全文获取类型
收费全文 | 254篇 |
免费 | 25篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 164篇 |
金属工艺 | 17篇 |
机械仪表 | 5篇 |
建筑科学 | 5篇 |
能源动力 | 3篇 |
轻工业 | 34篇 |
石油天然气 | 1篇 |
无线电 | 2篇 |
一般工业技术 | 32篇 |
冶金工业 | 6篇 |
原子能技术 | 1篇 |
自动化技术 | 8篇 |
出版年
2023年 | 5篇 |
2022年 | 33篇 |
2021年 | 34篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 8篇 |
2017年 | 14篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 18篇 |
2012年 | 10篇 |
2011年 | 15篇 |
2010年 | 10篇 |
2009年 | 13篇 |
2008年 | 10篇 |
2007年 | 11篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有279条查询结果,搜索用时 15 毫秒
31.
Zbigniew Czech Agnieszka Kowalczyk Janina Kabatc Jolanta Świderska 《Polymer Bulletin》2013,70(6):1911-1918
This article discusses thermal analysis of different molecular weight poly(2-ethylhexyl acrylates) synthesized by radical polymerization of 2-ethylhexyl acrylate. The main aim of this work was to investigate the thermal properties and degradation process of synthesized acrylic homopolymers and forming of thermal degradation products during their pyrolysis. As investigated method pyrolysis combined with gas chromatography was used. Poly(2-ethylhexyl acrylates) are used as plasticizers for pressure-sensitive adhesives applied in medical area. 相似文献
32.
Marzena Gawrysiak-Witulska Jolanta Wawrzyniak Antoni Ryniecki Juliusz Perkowski 《Journal of Stored Products Research》2008,44(4):360-365
Environmental microbiologists frequently use ergosterol, a fungal-specific membrane lipid, as an indicator of fungal infection in grain and other plant materials. Microbiological loading and technological quality of barley was determined directly after harvest, after post-harvest drying, and during storage. The conventional plate count method was used to measure fungal contamination (CFU). Ergosterol concentration (ERG) was determined by extraction, saponification and quantification using high-performance liquid chromatography (HPLC) with UV detection. The laboratory malting method was used to determine technological quality of the malt. Results showed a significant correlation between ERG and CFU (the coefficient of correlation was 0.92). Analyses also indicated that the high germinative energy and technological quality of the malt produced from dried barley was retained. 相似文献
33.
Jolanta Bryjak Andrzej Noworyta 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,57(1):79-85
The effects of glutaraldehyde, enzyme concentrations and reactants volumes, ionic strength, pH value and carrier particle diameter on immobilization of penicillin acylase onto acrylic carriers were studied. The activity of immobilized enzyme preparations was also studied over a range of pH values and temperatures and thermal and pH stabilities were determined. The use of the immobilized preparation for penicillin G hydrolysis in a batch reactor was investigated. The immobilized enzyme gave a significant reduction in hydrolysis time compared to hydrolysis by the native enzyme. 相似文献
34.
Jolanta Światowska-Mrowiecka Vincent Maurice Sandrine Zanna Lorena Klein Emrick Briand Ian Vickridge Philippe Marcus 《Journal of power sources》2007
Cyclic voltammetry, XPS, RBS and AFM have been combined to study the ageing mechanism of Li intercalation in V2O5 thin films prepared by thermal oxidation of vanadium metal. Multi-cycling tests were performed in 1 M LiClO4-PC in the potential range E ∈ [3.8, 2.8 V] versus Li/Li+, corresponding to the α-to-δ phase transition. XPS and AFM were performed using direct anaerobic and anhydrous transfer. Capacity fading remains inferior to 20% during ∼2500 cycles. XPS shows slight modifications of the oxide composition with a V4+ concentration increasing from ∼5% prior to cycling to ∼16–27% after cycling, due to Li trapped in the oxide film and to the loss of V2O5 active material. The presence of lithium carbonate and lithium-alkyl carbonate species evidences the formation of the so-called SEI layer. AFM evidences the loss of crystalline material by grain exfoliation from the outer V2O5 layer of the oxide film. By further exfoliation, the inner VO2 layer of the oxide film is reached and pits are formed, occupying ∼9–13% of the surface. This de-cohesion at grain boundaries is attributed to the strain generated by repeated lattice distortions. After 3300 cycles, the disappearance of lithium carbonates, whereas Li-alkyl carbonates and/or Li-alkoxides remain on the surface, indicates the dissolution and/or conversion of the SEI layer. After 4500 cycles, the oxide film became very labile and could be stripped away by rinsing to reveal the vanadium metal substrate. 相似文献
35.
Soluch W Brzozowski E Lysakowska M Sadura J 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(11):2469-2474
Mass density, dielectric, elastic, and piezoelectric constants of bulk GaN crystal were determined. Mass density was obtained from the measured ratio of mass to volume of a cuboid. The dielectric constants were determined from the measured capacitances of an interdigital transducer (IDT) deposited on a Z-cut plate and from a parallel plate capacitor fabricated from this plate. The elastic and piezoelectric constants were determined by comparing the measured and calculated SAW velocities and electromechanical coupling coefficients on the Z- and X-cut plates. The following new constants were obtained: mass density p = 5986 kg/m(3); relative dielectric constants (at constant strain S) ε(S)(11)/ε(0) = 8.6 and ε(S)(11)/ε(0) = 10.5, where ε(0) is a dielectric constant of free space; elastic constants (at constant electric field E) C(E)(11) = 349.7, C(E)(12) = 128.1, C(E)(13) = 129.4, C(E)(33) = 430.3, and C(E)(44) = 96.5 GPa; and piezoelectric constants e(33) = 0.84, e(31) = -0.47, and e(15) = -0.41 C/m(2). 相似文献
36.
Artur Pinski Alexander Betekhtin Jolanta Kwasniewska Lukasz Chajec Elzbieta Wolny Robert Hasterok 《International journal of molecular sciences》2021,22(14)
As cell wall proteins, the hydroxyproline-rich glycoproteins (HRGPs) take part in plant growth and various developmental processes. To fulfil their functions, HRGPs, extensins (EXTs) in particular, undergo the hydroxylation of proline by the prolyl-4-hydroxylases. The activity of these enzymes can be inhibited with 3,4-dehydro-L-proline (3,4-DHP), which enables its application to reveal the functions of the HRGPs. Thus, to study the involvement of HRGPs in the development of root hairs and roots, we treated seedlings of Brachypodium distachyon with 250 µM, 500 µM, and 750 µM of 3,4-DHP. The histological observations showed that the root epidermis cells and the cortex cells beneath them ruptured. The immunostaining experiments using the JIM20 antibody, which recognizes the EXT epitopes, demonstrated the higher abundance of this epitope in the control compared to the treated samples. The transmission electron microscopy analyses revealed morphological and ultrastructural features that are typical for the vacuolar-type of cell death. Using the TUNEL test (terminal deoxynucleotidyl transferase dUTP nick end labelling), we showed an increase in the number of nuclei with damaged DNA in the roots that had been treated with 3,4-DHP compared to the control. Finally, an analysis of two metacaspases’ gene activity revealed an increase in their expression in the treated roots. Altogether, our results show that inhibiting the prolyl-4-hydroxylases with 3,4-DHP results in a vacuolar-type of cell death in roots, thereby highlighting the important role of HRGPs in root hair development and root growth. 相似文献
37.
The oxidation of 2-methylnaphthalene in the solution of lithium acetate in glacial acetic acid has been investigated. It has been found that, within the range of potentials 1.10–1.25 V vs saturated mercury acetate electrode in glacial acetic acid, the oxidation process results in mono- and diacetates of 2-methylnaphthalene formation. The values of Eτ/4 for 2-methylnaphthalene, 1-acetate-2-methylnaphthyl and 1,4-diacetate-2-methylnaphthyl oxidation have been determined as 1.09, 1.05 and 1.13 V, respectively. The degree of 2-methylnaphthalene conversion to monoacetate reaches its maximum value at 1.25 V which is 32.8%. 相似文献
38.
Gregory S Watson Jolanta A Blach Dan V Nicolau Duy K Pham Jon Wright Sverre Myhra 《Polymer International》2003,52(9):1408-1414
Poly‐(tert‐butyl methacrylate) (P(tBuMA)) thin‐film surfaces were patterned by UV radiation at doses in the range 10–100 mJ cm?2, in order to induce laterally differentiated surface chemistry with µm resolution. The most likely pathway for the radiation chemistry predicts a transition from hydrophobicity to hydrophilicity. Outcomes of analysis by atomic force microscopy under air ambient conditions were consistent with that prediction. Topographic and lateral force imaging, in combination with friction loop analysis, revealed shrinkage and increased friction arising from exposure. Force versus distance analysis revealed greater adhesion in hydrophilic regions, due to greater meniscus force acting on the tip. The thickness of adsorbed moisture, increased by a factor of 2.5 from ca 0.8 nm for the unirradiated surface, as a result of greater hydrophilicity induced by radiation. The latter observation shows that the increased friction was due principally to the greater normal force on the tip from an additional meniscus force. Copyright © 2003 Society of Chemical Industry 相似文献
39.
Micha Bodzek Jolanta Bohdziewicz Magorzata Kowalska 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1994,61(3):231-239
A method for the preparation of membranes with immobilised enzymes for the biological degradation of phenols is described. In the first stage, an enzymatic fraction from bacterial strains has been isolated. The enzyme membranes were obtained by ultrafiltration of protein solution through a membrane support made of non-cellulose polymers. All enzymes were adsorbed onto the membrane surface. The enzyme membranes were found to degrade 70–80% of the phenol during single dead-end ultrafiltration at a pressure of 1 × 105?3 × 105 Pa. The retention coeffcient of the ultrafiltration process also amounted to 70–80%. 相似文献
40.
The main objective of this research is to develop and apply state-of-the-art computational tools to achieve an understanding of intermolecular interactions in molecular imprinting of theophylline into complex polymeric systems. Molecular dynamics (MD) simulations were carried out for different molecular systems in order to predict the interaction energies, the closest approach distances and the active site groups between the simulated molecular systems and different bio-ligands. The minimized structures of five ligands, theophylline and its derivatives (theobromine, theophylline-8-butanoic acid, caffeine and theophylline-7-acetic acid) have been obtained with the use of molecular mechanics approach. NVT MD simulations at room temperature were carried out to obtain equilibrated conformations in all cases.The first simulated molecular systems consisted of a ligand and commonly used functional monomers, polymers and a substrate. The second simulated molecular systems consisted of a ligand and a monomer or polymer using a solvent (ethanol).During this study, it was found that electrostatic interactions play the most significant role in the formation of molecular imprinting materials. The simulated functional monomers and polymers with ligands indicate that the functional groups interacting with ligands tends to be either -COOH or CH2CH-. It was also found that molecular substrate without functional side groups are recommended for molecular imprinting technology. For both the solvated monomer and polymer systems is that it appears that the presence of the solvent appears to favour the formation of more stable clusters with theophylline than with its derivatives. 相似文献