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101.
A procedure for determining the fatty acid composition of human adipose tissue using gas chromatography-mass spectrometry was developed. Adipose tissue was obtained from the lateral upper aspect of the right thigh by needle biopsy and prepared for analysis by lyophilisation, total lipid extraction and base-catalysed transesterification of the complexed fatty acids to form fatty acid methyl esters. Capillary column gas chromatography resolved thirty different peaks, ranging in carbon length from 12 to 24. Provisional identification of the peaks was by cochromatography with authentic standards and confirmed by gas chromatography-mass spectrometry using electron-impact ionisation. Fatty acid methyl esters were quantified in absolute amounts with respect to dry tissue weight and as a percentage of the total fat. Statistical analysis of the results from twenty healthy subjects using the two-tailed unpaired Student's t-test demonstrated women had significantly higher levels of myristoleic and palmitoleic acids (p less than 0.001) and lower levels of palmitic acid (p less than 0.05) in adipose tissue when compared with the male group. Similarly total saturated fatty acids was lower (p less than 0.05) and total monounsaturated fatty acids was higher in women than in men. 相似文献
102.
Sorption mechanism of bivalent metal ions on a weak cationic resin containing the carboxylic group is studied. The Gibbs-Donnan model is used to describe and then to predict the sorption through the determination of the intrinsic complexation constants. These quantities characterize the sorption being independent of experimental conditions. They are determined according to a well established procedure and using a recently proposed iterative method for calculation of counter ion concentration in the resin phase. Sorption mechanisms are also studied adding appropriate soluble ligands whose complexing properties are exactly known to the solution containing the resin and the metal ion. Competing with the resin for the complexation of the metal, they shift the sorption curve to higher pH and often this allows detecting other complexes between the metal and the resin. In this way for Mn(II), besides the 1:1 complex formed in the more acidic solution, with logbeta(110)=-4.55, the complex ML(2), characterized by logbeta(120)=-9.80, is found; for Cd(II), besides the ML complex, with logbeta(110)=-3.01, at pH higher than 7, the specie MLOH with logbeta(11-1)=-8.28. For Cu(II) the complex ML(2) is detected, confirming previous findings, with logbeta(120)=-7.24. In the presence of two different ligands, sulphosalicylic and malonic acid, a different complex, ML(2)OH, is identified, with the same intrinsic complexation constant for the two ligands, logbeta(12-1)=-13.35. As expected from the model, the intrinsic complexation constants, especially for the 1:1 complex, are in a good agreement with the complexation constants of acetic acid. 相似文献
103.
The paramagnetic adducts formed when photochemically generated Mn(CO)5 or Re(CO)5 radicals are trapped by N,Nt?-di-t-butyl-1,4-diaza-1,3-butadiene (t-Bu-DAB) have been characterized by ESR spectroscopy. Adducts containing phosphorus have also been observed but attempts to produce adducts containing As, Sb or Bi have been unsuccessful. In a number of systems an identical ESR spectrum was observed. This has been shown to arise from the N,N′-di-t-butylpyrazinium cation. 相似文献
104.
Vougioukalakis GC Roubelakis MM Alberti MN Orfanopoulos M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(31):9697-9705
The influence of the solvent on the triazolinedione-alkene ene reaction mechanism has been investigated. Both inter- and intramolecular kinetic isotope effects with tetramethylethylenes and 2,2,2-(trideuterio)methyl-7-methyl-2,6-octadiene-[D3]-1,1,1 provide, for the first time, strong evidence for changes in the mechanism of the reaction on going from non-protic to polar protic solvents. In non-protic polar or apolar solvents, an aziridinium imide that equilibrates to an insignificant extent with an open intermediate (a dipolar or a polarized biradical) is formed irreversibly in the first, rate-determining step of the reaction, which is followed by fast hydrogen abstraction. On the contrary, in polar protic solvents, hydrogen abstraction is rate limiting, allowing the main dipolar intermediate to equilibrate with its open intermediate(s) as well as with the starting reagents. 相似文献
105.
Laser ablation (LA) synthesis with simultaneous time-of-flight mass spectrometric (TOF MS) analysis was used to examine the formation and composition of ternary Pp Sq Ser clusters. Clusters formed by LA of various precursors are singular, binary and ternary. Formation of negative or positive singly charged Pp, Sq and Ser clusters, where Pp + (p = 1-249), Pp* (p = 1-191), Sq* (q = 1-15), Sq + (q = 1-12), Ser* (r = 1-8) and Ser+ (r = 1-9), was identified. High numbers of binary Pp Sq, Sq Ser (35) or ternary Pp Sq Ser (138) clusters were formed by LA synthesis from the various mixtures. Most of the ternary Pp Sq Ser clusters were formed either from a mixture of P4S3 with selenium (grey) or from a mixture of SeS2 with red phosphorus. In total, 138 new ternary Pp Sq Ser clusters were identified. The conditions for the formation of such possible prospective nano-materials are given. 相似文献
106.
Papp Ildik Simndi Bla Blazics Balzs Alberti gnes Hthelyi va Szke va Kry gnes 《Chromatographia》2008,68(1):125-129
The use of salicylate containing herbs as analgesic and antirheumatic remedies can be traced back to ancient times. While salicaceen contains only derivatives of salicylalcohol, Filipendula ulmaria is characteristic for various forms of volatile and non-volatile salicylates. The main pharmacological effect of Filipendula ulmaria is due to its salicylic acid component, which is released via oxidation from various aglycones (e.g. salicylaldehyde, methylsalicylate) developed from glycosides through hydrolysis in the digestive system. Our current study is focussed on the determination of volatile and non-volatile salicylates in various parts and extracts of the plant, using different chromatographic techniques. 相似文献
107.
Alberti A Galasso V Kovac B Modelli A Pichierri F 《The journal of physical chemistry. A》2008,112(25):5700-5711
The conformational preferences of capsaicin were investigated by using the hybrid meta density functional theory (DFT) method MPWB1K. Its flexible, pendant side chain allows for a multitude of conformations only slightly different in energy. The distinctive vibrational features of the most stable conformers were characterized. To elucidate the most favorable reaction sites of capsaicin for radical scavenging, various homolytic bond-dissociation energies were also calculated. Of the possible radical intermediates, the allyl and benzyl radicals are energetically preferred. The filled and empty electronic structures of capsaicin were investigated by exploiting the photoelectron and electron-transmission spectra also of reference molecules and suitable quantum-mechanical calculations. On this basis, a reliable pattern of the vertical ionization energies and electron-attachment energies of capsaicin was proposed. The frontier pi molecular orbitals are concentrated over the vanillyl moiety, with a modest influence of the amidic-aliphatic chain. The (negative) first vertical electron affinity is predicted to be similar to that of benzene. The absorption spectrum of capsaicin and its change by conversion into a phenolic deprotonated anion (modest bathochromic displacement) or a phenoxyl neutral radical (from colorless to red) were interpreted with time-dependent DFT calculations. ESR measurements following chemical or electrochemical reduction of capsaicin did not lead to detection of the corresponding radical anion. The spectra show fragmentation of the original molecule and formation of a variety of radical species which are believed to have a semiquinonic structure. 相似文献
108.
Pyrazolo[1,5-a]pyridines as p38 kinase inhibitors 总被引:1,自引:0,他引:1
Stevens KL Jung DK Alberti MJ Badiang JG Peckham GE Veal JM Cheung M Harris PA Chamberlain SD Peel MR 《Organic letters》2005,7(21):4753-4756
[reaction: see text] A convergent synthesis of substituted pyrazolo[1,5-a]pyridines has been achieved either via a regioselective [3 + 2] cycloaddition of N-aminopyridines with alkynes or by thermal cyclization of disubstituted azirines. Subsequent palladium-catalyzed introduction of pyridines or de novo synthesis of pyrimidines affords inhibitors of p38 kinase. 相似文献
109.
We prove that the space BV (ℝ
n) of functions with bounded variation on ℝ
n has the bounded approximation property. 相似文献
110.