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71.
72.
Alkyl sulfoxides were synthesized in good yields from the reaction of alkanesulfinyl chloride with Grignard reagents in the presence of zinc chloride. 相似文献
73.
IntroductionRecentlymuchattentionhasbeendevotedtothesynthesisofα ,β unsaturatednitrilessincetheyareim portantstructuralfeatureofseveralnaturallyoccurringbi ologicallyactivecompounds .1,2 Theintroductionoffluo rineortrifluoromethylgroupintobiologicallyactiv… 相似文献
74.
Madan G. Barthakur 《Tetrahedron letters》2006,47(28):4925-4927
An efficient one-pot synthesis of substituted 4H-thiopyrans has been accomplished from a three-component reaction of α,β-unsaturated ketones, Lawesson’s reagent and alkynes under microwave irradiation. 相似文献
75.
SynthesisandCrystalStructureof1,5-Bis(1'-phenyl-3'-methyl-5'-pyrazolone-4')-1-(4'-aminobutand-1'-imino)-5-pentaneone¥YangLu-Q... 相似文献
76.
An enantioselective high-performance liquid chromatographic method, with precolumn derivatization with Marfey’s chiral reagent,
sodium 2,4-dinitro-5-fluorophenyl-l-alanine amide, has been developed for resolution of the enantiomers of a new antiepileptic drug, pregabalin, in the bulk
drug. The diastereomers of the pregabalin enantiomers were resolved to baseline on a reversed-phase ODS column with a 60:40
(v/v) mixture of aqueous 0.2% triethylamine (pH adjusted to 3.5 with dilute orthophosphoric acid) and acetonitrile as mobile phase.
Resolution between the diastereomers was not less than five. The method was extensively validated and proved to be robust.
The calibration plot was indicative of an excellent linear relationship between response and concentration over the range
750 (LOQ) to 7,500 ng L−1 for the R enantiomer. The limits of detection and quantification of the R enantiomer were 250 and 750 ng L−1, respectively, for an injection volume of 10 μL. Recovery of the R enantiomer from bulk drug samples of pregabalin ranged from 97.5 to 101.76%. Solutions of pregabalin in water and in the
mobile phase were found to be stable for at least 48 h. The method was found to be suitable and accurate for quantitative
determination of the R enantiomer in the bulk drug. It can be also used to test the stability of samples of pregabalin. 相似文献
77.
The properties of porphyrinogen as a new chromogenic reagent were examined. 5,10,15,20-Tetrahydro-tetraphenylporphyrinogen (TPPN) is changed to 5,10,15,20-tetraphenylporphine (TPP) by the oxidative reaction involving six electrons, and its formation of the porphine ring significantly increased the absorbance in the Soret band.The horseradish peroxidase (HRP) accelerated the oxidative reaction as a catalyst and the increment of absorbance depended upon the increase in the concentration of HRP. The reaction proceeded in the presence of dissolved oxygen and in the neighborhood of pH 7. Based on these findings, a chemical analysis by catalytic action using HRP was developed.In the procedure for this determination, the difference in absorbance at 419 nm (ΔA419=As−Ab, where As and Ab are the absorbances of the sample solution containing HRP and the blank solution without HRP after 30 min, respectively), was measured. The determination range of HRP, which was obtained from the ΔA419—HRP concentration curve, was 0.05-1.0 mg/l. The relative standard deviation in the median of the calibration curve was 3.19% (seven determinations), and the detection limit (S/N=3) was 29 ng/l. Furthermore, when the proposed method was applied to the enzyme immunoassay, bisphenol A (BPA) was selectively and sensitivity determined. 相似文献
78.
Synthesis of new diheteroarylcarbazoles: a facile and simple route of 3,6-di(pyrazol-4-yl)carbazoles
Ramu Meesala 《Tetrahedron letters》2006,47(43):7557-7561
A short and facile route to the synthesis of new 3,6-di(pyrazol-4-yl)carbazoles is reported. Dipyrazolylcarbazoles were synthesized in two steps from 3,6-diacetylcarbazoles through a Vilsmeier reaction which led to the formation of carbazolyl-β-chlorovinyl aldehydes, followed by cyclization with hydrazine hydrate. The reaction of the Vilsmeier reagent with hydrazones of diacetylcarbazoles yielded the corresponding pyrazole dicarbaldehydes in good yields. 相似文献
79.
80.
Transition metal-catalyzed monoreduction of dichlorooligosilanes with Grignard reagents is reported. Among the examined catalysts, group 4 metal chlorides such as TiCl4 and Cp2TiCl2 gave the highest reactivity and good selectivity. The reducing power is effectively controlled by changing the catalysts and Grignard reagents to achieve sufficient selectivity depending on the oligosilane substrates. 相似文献