全文获取类型
收费全文 | 450篇 |
免费 | 21篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 119篇 |
金属工艺 | 2篇 |
机械仪表 | 9篇 |
建筑科学 | 19篇 |
能源动力 | 30篇 |
轻工业 | 44篇 |
水利工程 | 3篇 |
无线电 | 42篇 |
一般工业技术 | 63篇 |
冶金工业 | 29篇 |
原子能技术 | 3篇 |
自动化技术 | 100篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 28篇 |
2020年 | 20篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 15篇 |
2014年 | 19篇 |
2013年 | 32篇 |
2012年 | 18篇 |
2011年 | 33篇 |
2010年 | 29篇 |
2009年 | 23篇 |
2008年 | 25篇 |
2007年 | 22篇 |
2006年 | 19篇 |
2005年 | 16篇 |
2004年 | 17篇 |
2003年 | 8篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 5篇 |
1973年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有471条查询结果,搜索用时 671 毫秒
151.
Dietary Habits and Gut Microbiota in Healthy Adults: Focusing on the Right Diet. A Systematic Review
Giulia Gibiino Martina De Siena Monica Sbrancia Cecilia Binda Vittorio Sambri Antonio Gasbarrini Carlo Fabbri 《International journal of molecular sciences》2021,22(13)
Diet is the first to affect our intestinal microbiota and therefore the state of eubiosis. Several studies are highlighting the potential benefits of taking certain nutritional supplements, but a dietary regime that can ensure the health of the intestinal microbiota, and the many pathways it governs, is not yet clearly defined. We performed a systematic review of the main studies concerning the impact of an omnivorous diet on the composition of the microbiota and the production of short-chain fatty acids (SCFAs). Some genera and phyla of interest emerged significantly and about half of the studies evaluated consider them to have an equally significant impact on the production of SCFAs, to be a source of nutrition for our colon cells, and many other processes. Although numerous randomized trials are still needed, the Mediterranean diet could play a valuable role in ensuring our health through direct interaction with our microbiota. 相似文献
152.
Egidio Ragonese Angelo Scuderi Vittorio Giammello Giuseppe Palmisano 《Analog Integrated Circuits and Signal Processing》2011,67(2):121-130
This paper presents a fully integrated SiGe BiCMOS 24-GHz receiver front-end implemented for a ultra-wideband automotive short-range
radar sensor. The circuit consists of a homodyne I/Q down-converter and a 24-GHz synthesizer. The receiver front-end is able
to achieve a power conversion gain as high as 30 dB and a 6-dB noise figure, while preserving high linearity performance thanks
to a 1-bit gain control. The frequency synthesizer, which also includes an on-chip loop filter, guarantees a phase noise of
−104 dBc/Hz at 1-MHz offset from the 24.125-GHz carrier and a 4.7-GHz tuning range from 20.4 to 25.1 GHz. 相似文献
153.
Vittorio Giammello Egidio Ragonese Giuseppe Palmisano 《Analog Integrated Circuits and Signal Processing》2011,66(3):449-453
An amplifier topology based on a transformer-coupled cascode stage is presented and compared with the most used solutions
for sub-μm CMOS power amplifiers, which are the common-source stage, cascode stage, and capacitive-coupled cascode stage.
The comparison was carried out by designing each amplifier in a 65-nm CMOS technology and for a 60-GHz operating frequency.
The design was optimized for a trade off among power gain, saturated output power, and linearity. Operating from a 1.2-V supply
voltage, the proposed amplifier improves both small-signal and large-signal performance with respect to the most common approaches,
thus demonstrating effectiveness with sub-μm CMOS technologies and mm-wave operation. 相似文献
154.
In this study we investigate the potential of multiwall carbon nanotubes (MWCNTs) with low metal impurities (2.57% iron) as magnetic resonance imaging (MRI) contrast agents. Taking into account probable aggregation at high MWCNTs concentration analysis shows that the r(2) relaxivity of MWCNTs in 1% agarose gels at 19?°C is 564 ± 41 s(-1) mM(-1); this is attributed to both the presence of iron oxide impurities and also to the carbon MWCNT structure itself. Stem cells were labelled with MWCNTs to demonstrate the effectiveness of MWCNTs as MRI contrast agents for cellular MRI. The MWCNTs did not impair cell viability or proliferation. These results suggest that the MRI contrast agent properties of the MWCNTs could be used in vivo for stem cell tracking/imaging and during MWCNT-mediated targeted electro-chemotherapy of tumours. 相似文献
155.
Alessandro Vittorio Bergami Camillo Nuti 《土木工程与建筑:英文版》2014,(7):815-823
The research presented in this paper deals with the seismic protection of existing frame structures by means of passive energy dissipation. An iterative displacement-based procedure, based on capacity spectrum, to design dissipative bracings for seismic retrofitting of the frame structures is described, and some applications are discussed. The procedure can be used with any typology of dissipative device and for different performance targets. In this work, the procedure has been applied, with both traditional pushover (load profile proportional to first mode) and multimodal pushover, to an existing RC (reinforced concrete) frame building. In the application, the buckling restrained braces have been used in order to prevent damages to both the structure and non structural elements. The use of multimodal pushover proves to be more effective than pushover based on single mode in case of medium rise RC frame building (higher than 30 m) but, once this building is retrofitted, and therefore regularized, with a bracing system, the difference between using monomodal or multimodal pushover becomes insignificant. 相似文献
156.
Luca Ortolani Florent Houdellier Marc Monthioux Etienne Snoeck Vittorio Morandi 《Carbon》2011,(4):1423-1429
We used low-voltage transmission electron holography to probe surface electrostatic potentials in graphene membranes and carbon nanotubes, as the number of graphenes varies. Further, we measured the phase shift induced by an individual graphene, and mapped the phase shift variation throughout a whole few-graphene-crystal as a function of the local number of layers. We found a size/surface effect as the ratio between the surface and the total number of atoms increases for an individual nanotube or graphene membrane. This surface phase term can be related to a fine electrostatic potentials redistributions occurring at the outer layers in carbon nanotubes and graphene membranes. 相似文献
157.
Vincenzo Augugliaro Salvatore Coluccia Elisa García-López Vittorio Loddo Giuseppe Marcì Gianmario Martra Leonardo Palmisano Mario Schiavello 《Topics in Catalysis》2005,35(3-4):237-244
Photocatalytic degradation of acetonitrile was carried out in gas–solid regime by using two commercial TiO2 samples (Merck and Degussa P25) irradiated in two continuous annular photoreactors. The inlet gas flow consisted of oxygen,
nitrogen, acetonitrile and water vapours. The influence on the photodegradation rate of gas flow rate, acetonitrile, oxygen
and water concentrations and photon flux was investigated. The degradation products of acetonitrile were carbon dioxide and
hydrogen cyanide. The photocatalysts performance was not affected by the presence or absence of water vapour in the reacting
mixture. The Langmuir–Hinshelwood model describes adequately the photoreactivity results and provides the values of kinetic
and equilibrium adsorption constants. FT-IR spectroscopy was used to investigate the adsorption patterns and photo-oxidation
intermediates of acetonitrile on fully hydrated surface of TiO2 powders. Acetonitrile was adsorbed on Ti4+ surface ions and hydroxyl groups for both types of TiO2. In the absence of UV light this interaction was completely reversible for Merck catalyst whereas for Degussa P25 part of
adsorbed acetonitrile molecules reacted to form acetamide-like species. 相似文献
158.
Bandura Albert; Barbaranelli Claudio; Caprara Gian Vittorio; Pastorelli Concetta 《Canadian Metallurgical Quarterly》1996,71(2):364
This research examined the role of mechanisms of moral disengagement in the exercise of moral agency. Regulatory self-sanctions can be selectively disengaged from detrimental conduct by converting harmful acts to moral ones through linkage to worthy purposes, obscuring personal causal agency by diffusion and displacement of responsibility, misrepresenting or disregarding the injurious effects inflicted on others, and vilifying the recipients of maltreatment by blaming and dehumanizing them. The study examined the structure and impact of moral disengagement on detrimental conduct and the psychological processes through which it exerts its effects. Path analyses reveal that moral disengagement fosters detrimental conduct by reducing prosocialness and anticipatory self-censure and by promoting cognitive and affective reactions conducive to aggression. The structure of the paths of influence is very similar for interpersonal aggression and delinquent conduct. Although the various mechanisms of moral disengagement operate in concert, moral reconstruals of harmful conduct by linking it to worthy purposes and vilification of victims seem to contribute most heavily to engagement in detrimental activities. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
159.
160.
Caprara Gian Vittorio; Barbaranelli Claudio; Borgogni Laura; Steca Patrizia 《Canadian Metallurgical Quarterly》2003,95(4):821
Self- and collective-efficacy beliefs were examined as main determinants of teachers' job satisfaction. In 103 Italian junior high schools, 2,688 teachers filled out self-reports to assess self-efficacy beliefs, their perceptions of the extent to which other school constituencies, namely, the principal, colleagues, staff, students, and families, were behaving in accordance with their obligations toward school well-functioning, their collective-efficacy beliefs, and their job satisfaction. Multilevel structural equation functioning, modeling analyses corroborated a conceptual model in which individual and collective-efficacy beliefs represent, respectively, the distal and proximal determinants of teachers' job satisfaction. The perceptions that teachers have of other constituencies' behavior largely mediated the links between self- and collective-efficacy beliefs. Collective-efficacy beliefs, in turn, partially mediated the influence that teachers' perceptions of other school constituencies' behavior exerts on their own job satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献