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61.
This work focuses on the structure property co-relation study of Eu3+-doped ceria nanomaterials prepared through citrate auto-ignition process and sintered at three different temperatures. The microstructure and dielectric properties were found to be affected by the sintering temperature. The particle size was found to play a major role to the migration of charge carriers in the samples. The dielectric constant has been found to control the formation of dopant-vacancy interaction though columbic interaction in defect pair (Eu′Ce – Vo ??)? and neutral trimers (Eu′Ce – Vo ?? – Eu′Ce). The sample sintered at 800 °C shows the lowest value of lattice parameter due to the highest value of dopant-vacancy interaction. The migration energy for oxygen vacancy conduction was found to increase with particle size that reduces the ionic conductivity values. The rate of hopping was found to decrease due to blocking of charge-carrier diffusion due to the growth of particle. 相似文献
62.
Ghosh Bidisha Roy Shubham Bardhan Souravi Mondal Dhananjoy Saha Ishita Ghosh Saheli Basu Ruma Karmakar Parimal Das Kaustuv Das Sukhen 《Journal of fluorescence》2022,32(4):1489-1500
Journal of Fluorescence - This article reports the fluorometric detection of toxic hexavalent chromium Cr (VI)) in wastewater and Cr (VI) contaminated living cells using in-situ grown carbon... 相似文献
63.
64.
65.
Anirban Garg Abdul Aziz Ali Krishnaiah Damarla Arvind Kumar Diganta Sarma 《Tetrahedron letters》2018,59(45):4031-4035
A facile, efficient and mild copper catalyzed strategy for cascade synthesis of various 1,4-disubstituted 1,2,3-triazoles from arylboronic acids, sodium azide and alkynes was developed by using aqueous bile salt NaDC solution as an accelerating medium. Low catalyst loading (only 1?mol% Cu source was sufficient for in situ generation of azide followed by azide–alkyne coupling), green solvent, use of bio-surfactant as additive and short reaction time make this protocol highly accessible and environment friendly. 相似文献
66.
67.
P. C. Mandal D. K. Bardhan S. N. Bhattacharyya 《Journal of Radioanalytical and Nuclear Chemistry》1995,191(2):349-359
Reactions of carbonate radical (CO3
–), generated by photolysis or by radiolysis of a carbonate solution with nickel(II)-iminodiacetate (Ni(II)IDA) were studied at pH 10.5 and ionic strength (I)==0.2 mol·dm–3. The stable product arising from the ligand degradation in the complex is mainly glyxalic acid. Time-resolved spectroscopy and transient kinetics were studied using flash photolysis. From the kinetic data it was suggested that the carbonate radical initially reacts with Ni(III)IDA with a rate constant (2.4±0.4)·106 dm3·mol–1·s–1 to form a Ni(II)IDA species which, however, undergoes a first-order transformation (k=2.7·102·s–1) to give a radical intermediate of the type Ni(II)RNHCHCO
2
–
) which rapidly forms an adduct containing a Ni–C bond. This adduct decays very slowly to give rise to glyoxalic acid. From a consideration of equilibrium between Ni(II)IDA and Ni(III)IDA, the one electron reduction potential for the Ni(III)IDA/Ni(II)IDA couple was determined to be 1.467 V. 相似文献
68.
P. C. Mandal D. K. Bardhan S. N. Bhattacharyya 《Journal of Radioanalytical and Nuclear Chemistry》1992,166(2):87-96
Reactions of carbonate (CO
3
–·
) and bicarbonate (HCO
3
·
) radicals generated by photolysis of a carbonate or bicarbonate solution at pH 11.2 and 8.5, respectively, with Co(II) complexes of iminodiacetic acid (IDA) and ethylenediaminetetraacetic acid (EDTA) have been studied. The rate constants for the reactions were in the order of 106–107 dm3mol–1s–1. From the time-resolved spectroscopy of the products formed after reaction of CO
3·
–·
or HCO
3
·
, it is observed that CO
3
–·
or HCO
3
·
oxidize the metal center to its higher oxidation state. 相似文献
69.
Adjou Ané Sébastien Naud Sandrine Vidot Anirban Kar Didier Dubreuil 《Tetrahedron》2006,62(20):4784-4794
A mild and general procedure for the synthesis of α-thioglycosides from glycopyranoses is described. The method involves the treatment of pyranose reductive sugar with sodium hydride, carbon disulfide, and p-nitrobenzoyl chloride, as a key step, to yield p-nitrobenzoyl-α-d-thioglycopyranose intermediates with high stereoselectivity, in a one-pot-two-step process. The interest of the strategy highlights a direct stereoselective access to ether-protected 1-thiol-α-d-glycopyranose derivatives (Gal, Glc, and Man) from pyranoses in the absence of anomeric ‘Lewis acid’ promoters. 相似文献
70.
1-Alkyl-3-methylimidazolium cation based ionic liquids efficiently catalyze N-tert-butyloxycarbonylation of amines with excellent chemoselectivity. The catalytic role of the ionic liquid is envisaged as "electrophilic activation" of di-tert-butyl dicarbonate (Boc(2)O) through bifurcated hydrogen bond formation with the C-2 hydrogen of the 1-alkyl-3-methylimidazolium cation and has been supported by a downfield shift of the imidazolium C-2 hydrogen of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][NTf(2)]) from δ 8.39 to 8.66 in the presence of Boc(2)O in the (1)H NMR and a drastic reduction of the catalytic efficiency with 1-butyl-2,3-dimethylimidazolium ionic liquids that are devoid of the C-2 hydrogen. The differential time required for reaction with aromatic and aliphatic amines has offered means for selective N-t-Boc formation during inter and intramolecular competitions. Preferential N-t-Boc formation with secondary aliphatic amine has been achieved in the presence of primary aliphatic amine. Comparison of the catalytic efficiency for N-t-Boc formation with a common substrate revealed that [bmim][NTf(2)] is superior to the reported Lewis acid catalysts. 相似文献