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941.
A. V. Korzhak S. Ya. Kuchmii A. I. Kryukov 《Theoretical and Experimental Chemistry》1987,23(2):172-177
It was established that in UV irradiation of solutions of TiCl4 in methanol, ethanol, isopropanol, and butanol, alcohol-chloride complexes of titanium(III) are formed. The quantum yields of the formation of coordination compounds of titanium(III) depend on the nature of the alcohol: 0.08 (methanol); 0.13 (ethanol); 0.20 (butanol); 0.22 (isopropanol). As complexes of titanium(III) accumulate in solution, there is a liberation of molecular hydrogen. The quantum yields of the formation of hydrogen, determined in a steady-state process, are correlated with the values of the C-H bond energy at the -carbon atom of the alcohol and are equal to 2·10–3, 3.4·10–3, 4.3·10–3 and 1·10–2 for solutions in methanol, butanol, ethanol, and isopropanol, respectively. A substantial increase in the quantum yield of the formation of molecular hydrogen was detected when a heterogeneous catalyst (palladium on silica gel) was used, and the possible mechanism of the process of photocatalytic liberation of hydrogen from alcohols with the participation of titanium complexes is discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 3, No. 2, pp. 181–186, March–April, 1987.The authors would like to thank V. M. Granchak for his participation in the discussion of the results. 相似文献
942.
2-Trifluoromethyl-4H-thiochromene-4-thione obtained from 2-trifluoromethyl-4H-thiochromen-4-one and P2S5 reacts with aromatic amines, hydrazine hydrate, phenylhydrazine, and hydroxylamine at the C(4) atom of the chromene ring
to give the corresponding anils, azine, hydrazones, and oxime of thiochromone. 2-Trifluoromethyl-4H-thiochromen-4-one is oxidized by hydrogen peroxide in AcOH into 4-oxo-2-trifluoromethyl-4H-thiochromene 1,1-dioxide and reduced by NaBH4 to 2-trifluoromethyl-4H-thiochromen-4-ol or cis-2-(trifluoromethyl)thiochroman-4-ol. When treated with hydrazine hydrate, thiochromen-4-one gives 3(5)-(2-mercaptophenyl)-5(3)-trifluoromethylpyrazole.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 504–509, March, 2006. 相似文献
943.
Direct asymmetric aldol addition of methyl ketones to 2,2,2-trifluoro-1-phenylethanone and its ring-substituted derivatives was achieved using L-proline as a chiral promoter. Various optically active β-trifluoromethyl-β-hydroxy ketones were obtained in almost quantitative yields with moderate enantioselectivities up to 64 % ee. 相似文献
944.
Studies are presented of the infrared spectra (3200–400 cm?1) of monocrystal films of Fe (C5H5)2 Ru(C5H5)2, Os(C5H5)2 using polarized radiation, and of the laser-Raman spectra of solid samples of these compounds in the temperature range +20° to ?190°C. The samples were prepared by slow cooling of the melts. The infrared spectra of solid films of Ni(C5H5)2 made by deposition on a cold window, were also recorded. Assignments of the fundamental vibrational frequencies of these molecules are given. The fundamental modes of vibrations which are forbidden by symmetry appear in the spectra of the solid state. The vibrations of species E1u and E2u showed definite site group splitting. At the point of phase transition in the IR spectrum of Fe(C5H5)2 factor-group splitting to give 3–4 components for bands of species A1u and A2u and 6–8 components for bands of species e1u and E2u was observed. Factor-group analysis is more consistent with C1 site symmetry of the low-temperature phase of the crystal of ferrocene than Ci, as was proposed earlier. 相似文献
945.
V. L. Florent'ev N. A. Drobinskaya L. V. Ionova M. Ya. Karpeiskii 《Chemistry of Heterocyclic Compounds》1972,5(6):774-781
A method for the synthesis of analogs of pyridoxal-2-norpyridoxal, 6-methyl-2, 4-pyridoxal, and 6-methylpyridoxal—has been worked out. The reaction of 5-ethoxyoxazoles with maleic diesters gave diesters of substituted 3-hydroxycinchomeric acids, which were converted by reduction with lithium aluminum hydride into analogs of pyridoxine. The latter were oxidized with magnesium dioxide to the corresponding analogs of pyridoxal. The oximes of the aldehydes and their Schiff's bases with p-phenetidine have been obtained. Analogs of pyridoxamine have been obtained by the hydrogenation of the oximes. The UV absorption spectra of the compounds and the ratios of the ionic forms in aqueous solutions have been studied. 相似文献
946.
Yu.Ya. Gurevich M.D. Krotova Yu.V. Pleskov 《Journal of Electroanalytical Chemistry》1977,75(1):339-351
The laws of photoemission into electrolyte solutions from semiconductor electrodes have been studied theoretically and experimentally. Relations have been obtained for the frequency dependence of the photoemission current with allowance for the photogeneration of electrons by the direct and indirect transition mechanisms. The experimentally obtained dependence of the photoemission current from n- and p-type germanium and p-type gallium arsenide electrodes in aqueous solution on the light quantum energy, and at sufficiently negative potentials also on potential, is described by the three-halves law, characteristic of direct transitions in the bulk. A band scheme of the system has been constructed, from which the value of the semiconductor-solution Volta potential and the value of the potential in the space charge region of semiconductor have been found. 相似文献
947.
近年来亚硝酸甲酯分子(CHa0NO)的光解动力学研究十分活跃{‘5],主要集中在紫外激光的单光子解离的机理,光解过程的矢量相关性质和光解产物的态分布.CH30NO分子的解离能D。(CH30-NO)=174kJ·mol‘,若单从能量上看,人<689。的光就能使其解离,但人>400urn的光解离研究还未见报导.*H30*0分子在人>40onm的强激光场下是充电离还是先解离,是单光子解离还是多光子解离,以及通过哪个电子态解离都不清楚.时间飞行质谱不仅具有质量分辨率高、范围宽,而且响应快,因此适合做光解光电离过程初生态产物的探测.特别是时间飞… 相似文献
948.
V. P. Feshin S. A. Ciller L. Ya. Avota M. G. Voronkov 《Chemistry of Heterocyclic Compounds》1976,12(3):334-336
The effect of substituents in the pyridazone ring (including the carbonyl oxygen atom) on the chlorine atoms in the 3,4, or 5 positions was investigated on the basis of data from the Cl35 nuclear quadrupole resonance (NQR) spectra of chloro-substituted 6-pyridazones. The NQR frequencies of 1-phenyl-4,5-dichloro-6-pyridazone were compared with the reactivities of chlorine atoms in this compound in nucleophilic substitution reactions.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.3, pp. 392–395, March, 1976. 相似文献
949.
Kh. M. Minachev Ya. I. Isakov V. P. Kalinin Yu. S. Akhmetov 《Russian Chemical Bulletin》1976,25(5):1041-1048
1. | The catalytic properties of the Ni forms of various types of synthetic zeolites in the reaction of benzene with ethylene are determined by their structure, composition, and conditions under which they are used. |
2. | The NiNaA zeolites accelerate only the dimerization of C2H4, and are inactive in the alkylation of C6H6 with olefins. From benzene and ethylene it is possible to obtain on NiX and NiY either predominantly sec-butylbenzene (SBB) (selectivity 80–86%) or SBB and butenes in approximately equal amounts. |
950.
Xu QM Wang D Han MJ Wan LJ Bai CL 《Langmuir : the ACS journal of surfaces and colloids》2004,20(8):3006-3010
Scanning tunneling microscopy (STM) combined with cyclic voltammetry has been employed to investigate the adsorption of cinchonine on Cu(111). Similar to cinchonidine, cinchonine forms a long-range ordered adlayer with (4 x 4) symmetry on the substrate. The structural details on molecular adsorption were obtained by high-resolution STM images. On the basis of the previous results and obtained STM images, the quinoline ring is proposed to lie parallel to Cu(111) and serve as an anchoring group. The chiral quinuclidine moiety extends out of the surface to facilitate the interaction with the prochiral reactants. 相似文献