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排序方式: 共有125条查询结果,搜索用时 15 毫秒
1.
Raphaëlle Savoire Jean‐Louis Lanoisellé Hélène Ducatel Eugène Vorobiev 《European Journal of Lipid Science and Technology》2008,110(8):725-734
Seven linseed varieties were harvested at seven times before complete maturity. Microscale oilseed expressions were subsequently carried out on it. A pressure of 10 MPa was applied for 1 h under uniaxial stress. The results were characterized in terms of oil, water and mucilage content, harvest date and oil yield. The piston displacement versus time (creep curves) was described by a four‐Kelvin‐Voigt elements viscoelastic model. Parameters were derived from the model, such as the mechanical properties of seeds (compressibility moduli), showing that the viscoelastic model fits well the experimental data (R² ≈ 0.999). The modeling parameters were combined with some biochemical data in order to predict the kinetics of oil extraction. 相似文献
2.
Erucic acid‐enriched oil, sought for industrial purposes, from rapeseed (agronomic plant) and rocket seeds (non‐agronomic plant) was extracted by three different processes: supercritical CO2, mechanical expression, and hexane extraction. Oil extraction yields were determined and the extracted oils were characterized for their fatty acid and phenolic compound compositions. Higher oil yields were achieved using hexane compared to mechanical expression and supercritical CO2 extractions. Fatty acid analysis indicated a higher content of erucic acid in rapeseed oil than in rocket oil. In addition, supercritical CO2 extraction allowed better recovery of phenolic compounds with high antioxidant activities. The most prominent identified polyphenols were vanillin, sinapic acid, syringic acid, and apigenin. 相似文献
3.
Torres Luis Vanderlei Naldi Marcos Antônio Zoqui Eugênio José 《Journal of Materials Science》2021,56(19):11541-11556
Journal of Materials Science - This study sought to analyze the semi-solid behavior of commercial 332 aluminum alloy during thixoforming in a mechanical eccentric press (thixoforging). The... 相似文献
4.
Ascari J Dracz S Santos FA Lima JA Diniz MH Vargas EA 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2012,29(4):602-608
A quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous analyses of malachite green (MG), crystal violet (CV) and its major metabolites, leucomalachite green (LMG) and leucocrystal violet (LCV) residues in fish and shrimp samples has been validated. Fish and shrimp samples were extracted with citrate buffer/acetonitrile, and the extracts were purified on strong cation-exchange (SCX) solid-phase extraction (SPE) cartridge. After conversion of LMG into MG using a post column oxidation reactor containing lead (IV) oxide (PbO(2)), the effluents were analysed. Residues were analysed using positive-ion electrospray ionisation (ESI). Identification and quantification of analytes were based on the ion transitions monitored by multiple reaction monitoring (MRM). Validation of the method was carried out in accordance with the Decision 2002/657/EC, which establishes criteria and procedures for the validation of methods. The following parameters were determined: decision limit (CCα), detection capability (CCβ), linearity, accuracy, precision, selectivity, specificity and matrix effect. The decision limits (CCα) for MG, LMG, CV and LCV were 0.164, 0.161, 0.248 and 0.860 μg kg(-1). The respective detection capabilities (CCβ) were 0.222, 0.218, 0.355 and 1.162 μg kg(-1). Typical recoveries (intermediate precision) in shrimp, for MG, CV, LMG and LCV for 2.0 μg kg(-1) level fortified samples using the optimised procedure were in the range 69%, 97%, 80.3% and 71.8%, respectively. The findings demonstrate the suitability of the method to detect simultaneously MG, CV and its metabolite (LMG and LCV) in fish and shrimp. 相似文献
5.
The interactions between bitumen, or its components, and (especially) silicas have been studied using solution adsorption techniques. Bitumen dissolved in carbon disulphide or carbon tetrachloride forms multilayers on the solid surfaces. It is shown that the reactive part of the bitumen is the asphaltene which forms, by chemisorption on the silanol groups of the silica, a monolayer having a thickness which compares fairly well with the published dimensions of the asphaltene molecules. Adsorption of the asphaltenes onto other pigments demonstrates the specificity of the interaction. 相似文献
6.
Gelson Biscaia de Souza Alexandre Mikowski Carlos Maurício Lepienski Carlos Eugênio Foerster 《Journal of the European Ceramic Society》2010,30(9):1967-1969
Malzbender has suggested a model to determine hardness and elastic modulus as a function of the mechanical energies involved during tip penetration in instrumented indentations tests. However, the values obtained with these expressions are not consistent with the ones determined by the well-accepted Oliver and Pharr method. After revision, based on Malzbender's study itself, equations were rewritten and then, the obtained indentation hardness (H) for soda-lime glass was in agreement with the literature data. However, the reduced elastic modulus (Er) was still about 20% higher than the values in the literature. Developing Malzbender's proposal by the inclusions of additional mechanical energy assumptions, a new expression for Er is now suggested. Using the new expression, the hardness and reduced elastic modulus agreed very well with the Oliver and Pharr method. 相似文献
7.
Miguel Angelo Faria Eugénia Nunes Maria Beatriz P. P. Oliveira 《European Food Research and Technology》2008,227(3):845-850
Varietal wines are defined as made primarily from a single variety of grape, which is identified on the label. However the
inclusion of other varieties in their production is permitted under defined percentages. The fact that different grape varieties/varietal
wines present far different economical values can attract fraudulent practices. Thus the development of methods, which allow
the quantification of those varieties, is of crucial importance. The first approach to the method for the relative quantification
of must containing two varieties based on microsatellite DNA analysis is presented. Quantification was achieved by densitometry
measurements of the amplification products of the pooled varieties, obtained with loci VVMD6 and VVMD7, after their separation and staining on polyacrilamide gels. We have found that a good correlation between
the proportion of each variety in must and the signal intensity of the alleles are dependent on the variety (varietal effect)
and the microsatellite locus used. The relative quantification of musts can be accomplished by the presented method depending on the presence of overlapping
alleles, and the composition of the varieties and their relative amounts. 相似文献
8.
We consider the following problem. A signature authority issues RSA-signatures of certain types to an individual, and the individual tries, by using the signatures he received, to compute an RSA-signature of a type not issued by the authority. Is the individual able to do this? The RSA-signatures are products of rational powers of residue classes modulo the composite number N of the underlying RSA-system, and the residue classes are chosen at random by the signature authority. The rational exponents in the product determine the type of the signature. We prove that computing an RSA-signature of a particular type, from given RSA-signatures of other types, is polynomial time reducible to computing RSA-roots x 1/d (mod N) for random x and some positive integer d. This extends results of Akl and Taylor [1] and Shamir [11] from one variable to arbitrarily many variables. As an application of this, under the assumption that for the individual it is infeasible to compute RSA-roots, we give necessary and sufficient conditions describing whether it is feasible for that individual to compute RSA-signatures of a prescribed type from signatures of other types that he received before from the authority. 相似文献
9.
Abstract: This paper proposes a method to enzymatically treat poor‐quality cocoa almonds (known as “slate”) to ensure the formation of chocolate flavor precursors. The production of flavor precursors improves the quality of these almonds, which are usually responsible for the low quality of the liquor produced. Proteases and carboxypeptidases from different sources were tested under various conditions. The different treatments were evaluated by chemical analysis (hydrolysis efficiency) and sensory analysis of the treated material compared to good‐quality cocoa almonds. The results show that it is possible, through the use of microbial enzymes, to generate the mixture of compounds that will release, after roasting, the characteristic chocolate flavor in poor‐quality almonds. However, it is necessary to optimize the conditions of enzymatic treatment to obtain better results and thus establish a process that can be used for industrial purposes for manufacturing cocoa and chocolate. Practical Application: The basidiomycete Moniliophtora perniciosa is the causative agent of witches’ broom disease (WBD) of the cocoa tree, whose seeds are the source of chocolate. It is the most important phytopathological problem of cocoa‐producing areas of the American continent, and has decimated the Brazilian cocoa industry. In Bahia (Brazil), M. perniciosa was identified in 1989 and, as a consequence of its spreading, the annual production of cocoa almonds dropped from 450000 to 90000 tons within 12 y, reducing export values from an all‐time high of about US$ 1 billion to 110 million. The high incidence of WBD incapacitates Brazil to produce enough cocoa almonds even for the internal market, leading the country to import low‐quality cocoa almonds mainly from African countries. Our work proposes an enzymatic treatment to increase the quality of that cocoa almonds and, consequently, to improve the quality of the chocolate produced and consumed in the country. 相似文献
10.