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61.
The relationship between the postcuring conditions and the fracture toughness of a bisphenol A‐type epoxy resin cured with acid anhydride was investigated. The glass transition temperature and fragility parameter, derived from the thermo‐viscoelasticity, were used to characterize the epoxy resin postcured under various conditions. Relationship between these two parameters and the fracture toughness was then investigated, based on the fractography results of a microscopic roughness examination of a fractured surface. The values of the glass transition temperature and fragility greatly depended on the postcuring conditions. The glass transition temperature was approximately 400 K when the crosslinking reaction was saturated. The fragility was independent of the saturation of the reaction and varied between 50 and 180. The results of the fracture test and fractography examination showed that there was no direct correlation between the glass transition temperature, the fracture toughness, and the roughness. On the other hand, there was a correlation between the fragility, fracture toughness, and roughness when the glass transition temperature saturated (at 400 K). As the fragility decreased from 180 to 50, the fracture toughness increased from 0.6 to 1.1 MPa · m1/2 at the same glass transition temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 10: 2266–2271, 2002 相似文献
62.
Arachidonic acid hydroperoxide (15-hydroperoxyeicosatetraenoic acid; 15-HPETE) was introduced into human parotid saliva and
incubated at 37°C. Straight phase high-performance liquid chromatography analysis of the reaction mixture showed that 15-HPETE
was detoxified to its reduced form, 15-hydroxyeicosatetraenoic acid, in the presence of glutathione. Therefore, it is concluded
that human parotid saliva possesses fatty acid hydroperoxide-reducing ability. However, its effectiveness was found to be
lower than that of blood plasma. 相似文献
63.
Ti-oxides incorporated within the framework of microporous zeolites and mesoporous molecular sieves were found to exhibit
high and unique photocatalytic activity for the decomposition of NO into N2 and O2 as well as the reduction of CO2 with H2O to produce CH4 and CH3OH. Spectroscopic investigations of these catalytic systems using photoluminescence, UV-vis, XAFS (XANES and FT-EXAFS) and
IR analyses revealed that the charge transfer excited state of the isolated tetra-coordinated Ti-oxides plays a vital role
in these photocatalytic reactions. The reactivity of such Ti-oxides was found to depend strongly on their local structures
which were controlled by the unique framework structures of the micro- and mesoporous material supports. 相似文献
64.
This paper reports the development of a method for simultaneously measuring zeolite, silicate, and phosphate in laundry detergent
products by inductively coupled plasma atomic emission spectrometry. A sample is decomposed under alkaline oxidative conditions
to decompose zeolite, silicate, phosphate, and organic substances. Then hydrochloric acid is added to the decomposed solution
to dissolve aluminum hydroxide precipitate before analysis. This sample preparation procedure was investigated by using a
total organic carbon analyzer and was confirmed to be applicable to simultaneous measurements of zeolite, silicate, and phosphate.
Relative standard deviation for the analysis is less than 2.1%, recovery is more than 99.0%, and the calibration curve gives
a correlation coefficient ofR=1.000. The detection limit of this method for aluminum and silicon is 0.1%, and for phosphorus, 0.2% by weight in the product.
This method is applicable to various laundry detergent products that contain zeolite, silicate, or phosphate and is five times
faster than the three wet chemical methods. 相似文献
65.
Toshiro Hirai Jun-Ichi Yamaki Akihiko Yamaji 《Journal of Applied Electrochemistry》1985,15(3):441-445
To improve the performance of air electrodes, the dependence of iron phthalocyanine (FePc) catalytic effects on preparation methods was examined. The methods used were mixture (Electrode 1), impregnation (Electrode 2) and direct synthesis (Electrode 3). Electrodes 2 and 3 showed higher potentials during cathodic polarization up to 10 mA cm–2 than Electrode 1. The rate of chemical destruction of H2O2 decreased in the order Electrode 3 > Electrode 2 > Electrode 1. Electrode 3 showed the smallest potential drop for a discharge at 10 mA cm–2, 0.09 V after 50 h. However, the potential of Electrode 2 decreased with discharge, becoming 0.09 V lower than that of Electrode 3 after a 50 h discharge at 10mA cm–2. Once the potential drop occurred, the potential was not recovered by resting or by drying the electrode. The potential drop may be caused by deactivation of FePc. One possible reason for such deactivation is the presence of H2SO4, which remained on the electrode after impregnation of the FePc-H2SO4 solution. 相似文献
66.
Various polymeric phosphonium salts containing long alkyl chains (C10? C18) and their corresponding model compounds were prepared, which possess the same hydrophobic structure as that of the common disinfectants (quaternary ammonium salts), and their antibacterial activities were evaluated by means of the viable cell counting method against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative). The polymer with the decyl group exhibited a higher activity than that of the corresponding model compound, particularly against the Gram-positive strain. Furthermore, antibacterial activity of the polymers was found to decrease as the chain length increased. In contrast with the polymers, the antibacterial activity of the corresponding model compounds increased as hydrophobicity of the substituents increased. The antibacterial activity was strongly dependent on the structure, particularly on the length of the alkyl chain. © 1994 John Wiley & Sons, Inc. 相似文献
67.
The configurational sequences of 1,2-unit in a series of hydrogenated syndiotactic 1,2-polybutadienes were determined in relation to the sequence distribution of 1,2- and 1,4-units on the basis of the 13C-n.m.r. signal assignment of the methyl carbons. The observed triad distributions of 1,2- and 1,4-units and configurational distributions of the 1,2-unit are in good agreement with the calculated distributions from transition probabilities. The number average sequence lengths of the 1,2-unit and the 1,2-unit in the racemic addition are 5.7 to 8.0 and 4.1 to 5.4, respectively. From the extrapolation of the plot of the number average sequence length against the crystallinity of the starting 1,2-polybutadienes, the minimum sequence length for crystallization is estimated to be 3.7 for the 1,2-unit in the racemic addition. 相似文献
68.
The application of magnetohydrodynamics (MHD) in the continuous casting process started with the electromagnetic stirring of the stand pool with a traveling magnetic field. It has now advanced to the electromagnetic stirring of molten steel in the mold and the control of molten steel flow by an in-mold direct current magnetic field brake. These applied MHD techniques are designed to further improve the continuous casting process capability. They improve the surface quality of cast steel by homogenizing the meniscus temperature, stabilizing initial solidification, and cleaning the surface layer. They also improve the internal quality of cast steel by preventing inclusions from penetrating deep into the pool and promoting the flotation of argon bubbles. Applied MHD technology is still advancing in scope and methods in addition to the improvement of conventional continuously cast slab qualities. The continuous casting of bimetallic slab by suppressing mixing in the pool is one example of this progress. 相似文献
69.
S.M. Tamborim Takeuchi D.S. Azambuja A.M. Saliba-Silva I. Costa 《Surface & coatings technology》2006,200(24):6826-6831
In this investigation the effect of surface treatments on the corrosion resistance of a commercial NdFeB sintered magnet has been investigated. A solution of 10 g L− 1 NaH2PO4, acidified to pH 3.8 has been used for phosphating this magnet. The corrosion resistance of the phosphated magnet was investigated in a 0.10 mol L− 1 Na2SO4 solution by electrochemical impedance spectroscopy and cyclic voltammetry with rotating disc electrode. The obtained results reveal that the resistance decreases with exposure time due to the development of pores and/or defects in the conversion coating exposing the substrate to corrosive attack. The effect of tungstate incorporation into the phosphate conversion coating resulting from a phosphating treatment prior to immersion in the tungstate solution was evaluated. The proposed treatment consists of re-immersing the phosphated samples in a 0.1 mol L− 1 Na2WO4 solution during 72 h at the open circuit potential (OCP). Under these conditions, the corrosion resistance of the magnet was improved and this was attributed to the formation of a protective layer due to the adsorption of tungstate anions at the metallic substrate exposed in the coating, decreasing metal dissolution. 相似文献
70.
Akihiko Konagaya 《New Generation Computing》2015,33(3):211-212