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831.
Methods for determination of titratable acidity, other than traditional titration, i.e. methods without titration, are considered. A number of them use analytical acid-base reagents which quickly convert a mixture of strong and weak acids into a new system. This conversion makes it possible to obtain directly the analytical signal (pH, optical density, etc.) for titratable acidity calculation. These methods in stationary conditions and in flow injection analysis are discussed. Methods not using acid-base reagent (iodide-iodate, chromatographic, spectroscopic and others) are also described. The advantages of the alternative methods such as the decrease labour-consumption and analysis time, simplicity of automation and others are shown. 相似文献
832.
N. N. Sidamonidze L. K. Janiashvili R. O. Vardiashvili M. O. Isakadze 《Chemistry of Heterocyclic Compounds》2005,41(12):1534-1536
By hydrosilylation of 1-O-allyl-2,3,4,6-tetra-O-acetyl-β-D-glucopyranose and 1-O-allyl-2,3,4,6-tetra-O-acetyl-β-D-galactopyranose
with 1,3-bis(dimethylsilyl)-2,2,4,4-tetramethylcyclodisilazane in the presence of the catalyst Co2(CO)8, we have obtained 1,3-di[3-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)propyldimethylsilyl]-2,2,4,4-tetramethylcyclodisilazane
and 1,3-di[3-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyloxy)propyldimethylsilyl]-2,2,4,4-tetramethylcyclodisilazane. By deacetylation,
we obtained 1,3-di[3-(β-D-glucopyranosyloxy)propyldimethylsilyl]-2,2,4,4-tetramethylcyclodisilazane.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1859–1862, December, 2005. 相似文献
833.
The cycloheptano-isoxazoline 1, prepared from D-glucose, is converted to 6,7-dideoxy cycloheptitols which are suitable precursors for the synthesis of enantiomerically pure (+) and (−)-Calystegines B2. 相似文献
834.
L. I. Kryvenko A. T. Soldatenkov O. V. Zvolinskii L. N. Kuleshova V. N. Khrustalev V. N. Gryshev S. A. Soldatova 《Chemistry of Heterocyclic Compounds》1997,33(6):691-697
Reaction of 2-acetylpyridine with 4-[2.2]paracyclophanyllithium or 4-acetyl[2.2]paracyclophane with 2-pyridllithium gives 1-([2.2]paracyclophan-4-yl)-1-(2-pyridyl)ethanol. Its molecular and crystalline structures have been studied by x-ray analysis. It was found that heating this alcohol in acid medium causes dehydration and heterocyclization to give 1-paracyclophanyl-1-pyridylethylene and 10-methyl[2.2]paracyclophano[4,5-bindolizine.For communication 9 see [1]. This report is also communication [5] in the series Synthesis, Structure, and Biological Activity of [2.2]Paracyclophanes (for communication 4 see [2]).Russian University of National Friendship, Moscow 117198. A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, Moscow 117813. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 793–800, June, 1997. 相似文献
835.
V. V. Dunina M. Yu. Kazakova Yu. K. Grishin O. R. Malyshev E. I. Kazakova 《Russian Chemical Bulletin》1997,46(7):1321-1330
A new homochiral dimericortho-palladated complex bearing a bulkytert-butyl substituent at the carbon stereocenter was synthesized from optically activeN,N-dimethyl-α-tert-butylbenzylamine. Regioselective activation of only the aromatic C−H bond was shown to occur during the cyclometallation
process proceeding under very mild conditions due to steric effects. Spectral characteristics of mononuclear derivatives of
the new dimeric complex indicate that the five-membered palladacycle exists predominantly in one of two possible chiral conformations
with the axial position of thetert-butyl substituent.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1375–1384, July, 1997. 相似文献
836.
837.
Fomina N. Yu. Chaplygina O. A. Shebaldova A. D. Borodulin V. B. 《Russian Journal of General Chemistry》2002,72(5):704-709
Circular dichroism was used to study reaction of K2PdCl4 with polydeoxyribonucleotides and calf thymus DNA. The optical and structural characteristics of the molecular components were determined to show that K2PdCl4 reacts with natural and synthetic acids, producing profound rearrangements in their structure. 相似文献
838.
A. V. Koblik L. A. Murad'yan O. E. Kompan D. S. Yufit Yu. T. Struchkov Yu. A. Zhdanov L. P. Olekhnovich G. P. Zolotovskova 《Chemistry of Heterocyclic Compounds》1988,24(7):725-730
When 2,6-diaryl-4-phenylethynylpyrylium perchlorates are refluxed in water, methanol, or ethanol, they are converted to monomethinecyanines, the formation of which is explained by hydration of the phenylethynyl group and subsequent [2+2]-cycloaddition of the resulting 2,6-diaryl-4-benzoylmethylenepyrans to the starting pyrylium salt. The corresponding pyridine derivatives were obtained by the action of ammonia and aniline on the monomethinecyanines. The IR and PMR spectra of the compounds and the results of x-ray diffraction analysis of 2,6-diphenyl-4-[1-(2,6-diphenyl-4-pyranylidene)-2-phenyl-3-benzoylallyl]pyridine are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 885–890, July, 1988. 相似文献
839.
I. V. Sudmale V. Yu. Khodorkovskii A. S. Edzhinya O. Ya. Neiland 《Chemistry of Heterocyclic Compounds》1993,29(6):652-658
6-Hydroxy-5-methoxycarbonylthieno[2,3-d]-1,3-dithiol-2-thione, -2-one, and 2-selenone were prepared by intramolecular cyclocondensation of 4-methoxycarbonylmethylthio-1,3-dithiol-2-thione-, 2-one-, and 2-selenone-5-carboxylic acid methyl ester. 2,6(7)-Di(methoxycarbonylmethylthio)-3,7(6)-di(methoxycarbonyl)tetra-thiafulvalene, 2-methoxycarbonylmethylthio-3-methoxycarbonyl-6,7-ethylenedithiotetrathiafulvalene, and the corresponding thieno-condensed tetrafulvalene derivatives were synthesized from them. The electrochemical oxidation potentials of the new tetrafulvalene derivatives were determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 761–768, June, 1993. 相似文献
840.
N. P. Solov'eva O. S. Anisimova Yu. N. Sheinker M. P. Nemeryuk N. I. Traven' T. G. Arutyunyan E. A. Shatukhina T. S. Safonova 《Chemistry of Heterocyclic Compounds》1992,28(10):1219-1224
It is demonstrated by 13C NMR spectroscopy that the dipyrimidothiazines that are formed in the reaction of 1,3-dimethyl-5-nitro-6-chlorouracil with 4-R-5-amino-6-mercaptopyrimidines are dipyrimido[4,5-b][4,5-e] [1,4]thiazines. The tautomeric transformations of these compounds were studied.For communication 1, see [1]Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1426–1432, October, 1992. 相似文献