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1.
Larissa Canilha Walter Carvalho Marco Giulietti Maria Das Graças Almeida Felipe João Batista Almeida E Silva 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(5):715-721
BACKGROUND: Xylitol bioproduction from lignocellulosic residues comprises hydrolysis of the hemicellulose, detoxification of the hydrolysate, bioconversion of the xylose, and recovery of xylitol from the fermented hydrolysate. There are relatively few reports on xylitol recovery from fermented media. In the present study, ion‐exchange resins were used to clarify a fermented wheat straw hemicellulosic hydrolysate, which was then vacuum‐concentrated and submitted to cooling in the presence of ethanol for xylitol crystallization. RESULTS: Sequential adsorption into two anion‐exchange resins (A‐860S and A‐500PS) promoted considerable reductions in the content of soluble by‐products (up to 97.5%) and in medium coloration (99.5%). Vacuum concentration led to a dark‐colored viscous solution that inhibited xylitol crystallization. This inhibition could be overcome by mixing the concentrated medium with a commercial xylitol solution. Such a strategy led to xylitol crystals with up to 95.9% purity. The crystallization yield (43.5%) was close to that observed when using commercial xylitol solution (51.4%). CONCLUSION: The experimental data demonstrate the feasibility of using ion‐exchange resins followed by cooling in the presence of ethanol as a strategy to promote the fast recovery and purification of xylitol from hemicellulose‐derived fermentation media. Copyright © 2008 Society of Chemical Industry 相似文献
2.
Hans-Dirk Walter 《Informatik-Spektrum》2008,31(4):333-343
Zusammenfassung ,,Rich Internet Applications“ (RIA) sind Webapplikationen, die mit einer wesentlich interaktiveren Benutzerschnittstelle ausgestattet
sind, als wir das bisher von den auf HTML basierten ,,poor ugly web applications“ (PUWA) gewohnt waren. 相似文献
3.
Prof. Dipl.-Ing. Dr.techn. Walter Gretler Prof. Dr. Si-min Zeng 《Forschung im Ingenieurwesen》1996,62(5):105-115
A numerical simulation of unsteady compressible flow induced by two high-speed trains in oncoming traffic within a tunnel
is presented. The computations were carried out by means of a second-order accurate Harten-Yee type upwind TVD scheme. In
order to take the effect of friction into account, a source term is included in the governing flow equations. In the computation,
moving boundary configurations were used to simulate the two trains passing through the tunnel. As geometrical configuration,
the Einmalberg tunnel, where experimental data are available, was selected. The computational results agree reasonably well
with their experimental counter-part. The waves interaction and the waves propagation process at the tunnel entrance and exit
as well as within the tunnel are addressed. Finally, the influence on the transmitted waves at the tunnel exit portal and
the variation of the negative pressure drop during the passage of the two trains are discussed. 相似文献
4.
Systemised serendipity for producing computer art 总被引:4,自引:0,他引:4
David Walter 《Computers & Graphics》1993,17(6):699-700
Serendipity applied to Newton's method, and its derivative the Secant Method, produces unusual and beautiful fractal patterns. Serendipity may be systemised, for example, by the introduction of a perturbation parameter P1, [1] to facilitate searches for interesting pattern variations. 相似文献
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Samuel L. Manzello Richard G. Gann Scott R. Kukuck Kuldeep Prasad Walter W. Jones 《火与材料》2007,31(5):297-310
A gypsum wall assembly was exposed to an intense real‐scale compartment fire. For the wall assembly, temperatures were measured at the exposed face, within the stud cavity, and at the unexposed face during the fire exposure. Total heat flux gauges were used to measure the temporal variation of the energy incident on the walls, and cameras, both visual and infrared, were used to image the unexposed face of the wall assembly during the fire exposure. The behaviour of the wall assembly under the fire load is discussed as are current model results for a simulation of the fire test. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
10.
Walter Savassi Eddie Mancini 《The Structural Design of Tall and Special Buildings》2004,13(4):315-333
In a previous paper (Mancini and Savassi, 1999), it was shown that every plane panel, used to brace tall building structures, can be easily and generally approached through the use of the continuous medium technique (CMT) (Albigés and Goulet, 1960). In that paper, following a so‐called local formulation, i.e., by deriving the governing differential equations system of the panel, in terms of u(z) panel horizontal displacement and wi columns or walls axial displacements, the equivalence (likeness) of formal mathematics, and hence of structural behaviour, between the panel composed by a pair of shear walls associated by lintel beams and another panel formed by the plane association, by pinned horizontal bars, of one shear wall and one single bay frame, was also shown. In both cases, axial deformations due to axial forces on vertical members were taken into account. In this paper, confirming those conclusions, but now following a global formulation (i.e., considering the total potential energy of each panel: strain energy plus applied load potentials), the mathematical equivalence between those two types of plane panels is again revealed by comparison of their two total potential energy analytical expressions. Additionally, based on that variational approach, the one‐dimensional finite element formulation is presented. This enlarges the possibilities of solutions for more general types of panels, like those with variable geometry or loading, without any further difficulty. The procedure, for any type of panel, can be codified in one single computer program, very similar to those used to solve plain continuous beam problems. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献