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71.
Intramolecular Michael reaction of methyl (R)-6-(tert-butoxycarbonylamino)oxy-4-hydroxy-2-hexenoate, in turn obtained from tert-butyl (R)-3-hydroxy-4-pentenoate, paved the way to the synthesis of both enantiomers of 2-oxa-6-azabicyclo[3.3.0]octan-3-one (the Geissman-Waiss lactone), a precursor for necine bases. Key intermediates in this approach were represented by enantiomeric bicyclic lactones incorporating a [1,2]-oxazinane nucleus, which has been conveniently used to install the pyrrolidine framework of the target compounds through a synthetic scheme featuring the reduction of the nitrogen-oxygen bond and an intramolecular SN2 reaction. 相似文献
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Remarkable generality in scope of new C9-benzoylcupreines bearing electron-withdrawing substituents for the nitroaldol condensation with fluoromethyl ketones is presented. Both tri- and difluoromethyl ketones provided excellent levels of stereoinduction (ee 76-99%) under mild reaction conditions and low loading of catalyst (1-5 mol%). 相似文献
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Donato?BiniEmail author Francesco?De?Paolis Andrea?Geralico Gabriele?Ingrosso Achille?Nucita 《General Relativity and Gravitation》2005,37(7):1263-1276
The periastron position advance for geodesic motion in axially symmetric solutions of the Einstein field equations belonging to the Weyl class of vacuum solutions is investigated. Explicit examples corresponding to either static solutions (single Chazy-Curzon, Schwarzschild and a pair of them), or stationary solutions (single rotating Chazy-Curzon and Kerr black hole) are discussed. The results are then applied to the case of S2-SgrA* binary system of which the periastron position advance will be soon measured with a great accuracy. 相似文献
76.
Pier Giovanni Baraldi Gian Piero Pollini Daniele Simoni Achille Barco Simonetta Benetti 《Tetrahedron》1984,40(4):761-764
A convenient entry to both title compounds 1 and 2, as well as to cis- and trans-4-iodomethyl-bicyclo [3.1.0]-hexan-2-ones 3and 4 and to 4-methyl-bicyclo [3.1.0]-hex-3-en-2-one 5 involving base-promoted reactions of cis- and -trans-3,4-diiodomethylcyclopentanones 6 and 7 is reported, and the behaviour of 6 and 7 towards different bases. bfv40bp4761b 相似文献
77.
[reaction: see text] An efficient electrochemical synthesis of 5-methylene-1,3-oxazolidin-2-ones (2a-h) from acetylenic amines (1a-h) and carbon dioxide has been achieved by direct electrolysis of solution of MeCN and Et4NPF6 containing the amine, with subsequent CO2 bubbling and heating. The yields vary from good to excellent, the conditions are mild, and the use of toxic and harmful chemicals and catalysts is avoided. 相似文献
78.
Paola Stagnaro Giorgio Mancini Achille Piccinini Simona Losio Maria Carmela Sacchi Caterina Viglianisi Stefano Menichetti Alessandro Adobati Sara Limbo 《Journal of Polymer Science.Polymer Physics》2013,51(13):1007-1016
An efficient procedure for the copolymerization of ethylene (E) with a novel norbornenic comonomer (NArOH) bearing a stabilizing moiety analogous to commercial antioxidant 2,6‐di‐tert‐butyl‐4‐methylphenol (BHT) is successfully developed. This study is aimed at: i) tuning the concentration of the stabilizing function along the polymer chain, and ii) preparing “nonreleasing” polymeric additives specifically destined to protect commercial low‐density polyethylene (LDPE). Films obtained from blends of the novel E/NArOH copolymers with an antioxidant‐free LDPE matrix are characterized by superior thermal, thermo‐oxidative, and photostability when compared not only with neat LDPE films but also with films stabilized by the commercial BHT additive. Specific migration tests conducted in order to investigate the nonreleasing character of the novel macromolecular additives confirm the reduced risk of migration, from the films into food simulants, of unreacted comonomer or degradation products bearing the antioxidant moiety. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013 , 51, 1007–1016 相似文献
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Monica Orsini Isabella Chiarotto Mikhail N. Elinson Giovanni Sotgiu Achille Inesi 《Electrochemistry communications》2009,11(5):1013-1017
N-heterocyclic carbenes generated by electrochemical reduction under galvanostatic control of 1,3-dialkylimidazolium-based ionic liquids were employed as organocatalysts in the benzoin condensation reaction. Benzoin was isolated in a good yield (84%) by a catalytic amount of carbene (20%). The use of toxic, volatile molecular solvents as well as any addition of bases has been avoided. 相似文献