全文获取类型
收费全文 | 241篇 |
免费 | 13篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 83篇 |
金属工艺 | 13篇 |
机械仪表 | 7篇 |
建筑科学 | 2篇 |
能源动力 | 20篇 |
轻工业 | 9篇 |
无线电 | 17篇 |
一般工业技术 | 40篇 |
冶金工业 | 38篇 |
原子能技术 | 3篇 |
自动化技术 | 21篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 14篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 7篇 |
2017年 | 11篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 19篇 |
2012年 | 10篇 |
2011年 | 23篇 |
2010年 | 15篇 |
2009年 | 15篇 |
2008年 | 17篇 |
2007年 | 10篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 12篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1972年 | 1篇 |
1961年 | 2篇 |
1957年 | 2篇 |
1956年 | 1篇 |
排序方式: 共有254条查询结果,搜索用时 390 毫秒
1.
Virginia Veronica Visconti Ida Cariati Simona Fittipaldi Riccardo Iundusi Elena Gasbarra Umberto Tarantino Annalisa Botta 《International journal of molecular sciences》2021,22(8)
DNA methylation is one of the most studied epigenetic mechanisms that play a pivotal role in regulating gene expression. The epigenetic component is strongly involved in aging-bone diseases, such as osteoporosis and osteoarthritis. Both are complex multi-factorial late-onset disorders that represent a globally widespread health problem, highlighting a crucial point of investigations in many scientific studies. In recent years, new findings on the role of DNA methylation in the pathogenesis of aging-bone diseases have emerged. The aim of this systematic review is to update knowledge in the field of DNA methylation associated with osteoporosis and osteoarthritis, focusing on the specific tissues involved in both pathological conditions. 相似文献
2.
Diffractive optical elements have a large number of industrial applications, such as beam shaping and optical filtering. Traditionally, these elements modulate the phase of the incoming light or its amplitude, but not both. To overcome this limitation, full complex-amplitude modulation diffractive optical elements were developed. Well-established integrated circuit fabrication steps were employed to fabricate the devices with high precision. Using this approach, the new element‘s optical performances are improved also for near field operations. With this device it is possible to obtain 100% efficient spatial filtering and low noise reconstructed images. 相似文献
3.
Inflammation and coagulation cannot be considered as two separate processes, since there are several connecting points making them part of unique, defensive host response. The endothelium can be considered as the first link between inflammation and coagulation, since damaged endothelium during inflammation represents a surface where proteins involved in both coagulation and the development of inflammation are expressed. During inflammation, cytokines modulate the coagulation system by downregulating the expression of thrombomodulin and the activation of protein C pattern but, at the same time, they induce the expression of tissue factor, modifying, in this way, the balance between procoagulant and anticoagulant activities. At the same time, at the site of tissue injury, platelets become activated and release several mediators that modify tissue integrity. Thrombin, formed following activation of the coagulation cascade, is essential to promote haemostasis but also stimulates several cell functions, including chemotaxis and mitogenesis, which are responsible for the spreading of the lesion and the tissue repair process. Therefore, in the study of inflammation the involvement of the coagulation pathway has to be taken into account, since the interaction between coagulation and inflammation pathways is a critical issue. 相似文献
4.
Maria Chiara Mistretta Luigi Botta Francesco Paolo La Mantia Antonino Di Fiore Marco Cascone 《大分子材料与工程》2021,306(9):2100177
Films for agricultural applications, such as greenhouses films or mulching films are generally made of polyolefins such as linear low-density polyethylene (LLDPE) or low-density polyethylene. However, the use of biodegradable and/or compostable polymers is increasing, which enjoy the additional advantage that they can be left on the site since a fine life would be gradually assimilated to the underlying soil. Nevertheless, biodegradable polymeric films often do not have suitable mechanical performances. In this work, biodegradable polymer-based nanocomposite films are prepared by film blowing and compared with traditional LLDPE based nanocomposites. In particular, a biodegradable polymer blend and two different inorganic nanofillers (an organo-modified clay and a calcium carbonate with a hydrophobic coating) are used for the preparation of the nanocomposites. A detailed investigation of obtained materials is performed through rheological, mechanical, and optical characterizations. Adding nanofillers led to an increase of rigidity and tear strength of blown films without negatively affecting their ductility. 相似文献
5.
6.
Rgia Maria Cordeiro Brito Alzir Azevedo Batista Javier Ellena Eduardo E. Castellano Izaura Cirino Nogueira Digenes Luiz Gonzaga de Frana Lopes Jackson Rodrigues de Sousa Ícaro de Sousa Moreira 《Inorganic chemistry communications》2007,10(12):1515-1517
The cis-[Ru(dppb)(Me-bipy)(NCS)2], dppb = 1,4-bis (diphenylphosphino)butane, Me-bipy = 4,4′-dimethyl-2,2′-bipyridine, and NCS = thiocyanate, was synthesized and characterized by spectroscopic and electrochemical techniques and its structure was determined by crystal X-ray analysis. The crystal structure reveals that the coordination geometry around the Ru(II) center is distorted octahedron where two molecules of thiocyanate are bonded to the ruthenium through nitrogen atom in cis orientation. The half-wave formal potential value E1/2 = 0.8 V (versus Ag/AgCl) observed is considerable higher than that for the cis-[RuCl2(dppb)(Me-bipy)] complex, E1/2 = 0.6 V (versus Ag/AgCl), well illustrating the strong π-acceptor effect the NCS ligand toward the backbonding interaction with the Ru(II) metal center. The MLCT absorption bands of the thiocyanate complex present a higher molar absorptivity (about 12%) compared with the cis-[RuCl2(dppb)(Me-bipy)] complex, in the same experimental conditions. These properties make the complex potentially promising for the photosensitization process. 相似文献
7.
P. H. Eaves J. J. Spadaro E. L. D’Aquin A. J. Crovetto V. O. Cirino Mack F. Stansbury C. L. Hoffpauir 《Journal of the American Oil Chemists' Society》1956,33(12):639-645
Summary and Conclusions Crude lipides fractions were produced from raw, tempered, and cooked meats from two lots of cottonseed by a series of successive
stepwise extractions, designed to obtain fractional portions of the total lipides in the order of the difficulty of their
extraction. The proximate composition of the crude lipides fractions was determined. It was found that the composition of
successive lipides fractions varied with the degree of exhaustiveness of extraction. The fractions obtained by more exhaustive
extraction contained greater amounts of undesirable non-neutral oil material and lesser amounts of desirable neutral oil.
It was also established that the method used in preparing meats for extraction was of paramount importance in its effect on
the composition of the crude lipides obtained. The crude lipides fractions from raw and tempered meats contained large amounts
of impurities while the crude lipides fractions similarly obtained from cooked meats were relatively low in impurities.
Crude oils equivalent to varying degrees of total lipides extraction were reconstituted from the crude lipides fractions and
evaluated for refining characteristics. The impurities content of the reconstituted oils varied as the degree of total lipides
extraction and increases in the impurities content of the oils were generally reflected in disproportionate increases in refining
losses and/or refined oil color. The oils obtained from the cooked meats at all degrees of extraction were outstandingly low
in refining losses as compared to the oils from the raw and the tempered meats.
Presented in two parts at the spring meeting, American Oil Chemists’ Society, New Orleans. La., Apr. 18–20, 1955, and at the
fall meeting, Philadelphia, Pa., Oct. 10–12, 1995.
One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture. 相似文献
8.
Fairie Lyn Carter Vidabelle O. Cirino Layton E. Allen 《Journal of the American Oil Chemists' Society》1961,38(3):148-150
Except for a variation in the freeepsilon-amino lysine content of the protein, the Mexican screw-pressed meals were quite similar in their composition. The lysine
values for sesame protein obtained for the solvent-extracted meals were much higher than those obtained for the screw-pressed
meals. Screening of the endosperm and spermoderm from the solvent-extracted meals was effective in reducing the oxalate content
of the resulting flour although some epiderm fragments passed through a 60-mesh screen. The decortication process completely
removed the portion containing the oxalate from the seed and also reduced the calcium, sugar, and silica contents.
Presented at the annual meeting, American Oil Chemists' Society, Dallas, Tex., April 4–6, 1960.
One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U.S.
Department of Agriculture. 相似文献
9.
Thomas Silverston Olivier Fourmaux Alessio Botta Alberto Dainotti Antonio Pescapé Giorgio Ventre Kavé Salamatian 《Computer Networks》2009,53(4):470-484
The Internet is currently experiencing one of the most important challenges in terms of content distribution since its first uses as a medium for content delivery: users from passive downloaders and browsers are moving towards content producers and publishers. They often distribute and retrieve multimedia contents establishing network communities. This is the case of peer-to-peer IPTV communities.In this work we present a detailed study of P2P IPTV traffic, providing useful insights on both transport- and packet-level properties as well as on the behavior of the peers inside the network. In particular, we provide novel results on the (i) ports and protocols used; (ii) differences between signaling and video traffic; (iii) behavior of the traffic at different time scales; (iv) differences between TCP and UDP traffic; (v) traffic generated and received by peers; (vi) peers neighborhood and session duration. The knowledge gained thanks to this analysis is useful for several tasks, e.g. traffic identification, understanding the performance of different P2P IPTV technologies and the impact of such traffic on network nodes and links, and building more realistic models for simulations.1 相似文献