全文获取类型
收费全文 | 264篇 |
免费 | 10篇 |
专业分类
化学工业 | 140篇 |
金属工艺 | 5篇 |
机械仪表 | 3篇 |
建筑科学 | 6篇 |
矿业工程 | 1篇 |
能源动力 | 3篇 |
轻工业 | 41篇 |
水利工程 | 2篇 |
石油天然气 | 7篇 |
无线电 | 7篇 |
一般工业技术 | 21篇 |
冶金工业 | 11篇 |
原子能技术 | 3篇 |
自动化技术 | 24篇 |
出版年
2023年 | 2篇 |
2022年 | 23篇 |
2021年 | 25篇 |
2020年 | 3篇 |
2019年 | 9篇 |
2018年 | 13篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 15篇 |
2012年 | 16篇 |
2011年 | 20篇 |
2010年 | 13篇 |
2009年 | 3篇 |
2008年 | 4篇 |
2007年 | 8篇 |
2006年 | 15篇 |
2005年 | 5篇 |
2004年 | 7篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1967年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有274条查询结果,搜索用时 0 毫秒
91.
Traian Zaharescu Ludmila I. P. Kayan Marius Eduard Lungulescu Declerc F. Parra Ademar B. Lugão 《Iranian Polymer Journal》2016,25(8):725-730
The integration of waste ethylene–propylene–diene terpolymer (EPDM), containing carbon black into pristine EPDM can be achieved by γ-irradiation as a versatile procedure to process ethylene–propylene elastomers. The presence of acrylic acid in the material formulation allows the formation of intermolecular bridges by threefold increase in gel content. The possibility of achieving greater stability by the addition of acrylic acid in EPDM systems was analyzed. The start materials were EPDM containing 30 and 50 phr of EPDM powder loaded with 40 phr of carbon black aged by pre-exposure to electron beam irradiation. The advanced γ-irradiation exceeding 100 kGy represented the optimal radiation processing condition. Two procedures of chemiluminescence under isothermal and non-isothermal regimes for the evaluation of radiation stability were applied on γ-irradiated samples. The thermal strength of irradiated samples was characterized based on the radiolysis mechanism of EPDM. The variation in the activation energy required for the thermal oxidation of these samples and the modification in gel contents due to the gelation action of acrylic acid were presented for the validation of proposed recycling radiochemical technique. Charlesby–Pinner representation provided different values for the ratios between radiochemical yields of cross-linking and scission, proving that the presence of acrylic acid promoted the conversion of EPDM wastes into valuable materials. 相似文献
92.
Ludmila N. Turino Barbara Stella Franco Dosio Julio A. Luna Antonello A. Barresi 《Drug development and industrial pharmacy》2018,44(6):934-941
This paper is focused on the production and characterization of polymeric nanoparticles obtained by nanoprecipitation. The method consisted of using a confined impinging jet mixer (CIJM), circumventing high-energy equipment. Differences between the use of poly-ε-caprolactone (PCL) and poly(lactide-co-glycolide) (PLGA) as concerns particle mean size, zeta potential, and broad-spectrum antibiotic florfenicol entrapment were investigated. Other analyzed variables were polymer concentration, solvent, and anti-solvent flow rates, and antibiotic initial concentration. To our knowledge, no data were found related to PLGA and PCL nanoparticles comparison using CIJM. Also, florfenicol encapsulation within PCL or PLGA nanoparticles by nanoprecipitation has not been reported yet. The complexity of the nanoprecipitation phenomena has been confirmed, with many relevant variables involved in particles formation. PLGA resulted in smaller and more stable nanoparticles with higher entrapping of florfenicol than PCL. 相似文献
93.
Material challenges for solar cells in the twenty-first century: directions in emerging technologies
Samy Almosni Amaury Delamarre Zacharie Jehl Daniel Suchet Ludmila Cojocaru Maxime Giteau 《Science and Technology of Advanced Materials》2018,19(1):336-369
Photovoltaic generation has stepped up within the last decade from outsider status to one of the important contributors of the ongoing energy transition, with about 1.7% of world electricity provided by solar cells. Progress in materials and production processes has played an important part in this development. Yet, there are many challenges before photovoltaics could provide clean, abundant, and cheap energy. Here, we review this research direction, with a focus on the results obtained within a Japan–French cooperation program, NextPV, working on promising solar cell technologies. The cooperation was focused on efficient photovoltaic devices, such as multijunction, ultrathin, intermediate band, and hot-carrier solar cells, and on printable solar cell materials such as colloidal quantum dots. 相似文献
94.
We compare eleven methods for finding prototypes upon which to base the nearest prototype classifier. Four methods for prototype selection are discussed: Wilson+Hart (a condensation+error‐editing method), and three types of combinatorial search—random search, genetic algorithm, and tabu search. Seven methods for prototype extraction are discussed: unsupervised vector quantization, supervised learning vector quantization (with and without training counters), decision surface mapping, a fuzzy version of vector quantization, c‐means clustering, and bootstrap editing. These eleven methods can be usefully divided two other ways: by whether they employ pre‐ or postsupervision; and by whether the number of prototypes found is user‐defined or “automatic.” Generalization error rates of the 11 methods are estimated on two synthetic and two real data sets. Offering the usual disclaimer that these are just a limited set of experiments, we feel confident in asserting that presupervised, extraction methods offer a better chance for success to the casual user than postsupervised, selection schemes. Finally, our calculations do not suggest that methods which find the “best” number of prototypes “automatically” are superior to methods for which the user simply specifies the number of prototypes. © 2001 John Wiley & Sons, Inc. 相似文献
95.
Jana Hajlová Jii Davidek Ludmila Fierová und Jan Veliek 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1984,178(5):382-385
Zusammenfassung In Äpfeln, welche mit den Pesticiden Melprex 65 W und/oder Anthio 25 behandelt wurden, und weiterhin in nicht behandelten Früchten (Kontrolle) wurden bedeutende Mengen von Substraten der Polyphenoloxidasen festgestellt. In den Proben wurden unterschiedliche Mengen von o-Diphenolen und phenolischen Säuren gefunden. Eine signifikant niedrigere Menge dieser Stoffe wurde in den mit Melprex 65 W behandelten Früchten nachgewiesen. Die Aktivität der Polyphenoloxidasen in dieser Probe ist fast identisch mit der Kontrolle. In den mit Anthio 25 behandelten Früchten beobachtete man ein etwas geringeres Braunwerden. Interessant ist die Feststellung, daß Dodine, der aktive Bestandteil von Melprex 65 W, die Bildung von Farbprodukten bei den Reaktionen der enzymatischen Bräunung beeinflußt.
The influence of some pesticides on the quality of apples. I. Enzymatic browning reactions
Summary The contents of some significant substrates of apple polyphenol oxidase were determined either in fruit treated with Melprex 65 W and/or Anthio 25 and in untreated fruit. Some differences were found in the concentrations of o-Dihydroxyphenols and phenolic acids. The significantly lower content of these substances was checked in apples treated with Melprex 65 W. The activity of polyphenol oxidase in this sample was nearly the same as that in a control. A slightly lower rate of browning was observed in apples treated with Anthio 25. It was proved that dodine (active ingredient of Melprex 65 W) participates in the formation of coloured products originating during enzymatic browning reactions.相似文献
96.
Rainer Mahrwald Hans Schick Ludmila L. Vasil'eva Kasimir K. Pivnitsky Gisela Weber Sigfrid Schwarz 《Advanced Synthesis \u0026amp; Catalysis》1990,332(2):169-175
Starting with the racemic aldehyde 4 , prepared from the tris(trimethylsilyl) ether 3 , the possibility was demonstrated of converting a trimethylsilylated primary hydroxy group with high selectivity into an aldehyde group in the presence of two trimethylsilylated secondary hydroxy groups employing oxalyl chloride and dimethyl sulfoxide (Swern reagent) as oxidant. The alkynylation of this aldehyde with 1-metalated hept-1-yne afforded a chromatographically separable mixture of two diastereomeric alcohols, both being suitable intermediates for the synthesis of PGF2α. The diastereofacial selectivity of the addition strongly depends on the metal employed. Hept-1-yn-1-yllithium afforded a 67:33 mixture of (13 R*)- and (13 S*)-alcohol, hept-1-yn-1-yltriisopropoxytitanium, however, a 30:70 mixture. 相似文献
97.
Jan ermk Ludmila Soukupov Vclav Chvalovský Elena M. Kharkova Boris A. Krentsel 《Advanced Synthesis \u0026amp; Catalysis》1991,333(2):249-253
Sodium dihydridobis(2-methoxyethoxo)aluminate (SDMA) is a suitable reducing agent for in situ generation of zerovalent nickel in a catalytic system nickel(II) 2, 4-pentanedionate/phosphorus(III) ligand/reducing agent. Although generally less polymer is formed in the propadiene/propyne cooligomerization catalyzed by this system when the reducing agent is triethylaluminium, at molar ratios Al/Ni = 3 and P/Ni = 3 no polymer is formed with SDMA and the yield of oligomers is comparable to that obtained with triethylaluminium. 相似文献
98.
99.
Ludmila Kilhnkov Josef Mostek Andla Pizingerov 《Journal of the Institute of Brewing》1975,81(3):218-224
Four industrial strains of bottom brewer's yeast and a group of their spontaneous respiration deficient (RD) mutants were tested for rates of metabolism of glucose and maltose under aerobic and anaerobic conditions. Qo2 of all the RD mutants tested (26 isolates) ranged from 1·9 to 6·8 μl/mg yeast dry weight on glucose and was lowered to about one-half on maltose although the original strains had the same Qo2 values on both sugars. No isolate showed any increase in glucose fermentation in aerobic conditions as compared with the original strains and the decrease of Pasteur effect found in certain isolates was always accompanied by a strong decrease of glycolysis in both aerobic and anaerobic conditions. Two mutants showed a strongly negative Pasteur effect, for their fermentation rates were higher in aerobic conditions than in anaerobic ones. Two other mutants showed a strong negative Pasteur effect only on maltose. The ratio of QN2CO2 on glucose in most mutants was significantly lower than in their parental strains. 相似文献
100.
Zhao Li Sai‐Wing Tsang Xiaomei Du Ludmila Scoles Gilles Robertson Yanguang Zhang Floyd Toll Ye Tao Jianping Lu Jianfu Ding 《Advanced functional materials》2011,21(17):3331-3336
A series of alternating copolymers of cyclopenta[2,1‐b;3,4‐b′]dithiophene (CPDT) and thieno[3,4‐c]pyrrole‐4,6‐dione (TPD) have been prepared and characterized for polymer solar cell (PSC) applications. Different alkyl side chains, including butyl (Bu), hexyl (He), octyl (Oc), and 2‐ethylhexyl (EH), are introduced to the TPD unit in order to adjust the packing of the polymer chain in the solid state, while the hexyl side chain on the CPDT unit remains unchanged to simplify discussion. The polymers in this series have a simple main chain structure and can be synthesized easily, have a narrow band gap and a broad light absorption. The different alkyl chains on the TPD unit not only significantly influence the solubility and chain packing, but also fine tune the energy levels of the polymers. The polymers with Oc or EH group have lower HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy levels, resulting higher open circuit voltages (Voc) of the PSC devices. Power conversion efficiencies (PCEs) up to 5.5% and 6.4% are obtained from the devices of the Oc substituted polymer (PCPDTTPD‐Oc) with PC61BM and PC71BM, respectively. This side chain effect on the PSC performance is related to the formation of a fine bulk heterojunction structure of polymer and PCBM domains, as observed with atomic force microscopy. 相似文献