全文获取类型
收费全文 | 256篇 |
免费 | 15篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 113篇 |
金属工艺 | 3篇 |
机械仪表 | 4篇 |
建筑科学 | 13篇 |
能源动力 | 6篇 |
轻工业 | 44篇 |
水利工程 | 2篇 |
无线电 | 1篇 |
一般工业技术 | 47篇 |
冶金工业 | 21篇 |
自动化技术 | 15篇 |
出版年
2023年 | 3篇 |
2022年 | 24篇 |
2021年 | 30篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 9篇 |
2015年 | 14篇 |
2014年 | 15篇 |
2013年 | 11篇 |
2012年 | 19篇 |
2011年 | 16篇 |
2010年 | 15篇 |
2009年 | 15篇 |
2008年 | 10篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有271条查询结果,搜索用时 31 毫秒
121.
Annamária Mockovčiaková Marek Matik Zuzana Orolínová Pavol Hudec Erika Kmecová 《Journal of Porous Materials》2008,15(5):559-564
Natural zeolite of Slovak provenience has been modified with magnetic nanoparticles at selected temperatures of 20, 50 and
85 °C with the aim to enhance its sorption properties. The pore, surface and structural properties of zeolite/iron oxide composite
were characterized using nitrogen adsorption measurements, electron probe microanalysis and powder X-ray diffraction. The
crystallinity of the host zeolite was strongly influenced by the temperature of iron oxide particles precipitation, but it
was still retained. It followed from the nitrogen adsorption measurements that the surface area and the pore volume of zeolite
composites have increased in relation to the precipitation temperature, the best sorption properties were revealed at the
composite prepared at 85 °C. As followed also from the SEM images, the iron oxide nanoparticles being of size 30 nm are forming
mesoporous aggregates adsorbed on the zeolite surface. Fractal analysis used to describe the modified geometry of zeolite
composites has given the values of surface fractal dimension between 2.36 and 2.51. 相似文献
122.
Maria Vass Iva Diblikova Eloise Kok Kamil Stastny Karla Frgalova Karel Hruska 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2013,30(8):930-936
An enzyme-linked immunosorbent assay (ELISA) method is described for the semi-quantitative determination of semicarbazide (SEM), the marker residue for the banned nitrofuran drug, nitrofurazone, in chicken eggs. The sample homogenate is subjected to acid hydrolysis and derivatisation with o-nitrobenzaldehyde, followed by ethyl acetate/hexane extraction and detection by ELISA. The ELISA procedure has been validated using 0.3, 1.0 and 3 µg kg?1 of SEM in fortified samples. Detection capability (CCß) was based on the acceptance of 5% false compliant results for a given concentration level according to Commission Decision 2002/657/EC and was determined to be 0.3 µg kg?1 with a respective limit of detection of 0.13 µg kg?1. A validated LC–MS/MS method was used for the analysis of incurred egg samples and the results compared with ELISA. A good correlation between the results obtained from ELISA and LC–MS/MS within the concentration range 0.12–20.3 µg kg?1 was observed in samples collected from chickens fed with a medicated ration of nitrofurazone (r?=?0.992, n?=?14). Validated ELISA enabled reliable monitoring of SEM levels in eggs collected from incurred chickens over a 90-day period. 相似文献
123.
Emi Haladjova Maroš Smolíček Iva Ugrinova Denitsa Momekova Pavletta Shestakova Zuzana Kroneková Juraj Kronek Stanislav Rangelov 《应用聚合物科学杂志》2020,137(45):49400
Poly(2-methyl-2-oxazoline)-polyethylenimine (PMeOx-co-PEI) copolymers differing by degree of polymerization (DP = 50 and 200) and PEI content (from 37 to 99 mol%) were synthesized by living cationic ring-opening polymerization of 2-methyl-2-oxazoline, followed by partial hydrolysis. Upon mixing with DNA in a wide range of N/P ratios, they formed well-defined polyplex particles of small size (typically below 100 nm) and narrow size distribution. The polyplexes demonstrated good colloidal stability and very low in vitro cytotoxicity. The copolymers exhibited buffering capacity of over 50% relative to that of the reference PEI implying effective endo-lysosomal escape of the polyplexes. Increased cellular internalization of both PCR fragments and plasmid DNA, attributable to the strongly positive ζ potential and small size of the polyplexes, was observed. In spite of these favorable prerequisites, the transfection efficiency was low (below 20% relative to the control PEI) and was attributed to retarded swelling of the polyplex particles, endo-lysosomal rupture, and DNA release. 相似文献
124.
Hruska Bryce; Fallon William; Spoonster Eileen; Sledjeski Eve M.; Delahanty Douglas L. 《Canadian Metallurgical Quarterly》2011,25(3):405
Avoidance coping (AVC) is common in individuals with posttraumatic stress disorder (PTSD) and in individuals with alcohol use disorder (AUD). Given that PTSD and AUD commonly co-occur, AVC may represent a risk factor for the development of comorbid posttraumatic stress and alcohol use. In this study, the relationship between AVC and PTSD symptoms (PTSS) was examined in individuals with versus without AUDs. Motor vehicle accident (MVA) victims were assessed 6 weeks postaccident for AUD history (i.e. diagnoses of current or past alcohol abuse or dependence) and AVC. PTSS were assessed 6 weeks and 6 months post-MVA. All analyses were conducted on the full sample of MVA victims as well as on the subset of participants who were legally intoxicated (blood alcohol concentration ≥ 0.08) during the accident. It was hypothesized that the relationship between AVC and PTSS would be stronger in those individuals with an AUD history and especially strong in the subset of individuals who were legally intoxicated during the MVA. Results were largely supportive of this hypothesis, even after controlling for in-hospital PTSS, gender, and current major depression. Early assessment of AUD history and avoidance coping may aid in detecting those at elevated risk for PTSD, and intervening to reduce AVC soon after trauma may help buffer the development of PTSD + AUD comorbidity. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
125.
Qianqian Yang Zuzana Kučerová Zhihong Li Irma Kalinović Václav Stejskal George Opit Yang Cao 《Journal of Stored Products Research》2012
Liposcelis entomophila infests stored grain and is one of the most important psocid species worldwide. Six geographically isolated strains of L. entomophila from Asia, Europe, and United States of America (USA) were compared based on morphological attributes and by molecular methods. Decisive characters of morphological diagnosis were studied using body size measurements and Scanning Electron Microscopy (SEM). Molecular identification of the six strains was performed via identification of DNA sequence similarities and phylogenetic analyses based on a 655-bp fragment from the 5′ end of the standard mitochondrial gene cytochrome c oxidase I (COI) barcode region. The results showed that both morphological and molecular approaches were able to accurately identify this species. Kimura-2-Parameter (K2P) divergence between geographically isolated strains was on average 1.75% for the COI sequence. Phylogenetic analyses revealed that sequences of L. entomophila strains' COI barcodes formed clusters with tight cohesion that were clearly distinct from those of allied species. 相似文献
126.
127.
128.
Impact of oregano and virgin olive oil phenolic compounds on acrylamide content in a model system and fresh potatoes 总被引:1,自引:0,他引:1
In this study the effect of olive oil and oregano phenolic compounds on antioxidant activity (AOA) and acrylamide formation in a model system and fresh potatoes was evaluated. The addition of oregano phenolic extract in the model system resulted in an increase of AOA and in a reduction of acrylamide content, up to 49%, after heating. On the contrary, addition of olive oil extract resulted in AOA reduction and a concentration-dependent effect on acrylamide formation was observed with a reduction up to 15% (p < 0.05) followed by an increase up to 48%. The same trend, in acrylamide formation, was observed in fresh potatoes but to a lower extent. Finally, addition of tyrosol, oleuropein and p-hydroxyphenylacetic acid in the model system resulted in acrylamide reduction up to 50%. The discrepancy in acrylamide formation, caused by phenolic compounds, is ascribed to their structure and related to their terminal functional hydroxyl and aldehydic groups. 相似文献
129.
Kristína Kukurová Zuzana Ciesarová Burçe Ataç Mogol Özge Çetinkaya Açar Vural Gökmen 《European Food Research and Technology》2013,237(1):1-8
The impact of raising agents on formation of heat-induced contaminants, acrylamide and 5-hydroxymethylfurfural (HMF), with focus on the efficiency of enzyme asparaginase as a potent tool for acrylamide reduction was investigated in the model system of cereal products. Acrylamide formation was strongly supported by ammonium hydrogen carbonate (NH4HCO3), observing 6 times higher level in comparison with control sample without raising agents, and was suppressed effectively by sodium hydrogen carbonate (NaHCO3) up to 52 %. Sodium pyrophosphate (Na4P2O7) had no influence on the final acrylamide content. The level of HMF remained untouched by NH4HCO3 contrary to sodium raising agents that both diminished HMF concentration up to 95 % using NaHCO3. Furthermore, enzyme asparaginase eliminated acrylamide formation in the range from 23 to 75 % depending mainly on pH value of dough and time of enzyme incubation (15, 30 and 60 min). The optimum pH value for asparaginase action was in neutrality. Na4P2O7 shifted pH value of dough to the optimum in comparison with control (from 5.82 to 6.78). NH4HCO3 and NaHCO3 changed pH value out of optimum up to 7.82 and 8.10, respectively. The longer the enzyme treatment, the higher the acrylamide elimination was observed, with the main importance in cases of pH shifting by raising agents. These findings indicate that a product-specific optimization of the conditions for enzymatic treatment is still challenging in terms of achieving desired quality parameters with improved safety, although acrylamide mitigation by means of asparaginase was proved to be a very effective tool especially in cereal-based products. 相似文献
130.