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This review covers our extensive research activities in the area of fluorine containing phospha- and arsaalkenes as well as selenocarbonyls, which differ considerably in their properties and reactivities from their alkyl and aryl counterparts and thus contribute in a gratifying manner to the still growing field of unsaturated element-carbon compounds of 3rd and 4th row main group elements E. Of particular interest is the influence of the fluorine substituents and other small groups (OR, NR2) with either inductive and/or mesomeric effects on the polarity and reactivity of the EC bond. Addition reactions of proton acidic and hydridic polar HX reactants as well as [2+2], [3+2] and [4+2] cycloadditions have been thoroughly studied. The results obtained allow a classification of the EC systems within five different types, A to E, and prove a change from “normal” to “inverse” heteroalkenes in this sequence. The ligand properties of some derivatives have also been investigated in some detail. 相似文献
45.
Mustafa Odabaolu idem Albayrak Reit
zkanca Fatma Zehra Aykan Peter Lonecke 《Journal of Molecular Structure》2007,840(1-3):71-89
Some new substituted polyhydroxy azo–azomethine compounds were prepared by reaction of tris(hydroxymethyl)aminomethane with (E)-2-hydroxy-5-(phenyldiazenyl) benzaldehyde and its substituted derivatives. The structures of azo and azo–azomethine compounds were determined by IR, UV–vis, 1H NMR and 13C NMR spectroscopic techniques, and/or X-ray diffraction studies. According to IR spectra, all azo–azomethine compounds adopt keto form in solid state. UV–vis analysis has shown the presence of keto–enol tautomerism in solution for all azo–azomethine compounds, except that for nitro substituted derivative, enol form is dominantly favored in solution. At the same time, above mentioned derivative compounds were studied in vitro for their antimicrobial properties. Among the phenylazosalicylaldehyde series compound tested, 4-phenylazosalicylaldehyde, 4-(3-chlorophenylazo)salicylaldehyde, 4-(2-chlorophenylazo)salicylaldehyde, 4-(4-fluorophenylazo)salicylaldehyde, 4-(3-chlorophenylazo)salicylaldehyde and 4-(4-ethylphenylazo)salicylaldehyde showed a weak antimicrobial activity only against gram positive bacteria. On the contrary, phenylazosalicylaldehyde series compounds were reacted tris(hydroxmethyl)aminomethane, that exhibited a strong antimicrobial activity against gram positive bacteria, yeast and mould. Moreover, while the 2-{[1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylimino]methyl}phenol did not show an inhibition on tested microorganism, the addition of phenyldiazine groups to 2-{[1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylimino]methyl}phenol resulted in a strong increases in antimicrobial activity. 相似文献
46.
J. Magoński 《Journal of solution chemistry》1990,19(6):597-607
The significant role of the proton exchange and homoconjugation (formation of AHA– and A1HA
1
–
complexes) equilibria in protonic hetero systems (HA+A
1
–
) has been shown from analysis of published data and from my own simple experiments. It is concluded that there is a need to reconsider some basic hydrogen bond problems. One of these problems-the existence of heteroconjugates in polar solvents — has been verified and illustrated with suitable experimental evidence (IR and UV-VIS spectra). The most accepted experimental evidence for the double minimum potential in the hydrogen bridge has been questioned as being in disagreement with the equilibrium law. A simple relation between the heteroconjugation constant, the parent homoconjugation constants and the proton exchange constant is also postulated. This relation fulfills important theoretical requirements, however, it is not applicable in extreme cases.To the memory of Bogdan Przybyszewski. 相似文献
47.
The root of Carlina acanthifolia All. (Asteraceae) contained 1.0% of essential oil (expressed in g per 100 g of dried plant material). Using GC and GC/MS,
nine components were identified (100% of total oil). The structure of benzyl 2-furylacetylene (carlina oxide), which is the
principal component of the oil (91.5%), was spectrometrically identified.
__________
Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 331–332, July–August, 2005. 相似文献
48.
G. A. Gavrilova M. G. Voronkov N. N. Chipanina L. I. Gubanova O. M. Trofimova Yu. L. Frolov 《Russian Chemical Bulletin》1995,44(4):667-669
The IR spectra of solutions of (=OSi)-(benzoyloxymethyl)trifluorosilane (1),-(benzoyloxymethyl)methyldifluorosilane (2), and butyl benzoate (3) are examined in the region of thev(C=O) stretching vibrations in 24 solvents. The ability of compounds1—3 to undergo specific intermolecular interactions is evaluated from the dependence ofv(C=O) on the Kamlet-Taft (*,, ) parameters, which was obtained for the carbonyl groups involved in the intramolecular coordinate (=OSi) bond and for free carbonyl groups. The corresponding values of the coefficients in the Kamlet-Taft equations are indicative of a weak ability of pentacoordinate silicon compounds1 and2 to undergo acid-base interactions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 689–692, April, 1995. 相似文献
49.
The conditions of formation of Y, La and lanthanide (from Ce(III) to Lu) enanthates were worked out, their composition and their solubilities in water at 291 K were determined, and the conditions of their thermal decomposition were studied. They were prepared as crystalline solids with general formula Ln(C7H13O2)3·nH2O, wheren=2–10. On heating, they decompose in two or three steps. They first lose some water molecules and then decompose to the oxides directly (salts of Y and heavy lanthanides) or via the intermediate formation of Ln2O2CO3 (salts of La, Pr, Nd, Sm and Eu). Only yttrium enanthate dihydrate loses 2 water molecules on heating to form an anhydrous complex, which decomposes directly to Y2O3. The temperatures of dehydration are similar for all complexes (323–343 K), while the temperatures of oxide formation vary irregularly from 823 K for CeO2 to 1078 K for La2O3. 相似文献
50.