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81.
Suzuki-Miyaura cross-coupling reactions of tetrabromo-p-benzoquinone provide a convenient approach to tetraaryl-p-benzoquinones. 相似文献
82.
Lars
hrstrm Vratislav Langer Mohamed Ghazzali 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(8):m277-m279
In the title compound, [Fe(NCS)2(C12H10N4)(CH4O)2]n, at 153 (2) K, the Fe atom is located on an inversion centre, as is the centre of the N—N bond in the ligand molecule. The structure contains a one‐dimensional coordination polymer with an Fe...Fe distance of 15.866 (7) Å and can be described as two interpenetrating six‐connected primitive cubic (pcu) three‐dimensional networks when additional intermolecular O—H...S hydrogen bonds are taken into account. The compound is not isostructural with the corresponding MnII compound as they differ in the rotation around the M—O bond by 90°, giving rise to completely different hydrogen‐bond patterns. This study demonstrates the impact of conformational differences on the final supramolecular arrangement. 相似文献
83.
84.
Compounds of the novel 7,10a-methanocycloocta[c,d]indazole ring-system 5, 7 are obtained by the action of hydrazines on 1-chloro(or hydroxy)diisophor-2,7-en-3-ones 1–3 . Their formulation agrees with their origin and their chemical and spectral characteristics. Analogous syntheses of two comparable ring-systems include the production of a substituted 7,10a-methanocycloocta[g,h][2,1]benzisoxazole 10 by a facile cyclodehydration of the oxime of diisophorone 9a , and that of the indole-analogue 13 by the action of aniline on diisophorone-1-carboxylic acid 11 . 相似文献
85.
Raymond Langer Johannes Lotz Liming Cai Florian vom Lehn Klaus Leppkes Uwe Naumann Heinz Pitsch 《Proceedings of the Combustion Institute》2021,38(1):777-785
Many studies apply sensitivity analysis to explore the impact of reaction kinetic parameters on model predictions. The importance of thermochemical and transport data is often assumed to be relatively low. While this is true for specific combustion properties of hydrocarbons, the role of thermochemical and transport data in combustion processes of nitrogen-containing molecules remains to be investigated. Thus, this work applies adjoint sensitivity analysis to the complete set of parameters in combustion models, i.e., kinetics, thermodynamics, and transport data. This integral approach increases the number of parameters considered in the sensitivity analysis drastically. Compared to forward sensitivity analysis, the adjoint approach is very efficient for a large number of parameters, and analysis with several thousand parameters can be performed in seconds. Nitrogen oxide formation in methane/air flames and laminar burning velocities of ammonia/air flames are considered as prediction targets. Sensitivity analysis results for kinetic, thermochemical, and transport data are compared by jointly considering all appearing parameter uncertainties. The comparison reveals that, due to their importance for the equilibrium constants of elementary reactions, the optimization potential of thermodynamic properties is often similarly high as that of the kinetics parameters. Transport parameters are found to be of the lowest priority for the model development due to their low uncertainties, even though high sensitivities are determined for several of them. More specifically, the analysis for the laminar burning velocities of ammonia/air flames reveals a high optimization potential for parameters in the N2-amine chemistry, including the molar heat capacities of N2H2, N2H3, and NH. Interestingly, analyses with different mechanisms reveal strongly diverging results, especially regarding the importance of reactions with OH, which is uncommon when considering the combustion of hydrocarbons. 相似文献
86.
Mostafa Kiamehr Batoul Alipour Leyla Mohammadkhani Behzad Jafari Peter Langer 《Tetrahedron》2017,73(21):3040-3047
Various novel polycyclic thiopyranoindol annulated [3,4-c]quinolone derivatives were synthesized via domino Knoevenagel-hetero-Diels–Alder reactions of indoline-2-thions and novel N-acrylated anthranilaldehydes in refluxing ethanol as a solvent in the presence of 20 mol% ZnBr2 as a Lewis acid catalyst. All reactions proceed with high yields with excellent regio- and stereoselectivity. 相似文献
87.
Rasheed Ahmad Khera Rasheed Ahmad Nguyen Thai Hung Alexander Villinger Peter Langer 《Tetrahedron》2010,66(9):1643-1652
Functionalized triarylmethanes are prepared in two steps by FeCl3-catalyzed benzylation of acetylacetone to give 3-(diarylmethyl)pentane-2,4-diones and subsequent formal [3+3] cyclization of the latter with 1,3-bis(trimethylsilyloxy)-1,3-dienes. 相似文献
88.
The base-mediated cyclocondensation of 1,3-dicarbonyl compounds with 4-chloro-3-nitrocoumarin provides a convenient approach to various chromeno[3,4-b]pyrrol-4(3H)-ones. 相似文献
89.
Rasheed AhmadKhera Rasheed Ahmad Ihsan Ullah Obaid‐Ur‐Rahman Abid Olumide Fatunsin Muhammad Sher Alexander Villinger Peter Langer 《Helvetica chimica acta》2010,93(9):1705-1715
2‐Aryl‐2,3‐dihydro‐4H‐pyran‐4‐ones were prepared in one step by cyclocondensation of 1,3‐diketone dianions with aldehydes. The use of HCl (10%) for the aqueous workup proved to be very important to avoid elimination reactions of the 5‐aryl‐5‐hydroxy 1,3‐diones formed as intermediates. The TiCl4‐mediated cyclization of a 2‐aryl‐2,3‐dihydro‐4H‐pyran‐4‐one with 1,3‐silyloxybuta‐1,3‐diene resulted in cleavage of the pyranone moiety and formation of a highly functionalized benzene derivative. 相似文献
90.
Obaid-Ur-Rahman Abid Muhammad Nawaz Nasim Hasan Rama Peter Langer 《Tetrahedron letters》2010,51(4):657-7025
The [4+2] cycloaddition of 1-ethoxy-2-chloro-1,3-bis(trimethylsilyloxy)-1,3-diene with dimethyl acetylenedicarboxylate (DMAD) afforded dimethyl 4-chloro-3,5-dihydroxyphthalate. Site-selective Suzuki-Miyaura reactions of its bis(triflate) provide a convenient approach to 3,5-diaryl-4-chlorophthalates containing two different aryl groups. 相似文献