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61.
J. N. Moreira L. M. Almeida C. F. Geraldes M. L. Costa 《Journal of materials science. Materials in medicine》1996,7(5):301-303
Aiming at encapsulation of a hydrosoluble drug, large unilamellar liposomes (LUV) of egg phosphatidylcholine (PC) were coated with a natural polysaccharide derivative, O-palmitoylpullulan (OPP), and its in vitro stability evaluated using fluorescent probes. This coating (in OPP/PC weight ratio of 3) improved significantly the in vitro stability of LUV by decreasing both the permeability and fluidity of the liposomal membrane.This paper was accepted for publication after the 1995 Conference of the European Society of Biomaterials, Oporto, Portugal, 10–13 September. 相似文献
62.
Albert Lamperti Alan Conger Leslie Delaney Marvin Sodicoff 《Drug development and industrial pharmacy》1994,20(12):1971-1989
ABSTRACT
Our transdermal permeation studies of radioprotectors in permeation-enhancing vehicles led us to hypothesize that radiation-induced hair loss could be reduced by topical application of radioprotectors. In the present study we used a hair regrowth assay in “plucked” mice to measure the radioprotective effectiveness of WR-1065, cysteine and TEMPOL when they were dissolved in a variety of vehicles, i.e., saline, dimethyl formamide (DMF), propylene glycol (PG), dimethyl sulfoxide (DMSO), ethanol. Protector effectiveness varied with radiation dose and vehicles. At 600 R, WR-1065 or cysteine, in any vehicle, reduced radiation-induced baldness scores; at 800 R, only WR-1065 in DMF and cysteine in saline, produced some protection. TEMPOL in ethanol produced protection at both the 600 and 800 R. Results suggest that suitably chosen topical application of protector/vehicle combinations can reduce radiation-induced hair loss. 相似文献
Our transdermal permeation studies of radioprotectors in permeation-enhancing vehicles led us to hypothesize that radiation-induced hair loss could be reduced by topical application of radioprotectors. In the present study we used a hair regrowth assay in “plucked” mice to measure the radioprotective effectiveness of WR-1065, cysteine and TEMPOL when they were dissolved in a variety of vehicles, i.e., saline, dimethyl formamide (DMF), propylene glycol (PG), dimethyl sulfoxide (DMSO), ethanol. Protector effectiveness varied with radiation dose and vehicles. At 600 R, WR-1065 or cysteine, in any vehicle, reduced radiation-induced baldness scores; at 800 R, only WR-1065 in DMF and cysteine in saline, produced some protection. TEMPOL in ethanol produced protection at both the 600 and 800 R. Results suggest that suitably chosen topical application of protector/vehicle combinations can reduce radiation-induced hair loss. 相似文献
63.
Blind MPEG-2 video watermarking robust against geometric attacks: a set of approaches in DCT domain.
A set of robust MPEG-2 video watermarking techniques is proposed, focusing on commonly used typical geometric processing for bit-rate reduction, cropping, removal of any rows, arbitrary-ratio downscaling, and frame dropping. Both the embedding and the extraction of watermarks are done in the compressed domain, so the computational cost is low. Moreover, the watermark extraction is blind, i.e., no original unwatermarked MPEG-2 video is needed for watermark extraction. The presented technique is applicable not only to MPEG-2 video, but also to other DCT-based coding videos. Selected experimental results validate our techniques. 相似文献
64.
Preacher Kristopher J.; Rucker Derek D.; MacCallum Robert C.; Nicewander W. Alan 《Canadian Metallurgical Quarterly》2005,10(2):178
Analysis of continuous variables sometimes proceeds by selecting individuals on the basis of extreme scores of a sample distribution and submitting only those extreme scores to further analysis. This sampling method is known as the extreme groups approach (EGA). EGA is often used to achieve greater statistical power in subsequent hypothesis tests. However, there are several largely unrecognized costs associated with EGA that must be considered. The authors illustrate the effects EGA can have on power, standardized effect size, reliability, model specification, and the interpretability of results. Finally, the authors discuss alternative procedures, as well as possible legitimate uses of EGA. The authors urge researchers, editors, reviewers, and consumers to carefully assess the extent to which EGA is an appropriate tool in their own research and in that of others. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
65.
Fbio Gomes Costa Elias Andrade Braga Soraia Teixeira Brando Alexandre de Freitas Espeleta Zênis Novais da Rocha Lílian Maria Tosta Simplício Emerson Andrade Sales 《Applied Catalysis A: General》2005,290(1-2):221-226
Infrared and UV–vis studies of metallocene immobilization on silica are reported here. The results have indicated changes in the Zr coordination sphere of metallocene depending on the immobilization route used. The reaction of [(Cp)2ZrCl2] with silica formed [(Cp)2ZrCl]+[SiO]− species. The same metallocene, reacting with TMA modified silica, formed monomethylated and dimethylated species by the substitution of chloro for methyl ligands, stabilized on the surface by interaction with “MAO-like” species (methylaluminoxane, MAO). These monomethylated and dimethylated cationic zirconium species are the active centers for the polymerization reaction. Different order of TMA addition in the silica modification step generated surface species of a similar nature, differing in their relative quantities. The highest amount of these active species was obtained when the support was added to the TMA solution rather than adding the TMA solution to the silica support. This was the most significant parameter affecting catalytic activity in ethylene polymerization. 相似文献
66.
Pierre Darcy Patrick Da Costa Henry Mellotte Jean-Michel Trichard Grald Djga-Mariadassou 《Catalysis Today》2007,119(1-4):252-256
To comply with the new regulations on particulate matter, car manufacturers more and more commonly use diesel particulate filters (DPF). The working of these systems needs to periodically burn soot that has been accumulated during the loading of the DPF. This paper describes the kinetics of the non-catalytic and catalytic oxidation of real diesel soot with oxygen. From these experiments, mechanisms for catalyzed and non-catalyzed soot oxidation have been proposed. 相似文献
67.
Disassembly sequence planning in a disassembly cell context 总被引:2,自引:0,他引:2
In this paper a two-phase approach is proposed for determining the optimal disassembly sequence when the disassembly system has a cellular configuration. Operations are first grouped into cells based on the resources they require with the goal of minimizing machine acquisition costs. The aim is to group together those operations that use similar equipment in order to achieve good utilization levels of such equipment. A maximum cell size may be imposed. Once the cells have been formed and the operations have been assigned to them, a metaheuristic algorithm (namely GRASP) is used to search for the disassembly sequence for each product that leads to the minimum number of intercellular movements. To account for uncertainty regarding the condition in which the product may arrive, each disassembly task is assumed to be required with a certain probability, regardless of the other tasks. AND/OR precedence relations among the disassembly tasks are also considered. The proposed approach is illustrated on a randomly generated disassembly problem. 相似文献
68.
Juan Carlos Benítez Carlos A. Giúdice Vicente J. D. Rascio 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(8):387-394
This paper discusses the bioactivity of antifouling paints based on organotin toxicants, such as tributyltin fluoride (TBTF) and triphenyltin fluoride (TPTF). These compounds were used alone or mixed as the main toxicant in formulations. The use of TPTF or mixtures of TPTF and TBTF, with vinyl binders, led to paints with satisfactory bioactivity during a 24 months immersion period. With the same binders, TBTF alone provided only 12 months of antifouling protection. The correlation coefficients calculated from the fouling attachment values and the rosin content in the binder showed that the bioactivity of the tested formulations depended on the solubility of the toxicant in sea water and on the composition and solubility of the binders. 相似文献
69.
David N. Johnson Alan A. Johnson 《Fatigue & Fracture of Engineering Materials & Structures》1985,8(3):287-294
The results of Stan ton and Bairstow (1908) have been reanalyzed to yield information on the composition dependence of the low cycle impact fatigue properties of pearlitic plain carbon steels. It has been found that the energy absorbed per impact, Ei, and the number of impacts are failure, Nf, are related by the equation: In this equation q is determined by the carbon, manganese and silicon contents of the steel; Eo is the impact endurance limit; and C and D are constants. The curve represented by this equation intersects that representing the Johnson-Keller high cycle impact fatigue equation at a value of logeNf equal to 1/C. Thus, the transition from low to high cycle impact fatigue occurs at this value of logeNf. 相似文献
70.
Martin E. Valdez H. Shibata Alan W. Cramb 《Metallurgical and Materials Transactions B》2006,37(6):959-965
The objective of this study is to determine the conditions under which the inclusions present in liquid steel can act as heterogeneous
nucleants for solidification. In order to study the factors that define the undercooling of a given metal/oxide couple, the
undercooling of a pure iron sessile droplet in contact with Al2O3, ZrO2, and MgO substrates was measured under controlled oxygen partial pressures by observing droplet recalescence. The results
showed that the undercooling of iron, in contact with a particular substrate, did not have a unique value, but was significantly
affected by the oxygen content on the gas phase. For oxygen partial pressures between 10−21 and 10−19, the undercooling of iron on ZrO2 substrates was stable and around 290 °C. In the same range of oxygen partial pressure, the undercooling of iron on MgO substrates
remained below 100 °C due to the low stability of this oxide. At lower oxygen contents, substrate decomposition might be the
cause for the observed drop in the undercooling of iron on ZrO2 substrates to below 100 °C. The undercooling also decreased for increasing oxygen content as verified when the gas was changed
from gettered Ar/Ar-H2 to CO/CO2 mixtures. The variation in undercooling was related to the wetting of the substrate by the liquid metal, where the deep undercooling
observed in the ZrO2 experiments occurred when the highest contact angle between the liquid metal and the substrate was achieved. 相似文献