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排序方式: 共有78条查询结果,搜索用时 15 毫秒
1.
Rafael Bárcena Ainhoa Etxebarria 《International Journal of Control, Automation and Systems》2010,8(2):244-249
A study on the convenient tuning of fractional-order hold electronic devices for digital control systems is presented. When certain constraints are fulfilled, this study assures in advance the attainment of inverse stable discrete plants. The main result is based on classic numerical analysis techniques and is applicable when the process to be digitally controlled is described as a second order plant or as a first order plant with time delay. In such cases, by using a conveniently tuned fractional-order hold, the discretization nonminimum-phase zeros emerged when using a common zero-order hold are avoided. In this way, the performance of the digitally controlled system may be improved. 相似文献
2.
Poly(vinyl alcohol) (PVA) was reacted with three hydroxy acids (HA), namely D,L-lactic acid (LA), glycolic acid (GA) and D,L-3-hydroxybutyric acid (HB). The graft copolymers obtained were thoroughly characterized by 1H and 13C NMR, FTIR, and DSC. Copolymer compositions were in the range 14–45 mol% HA with average lateral chain lengths in the range 1.1–1.3. The CO stretching band, arising from the lateral polyester chains, presents significant differences from that of pure polyesters. In case of the VALA and VAGA copolymers, carbonyl groups are almost completely interassociated with hydroxyl groups and as a result the carbonyl band presents a single contribution; however, splitting appears in VAHB. The band at about 1735 cm?1 already observed for Poly(3-hydroxybutyrate) P3HB was reexamined in the light of molecular models for VAHB and the splitting observed was attributed to C–H???OC and to O–H???OC hydrogen bonding. The thermal analysis of copolymers demonstrates that esterification suppresses crystallinity and increases free volume, both accounting for a Tg reduction with regard to PVA. The stronger intermolecular hydrogen bonding interactions found in PVA with the chemically modified PVAs opens an interesting way towards miscibility with polyesters and other polymer systems containing carbonyl groups. 相似文献
3.
Ainhoa Martínez-Medina Maria Del Mar Alguacil Jose A. Pascual Saskia C.M. Van Wees 《Journal of chemical ecology》2014,40(7):804-815
The application of Trichoderma strains with biocontrol and plant growth-promoting capacities to plant substrates can help reduce the input of chemical pesticides and fertilizers in agriculture. Some Trichoderma isolates can directly affect plant pathogens, but they also are known to influence the phytohormonal network of their host plant, thus leading to an improvement of plant growth and stress tolerance. In this study, we tested whether alterations in the phytohormone signature induced by different Trichoderma isolates correspond with their ability for biocontrol and growth promotion. Four Trichoderma isolates were collected from agricultural soils and were identified as the species Trichoderma harzianum (two isolates), Trichoderma ghanense, and Trichoderma hamatum. Their antagonistic activity against the plant pathogen Fusarium oxysporum f. sp. melonis was tested in vitro, and their plant growth-promoting and biocontrol activity against Fusarium wilt on melon plants was examined in vivo, and compared to that of the commercial strain T. harzianum T-22. Several growth- and defense-related phytohormones were analyzed in the shoots of plants that were root-colonized by the different Trichoderma isolates. An increase in auxin and a decrease in cytokinins and abscisic acid content were induced by the isolates that promoted the plant growth. Principal component analysis (PCA) was used to evaluate the relationship between the plant phenotypic and hormonal variables. PCA pointed to a strong association of auxin induction with plant growth stimulation by Trichoderma. Furthermore, the disease-protectant ability of the Trichoderma strains against F. oxysporum infection seems to be more related to their induced alterations in the content of the hormones abscisic acid, ethylene, and the cytokinin trans-zeatin riboside than to the in vitro antagonism activity against F. oxysporum. 相似文献
4.
María?D.?GuillénEmail author Ainhoa?Ruiz Nerea?Cabo Rosana?Chirinos Gloria?Pascual 《Journal of the American Oil Chemists' Society》2003,80(8):755-762
Three oil samples obtained from sacha inchi (Plukenetia volubilis L.) seeds were studied by means of FTIR and 1H NMR. Frequency data of the most significant bands of the IR spectrum of this oil are given. These data show that sacha inchi
oil has a high degree of unsaturation. The same fact is deduced from the ratio between the absorbance of the bands due to
the stretching vibrations of the cis olefinic CH double bonds at 3010.5 cm−1 and to the methylene symmetrical stretching vibrations at 2855.1 cm−1. The proportions of monounsaturated, polyunsaturated, and saturated acyl groups were predicted from the frequency of some
IR bands, and these were in satisfactory agreement with the values obtained through FAME generation and their quantification
by GC. Likewise, simple observation of the 1H NMR spectra provided a great deal of information about sacha inchi oil, with regard not only to the relative proportions
of the different acyl groups but also to their nature. Thus, the presence of γ-linolenic acyl groups was discounted. Furthermore,
the area of some 1H NMR signals was used to determine the proportion of saturated and mono-, di-, and triunsaturated acyl groups, which also
were in satisfactory agreement with the values obtained by classical methods. IR and 1H NMR determinations take very little time in comparison with classical methods and do not require chemical manipulation or
transformation of the sample. A comparison was also made between the compositions of sacha inchi and linseed oil. Both oils
are important sources of the healthful n−3 linolenic acyl groups, and sacha inchi also contains high proportions of the n−6
linoleic acyl groups. 相似文献
5.
Technology-aided participative methods in environmental assessment: An international perspective 总被引:1,自引:0,他引:1
Ainhoa Gonzlez Alan Gilmer Ronan Foley John Sweeney John Fry 《Computers, Environment and Urban Systems》2008,32(4):303
Provisions for citizen involvement in the assessment of potential environmental effects of certain plans, programmes and projects are present in current legislation. An international survey revealed that public participation is common practice in European and some other countries worldwide. However, a number of issues are observed to affect public involvement in EIA/SEA processes and expert opinion differs when evaluating the effectiveness of existing participative methods.Results suggest that technology-aided methods can improve traditional participation processes. In particular, GIS has the potential to increase community knowledge and enhance involvement by communicating information more effectively. Variable accessibility to technology and data quality remain issues. Combining technology with more conventional ways of gathering, evaluating and presenting data are seen as offering a solution to the need to promote the integration of public perceptions in environmental assessment procedures. Recommendations to improve current public participation methods and measures for making GIS available to the general public are provided. 相似文献
6.
The oxidation process of rapeseed, walnut and linseed oils, rich sources of linolenic acyl groups, was studied by means of 1H nuclear magnetic resonance spectroscopy. The visible changes in some spectrum signals, especially in those of methylic, allylic and bis‐allylic hydrogen atoms, provide information about the degradation of the different acyl groups throughout the oxidation process. The rate of the changes produced in the three oils was compared, not only in relation to the rate of degradation of the different acyl groups, but also to both the formation and degradation of primary as well as to the formation of secondary oxidation products. Among the secondary oxidation products, the study was focused on the formation of aldehydes, their nature and evolution throughout the oxidation process of these three oils. The formation of n‐alkanals, trans‐2‐alkenals, trans,trans‐2,4‐alkadienals, as well as of the well known geno‐ and cytotoxic 4,5‐epoxy‐, 4‐hydroperoxy‐ and 4‐hydroxy‐trans‐2‐alkenals, was proved to take place. 相似文献
7.
Ainhoa Fernández-Tena Itziar Otaegi Lourdes Irusta Victor Sebastián Gonzalo Guerrica-Echevarria Alejandro Jesus Müller Nora Aranburu 《大分子材料与工程》2023,308(12):2300213
In this work, the effectiveness of seven commercial compatibilizers is tested in polylactide (PLA)/poly(ε-caprolactone) (PCL) blends with different compositions to obtain a high-impact PLA. None of the compatibilizers is effective for 90/10 and 80/20 PLA/PCL compositions, as no improvement of the impact strength is observed. For the 70/30 composition, compatibilizers having glycidyl methacrylate (GMA) and acrylate groups in their structure are proved the most effective, as the morphological change towards co-continuity induced by them leads to significant impact strength improvements (of ≈345% and 90% with respect to the neat PLA and the noncompatibilized PLA/PCL 70/30 blend, respectively). The 70/30 PLA/PCL composition, as it shows the best balance of properties, and the best compatibilizer (ElvaloyPTW) are chosen to carry out the optimization of the compatibilizer content. It is found that adding 6 phr to the blend results in highly toughened and ductile blends while maintaining a high modulus and yield strength values. Larger compatibilizer contents lead to even higher impact strength values, but the low-strain mechanical properties are notably reduced. Thus, in this work, a simple and easily scalable method to produce high-impact PLA is shown, as it implies the compounding of three commercially available components without involving any toxic solvents. 相似文献
8.
Maria D Guilln Ainhoa Ruiz Nerea Cabo 《Journal of the science of food and agriculture》2004,84(12):1528-1534
Farmed salmon fillets were dry‐salted for 24 h. Both salted and unsalted samples were submitted to oxidative conditions at 50 °C in an oven with circulating air. Lipids of both samples were extracted daily from aliquots and studied by Fourier transform infrared spectroscopy. The infrared spectra of salmon lipids are similar to those of vegetable edible oils, with differences in the frequency and absorbance of some bands due to their different acyl group compositions. The infrared spectra of salted and unsalted fish lipid samples remain unchanged during a period of time, which is shorter for the salted salmon. After this period, changes in the frequency and absorbance of some bands of the spectrum are observed owing to the presence of oxidation products. Therefore the reduction in the oxidative stability of farmed salmon lipids caused by the dry‐salting process is proved and the usefulness of this technique for studying the oxidative stability of fish lipid samples as well as their oxidation degree is shown. Copyright © 2004 Society of Chemical Industry 相似文献
9.
Several studies, including histochemical ones, have indicated that nitric oxide (NO) of endothelial origin may be related to the pulmonary vasodilation that occurs at birth. Since no histologic studies have been done of the possible parallel perinatal increase in production of neuronal NO synthase (nNOS) by pulmonary nerve plexuses, we investigated the distribution of nNOS in fetal, neonatal, and adult mouse lung. Lungs from mice aged 13 d gestation to 6 d after birth and lungs of adults were studied through histochemistry for nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity and immunocytochemistry. Both techniques gave almost similar results in relation to time of appearance, distribution, and frequency of neural structures positive for NADPH-d and NOS. NADPH-d staining was also applied to whole mounts of developing and adult tracheae. Staining was found from gestational days 13 to 15 onward in a small portion of the neuronal population. In all stages studied, NADPH-d/NOS staining was found in neuron cell bodies in the hilar region and bronchiolar wall, as well as in neuronal processes. Labeled terminal nerve fibers with varicosities were more frequent in pulmonary blood vessels than in airways. In tracheae, similar NADPH-d/NOS-positive nerve plexuses were found. The presence of nNOS in fetal and neonatal mouse respiratory tract suggests that neurally derived NO must play a role in developing lung physiology. However, because no perinatal increase in the number or intensity of staining of nNOS-positive nerve structures was seen, no apparent relation between neural NO and vasodilation can be established at birth. 相似文献
10.
Ana Arizaga Gemma Ibarz Rafael Piñol Ainhoa Urtizberea 《Journal of Experimental Nanoscience》2014,9(6):561-569
A multiresponsive system that consists on pH-responsive polymer microspheres with encapsulated iron oxide magnetic nanoparticles that rendered the core magnetic to enable externally controlled actuation under magnetic induction has been developed. The inorganic nanoparticles were first prepared and, then, further encapsulated in a pH-sensitive poly(4-vinylpyridine). These spheres have been obtained by a modification of the simple, rapid and high-reproducible nanoprecipitation method. Magnetic measurements showed that the iron oxide nanoparticles are superparamagnetic and, therefore, able to undergo a local increase of the temperature when an oscillating magnetic field is applied. Magnetically triggered heating and pH sensitivity can be useful for biomedical applications. 相似文献