全文获取类型
收费全文 | 1761篇 |
免费 | 100篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 780篇 |
金属工艺 | 13篇 |
机械仪表 | 40篇 |
建筑科学 | 53篇 |
能源动力 | 49篇 |
轻工业 | 286篇 |
水利工程 | 18篇 |
石油天然气 | 3篇 |
无线电 | 57篇 |
一般工业技术 | 220篇 |
冶金工业 | 81篇 |
原子能技术 | 6篇 |
自动化技术 | 250篇 |
出版年
2024年 | 2篇 |
2023年 | 28篇 |
2022年 | 159篇 |
2021年 | 188篇 |
2020年 | 59篇 |
2019年 | 50篇 |
2018年 | 39篇 |
2017年 | 45篇 |
2016年 | 74篇 |
2015年 | 67篇 |
2014年 | 65篇 |
2013年 | 127篇 |
2012年 | 99篇 |
2011年 | 129篇 |
2010年 | 77篇 |
2009年 | 82篇 |
2008年 | 106篇 |
2007年 | 65篇 |
2006年 | 37篇 |
2005年 | 50篇 |
2004年 | 39篇 |
2003年 | 41篇 |
2002年 | 34篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 23篇 |
1998年 | 26篇 |
1997年 | 17篇 |
1996年 | 19篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1861条查询结果,搜索用时 15 毫秒
71.
D. Caccavo P. Apicella G. Lamberti A. A. Barba 《Chemical Engineering Communications》2017,204(12):1333-1340
One of the main aims in agriculture is to guarantee soil wellness, which is a fundamental requirement to produce high-quality crops with high yields. Focused on this aim, periodical administrations of nutrients or phytostrengtheners are often necessary. The most relevant disadvantages of these administrations are the high dosage number required and the low availability of the substance within the soil. For these reasons, a crucial goal to increase the economic and environmental sustainability of the cultivation process is to reduce the dosage number, which can be obtained increasing the active substance availability in the soil. A granular hydroxypropyl methylcellulose (HPMC) matrix, produced using the wet granulation process, was used to encapsulate a phytostrengthener and to guarantee its controlled release. The granular product was characterized in terms of granules properties and phytostrengtheners leaching within the soil. The results showed good flowability and mechanical properties of the granules as well as the possibility to reduce the product leaching with the phytostrengtheners encapsulation in the HPMC matrices. 相似文献
72.
Pedrini Matteo Langella Valentina Battaglia Mario Alberto Zaratin Paola 《Scientometrics》2018,114(3):1227-1250
Scientometrics - In recent year, a growing attention is dedicated to the assessment of research’s social impact. While prior research has often dealt with results of research, the last decade... 相似文献
73.
Paola Pellegrini Franco Mascia Thomas Stützle Mauro Birattari 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2014,18(11):2177-2190
In this paper, we assess the sensitivity of reactive tabu search to its meta-parameters. Based on a thorough experimental analysis of reactive tabu search applications to the quadratic assignment and the maximum clique problem, we show that its performance is relatively insensitive to its meta-parameters. This is particularly evident when compared to the sensitivity of tabu search to its parameters: tabu search is rather penalized if used with sub-optimal parameter settings. Reactive tabu search does not strongly pay its high parameter robustness in terms of performance, although it does not improve the peak performance of tabu search. 相似文献
74.
75.
Adele Chimento Anna Santarsiero Domenico Iacopetta Jessica Ceramella Arianna De Luca Vittoria Infantino Ortensia Ilaria Parisi Paola Avena Maria Grazia Bonomo Carmela Saturnino Maria Stefania Sinicropi Vincenzo Pezzi 《International journal of molecular sciences》2021,22(10)
Resveratrol (RSV) is a natural compound that displays several pharmacological properties, including anti-cancer actions. However, its clinical application is limited because of its low solubility and bioavailability. Here, the antiproliferative and anti-inflammatory activity of a series of phenylacetamide RSV derivatives has been evaluated in several cancer cell lines. These derivatives contain a monosubstituted aromatic ring that could mimic the RSV phenolic nucleus and a longer flexible chain that could confer a better stability and bioavailability than RSV. Using MTT assay, we demonstrated that most derivatives exerted antiproliferative effects in almost all of the cancer cell lines tested. Among them, derivative 2, that showed greater bioavailability than RSV, was the most active, particularly against estrogen receptor positive (ER+) MCF7 and estrogen receptor negative (ER-) MDA-MB231 breast cancer cell lines. Moreover, we demonstrated that these derivatives, particularly derivative 2, were able to inhibit NO and ROS synthesis and PGE2 secretion in lipopolysaccharide (LPS)-activated U937 human monocytic cells (derived from a histiocytoma). In order to define the molecular mechanisms underlying the antiproliferative effects of derivative 2, we found that it determined cell cycle arrest at the G1 phase, modified the expression of cell cycle regulatory proteins, and ultimately triggered apoptotic cell death in both breast cancer cell lines. Taken together, these results highlight the studied RSV derivatives, particularly derivative 2, as promising tools for the development of new and more bioavailable derivatives useful in the treatment of breast cancer. 相似文献
76.
Anna Rita Bavaro Mariaelena Di Biase Amalia Conte Stella Lisa Lonigro Leonardo Caputo Annamaria Cedola Matteo Alessandro Del Nobile Antonio Francesco Logrieco Paola Lavermicocca Francesca Valerio 《International Journal of Food Science & Technology》2021,56(7):3197-3208
Production of the traditional Italian Focaccia bread (FcBread) requires reformulation to meet the new rules for healthier foods. We tested the applicability of a short-fermented (15 h) liquid sourdough (LS) (dough yield, DY, 250), obtained using quinoa (Q) or amaranth (Am) flour fermented with a Weissella cibaria strain (C43-11) producing exopolysaccharides (EPS) as fat replacer in yeast-leavened FcBread. The LSs were applied during the FcBread-making process at industrial pilot plant, reducing the added fat amount by 20% (FcBread-QLS and FcBread-AmLS) and products were compared with reference samples not containing EPS. All the products were analysed for physico-chemical properties (pH, TTA, organic acids, protein content and profile, instrumental colour), textural properties, sensory quality and glycemic index. The application of both pseudo-cereal-based W. cibaria LSs in FcBread allowed obtaining products with a reduced amount of fat, increased protein amount, mainly due to the albumin and glutenin/glutelin fractions, reduced glycemic index, improved texture and preserved in the traditional sensory profile of ‘focaccia’. 相似文献
77.
Chiara Manneschi Paola Fanzio Elena Angeli Giuseppe Firpo Luca Ceseracciu Valentina Mussi Luca Repetto Ugo Valbusa 《Microfluidics and nanofluidics》2013,14(1-2):21-30
Peculiar transport phenomena appear at nanoscale, since surface effects strongly affect the behaviour of fluids. Electrostatic and steric interactions, capillary forces and entropic effects play a key role in the behaviour of fluids and biomolecules. Since these effects strongly depend on the size of the nanofluidic system, a careful characterization of the fluidic environment is necessary. Moreover, the possibility to dynamically modulate the size of nanochannels is very appealing in the field of biomolecule manipulation. Recently, we have developed a lab-on-chip made of poly(dimethylsiloxane) (PDMS). This polymeric device is based on a tuneable nanochannel able to dynamically change its dimension in order to fit the application of interest. In fact, a mechanical compression applied on the top of the elastomeric device squeezes the nanochannel, reducing the channel cross section and allowing a dynamical optimization of the nanostructures. In this paper, this squeezing process is fully characterized both numerically and experimentally. This analysis provides information on the reduction of the nanochannel dimensions induced by compression as a function of the work of adhesion and of the stiffness of the materials composing the device. Moreover, calculations demonstrate the possibility to predict the change of the nanochannel size and shape induced by the compression. The possibility to dynamically tune the channel size opens up new opportunities in biomolecular sensing or sieving and in the study of new hydrodynamics effects. 相似文献
78.
Marco Albertini Francesca Vallese Marilena Di Valentin Paola Berto Giorgio M. Giacometti Paola Costantini Donatella Carbonera 《International Journal of Hydrogen Energy》2014
[FeFe]-hydrogenases contain a complex [4Fe–4S]-2Fe cluster (H-cluster) and are able to efficiently reduce protons to H2. Due to their potential exploitation for renewable energy production biotechnologies, significant efforts have been put into understanding the mechanisms driving the H-cluster assembly, which involves three conserved proteins. Among them, HydF works as scaffold upon which the H-cluster precursor is synthesized and carrier to deliver it to the hydrogenase, resulting in its activation. A FeS cluster binding sequence (CxHx46-53HCxxC) is conserved in all HydF proteins and should in principle provide four ligands to coordinate the Fe atom. However, we found that alternative metal coordination may exist in different HydF proteins and that only the three cysteines are strictly required, whereas the fourth ligand may vary and is, in any case, readily exchangeable. In this work we analyzed by EPR/HYSCORE the FeS cluster proton environment of HydF from Thermotoga neapolitana to determine the possible role of surrounding residues in the non-cysteinyl iron ligation of the protein. 相似文献
79.
This paper aims at evaluating the sources of differences among countries' innovative performances in the renewable energy (RE) sector. Namely, we focus on the national innovative capacity, the knowledge developed abroad and the related knowledge spillovers. We claim that a country is more likely to develop RE innovation: (i) the larger the knowledge stocks of other countries in the same sector; (ii) especially when those other countries share established linkages with the focal country. Relying on a knowledge production function, we model country-level innovative performances in the RE sector for 18 OECD countries in the period 1990–2006. Our findings confirm that, once controlling for climate-energy policies, international knowledge spillovers contribute significantly to RE innovation, and their effect is comparable with domestic R&D and human capital. In addition, international spillovers are more likely if countries share stronger linkages. 相似文献
80.
Mulloni Viviana Margesin Benno Farinelli Paola Marcelli Romolo Lucibello Andrea De Angelis Giorgio 《Microsystem Technologies》2017,23(9):3843-3850
Microsystem Technologies - Contact resistance is the main parameter used for assessing the high cycling reliability of RF microelectromechanical (RF-MEMS) switches. In this paper the use of a... 相似文献