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91.
92.
Alemani M Peters MV Hecht S Rieder KH Moresco F Grill L 《Journal of the American Chemical Society》2006,128(45):14446-14447
The electric field applied between the tip of a scanning tunneling microscope and a metallic surface is shown to induce the reversible trans-cis isomerization of single azobenzene derivatives adsorbed on a Au(111) surface. The investigated molecule is symmetrically equipped with four tert-butyl groups, which decouple the azobenzene core from the metallic surface, facilitating the formation of highly ordered islands. Due to the spatial extension of the electric field, it is possible to switch many molecules within the same island simultaneously. 相似文献
93.
Certified reference materials (CRMs) of different origin were used to validate the direct determination of total mercury by solid sampling Zeeman atomic absorption spectrometry (SS-ZAAS) and a specially designed furnace. The temperature program provides only for one step. Atomisation of mercury and pyrolysis of the matrix is performed at a constant temperature in the range of 900–1000 °C. Calibration points achieved by CRMs and aqueous solutions are covered by one calibration line, indicating the absence of matrix effects. Relatively high amounts of chlorine, known for causing problems in mercury determination do not influence analytical results. The excellent accuracy of the method results in a very good agreement with the certified values. The precision of SS-ZAAS measurements in a range from 0.5 to 50 ng Hg does not exceed 3% R.S.D. A limit of quantification of 0.008 μg g−1 Hg was achieved. 相似文献
94.
Hamidreza?SalimiEmail author Karl-Heinz?Wolf Johannes?Bruining 《Transport in Porous Media》2012,91(2):391-422
This article deals with developing a solution approach, called the non-isothermal negative saturation (NegSat) solution approach.
The NegSat solution approach solves efficiently any non-isothermal compositional flow problem that involves phase disappearance,
phase appearance, and phase transition. The advantage of the solution approach is that it circumvents using different equations
for single-phase and two-phase regions and the ensuing unstable procedure. This paper shows that the NegSat solution approach
can also be used for non-isothermal systems. The NegSat solution approach can be implemented efficiently in numerical simulators
to tackle modeling issues for mixed CO2–water injection in geothermal reservoirs, thermal recovery processes, and for multicontact miscible and immiscible gas injection
in oil reservoirs. We illustrate the approach by way of example to cold mixed CO2–water injection in a 1D geothermal reservoir. The solution is compared with an analytical solution obtained with the wave-curve
method (method of characteristics) and shows excellent agreement. A complete set of simulations is carried out, which identifies
six bifurcations. The two main bifurcations are (1) when the most downstream compositional wave is replaced by a compositional
shock and (2) when an extra Buckley–Leverett rarefaction appears. The plot of the useful energy (exergy) versus the CO2 storage capacity shows a Z-shape. The top horizontal part represents a branch of high exergy recovery/relatively lower storage capacity, whereas the
bottom part represents a branch of lower exergy recovery/higher storage capacity. 相似文献
95.
Torsten Kolb Thorsten Kroker Jan H. Voigt Karl-Heinz Gericke 《Plasma Chemistry and Plasma Processing》2012,32(6):1139-1155
The influence of water on the plasma assisted conversion of methane and carbon dioxide in a dielectric barrier discharge (DBD) plug flow reactor was studied. The plasma at atmospheric pressure was ignited by a power supply at a frequency of 13.56?MHz. Product formation was studied at a power range between 35 and 70?W. The concentrations of the three gases were altered and diluted with helium to 3?%. FTIR spectroscopy and mass spectroscopy were applied to analyze the inlet and the product streams. The main product of this process are hydrogen, carbon monoxide and ethane. Ethene, ethine, methanol and formaldehyde are generated beside the main products in this DBD in lower concentrations. The conversion of methane, the ratio of the synthesis gas components (n(H2):n(CO)), and the yield of oxygenated hydrocarbons and hydrogen increases by adding water. The total consumed energy reaches lower values for small amounts of water. Additional water does not influence the generated amount of C2 hydrocarbons and of CO, but decreases the carbon dioxide conversion. 相似文献
96.
Xinlai Cheng Hamed Alborzinia Karl-Heinz Merz Herbert Steinbeisser Ralf Mrowka Catharina Scholl Igor Kitanovic Gerhard Eisenbrand Stefan Wölfl 《Chemistry & biology》2012,19(11):1423-1436
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97.
Karl-Heinz Niggl 《Archive for Mathematical Logic》2000,39(7):515-539
Two simply typed term systems and are considered, both for representing algorithms computing primitive recursive functions. is based on primitive recursion, on recursion on notation. A purely syntactical method of determining the computational complexity of algorithms in , called
$\mu$
-measure, is employed to uniformly integrate traditional results in subrecursion theory with resource-free characterisations of sub-elementary
complexity classes. Extending the Schwichtenberg and Müller characterisation of the Grzegorczyk classes for , it is shown $\mathcal{E}_{n+1} = \mathcal{R}^n_1n\ge 1\mathcal{R}^n_i$ denotes the \emph{th modified Heinermann class} based on . The proof does not refer to any machine-based computation model, unlike the Schwichtenberg and Müller proofs. This is due
to the notion of modified recursion lying on top of each other provided by . By Ritchie's result, characterises the linear-space computable functions. Using the same method, a short and straightforward proof is presented,
showing that characterises the polynomial time computable functions. Furthermore, the classes and coincide at and above level 2.
Received: 22 September 1997 / Revised version: 12 May 1999 相似文献
98.
Glasfibre structures feature high potentials for optimization and substitution of conventional materials like steel and aluminum and their alloys. The paper deals with the insertion of glasfibre trusses into thin glasfibre structures to reinforce them. The effective material properties of the glasfibre structures were estimated by experiments and simulations. Furthermore the Young's modulus of the trusses was obtained by bending tests and tension tests. A comparison between bending experiments and bending simulations is given. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
99.
100.
The measure-valued (mv) solutions are commonly defined in the literature simply by putting Young measures into the respective partial differential equations. Here a few examples of mv-solutions to evolution problems (conservation laws, fluid dynamics and a so-called backward-forward heat problem) are re-investigated to show that such definitions are not satisfactorily selective, i.e. they admit (sometimes surprisingly) many mv-solutions apparently without any physical sense. Then an attempt for a selective definition in the case of the backward-forward heat problem is made, resulting to a certain evolution variational inequality. 相似文献