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121.
Dr. Gerhard Banik Herbert Stachelberger Alfred Vendl Robert Kellner Manfred Grasserbauer 《Mikrochimica acta》1981,76(1-2):93-109
Summary The fundamental importance of scientific research for the preservation and restoration of works of art is uncontestable. The methods described in this paper, such as light microscopy, microchemical tests, emission spectroscopy, chromatography, scanning electron analysis, electron microprobe analysis and infrared spectroscopy, are of special significance in this filed. Nevertheless a better understanding of the problems that arise out of new special questions of art history can be obtained only by the right interpretation of the data obtained by scientific methods.
Mikrochemische Charakterisierung von Gemälden
Zusammenfassung Die grundlegende Bedeutung wissenschaftlicher Forschung für die Erhaltung und Restaurierung von Kunstwerken ist unbestritten. Die hier beschriebenen Methoden (Lichtmikroskopie, mikrochemische Reaktionen, Emissionsspektroskopie, Chromatographie, Rasterelektronen-Analyse und Infrarotspektroskopie) sind hierfür von zunehmender Bedeutung. Sie ermöglichen ein besseres Verständnis neuerer kunsthistorischer Probleme nur durch die richtige Interpretation der Ergebnisse wissenschaftlicher Methoden.相似文献
122.
Summary The acid-catalysed decarboxylation of thecis-- andcis--[CoL(CO3)]+ complexes (L = 3,6-dimethyl-1,8-diamino-3,6-diazaoctane) have been studied over a range of HClO4 concentrations and the temperatures 25, 35 and 45° at I = 1.0 mol dm–3 (NaClO4). The rate expression takes the form kobs = k0 + k1[H+] where kobs is the observed first order rate constant at constant hydrogen ion concentration. The k0 term makes only a minor contribution to the overall reaction. Both complexes display solvent deuterium isotope effects ofca. 2.6 for the acid-catalysed decarboxylation, consistent with a rapid proton pre-equilibrium mechanism. Activation parameters have been determined and the mechanism of the reaction discussed. The magnitude of the solvent isotope effect is consistent with an A-1 type mechanism involving formation of a 5-coordinate intermediate. 相似文献
123.
Jim Bashkin Clive E. Briant D. Michael P. Mingos Robert W. M. Wardle 《Transition Metal Chemistry》1985,10(3):113-114
Summary [(Ph3P)AuCo(CO)3(PPh3)] has been synthesised from [(Ph3P)AuCo(CO)4], PPh3v and Me3NO in acetonitrile. Its molecular structure, determined by single-crystal x-ray crystallography, consists of an almost linear
P-Au-Co-P arrangement in which the Co atom is in a slightly distorted trigonalbipyramidal geometry, with the Au and P atoms
occupying the apical sites. The Au-Co bond length of 2.450(1) ? is shorter than that reported for [(Ph3P)AuCo(CO)4]. The carbonyl ligands are bent towards the Au atom and the mean Au-Co-C angle is 81(1)°. 相似文献
124.
125.
Robert F. Tichy 《Rendiconti del Circolo Matematico di Palermo》1987,36(2):332-342
LetX be a compact metric space, le μ be a non-negative normalized Borel measure onX and letf be a measurable bounded real-valued function defined onX such thatf is μ-almost everywhere continuous and different from zero. It is proved that a sequence (x n ),n=1,2, … of points inX is μ-uniformly distributed if and only if for every Borel setE?X with μ(Bd(E))=0 we have \(\mathop {\lim }\limits_{N \to \infty } \frac{1}{N}\sum\limits_{n = 1}^N {f(x_n )} 1_E (x_n ) = \int\limits_E {f(x)d\mu (x)} ,\) where 1 E denotes the characteristic function ofE andbdE the boundary ofE. Furthermore some quantitative aspects and generalizations of this theorem are discussed. 相似文献
126.
Robert A. Leacock 《Foundations of Physics》1987,17(8):799-807
The quantum harmonic oscillator is described in terms of two basic sets of coordinates: linear coordinates x, px and angular coordinates ei, P (action-angle variables). The angular coordinate ei is assumed unitary, the conjugate momentum p is assumed Hermitian, and ei and p are assumed to be a canonical pair. Two transformations are defined connecting the angular coordinates to the linear coordinates. It is found that x, px can be physical, i.e., Hermitian and canonical, only under constraints on the p eigenvalue spectrum. The conclusion is that ei can be a unitary operator. A parallel analysis of the classical harmonic oscillator is done with equivalent results. 相似文献
127.
Blaylock GT Bolton T Brown JS Bunnell KO Burnett TH Cassell RE Coffman D Cook V Coward DH Dorfan DE Dubois GP Eigen G Eisenstein BI Freese T Gladding G Grab C Heusch CA Hitlin DG Izen JM Köpke L Li A Lockman WS Mallik U Matthews CG Mir R Mockett PM Mozley RF Nemati B Odian A Parker J Parrish L Partridge R Pitman D Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A Simopoulos C Stockdale IE Stockhausen W Thaler JJ Toki W Tripsas B Villa F Wasserbaech S Wattenberg A Weinstein AJ 《Physical review letters》1987,58(21):2171-2174
128.
129.
Robert Kosler 《Numerische Mathematik》1986,50(1):45-55
Summary Operator equationsTu=f are approximated by Galerkin's method, whereT is a monotone operator in the sense of Browder and Minty, so that existence results are available in a reflexive Banach spaceX. In a normed spaceY error estimates are established, which require a priori bounds for the discrete solutionsu
h in the norm of a suitable space
. Sufficient conditions for the uniform boundedness u
h
Z
=O(1) ash0 are proved. Well-known error estimates in [3] for the special caseX=Y=Z are generalized by this. The theory is applied to quasilinear elliptic boundary value problems of order 2m in a bounded domain
. The approximating subspaces are finite element spaces. Especially the caseX=W
0
m, p
(), 1<p<,Y=W
0
m. 2
(),Z=W
0
m. max (2,p)
()Wm, () is treated. Some examples for 1<p<2 are considered. Forp2 a refined technique is introduced in the author's paper [7]. 相似文献
130.
J Robert Huber 《Chemphyschem》2004,5(11):1663-1669
This Minireview gives an account of the photochemical decay of nitric acid HNO3 in the gas phase, which has been well investigated under bulk and molecular-beam conditions. Due to the importance of this molecule in atmospheric chemistry, attention was paid to the irradiation regions around 300 and 200 nm, where solar photolysis of HNO3 is expected to be particularly efficient. While the low-energy region is characterized by the products OH and NO2, the high-energy region gives rise to a variety of photochemical decay pathways, dominated by channels which lead to the products HONO + O in different electronic states. 相似文献