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81.
The use of azo dyes in industrial activities generates a large volume of contaminated wastewater; these pollutants in water bodies affect aquatic biota and human health. A functional biocomposite sorbent material was synthesized using cross-linked chitosan with oxalic acid that forms a coating on alumina ceramic particles (AOCh). The removal of Reactive Red 195, a reactive azo dye, using a fixed-bed adsorption column filled with this material was tested. AOCh was physico-chemically characterized by Fourier transform infrared spectroscopy–total attenuated reflection (FTIR-ATR), scanning electron microscopy–energy dispersion spectrometry X-ray (SEM-EDS), X-ray diffraction (XDR), thermo-gravimetric analysis (TGA), and Z-potential. The dynamic adsorption performance was analyzed from experimental breakthrough curves obtained in fixed-bed columns by modifying different operating conditions (bed depth, volumetric flow rate, and dye inlet concentration). Equilibrium adsorption isotherms were determined under dynamic conditions and compared with batch results. The maximum adsorption capacity of the dynamic equilibrium isotherm obtained from the continuous assays was 331 mg/g; this value was the highest in comparison to other tested materials reported in the literature. Different dynamic adsorption models were applied to fit experimental data, including Thomas, Bohart–Admas, Yoon–Nelson, logistic general model, bed depth surface time (BDST), and modified dose response (Yan) models. A critical analysis of these equations was presented, showing the equivalences and the relationship among the coefficients. The Yan model achieved the highest level of agreement between the experimental and predicted values of the breakthrough curves. The use of this model enables scaling-up the industrial process for dye removal. The present work proposed a novel biosorbent material and contributes to the analysis of industrial dye removal under dynamic conditions. 相似文献
82.
M Victoria Avanza M Cristina Añón 《Journal of the science of food and agriculture》2007,87(4):616-623
The effect of thermal treatment of proteins from Amaranthus hypochondriacus was studied. Two protein isolates were obtained from the defatted flour by water extraction at a pH of 9 (A9 isolate) and 11 (A11 isolate), followed by isoelectric precipitation at a pH of 5. Effect of thermal treatment (70 and 90 °C, during 3, 5, 10, 15 and 30 min) on A9 and A11 dispersions were analyzed by differential scanning calorimetry (DSC), polyacrylamide gel electrophoresis, UV spectrophotometry, superficial hydrophobicity and solubility in water. Thermal treatment induced the aggregate formation of high molecular mass stabilized by disulfide and non‐covalent bond. Thermal treatment at 70 °C produced a 30% denaturation in both, while at 90 °C A9 was more denatured than A11 (75% and 55% of denaturation, respectively). An increase in thermal stability was also detected by DSC in A9 treated at 90 °C. The denaturation process was accompanied at short heating times by an increase in UV absorbance and changes in superficial hydrophobicity. A decrease in water solubility (35–50%, depending on time–temperature conditions) was also observed for the A9 isolates. The results suggest that the A9 isolates, enriched in a globulin protein fraction, are more sensitive to thermal treatment than isolates A11 enriched in glutelin protein fraction. The changes shown by both isolates, indeed, could affect their functional properties and could definitely limit their use in food products. Copyright © 2007 Society of Chemical Industry 相似文献
83.
Localization and speciation of chromium in subterranean clover using XRF, XANES, and EPR spectroscopy 总被引:2,自引:0,他引:2
Howe JA Loeppert RH DeRose VJ Hunter DB Bertsch PM 《Environmental science & technology》2003,37(18):4091-4097
Optimization of phytoremediation and assessment of potential health hazards from metals in the environment requires an understanding of absorption, localization, and transport of the target metal by plants. The objectives of this study were to localize Cr and determine the oxidation state and possible complexation mode of Cr in intact plant tissue by means of XANES, synchrotron XRF microprobe spectroscopy, and EPR spectroscopy. Subterranean clover (Trifolium brachycalycinum) was grown hydroponically with Cr(VI) (0.04-2.0 mmol L(-1)) and compared with plants grown without Cr and with inorganic Cr(III) and various Cr(III)-organic sources. The uptake, translocation, and form of Cr in the plant were dependent on the form and concentration of supplied Cr. Chromium was found predominately in the +3 oxidation state, regardless of the Cr source supplied to the plant, though at high Cr(VI) treatment concentrations, Cr(VI) and Cr(V) were also observed. At low Cr(VI) concentrations, the plant effectively reduced the toxic Cr(VI) to less toxic Cr(III), which was observed both as a Cr(III) hydroxide phase at the roots and as a Cr(III)-organic complex in the roots and shoots. At low Cr(VI) treatment concentrations, Cr in the leaves was observed predominately around the leaf margins, while at higher concentrations Cr was accumulated at leaf veins. 相似文献
84.
Navas J Ortiz S López P López V Martínez-Suárez JV 《Journal of food protection》2007,70(12):2851-2854
This study aimed to evaluate the effect of different enrichment procedures on the detection of Listeria monocytogenes in food, by a comparison of subculture onto chromogenic agar with real-time PCR. Two different culture media, the primary and secondary enrichment broths of the U.S. Food Safety and Inspection Service (FSIS) method used for PCR detection of L. monocytogenes, were compared for the primary enrichment of retail ground chicken samples. L. monocytogenes was detected after the completion of each enrichment procedure in 63% (complete FSIS procedure) and 60% (plain FSIS secondary enrichment broth incubated for 48 h) of the samples by both culture and PCR, whereas a combination of the results for the two enrichment procedures revealed 86% of the samples to be positive. Most of the samples analyzed contained a mixture of lineage I and II strains, and their ratio varied for each enrichment procedure. This mixture could have a significant effect on the result of detection of L. monocytogenes for each individual sample, explaining the increase in positive samples when the results of the two enrichment procedures were combined. The use of different isolation procedures can affect the specific samples identified as positive and the specific strains isolated. 相似文献
85.
Ultra‐high‐pressure homogenization (UHPH) system for producing high‐quality vegetable‐based beverages: physicochemical,microbiological, nutritional and toxicological characteristics 下载免费PDF全文
86.
Victoria Watson 《The Journal of Architecture》2013,18(1):99-112
This paper looks at two theoretical statements about ‘space’, both of which are grounded in a vitalist philosophy. The first is Henri Lefebvre's formulation of ‘spatial architectonics’, a structure of concepts which he develops in The Production of Space; the second is Mies van der Rohe's intuition of something he termed ‘authentic form’, a means of triggering new experiences and understandings through sensual engagement with space. Since there are other philosophers and other architects whose thinking about space has been influenced by vitalist philosophy, the discussion will begin with an explanation as to why Lefebvre and van der Rohe have been selected for reciprocal examination. 相似文献
87.
Jeyasankar Alagarmalai David Nestel Daniela Dragushich Ester Nemny-Lavy Leonid Anshelevich Anat Zada Victoria Soroker 《Journal of chemical ecology》2009,35(5):542-551
The Ethiopian fruit fly, Dacus ciliatus, is an oligophagous pest of cucurbit crops, particularly melons, cucumbers, and marrows (summer squash). The present study
aimed to identify host attractants for D. ciliatus and was guided by a behavioral bioassay and an electrophysiological assay. We tested volatile compounds from the fruits of
a host plant, ripe and unripe Galia melon, Cucumis melo var. reticulates. Both sexes were attracted to melon volatiles. Those of ripe melon were preferred. Gas chromatography-electroantennographic
detection analysis of the behaviorally active ripe melon volatiles consistently showed that 14 compounds elicited similar
antennal responses from both sexes. Twelve compounds were identified by gas chromatography-mass spectrometry (GC-MS) using
GC-MS libraries, retention indices (RI), and authentic standards. The electrophysiological activities of the compounds that
were present at sufficient levels for identification, benzyl acetate, hexanyl acetate, (Z)-3-hexenyl acetate, (Z)-3-octenyl acetate, octanyl acetate, (Z)-3-decenyl acetate, and (E)-β-farnesene, were evaluated at six different dosage levels by using electroantennography (EAG). Benzyl and hexanyl acetates
elicited dose responses only in males, while other tested compounds elicited dose responses in both sexes. The strongest responses
were observed for doses between 100 ng and 10 μg. The dose response, in terms of attractiveness to synthetic compounds within
the active range (as determined by EAG), also was evaluated in the behavioral bioassay. Synthetic acetates were attractive
to both sexes when tested individually. Significant attraction was observed when individual compounds were applied in the
bioassay arena at doses of 0.5–1 μg/dispenser. Blends of compounds in equal proportions also were attractive to the insects.
The most attractive blend was a mixture of four or five identified acetates. The addition of an equal proportion of (E)-β-farnesene to this mixture had a deterrent effect. 相似文献
88.
Graesser Arthur C.; Bowers Cheryl; Olde Brent; Pomeroy Victoria 《Canadian Metallurgical Quarterly》1999,91(2):284
One dimension of reading literacy involves the tracking of agents associated with the text. In a literary short story, there is a society of character agents and pragmatic agents. This study investigated the relative salience of different classes of agents in memory. Two experiments measured source memory as an index of agent salience in long-term memory. Patterns of source memory scores supported an invisible third-person narrator hypothesis and an agent amalgamation hypothesis, but not a structural prominence hypothesis: First-person narrator > nonnarrator character > third-person narrator > 0. Statement detection parameters did not significantly differ among the 3 classes of agents, so differences in source memory could not be explained by differences in the content of the speech acts. Source memory scores also could not be explained by surface features of the text, differences among readers, and sophisticated guessing on the basis of a story abstract. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
Adaptation of the van Genuchten expression to the effects of temperature and density for compacted bentonites 总被引:2,自引:0,他引:2
Abel Carlos Jacinto María Victoria Villar Roberto Gmez-Espina Alberto Ledesma 《Applied Clay Science》2009,42(3-4):575-582
The main objective of this work is to highlight the influence of variables like temperature and porosity (dry density) on the water retention curve of expansive clays for the analysis of thermo-hydro-mechanical coupled processes (THM problem).The paper presents retention curves of MX-80 bentonite measured under isochoric conditions for different dry densities and temperatures. The influence of dry density on the water retention capacity depends on the suction range, the limiting value being around 30 MPa. For suctions above this threshold value, the retention capacity in terms of water content is higher as the dry density increases, whereas for lower suctions, the lower the dry density the higher the water content for a particular suction. The retention capacity decreases with temperature, more than predicted by the change in interfacial tension of air–water, especially for high temperatures and low suctions.Accordingly, some modifications of the van Genuchten [van Genuchten, M.Th., 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J., 44, 892–898.] law have been proposed to fit the experimental values. Effects of temperature and porosity on the water retention capacity (other than the traditionally included in the air entry value coefficient) were incorporated through empirical laws that resemble the experimental evidences. By a fitting process, values of the coefficients in those laws were determined for the material used in this work.Finally, several 1D THM simulations using the computer code “CODE_BRIGHT” have been performed in order to analyse the consequences of considering or not temperature and density influences on the water retention curve. 相似文献
90.
Sergio Bravo Javier García‐Alonso Gala Martín‐Pozuelo Victoria Gómez Verónica García‐Valverde Inmaculada Navarro‐González María Jesús Periago 《International Journal of Food Science & Technology》2013,48(8):1744-1749
Light red tomatoes were exposed to different doses of ultraviolet C (UV‐C) irradiation (1.0, 3.0 and 12.2 kJ m?2). After treatment, the tomatoes were stored for 2 days at room temperature, and then analysed to determine the effect of irradiation on the main antioxidants, carotenoids and phenolic compounds and the results compared with the control samples. The lycopene content was found to have increased by 14% with respect to the control samples, while β‐carotene decreased. Cis‐isomers from lycopene also increased when the tomatoes were exposed to irradiation for more than 3 h. UV‐C irradiation also had a positive effect on total phenolic compounds; however, the same effect was not observed in the individually analysed phenolic compounds. While chlorogenic and ferulic acids increased in content, naringenin and rutin contents decreased. These results suggest that UV‐C irradiation of tomatoes could improve the beneficial effect of red tomatoes for human health by increasing the levels of certain bioactive compounds; it could also be used to obtain higher content of bioavailability components, such as cis‐isomers from lycopene. 相似文献