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51.
Monobromoferrocene (1) was obtained in 95% yield from ferrocene via lithiation with tert-BuLi/KO-tert-Bu and bromination with dibromotetrachloroethane. Starting from 1 mixtures of 1,2-dibromoferrocene (2) and apparently unreacted 1 (ranging from 80:20 to 50:50, depending on the reaction conditions) can be obtained via a lithiation- zincation- bromination sequence. These mixtures can be transferred directly with a tenfold excess of Lithium-tetramethylpiperidinide, followed by bromination with 1,1,2,2-tetrabromoethane to pentabromoferrocene (3), in an overall yield of 36% starting from ferrocene. The molecular structures of 3 and of 1,2,3-tribromoferrocene (4) have been determined by X-Ray diffraction. 相似文献
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To be able to meet the demands of low emissions and fuel consumption ofmodern combustion engines, new ways have to be found to control thecombustion. We use new sensors to measure the pressure in the combustionchamber and analyze this signal with a neural network in order to receiveseveral form factors which can be used to control the ignition timing. Theneural network is trained off line with measured data and used on line toderive the form factors. The proposed algorithm can be computed in real timeon conventional digital signal processors and adapted to new engines withvery little effort. 相似文献
54.
Roland Rieger Karlheinz Ballschmiter 《Fresenius' Journal of Analytical Chemistry》1995,352(7-8):715-724
A municipal sewer system has been investigated for the sources of a set of semivolatile compounds, such as polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethene (4,4'-DDE), and chlorinated paraffins (CP), using sewer films as the sampling medium. A cleanup method for these semivolatile compounds in sewer films is described. The project has been undertaken for the differentiation and localization of specific inputs of xenobiotics from defined regions of the city. A unique pattern of PCDD/PCDF found in sewage sludge has led to the search for a specific source within the sewer system, which has finally been localized as a distinct plant. Other organochlorine compounds proved to be significant indicators for industrial and domestic sewers. PCB appeared as an industry correlated parameter, while 4,4'-DDE indicated domestic sewers. Chlorinated paraffins have been detected in the mg/kg range and are markers and indicators for metal-working industries. Finally, the release of CP by the sewage treatment plant, into the nearby river, has been investigated.Dedicated to Professor Dr. Dr. h.c. mult. J. F. K. Huber on the occasion of his 70th birthday 相似文献
55.
Karlheinz Gröchenig 《Advances in Computational Mathematics》2003,18(2-4):149-157
It is shown that every localized frame is a finite union of Riesz sequences. This is a partial solution to a question of Feichtinger. 相似文献
56.
A study of the Xαβ-exchange approximation on atoms for use in molecular and solid-state calculations
Karlheinz Schwarz 《Chemical physics》1975,7(1):94-99
The Xαβ exchange approximation is applied to atoms and its universal (Z-independent) character is demonstrated. Its practical applicability to molecules and solids is critically analysed by a comparison with the Xα- and HF approximations. The influence of the modifying function which is needed to make the exchange inhomogeneity correction (β-term) finite for large r is studied. The validity of the virial theorem is discussed. 相似文献
57.
Karlheinz Spallek 《Mathematische Annalen》1977,227(3):277-286
Ohne Zusammenfassung 相似文献
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Thom Karlheinz Schneider Richard T. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1977,5(4):259-272
Gaseous Fuel Nuclear Reactors are externally moderated and contain the fissile material inside a cavity where it is suspended by fluid mechanics forces. The gaseous phase of the nuclear fuel permits operation of the reactor at temperatures much higher than the melting point of all materials. NASA has originally supported relevant research for space propulsion. The continuation of this work includes now research on power generation on Earth for improved economy and environmental acceptability. In reactor experiments with enriched uranium hexafluoride, UF6, a critical mass of 6 kg is determined. Pressurized UF6 remains chemically stable at temperatures up to 2000 kelvins. The interaction of fission fragments with their gaseous environment causes preferential excitation and ionization, leading to non-equilibrium optical radiation. Powerful fluxes of photons are expected to become a superior mechanism of energy extraction from the fissioning gas or plasma in the reactor. The pumping of lasers solely by fission fragments is realized in a variety of lasants. A near term objective of the NASA gaseous fuel reactor program is a benchmark experiment at 100 kw power and at a gas temperature of 1600 kelvins, demonstrating the feasibility of major advances in reactor technology. A concerted research effort is leading to this experiment. A plasma core cavity reactor for high specific impulse propulsion in space reminas a long range goal. 相似文献
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