-N,N-dimethylammonium)methyl]benzene tetrabromide (1) onto a thin film made from alternating layers of poly(diallydimethylammonium chloride) (PDADMA) and poly(4-styrenesulfonate) (PSS) ions affords a uniform fluorinated surface of low energy. An analogous surface that has been constructed by self-assembly shows the same critical surface tension of 16.5 dyn/cm. A comparison of Zisman plots for these two modified films, in combination with analysis by X-ray photoelectron spectroscopy, indicates that Langmuir-Blodgett deposition produces a higher quality and more densely packed fluorocarbon surface that is very hydrophobic. In sharp contrast, the use of a single-chain analog (i.e., N-(perfluoroundecanoamidoethyl)-N,N,N-trimethylammonium bromide) (2)) affords relatively high energy surfaces by Langmuir-Blodgett deposition and by self-assembly. 相似文献
533.
S. M. Zhuk 《Nonlinear Oscillations》2007,10(4)
For a linear operator generated by the differential equation
we prove that its graph is closed and determine the adjoint operator . For elements of the linear manifolds and , we propose an analog of the formula of integration by parts. We establish a criterion for the existence of a pseudosolution
of the operator equation and formulate sufficient conditions for the normal solvability of the operator in terms of relations for blocks of the matrix C(t). The results obtained are illustrated by examples.
__________
Translated from Neliniini Kolyvannya, Vol. 10, No. 4, pp. 464–480, October–December, 2007. 相似文献
534.
Kashapov RR Pashirova TN Kharlamov SV Ziganshina AY Ziltsova EP Lukashenko SS Zakharova LY Habicher WD Latypov SK Konovalov AI 《Physical chemistry chemical physics : PCCP》2011,13(35):15891-15898
Mixed association of calix[4]resorcinarene with ethyl sulfonate groups on the lower rim and dimethylaminomethyl groups on the upper rim (CR) and cationic surfactant 4-aza-1-hexadecyl-azoniabicyclo[2.2.2]octane bromide (DABCO-16) is studied by methods of tensiometry, conductometry, potentiometry and NMR spectroscopy at fixed CR concentration and varied surfactant concentration. Beyond ca. 0.4 mM of DABCO-16, mixed aggregates enriched by CR are proved to be formed due to electrostatic forces, while beyond ca. 5 mM, aggregates enriched by surfactant occur due to the hydrophobic effect. Spectrophotometry monitoring of the solubilization of a hydrophobic dye, Orange OT, demonstrated that only the second type of mixed aggregate enriched by DABCO-16 is capable of binding the organic probe, while the mixed system where the surfactant is a minor component shows no binding capacity towards Orange OT. This finding can be used for the design of nanocontainers with controllable binding/release properties. 相似文献
535.
The formulation for the coupled electromechanical problem of forced vibration of a simply supported inelastic sandwich beam with piezoelectric layers is developed. An approximate formulation for the problem in terms of the amplitudes of the main electromechanical field variables is produced by applying the monoharmonic (single-frequency) approach along with the concept of complex moduli to characterize the cyclic properties of the material. Accuracy of the developed monoharmonic approach is estimated. It is achieved through the comparison of the results computed for the transient response of the beam using the complete model with those found using the approximate model. Limitations on the approximate monoharmonic method application are specified. The effect of physically nonlinear behaviour of the passive layer on the beam response is investigated. The possibility of damping the forced vibrations of a structure with the help of harmonic voltages applied to the external piezoactive layers is also discussed. 相似文献
536.
Ivan L. Volkov Ruslan R. Ramazanov Dr. Evgeniy V. Ubyivovk Valerij I. Rolich Dr. Alexei I. Kononov Prof. Dr. Nina A. Kasyanenko 《Chemphyschem》2013,14(15):3543-3550
We study the formation and fluorescent properties of silver nanoclusters encapsulated in condensed DNA nanoparticles. Fluorescent globular DNA nanoparticles are formed using a dsDNA–cluster complex and polyallylamine as condensing agents. The fluorescence emission spectrum of single DNA nanoparticles is obtained using tip‐enhanced fluorescence microscopy. Fluorescent clusters in condensed DNA nanoparticles appear to be more protected against destructive damage in solution compared to clusters synthesized on a linear polymer chain. The fluorescent clusters on both dsDNA and ssDNA exhibit the same emission bands (at 590 and 680 nm) and the same formation efficiency, which suggests the same binding sites. By using density functional theory, we show that the clusters may bind to the Watson–Crick guanine–cytosine base pairs and to single DNA bases with about the same affinity. 相似文献
537.
Kev M. Salikhov Aydar Ye. Mambetov Marcel M. Bakirov Iskander T. Khairuzhdinov Ravil T. Galeev Ruslan B. Zaripov Barney L. Bales 《Applied magnetic resonance》2014,45(9):911-940
Kinetic equations for the spin density matrix which take into account binary collisions and a method of calculating the spin exchange effective radius have been generalized to the case of dilute solutions of charged paramagnetic particles. The effective radius of the spin exchange and rate constant of the bimolecular spin exchange between charged paramagnetic particles in solutions have been calculated numerically. Calculations have been performed under the assumption that the exchange interaction is isotropic and decays exponentially with the increase in the distance between radicals, and the solution has a given dielectric permittivity and Debye screening radius. Dependences of the spin exchange rate constant on the mutual diffusion coefficient, exchange and electrostatic interactions parameters have been found numerically. The theory has been applied to experimental results taken from the literature. The rate constant of the spin exchange between radicals of like charge found from the experiment and calculated within the developed theory are in good qualitative agreement . 相似文献
538.
The compound Fe[N(SiMe 3) 2] 2 is shown to be a useful precursor to dinuclear and trinuclear iron-sulfur-silylamido complexes by reaction with thiols or thiols and sulfur in tetrahydrofuran (THF) or toluene. Reaction with 1 equiv of p-tolylthiol affords [Fe 2(mu 2-S- p-tol) 2(N(SiMe 3) 2) 2(THF) 2] ( 1); with 0.5 equiv of adamantane-1-thiol, [Fe 2(mu 2-S-1-Ad)(mu 2-N(SiMe 3) 2)(N(SiMe 3) 2) 2] ( 2) is formed. The clusters [Fe 3(mu 3-Q)(mu 2-SR) 3(N(SiMe 3) 2) 3] are available by three methods: (i) self-assembly in the systems Fe[N(SiMe 3) 2] 2/RSH/S or Se [Q = S, R = p-tol ( 3) and 1-Ad ( 5)]; (ii) reaction of 1 with Q = S or Se to yield 3 or [Fe 3Se(S- p-tol) 3(N(SiMe 3) 2) 3] ( 4); (iii) reaction of 2 with 1-AdSH and S to give 5. Structures of 1- 5 are presented. Complexes 1 and 2 contain planar Fe 2S 2 and Fe 2SN rhombs. Clusters 3- 5 contain a mixed-valence Fe 3Q(SR) 3 core with trigonal (cuboidal) geometry. Of known iron-sulfur clusters, these most closely resemble previously reported [Fe 3S(S-R-S) 3] (2-) stabilized by bidentate thiolate ligands. Complexes 1- 5, together with a small set of recently described clusters of nuclearities 2, 4, and 8, constitute a new class of iron-sulfur-silylamido clusters. Complexes 3- 5 constitute a new structure type of mixed-valence iron-sulfur clusters. 相似文献
539.
Magnetic susceptibility of the Bi2BaCu x Nb2?x O9?δ solid solutions (0.01 < x < 0.20) with the layered perovskite-like structure was studied. In dilute solid solutions, copper atoms are in the form of Cu(II) monomers. As the concentration increases, the fraction of monomers decreases and the fraction of exchange-bonded aggregates (dimers) of Cu(II) with antiferromagnetic exchange increases. The antiferromagnetic exchange parameter in the copper dimers was estimated at ?300 cm?1. 相似文献
540.
Expanded bodipy dyes: anion sensing using a bodipy analog with an additional difluoroboron bridge 总被引:1,自引:0,他引:1
Oxalyl-tethered pyrroles can be doubly bridged with two difluoroboron chelating units to yield bright orange dyes. Interestingly, in polar organic solvents, the addition of fluoride and cyanide result in reversible detachment of the otherwise stable difluoroboron bridges, resulting in sharp changes in color. Thus, this novel compound behaves as a highly selective chromogenic sensor for fluoride and cyanide ions. 相似文献