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821.
Hyung-Jun Kim Sung-Sik Lee Jin-Eon Sohn Eiji Furuya Yasushi Takeuchi Kenneth E. Noll Seiichi Yamashita 《Korean Journal of Chemical Engineering》1996,13(4):399-403
Experimental uptake curves wore collected by a shallow bed technique at 298.2 K. Adsorbent particles employed were macroreticular
(MR) resins and adsorbates were phenol and its derivatives. From the uptake curves and equilibrium data obtained by the so-called,
batch bottle technique, equilibrium and kinetic parameters were determined and the effects of functional groups within both
adsorbate molecules and adsorbent particles on those parameters are discussed. From the results, it became clear that physical
and chemical properties, surface area of adsorbent functional group, and solubility of adsorbates affected adsorption equilibria.
Also, nitro-functional groups seemed to hinder adsorption equilibria and kinetics. Results can be explained by the resonance
effects of functional groups. 相似文献
822.
Recent efforts to improve the accuracy of performance appraisal ratings have concentrated on individuals, with little attention given to the role groups might play as performance raters. Thus, the goal of this study was to compare the behavioral rating accuracy of groups vs individuals. Using a behavioral checklist, 191 Ss rated the behavior of a police officer individually or in 4-person groups. Ratings were made immediately or after a 5-day delay. Measures of memory sensitivity and decision criteria indicated that in the delayed rating condition, groups remembered the behaviors more accurately than did individuals, whereas in the immediate rating condition, groups and individuals did not differ. However, groups also demonstrated greater response bias, adopting a more liberal decision criterion than individuals. Results suggest that groups can be a help, but they are not a panacea for the problems of rating accuracy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
823.
A prediction method for the fatigue life of polymercomposites under arbitrary frequency, load ratio andtemperature was extended to that of polymer compositestructures. The method is based upon fourhypotheses: (a) the same mechanism applies to static,creep and fatigue failure, (b) the same time-temperaturesuperposition principle holds for all failure loads, (c) thelinear cumulative damage law applies to monotone loading, and(d) there exists a linear dependence of fatigue failure load uponload ratio. The tensile tests of a conically shapedjoint system for fiber reinforced plastics (FRP joint)for static, creep and fatigue loadings were conductedat various temperatures. The validity of theproposed method and the applicability of thehypotheses for this FRP joint are discussed. 相似文献
824.
Needle shaped single crystals of polyoxymethylene were found to provide a unique substrate for the crystallization of polymers from the molten state, as the formation of ‘shish-kebabs’ had been observed from solutions. When needle shaped crystals were embedded in the melt of the same polymer, polyoxymethylene, or a copolymer, the crystallization started from the surface and the growth proceeded in the form of a cylindrite, comprising a pile of chain-folded lamellar crystallites. Since the epitaxy required much smaller under cooling, transformation by this mechanism was distinct and pre-dominated over the normal, spherulite formation. The same kind of effect was also observed for polyethylene. The feature was elucidated by means of microscopic observations, differential scanning calorimetry, small-angle X-ray scattering etc. and the mechanism, discussed. 相似文献
825.
826.
A comparative study of the stress induced crystallization of natural (Hevea, Guayule) and synthetic high cis-1,4-polyisoprenes at room temperature is presented. Hevea and Guayule are both found using WAXS to crystallize into the unit cell of Morss and Bunn previously described for Hevea. DSC studies of polyisoprenes held at ?25°C indicate that Hevea and Guayule crystallize more rapidly than synthetics. Studies of relative birefringence and stress decay following uniaxial extension confirm this. Under conditions of comparison at the same stress, raw Hevea crystallizes more rapidly than extracted Hevea, Guayule, and the other polyisoprenes. 相似文献
827.
Kinetic studies have been made on the over-crystallisation of polyoxymethylene on needle-like crystals, which takes place cylindrically around the needles by forming a pile of lamellar crystallites, using the ordinary spherulitic crystallisation as reference. The growth kinetics were investigated, by means of microscopy and differential scanning calorimetry (DSC), and the resultant structure was examined by small-angle X-ray scattering and melting temperature measurements. The discontinuity found for their theoretical plot was assumed to be attributable to the difference in the type of crystallisation. The lamellar surface free energies obtained for the over-growth were smaller than those for the spherulitic growth, i.e., σe = 42.1 and σs = 2.94 erg/cm2 against σe = 53.4 and σs = 4.97 erg/cm2. The epitaxy effect was elucidated from the analysis of DSC curves during cooling and the combined free-energy, σeσs = 89.4 erg2/cm4, was estimated for the initial deposit on the needle surface. 相似文献
828.
829.
The electrical breakdown of alumina materials is one of the difficulties in higher electric field applications. This breakdown takes place due to localized excess heating, which is induced by surface defects, multipactor, and surface discharge. These factors were evaluated for several commercial alumina ceramics using a scanning electron microscope and comparing these observations with high-power rf transmission tests. The results indicate that alumina ceramics without F-center defects and lower surface charging are feasible for higher electric field operation. 相似文献
830.
TiN film is often coated on alumina rf windows to suppress multipactor due to high secondary electron emission (SEE) coefficients. In this paper, SEE coefficients of alumina ceramics and sapphire coated with TiN films of various thicknesses are investigated. The SEE coefficients were measured using a scanning electron microscope with a single-pulse electron beam (100 pA, 1 ms). The SEE coefficients of TiN-coated alumina ceramics were lower than those of uncoated ones and nearly unity for TiN thickness of more than 1 nm, even with incident energy of 1 keV. To emulate multipactor-induced surface heating, the SEE coefficients were also measured at high temperature. The results showed a decrease in the SEE coefficients with temperature for TiN thickness of more than 0.5 nm. TiN coating on an rf window should be as thin as possible, and 0.5-1 nm may be the optimum thickness for suppressing multipactor. 相似文献