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1.
C. Vaca‐Garcia G. Gozzelino W. G. Glasser M. E. Borredon 《Journal of Polymer Science.Polymer Physics》2003,41(3):281-288
The main transitions of cellulose fatty esters with different degrees of substitution (DSs) were investigated with dynamic mechanical thermal analysis. Two distinct main relaxations were observed in partially substituted cellulose esters (PSCEs). They were attributed to the glass‐transition temperature and to the chain local motion of the aliphatic substituents. The temperatures of both transitions decreased when DS or the number of carbon atoms (n) of the acyl substituent increased. Conversely, all the transitions of fully substituted cellulose esters occurred within a narrow temperature range, and they did not vary significantly with n. This phenomenon was explained by the formation of a crystalline phase of the fatty substituents. The presence of few residual OH groups in PSCEs was responsible for a large increase in the storage bending modulus, and it eliminated the effect of n on damping. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 281–288, 2003 相似文献
2.
Fluoroalkylated 1,2,3-triketone 2-arylhydrazones and 2-arylhydrazono-3-oxo esters react variously with methylamine depending on the structure of the fluorinated substituent. 2-Arylhydrazono-1,3-dicarbonyl compounds having “short” fluoroalkyl substituents condense with methylamine at the carbonyl group attached to the non-fluorinated substituent whereas ones containing a lengthy polyfluoroalkyl substituent undergo haloformic cleavage as a result of the amine addition at the carbonyl group bearing such a substituent. The resulting 2-arylazo-3-(N-methyl)amino-1-polyfluoroket-2-en-1-ones and 1-(N-methyl)amino-2-arylhydrazono-3-fluoroalkyl-3-oxopropanamides have complexing properties, and they can bind to nickel(II) and copper(II) ions. Nickel chelates can be obtained by a three-component condensation of 2-arylhydrazono-1,3-dicarbonyl compounds and methylamine in the presence of nickel(II) cations. 相似文献
3.
Characteristic features of reactions involving esters of phosphorus-containing acids in highly organized media (micelles, liquid crystals, vesicles, and emulsions) are surveyed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 298–312, February, 1996. 相似文献
4.
We report the first enzyme-catalysed kinetic resolution of epoxy enol esters. The lipase-promoted hydrolysis of these compounds provided α-hydroxyketones or α-hydroxyaldehydes (arising from the spontaneous rearrangement of the epoxy enols) and the residual esters with moderate to good enantioselectivity (E up to 100). 相似文献
5.
The reaction of various α-silyl-α-keto esters with thiosemicarbazide at 50 °C in ethyl acetate was found to give α-silyl-substituted thiosemicarbazone-acetic acid esters in good yield. These may then be converted to their corresponding silyl-substituted 1,2,4-triazin-5-ones by cyclization under basic conditions. 相似文献
6.
A one-step synthesis of alkylN-(-amidomethyl)glycinates from glycine esters or their salts, formaldehyde, and aroylamides was developed. The effect of the structure of the amide component and the reaction conditions on the yields of the products was investigated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1078–1080, June, 1994. 相似文献
7.
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
8.
Paolo Davoli 《Tetrahedron》2005,61(18):4427-4436
The enantioselective total synthesis of the actin-targeting metabolite (−)-microcarpalide is described. Key steps include ring-closing metathesis (RCM) for the final construction of the 10-membered lactone framework and stereoselective homologation of boronic esters for the insertion of all stereocentres with the desired absolute configuration. In particular, the acidic fragment was prepared in seven steps from a suitable chiral bromomethane boronate by means of two sequential stereoselective homologations to install the two stereocentres with the correct final R stereochemistry, employing (−)-pinanediol as the chiral director. Subsequent elaboration to the required C7 backbone entailed nucleophilic displacement with a vinyl Grignard reagent, oxidative cleavage of the boronic scaffold and protection-deprotection manipulations. Interestingly, when the tribenzyloxy diene ester resulting from DCC-mediated coupling of the two key synthons was subjected to RCM in the presence of Grubbs' catalyst, the reaction proceeded stereoselectively to yield the desired trans oxecin-2-one, albeit with poor conversion. 相似文献
9.
N. E. Golantsov A. V. Karchava M. A. Yurovskaya 《Chemistry of Heterocyclic Compounds》2006,42(8):1021-1024
Methods of obtaining ketones and enamino esters have been developed on the basis of reactions of 1-(1-phenylethyl)indole-2-carbonitrile
with organomagnesium and organozinc compounds. Removal of a benzyl group from the indole nitrogen atom by the Grignard reagent
has been discovered.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1179–1183, August, 2006. 相似文献
10.
在SmI_2-HMPA-THF-t-BuOH体系中,硫代碳酸酯的酰硫键发生还原断裂反应,得到相应的二硫醚产物。 相似文献