全文获取类型
收费全文 | 270篇 |
免费 | 35篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 159篇 |
金属工艺 | 5篇 |
机械仪表 | 5篇 |
建筑科学 | 3篇 |
能源动力 | 7篇 |
轻工业 | 70篇 |
无线电 | 7篇 |
一般工业技术 | 27篇 |
冶金工业 | 6篇 |
自动化技术 | 14篇 |
出版年
2022年 | 38篇 |
2021年 | 42篇 |
2020年 | 10篇 |
2019年 | 19篇 |
2018年 | 13篇 |
2017年 | 20篇 |
2016年 | 11篇 |
2015年 | 14篇 |
2014年 | 13篇 |
2013年 | 13篇 |
2012年 | 19篇 |
2011年 | 12篇 |
2010年 | 15篇 |
2009年 | 7篇 |
2008年 | 14篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1992年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 2篇 |
排序方式: 共有305条查询结果,搜索用时 15 毫秒
1.
2.
Here, we report on the application of corroles as analytically active compounds in liquid membrane electrodes (ISE) that are sensitive towards salicylic acid and salicylate.The potentiometric signals generated by corrole-incorporated ISEs strongly depend on the pH of the aqueous sample solution and the membrane composition, such as the presence of lipophilic sites. Corrole incorporating ISEs are characterised by a low detection limit (4.0 × 10−5 M) and a wide linear range (4.0 × 10−5 to 5.3 × 10−3 M). Also, they are free from interference versus other organic anions.The mechanism of the generation of the potentiometric signals of corrole incorporating ISEs in the presence of salicylate anion, as well salicylic acid, will be discussed. 相似文献
3.
The general objective of this paper is to investigate the separation, with microfluidics, of the components of a ternary mixture, when using vacuum or purge gas pervaporation. The ternary mixture considered is a mixture of methanol (MeOH), water (H2O) and hydrogen peroxide (H2O2). In a previous work (Ziemecka in Lab Chip 15:504–511, 2015), we presented the proof of concept of a microfluidic device, which was able to partially separate MeOH from the other components of such a mixture, by using vacuum pervaporation. Here, our goal is to optimize the operation of this device, by considering vacuum pervaporation, but also purge gas pervaporation. First, we provide a mathematical model of the device. This model is used to discuss the influence of the operating parameters on the device operation. To apply this model to the considered mixture, we determined the MeOH and H2O permeability coefficients of PDMS membranes prepared from different concentrations of the curing agent. The model is then successfully compared to experimental data. The model and the experiments show that high efficiencies can be reached for both vacuum and purge gas pervaporation, provided a fine-tuning of the operating parameters. For instance, a good efficiency of the vacuum pervaporation is reached at high temperature and low pressure. For purge gas pervaporation, it is reached for low temperature and high pressure. 相似文献
4.
Iwona Pokorska 《Structural and Multidisciplinary Optimization》2008,37(1):77-89
The purpose of this paper is to analyze the sensitivity problems in metal forming of rigid-visco-poroplastic materials. A
repressing powder forging process is analyzed. Parameter sensitivity, material derivative, and control volume approaches to
shape sensitivity analysis are presented, analyzed, and compared. Discretization of the continuum expressions is presented.
The numerical solutions for parameter sensitivity in forging problems have been described. Numerical examples concerning simple
compression test of cylindrical porous specimen are presented. 相似文献
5.
Iwona Radziejewska Katarzyna Supruniuk Micha Tomczyk Wiktoria Izdebska Magorzata Borzym-Kluczyk Anna Bielawska Krzysztof Bielawski Anna Galicka 《International journal of molecular sciences》2022,23(15)
Abnormal glycosylation of cancer cells is considered a key factor of carcinogenesis related to growth, proliferation, migration and invasion of tumor cells. Many plant-based polyphenolic compounds reveal potential anti-cancer properties effecting cellular signaling systems. Herein, we assessed the effects of phenolic acid, p-coumaric acid and flavonoids such as kaempferol, astragalin or tiliroside on expression of selected cancer-related glycoforms and enzymes involved in their formation in AGS gastric cancer cells. The cells were treated with 80 and 160 µM of the compounds. RT-PCR, Western blotting and ELISA tests were performed to determine the influence of polyphenolics on analyzed factors. All the examined compounds inhibited the expression of MUC1, ST6GalNAcT2 and FUT4 mRNAs. C1GalT1, St3Gal-IV and FUT4 proteins as well as MUC1 domain, Tn and sialyl T antigen detected in cell lysates were also lowered. Both concentrations of kaempferol, astragalin and tiliroside also suppressed ppGalNAcT2 and C1GalT1 mRNAs. MUC1 cytoplasmic domain, sialyl Tn, T antigens in cell lysates and sialyl T in culture medium were inhibited only by kaempferol and tiliroside. Nuclear factor NF-κB mRNA expression decreased after treatment with both concentrations of kaempferol, astragalin and tiliroside. NF-κB protein expression was inhibited by kaempferol and tiliroside. The results indicate the rationality of application of examined polyphenolics as potential preventive agents against gastric cancer development. 相似文献
6.
Iwona Golonka Beata Kizior Bartomiej M. Szyja Mateusz P. Damek Witold Musia 《International journal of molecular sciences》2022,23(15)
(1) Background: Depending on the type of hydrophilic polymer used, different types of hydrogels may be chemically stable or may degrade and eventually disintegrate, or dissolve upon exposure to sunlight. Many over-the-counter medications are now stored with a limited control of temperature, humidity and lighting. Therefore, in this study, the photostability of a gel made of cross-linked polyacrylic acid (PA), methylcellulose (MC) and aristoflex (AV) was assessed, and the interaction between the polymers used and ascorbic acid and its ethylated derivative was investigated. (2) Methods: The samples were continuously irradiated at constant temperature for six hours. The stability of the substance incorporated into the gels was assessed using a UV-Vis spectrophotometer. FTIR-ATR infrared spectroscopy was used to measure changes during the exposure. (3) Results: Ascorbic acid completely decomposed between the first and second hours of illumination in all samples. The exception is the preparation based on polyacrylic acid with glycerol, in which the decomposition of ascorbic acid slowed down significantly. After six hours of irradiation, the ethylated ascorbic acid derivative decomposed in about 5% for the polyacrylic acid-based gels and aristoflex, and in the methylcellulose gel it decomposed to about 2%. In the case of ascorbic acid, the most stable formulation was a gel based on polyacrylic acid and polyacrylic acid with glycerol, and in the case of the ethyl derivative, a gel based on methylcellulose. (4) Conclusions: The experiment showed significant differences in the decomposition rate of both compounds, resulting from their photostability and the polymer used in the hydrogel. 相似文献
7.
8.
The study of chemical composition and dough rheology changes in sieve‐classified two fractions (up to 60 and 60–240 μm particles) of wheat flour was the subject of this study. The straight grade flours were obtained by the milling of three Polish varieties of spring wheat, differing in ?? abbreviation? (PSI) values. The flours were separated with the use of a SZ‐1 laboratory sifter. The yield of fine fraction was in the range 50.0–55.7%. The obtained fractions were assayed for the content and composition of free lipids, gluten proteins, damaged starch, ash, water absorption and amylograph viscosity. Dough rheology (extrusion in OTMS cell, alveograph and farinograph tests) and baking trials were also performed. The content of free lipids, including the non‐polar and phospholipids was lower and the content of glycolipids was higher in fine flours. Those fractions were more rich in linoleic acid but the lower content of oleic and linolenic acids resulted in a higher oxidizability index of free lipids. Fine flours contained less ash and significantly more damaged starch. At the same time, they were characterized by a higher content of wet gluten, water absorption, amylograph viscosity and better dough parameters. This was reflected in the bread volume, which was higher by 6.3–10.7%. The influence of the changes in composition and the content of free lipids upon the rheology of the dough after the 90 days flour storage has not been defined unambiguously and requires further research. 相似文献
9.
Katarzyna Grzybowska Zaneta Wojnarowska Andrzej Grzybowski Marian Paluch Juan M. Giussi M. Susana Cortizo Iwona Blaszczyk-Lezak Carmen Mijangos 《Polymer》2014
In this paper, dielectric and calorimetric studies of the small-molecule glass former allyl acetoacetate monomers as well as its newly synthetized homopolymer and copolymers with different styrene composition were performed in both the liquid and glassy states. The molecular dynamics studies by the broadband dielectric spectroscopy and the stochastic temperature modulated differential scanning calorimetry enabled us to explore relaxation processes of examined materials in the wide frequency range. We found that the copolymers reveal two co-existing glass transitions characterized by the glass transition temperatures, which are very close to those of the corresponding homopolymers. These results suggest that the copolymers exhibited some sequences of acetoacetate units with a microphase-separated morphology in agreement with the value of reactivity ratio previously determined. We investigated effects of copolymerization compositions on the glass transition temperature, the isobaric fragility index, the dielectric and calorimetric intensity, and the dynamic heterogeneity on the glass transitions of the materials. 相似文献
10.
Iwona Wilczek 《建筑学研究前沿(英文版)》2021,10(2):351-368
This paper aims to analyse new architectural works that were created within the ruins of castles and fortifications. The contribution addresses the question whether it is possible to indicate common features in these types of objects, by studying what changed and how it changed in the complexes of historic ruins by introducing a new layer: a new form in their space. The analysis covers eight complexes of castle ruins located in Europe, all being important elements of local historical heritage, all preserved in their historical forms as permanent ruins. Such places are characterised by high imageability, which is conducive to maintaining interest, despite political or ideological changes. The need to introduce new functions, which is connected with this interest, raises questions related to preserving the identity and authenticity of the place, while at the same time building relationships with modern architecture. The research concerned examples from Europe, mostly post-competition works. Research and analysis have shown that all the objects are characterised by well thought-out urban solutions and carefully selected locations of new buildings within the existing historic ruins, thereby helping maintain the structural order between the existing and the new spatial forms. Interventions within the castle ruins were carried out using modern architectural language, using modern techniques and solutions, with great attention to detail. They are characterised by the abstraction of new forms and the creative reinterpretation of existing architectural elements and material solutions of the monuments. The consciously applied contrast of forms and materials means that the historical heritage is being rediscovered, enriched with new, currently necessary functions. In all the described works, the introduction of new spatial experiences within existing objects constituted a significant value. The examples analysed show that the experience and analysis of the broadly understood historical, urban and architectural context are conducive to the creation of valuable architectural works. The characteristics of these examples may contribute to a broader debate on the dialogue between historical heritage and contemporary architecture. 相似文献