全文获取类型
收费全文 | 188篇 |
免费 | 33篇 |
专业分类
化学工业 | 76篇 |
金属工艺 | 1篇 |
建筑科学 | 5篇 |
能源动力 | 1篇 |
轻工业 | 57篇 |
无线电 | 20篇 |
一般工业技术 | 47篇 |
冶金工业 | 5篇 |
自动化技术 | 9篇 |
出版年
2023年 | 4篇 |
2022年 | 20篇 |
2021年 | 23篇 |
2020年 | 6篇 |
2019年 | 2篇 |
2018年 | 16篇 |
2017年 | 5篇 |
2016年 | 17篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 9篇 |
2012年 | 15篇 |
2011年 | 9篇 |
2010年 | 9篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1985年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有221条查询结果,搜索用时 15 毫秒
61.
62.
The effect of processing and cooking on phenolic acids profile and antioxidant properties of durum wheat (Triticum turgidum L. var. durum) pasta samples enriched with debranning fractions of an Italian wheat (Triticum aestivum L.) cultivar were studied. 相似文献
63.
Antonietta Baiano Tommaso Gomes & Francesco Caponio 《International Journal of Food Science & Technology》2005,40(8):829-834
The hydrolytic and oxidative degradation of olive oil and extra‐virgin olive oil, used as covering liquids in canned dried tomatoes, was studied during storage by means of conventional (acidity, peroxide value, p‐anisidine value) and non conventional (polar compounds) analyses. The effects of the addition of spices were also considered. The hydrolysis and oxidation of olive oil increased faster and was higher than that of extra‐virgin olive oil in terms of absolute values but some other indices, such as percentage of oligopolymers and percentage of oxidized triglycerides, increased faster in extra‐virgin olive oil than in olive oil. The antioxidant effect given by a higher concentration of polyphenols in the extra‐virgin olive oil was shown by a reduced amount of secondary oxidation. However, olive oil and extra‐virgin olive oils showed similar behaviour in terms of peroxide formation. 相似文献
64.
An oxidation process observed in dilute aqueous solutions of ammonia was investigated under steady-state conditions with gold microelectrodes with radii in the range 2.5-30 microm. Over the ammonia concentration range 0.1-10 mM, a well-defined voltammetric wave was observed at approximately 1.4 V versus Ag/AgCl. It was attributed to the oxidation of hydroxide ions that arise from the dissociation of the weak base. The steady-state limiting current was found to depend on the concentration of supporting electrolyte, and in solution with low electrolyte, it was enhanced by migration contribution, as expected for a negatively charged species that oxidizes on a positively charged electrode. In addition, the steady-state limiting current was proportional to both the ammonia concentration and the electrode radius. The overall electrode process was analyzed in terms of a CE mechanism (homogeneous chemical reaction preceding the heterogeneous electron transfer) with a fast chemical reaction when measurements were carried out in solutions containing NH3 at < or = 5 mM and with electrodes having a radius of > or = 5 microm. This was ascertained by comparing experimental and theoretical data obtained by simulation. The formation of the soluble complex species Au(NH3)2+ was also considered as a possible alternative to explain the presence of the oxidation wave. This process however was ruled out, as the experimental data did not fit theoretical predictions in any of the conditions employed in the investigation. Instead, the direct oxidation of NH3, probably to N2O, was invoked to explain the anomalous currents found when the CE process was strongly kinetically hindered. Throughout this study, a parallel was made between the CE mechanism investigated here and that known to occur during the hydrogen evolution reaction from weak acids. 相似文献
65.
Yongjie Wang Kunyuan Lu Lu Han Zeke Liu Guozheng Shi Honghua Fang Si Chen Tian Wu Fan Yang Mengfan Gu Sijie Zhou Xufeng Ling Xun Tang Jiawei Zheng Maria Antonietta Loi Wanli Ma 《Advanced materials (Deerfield Beach, Fla.)》2018,30(16)
Current efforts on lead sulfide quantum dot (PbS QD) solar cells are mostly paid to the device architecture engineering and postsynthetic surface modification, while very rare work regarding the optimization of PbS synthesis is reported. Here, PbS QDs are successfully synthesized using PbO and PbAc2 · 3H2O as the lead sources. QD solar cells based on PbAc‐PbS have demonstrated a high power conversion efficiency (PCE) of 10.82% (and independently certificated values of 10.62%), which is significantly higher than the PCE of 9.39% for PbO‐PbS QD based ones. For the first time, systematic investigations are carried out on the effect of lead precursor engineering on the device performance. It is revealed that acetate can act as an efficient capping ligands together with oleic acid, providing better surface coverage and replace some of the harmful hydroxyl (OH) ligands during the synthesis. Then the acetate on the surface can be exchanged by iodide and lead to desired passivation. This work demonstrates that the precursor engineering has great potential in performance improvement. It is also pointed out that the initial synthesis is an often neglected but critical stage and has abundant room for optimization to further improve the quality of the resultant QDs, leading to breakthrough efficiency. 相似文献
66.
Horacio Rodríguez Salvador Climent Piek Vossen Laura Bloksma Wim Peters Antonietta Alonge Francesca Bertagna Adriana Roventini 《Computers and the Humanities》1998,32(2-3):117-152
This paper describes two fundamental aspects in the process of building of the EuroWordNet database. In EuroWordNet we have chosen for a flexible design in which local wordnets are built relatively independently as language-specific structures, which are linked to an Inter-Lingual-Index (ILI). To ensure compatibility between the wordnets, a core set of common concepts has been defined that has to be covered by every language. Furthermore, these concepts have been classified via the ILI in terms of a Top Ontology of 63 fundamental semantic distinctions used in various semantic theories and paradigms. This paper first discusses the process leading to the definition of the set of Base Concepts, and the structure and the rationale of the Top Ontology. 相似文献
67.
Lorenza Brocca Maira Rossi Monica Canepari Roberto Bottinelli Maria Antonietta Pellegrino 《International journal of molecular sciences》2022,23(1)
A large set of FoxOs-dependent genes play a primary role in controlling muscle mass during hindlimb unloading. Mitochondrial dysfunction can modulate such a process. We hypothesized that endurance exercise before disuse can protect against disuse-induced muscle atrophy by enhancing peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) expression and preventing mitochondrial dysfunction and energy-sensing AMP-activated protein kinase (AMPK) activation. We studied cross sectional area (CSA) of muscle fibers of gastrocnemius muscle by histochemistry following 1, 3, 7, and 14 days of hindlimb unloading (HU). We used Western blotting and qRT-PCR to study mitochondrial dynamics and FoxOs-dependent atrogenes’ expression at 1 and 3 days after HU. Preconditioned animals were submitted to moderate treadmill exercise for 7 days before disuse. Exercise preconditioning protected the gastrocnemius from disuse atrophy until 7 days of HU. It blunted alterations in mitochondrial dynamics up to 3 days after HU and the expression of most atrogenes at 1 day after disuse. In preconditioned mice, the activation of atrogenes resumed 3 days after HU when mitochondrial dynamics, assessed by profusion and pro-fission markers (mitofusin 1, MFN1, mitofusin 2, MFN2, optic atrophy 1, OPA1, dynamin related protein 1, DRP1 and fission 1, FIS1), PGC1α levels, and AMPK activation were at a basal level. Therefore, the normalization of mitochondrial dynamics and function was not sufficient to prevent atrogenes activation just a few days after HU. The time course of sirtuin 1 (SIRT1) expression and content paralleled the time course of atrogenes’ expression. In conclusion, seven days of endurance exercise counteracted alterations of mitochondrial dynamics and the activation of atrogenes early into disuse. Despite the normalization of mitochondrial dynamics, the effect on atrogenes’ suppression died away within 3 days of HU. Interestingly, muscle protection lasted until 7 days of HU. A longer or more intense exercise preconditioning may prolong atrogenes suppression and muscle protection. 相似文献
68.
Summary: Blends of poly(propylene) (PP) were prepared with poly[ethylene‐co‐(methyl acrylate)] (EMA) having 9.0 and 21.5% methyl acrylate comonomer. A similar series of blends were compatibilized by using maleic anhydride grafted PP. The morphology and mechanical properties of the blends were investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) in tensile mode. The DMA method and conditions were optimized for polymer film specimens and are discussed in the experimental section. The DSC results showed separate melting that is indicative of phase‐separated blends, analogous to other PP‐polyethylene blends but with the added polarity of methyl acrylate pendant side groups that may be beneficial for chemical resistance. Heterogeneous nucleation of PP was decreased in the blends because of migration of nuclei into the more polar EMA phase. The crystallinity and peak‐melting temperature did not vary significantly, although the width of the melting endotherm increased in the blends indicating a change had occurred to the crystals. DMA analysis showed the crystal‐crystal slip transition and glass transition (Tg) for PP as well as a Tg of the EMA copolymer occurring chronologically toward lower temperatures. The storage modulus of PP and the blends was generally greater with annealing at 150 °C compared with isothermal crystallization at 130 °C. The storage modulus of the blends for isothermally crystallized PP increased with 5% EMA, then decreased for higher amounts of EMA. Annealing caused a decrease with increasing copolymer content. The extent of the trend was greater for the compatibilized blends. The Tg of the blends varied over a small range, although this change was less for the compatibilized blends.
69.
70.
Gatti AM Montanari S Gambarelli A Capitani F Salvatori R 《Journal of materials science. Materials in medicine》2005,16(12):1213-1219
Through an innovative electron microscopy technique, thrombi and fibrotic tissue taken from 14 explanted vena cava filters
were observed. Twelve cases showed the presence of micro-and nano-sized inorganic, non biodegradable nor biocompatible particles
which did not belong to the metal the device was made of and which could be the sole cause or, more likely, a pre-existing
cause for thrombosis. In two cases, those debris activated immunological reactions typical of a foreign body. The presence
of inorganic particles in the blood was never detected before and their effects on human health are hardly known. Their thrombogenicity
should be added to the Virchow's Triad as a fourth factor and could be the explanation to many of the cases of pulmonary embolism
where no thrombotic focus could be demonstrated. 相似文献