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151.
The reaction of the tetramethylcyclopentadiene-silyl substituted derivative C5Me4(SiMe3)(SiMe2Cl) with MCl4 afforded the trichloro mono-tetramethylcyclopentadienyl complexes M(η5-C5Me4SiMe2Cl)Cl3 [M=Ti (1), Zr (2)] with selective elimination of SiMe3Cl. Compound 1 reacts with deoxygenated water in methylene chloride, with the evolution of HCl, to give the dinuclear titanium compound {Ti[μ-(η5-C5Me4SiMe2O-κO)]Cl2}2 (3), which was converted into the μ-oxo complex {Ti[μ-(η5-C5Me4SiMe2O-κO)]Cl}2(μ-O) (4) by a further hydrolysis reaction which occurred when a solution of 3 in toluene was refluxed for a long period of time in the air. Depending on the size of the alkyl ligand, reactions of the mononuclear compound 1 with an appropriate alkylating reagent rendered the peralkylated Ti(η5-C5Me4SiMe2R)R3 [R=Me (5), CH2Ph (6)] or partially alkylated {Ti[(η5-C5Me4SiMe2(CH2SiMe3)]Cl(CH2SiMe3)2} (7) compounds by a salt metathesis route. Attempts to synthesise a partially methylated or benzylated complex were unsuccessful. Treatment of the dinuclear compound 3 with four equivalents of MgClMe yielded the tetramethyl derivative {Ti[μ-(η5-C5Me4SiMe2O-κO)]Me2}2 (8), while the same reaction carried out with MgCl(CH2Ph) or Mg(CH2Ph)2·2THF gave the chloro-benzyl derivative {Ti[μ-(η5-C5Me4SiMe2O-κO)]Cl(CH2Ph)}2 (9) as an equimolar mixture of diastereomers, regardless of the molar ratio of the alkylating reagent used. All of the new compounds were characterised by elemental analysis and NMR spectroscopy. 相似文献
152.
The protonation and alkylation of cross-conjugated ketones containing a terminal N-methylpyrrole ring takes place at the oxygen atom. Protonation is accompanied by a strong bathochromic shift of the absorption maximum in the electron spectrum, while alkylation leads to ethoxypolymethine salts. The possibility of using these salts for the synthesis of ethoxycyanine dyes was studied. 相似文献
153.
V. I. Pet’kov I. A. Shchelokov A. V. Markin N. N. Smirnova M. V. Sukhanov 《Journal of Thermal Analysis and Calorimetry》2010,102(3):1147-1154
The temperature dependence of the heat capacity of crystalline barium zirconium phosphate C p o = f(T) was measured over the temperature range 6–612 K. The experimental data obtained were used to calculate the standard thermodynamic functions C p o (T), H°(T) ? H°(0), S°(T), G°(T) ? H°(0) over the temperature range from T → 0 to 610 K and standard entropy of formation at 298.15 K. The data on the low-temperature (6 ≤ T/K ≤ 50) heat capacity were used to determine the fractal dimension of Ba0.5Zr2(PO4)3. Conclusions concerning the topology of the structure of phosphate were drawn. Thermodynamic properties of M0.5Zr2(PO4)3 (M = Ca, Sr, Ba) were compared. 相似文献
154.
N. N. Smirnova A. V. Markin Yu. A. Zakharova N. V. Kuchkina A. L. Rusanov Z. B. Shifrina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(4):548-553
The temperature dependence of heat capacity C p o = f (T) of second generation hard poly(phenylene-pyridyl) dendrimer (G2-24Py) was measured by a adiabatic vacuum calorimeter over the temperature range 6–320 K for the first time. The experimental results were used to calculate the standard thermodynamic functions: heat capacity C p o (T), enthalpy H o(T)–H o(0), entropy S o(T)–S o(0) and Gibbs function G o(T)–H o(0) over the range from T → 0 K to 320 K. The standard entropy of formation at T = 298.15 K of G2-24Py was calculated. The low-temperature heat capacity was analyzed based on Debye’s heat capacity theory of solids. Fractal treatment of the heat capacity was performed and the values of the temperature characteristics and fractal dimension D were determined. Some conclusions regarding structure topology are given. 相似文献
155.
Elena V Chubarova Denis G. Samsonenko Maxim N. Sokolov Olga A. Gerasko Vladimir P. Fedin Javier G. Platas 《Journal of inclusion phenomena and macrocyclic chemistry》2004,48(1-2):31-35
A new inclusion compound which is a supramolecular adduct of cucurbit[8]uril with two guest molecules of phenylphosphonic acid, PhP(O)(OH)2, included into the cavity as ``two guests in host'' is reported. The guests match both size and hydrophilicity/hydrophobicity requirements. Two phenyl groups of molecules of PhP(O)(OH)2 are directed toward the center of the large hydrophobic cavity whereas the PO(OH)2 groups are outward-looking and bound with each hydrophilic portal of cucurbit[8]uril by a short hydrogen bond. 相似文献
156.
Alexei Yu. Lukin Sergei V. Shevyakov Alexei V. Laptev Olga I. Davydova Vitali I. Shvets Olga V. Demina Yury P. Strokach Valery A. Barachevsky Michail V. Alfimov Sergei P. Gromov Artem I. Vedernikov Johan Lugtenburg Andrey A. Khodonov 《Journal of inclusion phenomena and macrocyclic chemistry》2004,49(1-2):153-161
An effective synthetic approach to the preparation of a new crown-ether vinylogs involving the Horner–Emmons olefination of carbonyl precursors with the use of C2- and C5-phosphonates was proposed. The effects of the conjugation chain length and the nature of the terminal polar functions in the phosphonate reagent on the yield and process stereoselectivity were discussed. 相似文献
157.
The gold(I) selenolate compound [Au(2)(SePh)(2)(mu-dppf)] (dppf = 1,1'-bis(diphenylphosphino)ferrocene) has been prepared by reaction of [Au(2)Cl(2)(mu-dppf)] with PhSeSiMe(3) in a molar ratio 1:2. This complex reacts with gold(I) or gold(III) derivatives to give polynuclear gold(I)-gold(I) or gold(I)-gold(III) complexes of the type [Au(4)(mu-SePh)(2)(PPh(3))(2)(mu-dppf)](OTf)(2), [Au(3)(C(6)F(5))(3)(mu-SePh)(2)(mu-dppf)], or [Au(4)(C(6)F(5))(6)(mu-SePh)(2)(mu-dppf)], with bridging selenolate ligands. The reaction of [Au(2)(SePh)(2)(mu-dppf)] with 1 equiv of AgOTf leads to the formation of the insoluble Ag(SePh) and the compound [Au(2)(mu-SePh)(mu-dppf)]OTf. The complexes [Au(4)(C(6)F(5))(6)(mu-SePh)(2)(mu-dppf)] and [Au(2)(mu-SePh)(mu-dppf)]OTf (two different solvates) have been characterized by X-ray diffraction studies and show the presence of weak gold(I)-gold(III) interactions in the former and intra- and intermolecular gold(I)-gold(I) inter-actions in the later. 相似文献
158.
159.
160.
Anna Katafias Olga Impert Przemysław Kita Grzegorz Wrzeszcz 《Transition Metal Chemistry》2004,29(8):855-860
Oxidation of the trans-[Cr(cyca)(OH)2]+ complex, where cyca = meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, by [Fe(CN)6 ]3- ion in strongly alkaline media, leading to [CrV O(cycaox )]3+ ion, has been studied using electronic and e.p.r. spectroscopy. The kinetics of the CrIII → CrIV transformation have been studied using a large excess of the reductant and OH- ion over the oxidant. The reaction is a second order process: first order in [CrIII] and [FeIII] at constant [OH-]. The second order rate constant is higher than linearly dependent on the OH- concentration. The mechanism of the reaction has been discussed. A relatively inert intermediate chromium(V) species was detected based on characteristic bands in the visible region and the e.p.r. signal at giso = 1.987 for the systems where an excess of oxidant was used. The hyperfine structure of the main e.p.r. signal is consistent with the d1 -electron interactions with four equivalent nitrogen nuclei and [CrV = O(cycaox)]3+ formula, where cycaox = oxidized cyca, can be postulated for the intermediate CrV complex. 相似文献