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41.
42.
Arno van den Essen Peter van Rossum 《Transactions of the American Mathematical Society》2004,356(5):1691-1703
This paper studies coordinates in two variables over a -algebra. It gives several ways to characterize such coordinates. Also, various results about coordinates in two variables that were previously only known for fields, are extended to arbitrary -algebras.
43.
Adsorption isotherms of carbon dioxide were measured on cation-exchanged (Li+, Na+, K+, Cs+) MCM-22 zeolite with the molar ratio of Si/Al=15 and series of Na-MCM-22 of Si/Al molar ratios varying in the range from
15 to 40 at 273, 293, 313 and 333 K. Based on the known temperature dependence of CO2 adsorption, isosteric heats of adsorption were calculated. The obtained dependences of isosteric heats related to the amount
of CO2 adsorbed have provided detailed insight into the interaction of carbon dioxide molecule with alkali metal cations. 相似文献
44.
45.
Dr. Sebastian Huber Prof. Dr. Arno Pfitzner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13683-13688
Li17Sb13S28 was synthesized by solid‐state reaction of stoichiometric amounts of anhydrous Li2S and Sb2S3. The crystal structure of Li17Sb13S28 was determined from dark‐red single crystals at room temperature. The title compound crystallizes in the monoclinic space group C2/m (no. 12) with a=12.765(2) Å, b=11.6195(8) Å, c=9.2564(9) Å, β=119.665(6)°, V=1193.0(2) Å3, and Z=4 (data at 20 °C, lattice constants from powder diffraction). The crystal structure contains one cation site with a mixed occupation by Li and Sb, and one with an antimony split position. Antimony and sulfur form slightly distorted tetragonal bipyramidal [SbS5E] units (E=free electron pair). Six of these units are arranged around a vacancy in the anion substructure. The lone electron pairs E of the antimony(III) cations are arranged around these vacancies. Thus, a variant of the rock salt structure type with ordered vacancies in the anionic substructure results. Impedance spectroscopic measurements of Li17Sb13S28 show a specific conductivity of 2.9×10?9 Ω?1 cm?1 at 323 K and of 7.9×10?6 Ω?1 cm?1 at 563 K, the corresponding activation energy is EA=0.4 eV below 403 K and EA=0.6 eV above. Raman spectra are dominated by the Sb?S stretching modes of the [SbS5] units at 315 and 341 cm?1 at room temperature. Differential thermal analysis (DTA) measurements of Li17Sb13S28 indicate peritectic melting at 854 K. 相似文献
46.
Arno Behr Thomas Beckmann Pierre Schwach 《Journal of organometallic chemistry》2008,693(18):3097-3102
Two different routes to acetoxyoctadiene are presented. The first one uses the well-known telomerisation of butadiene with acetic acid operating in a multiphase semi-batch mode. The second reaction involves the cleavage of acetic anhydride, hydrogen transfer via ketene formation and thus a telomerisation as well. 相似文献
47.
Striped high-T(c) superconductors such as La(2-y-x)Nd(y)Sr(x)CuO(4) and La(2-x)Ba(x)CuO(4) near x = 1/8 show a fascinating competition between spin and charge order and superconductivity. A theory for these systems therefore has to capture both the spin correlations of an antiferromagnet and the pair correlations of a superconductor. For this purpose we present here an effective Hartree-Fock theory incorporating both electron pairing with finite center-of-mass momentum and antiferromagnetism. We show that this theory reproduces the key experimental features such as the formation of the antiferromagnetic stripe patterns at 7/8 band filling or the quasi-one-dimensional electronic structure observed by photoemission spectroscopy. 相似文献
48.
The role of extra-framework and framework aluminium in wet-ion exchanged Fe-ZSM5 has been studied using 29Si NMR and 27Al triple quantum magic angle spinning (3QMAS) NMR. A series of samples were studied, the parent material, the wet ion exchanged Fe-ZSM5 and Fe-ZSM5 that has been used in the decomposition of N2O with varying reaction conditions. Various framework and extra-framework aluminium species have been identified. It was found that cationic Fe species prefer to replace the Brønsted acid protons in their charge balancing role at those aluminium sites associated with the largest quadrupolar product. The framework aluminium atoms that pertain to the smaller quadrupolar product, which are either charge balanced by extra-framework aluminium or a proton, are much less prone to exchange. In the catalytic decomposition of N2O it seemed that water present in small amounts enhances the catalytic activity. However, water also decreases the long term stability and performance by dealuminating the zeolite framework. With a high amount of water present, Fe-ZSM5 was destabilised and catalytically inferior. 相似文献
49.
Arno Pauly 《Mathematical Logic Quarterly》2010,56(5):488-502
Continuous reducibilities are a proven tool in Computable Analysis, and have applications in other fields such as Constructive Mathematics or Reverse Mathematics. We study the order‐theoretic properties of several variants of the two most important definitions, and especially introduce suprema for them. The suprema are shown to commutate with several characteristic numbers (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
50.