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51.
52.
The mechanism of silicon epitaxy on porous Si(111) layers is investigated by the Monte Carlo method. The Gilmer model of adatom
diffusion extended to the case of arbitrary surface morphology is used. Vacancies and pendants of atoms are allowed in the
generalized model, the activation energy of a diffusion hop depends on the state of the neighboring positions in the first
and second coordination spheres, and neighbors located outside the growing elementary layer are also taken into account. It
is shown that in this model epitaxy occurs by the formation of metastable nucleation centers at the edges of pores, followed
by growth of the nucleation centers along the perimeter and the formation of a thin, continuous pendant layer. Three-dimensional
images of surface layers at different stages of epitaxy were obtained. The dependence of the kinetics of the epitaxy process
on the amount of deposited silicon is determined for different substrate porosities.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 512–517 (10 April 1998) 相似文献
53.
54.
Dragan DJURCIC Aleksandar TORGASEV 《数学学报(英文版)》2006,22(3):689-692
In this paper, we prove some properties of the Seneta sequences and functions, and in particular we prove a representation theorem in the Karamata sense for the sequences from the Seneta class SOc. 相似文献
55.
56.
The stoichiometric reactions of trimethylaluminum with 2,6‐(MeOCH2)2C6H3OH (LH) revealed compounds L3Al ( 1 ) and L2AlMe ( 2 ). On the other hand reaction of 1 equiv. of LH with trimethylaluminum did not lead to the formation of complex LAlMe2 ( 3 ), rather 2 together with Me3Al were observed as a result of a disproportionation of 3 . Compounds 1 and 2 were characterized by elemental analysis, 1H and 13C NMR spectroscopy and in the case of 1 by X‐ray diffraction. Derivative 2 underwent transmetalation with Ph3SnOH, giving LSnPh3 ( 4 ) as the result of a migration of ligand L from the aluminum to the tin atom. The identity of 4 was established by elemental analysis, 1H, 13C and 119Sn NMR spectroscopy and 1H, 119Sn HMBC experiments. The system 2 and B(C6F5)3 in a 1:1 molar ratio was shown to be active in the polymerization of propylene oxide and ε‐caprolactone. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
57.
S. L. Grigor’ev 《Technical Physics》2002,47(2):156-159
Inversion in the structure of polyaminoacids and proteins is discussed, and the electrodynamic quantum-optical model of a neuron is constructed. The feasibility of the quantum-logical summation of exciting pulses by a nanomembrane is considered. The model is consistent with the physiology foundations and assumes implementation by means of techniques used in microelectronics, integrated optics, and nanooptics. 相似文献
58.
T. V. Esipova A. A. Borisenko P. B. Terent’ev G. V. Grishina R. Herzshuh 《Russian Journal of Organic Chemistry》2006,42(5):742-747
A new class of endocyclic enamines, 1,6-disubstituted 1,2,3,4,5,6,7,8-octahydro-1,6-naphthiridines, was synthesized from 4-piperidone imines by successive subjecting the latter to lithiation with lithium diethylamide, to alkylation with 1-bromo-3-chloropropane, and to intramolecular cyclization. All stages were carried out as a unique process without isolation of the intermediate compounds. A thorough optimization of the process conditions, workup, and product storage was carried out. The conformational study of 1,6-disubstituted 1,2,3,4,5,6,7,8-octahydro-1,6-naphthiridines was performed. 相似文献
59.
Monoclinic (N2H6)3Zr2F13·F crystallizes in space group P21-C
2
2
(No. 4) with unit cell dimensionsa=5.670(1),b=10.984(2),c=10.601(2) Å,=93.88(1)°,V=658.7(4) Å3 andZ=2. Two different types of N2H6
2+ ions are present. One is involved in strong H-bonds to F– ions in infinite chains running along the a axis (the shortest N-F distance is 2.437(5) Å), and the other links the structure through weaker bi- and trifurcated H-bonds to fluorine ligands of the Zr2F13
5– ions. The N-N bond lengths range from 1.430(5) to 1.446(5) Å with apparently no meaningful correlation to the type of N2H2
2+ ions. The Zr2F13
5– ions have very nearly C2 point symmetry and are formed by joining two distorted bicapped trigonal prisms of ZrF8-units through a common face. Distances of Zr-F terminal bonds range from 2.015(2) to 2.112(2) Å and of bridging bonds from 2.133(2) to 2.212(2) Å. (N2H6)3Hf2F13·F is isomorphous. The vibrational spectra of the two compounds are nearly identical, with the exception of a strong infrared band, which is assigned to a stretching mode with the moving central atom within the anion. The anion part of the spectrum is simple, showing broad unresolved bands. The cation part shows two types of N2H6
– ions. H-Bonding is strongly present in the spectra, but no simple correlations with the H-bond strength is evident. 相似文献
60.
Alkynyl-substituted indene was first used as a ligand for the synthesis of transition metal complexes. ansa-Zirconocenes containing ethylene and dimethylsilylene bridges were synthesized starting from 2-(phenylethynyl)-1H-indene. The structure of the former compound was established by X-ray diffraction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 68–73, January, 2007. 相似文献