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101.
An electrothermal atomic absorption (ETAAS) method for the determination of traces of iron (0.1-1.0 microgram g-1) in Fe-doped indium phosphide (InP) has been developed. In order to overcome the indium matrix-effect and to achieve a useful detection limit, a preliminary solvent-extraction of Fe(III) with acetylacetone (HAA) is necessary. After sample dissolution with hydrochloric acid (1 + 1) the digest is evaporated to dryness, Fe(II) is oxidized to Fe(III) with nitric acid, the residue is dissolved in 0.01 mol L-1 HCl and the iron is extracted at pH 2.0 with 0.5 mol L-1 HAA in toluene. The organic phase is injected into the graphite furnace and the iron is directly evaluated by external organic standard calibration. The limit of detection (3SB) resulting from further in-situ preconcentration is 0.03 microgram g-1. When the method was applied to the analysis of real samples containing 0.2-0.7 microgram g-1 Fe, the RSD was in the range 8-21%. Results were compared with those independently obtained on the decomposed sample solution with inductively coupled atomic emission spectrometry (ICP-AES). The detection limit of the ICP-AES method, that needs matrix-matched standards, is 0.20 microgram g-1. 相似文献
102.
103.
Marina S. Fonari Yurii A. Simonov Victor Ch. Kravtsov Janusz Lipkowski Gabriele Bocelli Edward V. Ganin Vladimir O. Gelmboldt 《Journal of chemical crystallography》1999,29(12):1245-1254
Synthesis and single-crystal X-ray structures are recorded for three adducts of SbF3 with different azacrown ethers. [SbF3·H2O·L1], 1, (L1 = 12,13-benz-1,10-di(azamethyl)-4,7-dioxacyclotetradecane-1,14-dione), triclinic,
, a = 11.234(2), b = 11.691(2), c = 8.869(2) Å, = 94.66(3), = 113.12(3), = 67.82(3)°, Z = 2. [SbF3Cl·H2O·(HL2)], 2, (L2 = monoaza-18-crown-6), orthorhombic, P212121, a = 8.763(2), b = 13.003(3), a = 16.836(3) Å, Z = 4. [(SbF3)2Cl2·(H2L3)], 3, (L3 = 1,10-diaza-18-crown-6), triclinic,
, a = 8.284(2), b = 9.016(2), c = 9.134(2) Å, = 82.92(3), = 65.24(3), = 63.38(3)°, Z = 1. All three structures include SbF3 neutral molecules in the pyramidal mode and the antimony second coordination sphere is completed up to six in different fashions. In 1 the dimeric (SbF3)2 adducts are made up due to the involvement of the symmetry-related fluorine atom in coordination. The distorted octahedron is then completed by water molecule and carbonyl oxygen of L1. The neutral molecules are joined by coordination and hydrogen bonds in the infinite ribbons. 2 and 3 are both comprised of neutral and charged species also bounded via coordination and hydrogen bonds. L2 and L3 in the complexes adopt the form of single and double-charged cations, respectively. The inorganic backbone unites the neutral SbF3 molecules and chloride anions in the alternative mode. The sixth coordination site in the antimony polyhedron is completed by the water molecule in 2 and the ethereal oxygen atom in 3. Alignment of the inorganic entities within the structures of 2 and 3 is strikingly similar. Hydrogen bonding patterns are discussed. 相似文献
104.
M. Costa G. P. Chiusoli R. Gaetti B. Gabriele G. Salerno 《Russian Chemical Bulletin》1998,47(5):936-940
New rhodium-catalyzed amination reactions of arylacetylenes and cyclohexen-1-ylacetylene in the presence of strong bases with
the use of carbon dioxide as an auxiliary are described. Secondary amines attack the terminal carbon atom of the triple bond
followed by protonation of the adjacent carbon atom. Alternatively, the reaction can proceed further with the addition of
the second alkyne molecule. The conditions for the selective synthesis of enamines (up to 87% yield) or α-substituted propynylamines
(up to 86% yield) are reported.
Dipartimento di Chimica Organica e Industriale dell'Università, Viale delle Scienze, I-43100 Parma, Italia.
Dipartimento di Chimica, Università della Calabria, Arcavacata di Rende, I-80036 Cosenza, Italia.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 966–970, May, 1998. 相似文献
105.
106.
107.
Gabriele Korchmáros 《Annali di Matematica Pura ed Applicata》1978,116(1):189-205
Summary The purpose of the present paper is to prove the following theorem: Let Ω be an oval in the projective plane P of odd order
n. If P admits a collineation group G wich maps Ω onto itself and is doubly transitive on Ω, then P is desarguesian, Ω is
a conic and G contains all collineations in the little projective group PSL(2, n) of P wich leaves Ω invariant.
Entrata in Redazione il 5 april 1977. 相似文献
Entrata in Redazione il 5 april 1977. 相似文献
108.
Köhn RD Pan Z Haufe M Kociok-Köhn G 《Dalton transactions (Cambridge, England : 2003)》2005,(16):2793-2797
As the first 1st-row transition metal complexes having six tertiary amine donor groups, bis(triazacyclohexane) sandwich complexes [L2M](BF4)2 (L = benzyl- or p-fluorobenzyl-triazacyclohexane, M = Cu or Zn) have been obtained by the protonolysis of Et2Zn in the presence of L or by reaction of [Cu(MeCN)4](BF4) with L in CH2Cl2 and subsequent air oxidation via an unprecedented Cu(I)(2) sandwich complex containing a short Cu-Cu contact. 相似文献
109.
110.
Gabriele Tamborini 《Mikrochimica acta》2004,145(1-4):237-242
In the framework of the projects Environmental Sampling and High Performance Trace Analysis in support to the International Atomic Energy Agency (IAEA) and the Euratom Safeguards Office (ESO), the research has been focused on the identification and characterisation of particles of interest containing mainly U and other actinides.Multiple analyses, elemental and isotopic, of single radioactive particles in the µm-size range are key-tools in environmental research and in nuclear forensics. The main purpose in the analysis of single particles by SIMS is the determination of their isotopic composition that has been demonstrated successfully for uranium and plutonium particles. From these results, the enrichment of the material produced, the process used for the enrichment as well as the starting material employed (natural or reprocessed uranium) can be identified. 相似文献