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41.
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43.
The rubber elasticity characteristics of poly(n-butyl acrylate) networks crosslinked with tetrafunctional (EGDM and TEGDM), hexafunctional (TMPTM), and octafunctional (PETMA) vinyl crosslinkers were investigated. Both gel—sol analyses and crosslinking efficiency theories were used to evaluate the chemical crosslink contribution vc and the entanglement contribution vp to the elastically effective network chains ve, and the effect of the crosslink junction functionality f on the front factor g. The front factors obtained were in the range of 0.50–0.92, depending upon the network system and the counting method for vc. The relationship of g = [(f ? 2)/f]/〈r2〉/〈r2〉o seems reasonable in the case of the tetrafunctional and hexafunctional networks, but deviates in the case of the octafunctional network. It is also evident that the functionality scheme for the front factor could only be valid under the postulate of a high vp, which increases with increasing vc, especially in the high vc region near the Gaussian limit. The average energetic contribution to the retractive force of the present systems, expressed as Fe/F, is ?0.30 ± 0.1. 相似文献
44.
Young Jae Shin Do Hyeon Yang Mee Hye Oh Yeo Seong Yoon Jae Sup Shin 《Journal of Industrial and Engineering Chemistry》2009,15(2):238-242
Hard coatings were deposited on a polycarbonate plate using a sol–gel process with a melamine derivative, poly(vinyl alcohol) (PVA), and silicates and examined as potential substitutes for glass in cars. PVA was partially functionalized with (3-isocyanatopropyl)triethoxysilane, and the synthesized polymer was used to form a coating solution with methylated poly(melamine-co-formaldehyde), tetraethoxysilane, and methyltriethoxysilane. The coatings that contained both the melamine and silicate structures were deposited using a sol–gel process. The optimum conditions and formulation to obtain excellent physical properties of the coating were determined. Smooth coatings with the hardness of a 3H class pencil, excellent abrasion resistance and transparency were formed. 相似文献
45.
Park MH Jeong MK Yeo J Son HJ Lim CL Hong EJ Noh BS Lee J 《Journal of food science》2011,76(1):C80-C88
Headspace volatiles of sesame oil (SO) from sesame seeds roasted at 9 different conditions were analyzed by a combination of solid phase microextraction (SPME)-gas chromatography/mass spectrometry (GC/MS), electronic nose/metal oxide sensors (MOS), and electronic nose/MS. As roasting temperature increased from 213 to 247 °C, total headspace volatiles and pyrazines increased significantly (P < 0.05). Pyrazines were major volatiles in SO and furans, thiazoles, aldehydes, and alcohols were also detected. Roasting temperature was more discrimination factor than roasting time for the volatiles in SO through the principal component analysis (PCA) of SPME-GC/MS, electronic nose/MOS, and electronic nose/MS. Electronic nose/MS showed that ion fragment 52, 76, 53, and 51 amu played important roles in discriminating volatiles in SO from roasted sesame seeds, which are the major ion fragments from pyrazines, furans, and furfurals. SO roasted at 213, 230, and 247 °C were clearly differentiated from each other on the base of volatile distribution by SPME-GC/MS, electronic nose/MOS, and electronic nose/MS analyses. Practical Application: The results of this study are ready to apply for the discriminating samples using a combinational analysis of volatiles. Not only vegetable oils prepared from roasting process but also any food sample possessing volatiles could be targets for the SPME-GC/MS and electronic nose assays. Contents and types of pyrazines in sesame seed oil could be used as markers to track down the degree of roasting and oxidation during oil preparation. 相似文献
46.
Packaged wheat flour stored in direct contact with chlordane-treated shelf paper adsorbed with time appreciable amounts of the pesticide from the paper. Direct contact of the package with the paper was more conducive to flour contamination than it was from exposure of the flour to the vaporized pesticide components from the paper. Sorption effects of the pesticide with flour varied with the mode of exposure and the type of bag used, i.e. when the bags were in direct contact with the shelf paper, the flour packaged in polyethylene bags contained the largest amount of chlordane residue (29 ppm), which decreased about 10 per cent when packaged in single-thickness kraft paper bags and about 35 per cent in double-thickness kraft paper bags. When the bags were separated from direct contact with the shelf paper by means of open glass containers, contamination of the flour was tangibly decreased, whereby the amounts of residue found in the kraft single- and double-thickness paper bags were 0·4 and 0·3 ppm, respectively, compared to only 0·06 ppm in the polyethylene bags. 相似文献
47.
Study of Residual Stress and Surface Morphology Changes in Al2O3 Induced by Nd:YAG Laser Irradiation
Sunmog Yeo Sung-Ki Hong Sung-Jun Lee Changhwan Lim Jae-Won Park 《Journal of Materials Engineering and Performance》2012,21(1):137-142
In this study, the residual stress and surface morphology changes in alumina plates by the irradiation of a Q-switched Nd:YAG
laser were investigated. The results of x-ray diffraction using the sin2ψ technique show that laser irradiation induces tensile residual stresses on the surface of the plates, which increase with
the increasing energy density of the laser beam. Residual stress and surface morphology are sensitive to the irradiation conditions.
The surface morphology of the plates systematically changed with the laser energy density and the presence of an aluminum
foil or water on the plates. The physical reasons for these changes are discussed in this article. 相似文献
48.
The marine operation of floating liquefied natural gas (FLNG) demands process compactness, flexibility, simplicity of operation, safety, and higher efficiency. The modified single mixed refrigerant (MSMR) process satisfies the FLNG process requirements and is accepted as a suitable technology for FLNG operation. The aim of this study was to develop a plant-wide control structure or strategy that can sustain the economic efficiency of the MSMR process. The NGL recovery and liquefaction units were integrated in the MSMR process to provide a compact plant structure with an efficient operation. Steady-state optimality analysis was intensively conducted in a rigorous dynamic simulation environment to determine the correct variable to sustain the economic efficiency of MSMR process. The results showed that the flow rate ratio of heavy and light mixed refrigerant (HK/LK ratio) is a promising self-optimizing controlled variable. Controlling this variable can sustain the MSMR optimality, even when the process is operated under off-design operating conditions or in the presence of disturbances. Based on the control structure tests, the control configuration with the HK/LK ratio loop showed excellent performance, maintaining the process stability against a range of disturbances. The proposed approach can also be applied to any cryogenic liquefaction technology for determining a possible optimizing controlled variable. 相似文献
49.
We investigated the effects of perilla oil containing a high level of α-linolenic acid onin vivo phospholipid metabolism, particularly three subclasses of choline glycerophospholipids (CGP) and ethanolamine glycerophospholipids
(EGP), in rat kidney. After three weeks of feeding, a significantly lower proportion (by 35%) of the alkylacyl subclass of
CGP was found in the perilla oil, as compared to corn oil-fed animals. The alkylacyl species of EGP was also higher in the
perilla oil than in the corn oil-fed animals. These alterations were accompanied by a remarkably lower proportion of arachidonic
acid and a higher level of eicosapentaenoic acid (EPA) in all six subclasses of CGP and EGP in the perilla oil-fed animals.
The levels of linoleic acid were even higher in the diacyl subclasses of CGP and EGP in the perilla oil group, suggesting
that desaturase and elongase enzymes prefer n−3 to n−6 fatty acids as substrates for diacyl species. These data are useful
in defining the effects of α-linolenic acid on the biosynthesis of renal phospholipids and on the replacement of n−6 with
n−3 fatty acids in the six CGP and EGP subclasses. 相似文献
50.
Mi Soon Yeo Duk Hui Kang Se Kyung Kim Hyun Shik Yun Yoon Mo Koo Youn-Woo Lee Kyung Ho Row 《Korean Journal of Chemical Engineering》2002,19(5):815-817
Ceramide was prepared by the cultivation ofSaccharomyces cerevisiae from cell extracts by solvent exfraction and analyzed by NP-HPLC using a UV detector. The mobile phase was composed of hexane,
methanol, and IPA. From the experimental conditions, the composition of mobile phase was 72/5/23 (hexane/IPA/methanol, vol%).
Quantitative analysis of ceramide was performed. Based on the analytical conditions, the effect of cultivation temperature
for the production of ceramide was investigated and the optimum cultivation temperature was found to be 35°C.
This paper is dedicated to Dr. Youn Yong Lee on the occasion of his retirement from Korea Institute of Science and Technology. 相似文献