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11.
The preparation and characterization of MnII, FeIII and CuII complexes of three tridentate pyridyl hydrazones are reported.
The ligands were prepared via Schiff base condensation of 6-chloro-2-hydrazopyridine with alpha-formyl-(L1), alpha-acetyl-(L2),
or alpha-benzoyl-(L3) pyridine. The structural characterization of the compounds prepared was based on elemental analyses,
electrical conductance and magnetic moment measurements, 1H-n.m.r., i.r., u.v.-vis. and e.s.r spectroscopic methods. The overall
structure and reactivity of the metal chelates critically depend on the ligand substituents within the carbonyl moiety. Octahedral
and tetrahedral monomeric species were proposed for MnII complexes, and an octahedral environment for the FeIII complexes.
Regarding the copper(II) complexes, a monomeric square-planar and a dimeric structure with a chloride bridge in square-pyramidal
geometry were suggested. In the presence of molecular oxygen, MnII and CuII complexes catalyse the oxidative transformation
of catechol (benzene-1,2-diol) to the corresponding o-benzoquinone. Iron(III) complexes catalyse the aerobic oxidation of
catechol to the intradiol cleavage product. The catalytic activity has been correlated with the Lewis acidity of the metal
centres created according to the nature of the ligand substituents. The probable mechanistic implications of the catalysed
oxidation reactions are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
12.
Dimethyl and diethyl fluoromalonates were prepared from hexafluoropropene by its exhaustive alcoholysis or alternatively its ammonolysis and alcoholysis. Fluoromalonates thus obtained or their alkylated derivatives were condensed with o-phenylenediamine or its substituted derivatives to give a number of 1H-3-fluoro-1,5-dibenzodiazepin-2,4(3H,5H)-diones. 相似文献
13.
Anwar Usman Ibrahim Abdul Razak Suchada Chantrapromma Hoong‐Kun Fun Varughese Philip A. Sreekanth M. R. Prathapachandra Kurup 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):o652-o654
The title compound, C16H17N5S, is in the thione form and crystallizes with two independent molecules in the asymmetric unit. In both molecules, the pentamethyleneimine five‐membered ring adopts an envelope conformation, and in one of the molecules this ring shows positional disorder. The thione S and hydrazine N atoms are in the Z configuration with respect to the C—N bond. 相似文献
14.
Ibrahim El-Sayed El-Kholy Morcos Michael Mishrikey Hassan Mostafa Feid-Allah 《Journal of heterocyclic chemistry》1981,18(1):105-110
The reaction of piperidine, morpholine, piperazine or dimethylamine with several coumarins, 3-bromocoumarin, 4,6-diaryl-2H-pyran-2-ones and 3-bromo-4,6-diaryl-2H-thiopyran-2-ones gave o-hydroxycinnamic acid amides, benzofurans, open-chain δ-oxoamides and thiophene derivatives, respectively. 相似文献
15.
Preparation of cellulose and cellulose derivative azo compounds 总被引:1,自引:0,他引:1
Maha Ibrahim 《Cellulose (London, England)》2002,9(3-4):337-349
Wood pulp and cotton linter are the most common sources of cellulose forindustrial use. Methyl cellulose (MC) and cellulose sulfate (CS) were preparedusing bleached wood pulp and cotton linter. Coloured azo compounds were alsoprepared from coupling cellulose, wood pulp, MC and CS with aromatic diazoniumsalt. The presence of electron-releasing or withdrawing substituents affectedthe electrophilic substitution reaction. The produced azo compounds werecharacterized by FT-IR methodology, as well as mass spectrometry, in which thefunctional groups and the ion fragments of the products were analyzed. 相似文献
16.
Square-planar copper(II) and nickel(II) derivatives of the cis-dithiolate N(2)S(2) ligand bis(N,N'-2-mercapto-2-methylpropyl)-1,5-diazocyclooctane, (bme*daco)M, nucleate four Cu(I)Cl moieties, forming M(II)(2)Cu(I)(4)S(4) clusters with unusual triply bridging thiolates, mu(3)-SR, in the topological form of adamantane. As determined by X-ray crystallography, the (bme*daco)M (M = Cu or Ni) metallothiolate serves as a bidentate ligand that bridges four Cu(I) ions, utilizing all lone pairs on sulfurs. Further characterization by electrochemical and electronic spectral measurements suggests greater electron delocalization in the all-copper complex as compared to the NiCu heterometallic complex. Mass spectral data imply that the mixed-metal Ni(II)(2)Cu(I)(4)S(4) is more stable toward CuCl loss than Cu(II)(2)Cu(I)(4)S(4), a result that is corroborated by extraction of Cu(I) by 1,2-bis(diphenylphosphino)ethane in the latter but not the former. 相似文献
17.
Tawarah Khalid M. Jibril Ibrahim Bani-Fwaz Mutasem Z. 《Transition Metal Chemistry》2000,25(6):659-663
The kinetics of the photolytic CO-substitution of CpFe(CO)2SCOR [Cp = C5H5, Bu
t
C5H4, 1,3-Bu2
t
C5H3; R = Me, Bu
t
, Ph, 2-(O2N)C6H4, 3-(O2N)C6H4, 4-(O2N)C6H4, 3,5-(O2N)2C6H3] with PPh3 were studied in CH2Cl2 at 0 °C by i.r. spectroscopy. The reactions yielded exclusively the mono-CO-substituted derivatives, CpFe-(CO)(PPh3) SCOR, and were found to follow second order kinetics with first order dependence on the concentration of each reactant. The differences in rates are discussed in terms of current knowledge pertaining to such reactions. An associative mechanism is proposed to account for the kinetic data of the reactions described. 相似文献
18.
M. E. Kassem T. G. Abdel-Malik M. El-Shabasy R. M. Abdel-Latif A. A. Ibrahim 《Journal of Thermal Analysis and Calorimetry》1987,32(5):1531-1537
The influence of chloroacetic acid amide (AC) on the temperature-dependence of the electrical conductivity (), thermal expansion (ij) and specific heat ((C
p) of triglycine sulphate crystals was studied in the phase transition range (T
c=49°). The addition of isostructural AC increased the electrical conductivity, decreased the thermal expansion and changed theC
p peak. The mechanism is discussed on a thermodynamic basis.
Zusammenfassung Der Einfluß der Zumischung von Chloressigsäureamid (AC) auf die Temperaturabhängigkeit der elektrischen Leitfähigkeit, der Wärmeausdehnung ij und der spezifischen WärmeC p von Triglycinsulfat-Kristallen wurde im Phasenübergangsgebiet (T c=49 °C) untersucht. Die Beimischung von isostrukturellem AC erhöht die elektrische Leitfähigkeit und vermindert die Wärmeleitfähigkeit, während derC p-Peak verändert wird. Der Mechanismus kann thermodynamisch diskutiert werden.
(), () ij) () , T c=49°. , , , , C p. .相似文献
19.
John S. Davies Mark C. Eaton M. Nazar Ibrahim 《Journal of heterocyclic chemistry》1980,17(8):1813-1814
Dedicated to Professor John C. Sheehan on the occasion of his sixty-fifth birthday Nmr and glc analysis of diastereoisomeric mixtures of dipeptides has been used to study the asymmetric hydrogenation of model benzoyldidehydro- and trifluoroacetyldidehydro-dipeptide methyl esters. Chiral enhancement of one isomeric form appears to be independent of the N-terminal acyl group, but is significantly influenced by the choice of amino-acid in the C-terminal position. C-Terminal aromatic amino-acids and their derivatives give the best chiral enhancement during hydrogenation of a neighbouring dehydroamino-acid residue. 相似文献
20.
Alsharaeh EH Ibrahim YM El-Shall MS 《Journal of the American Chemical Society》2005,127(17):6164-6165
We present here direct evidence for the thermal self-initiated polymerization of styrene in the gas phase and establish that the initiation process proceeds via essentially the same mechanism (the Mayo mechanism) as in condensed phase polymerization. Furthermore, we provide structural identifications of the dimers and trimers formed in the gas phase. 相似文献