全文获取类型
收费全文 | 149篇 |
免费 | 16篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 56篇 |
建筑科学 | 5篇 |
矿业工程 | 1篇 |
能源动力 | 1篇 |
轻工业 | 32篇 |
水利工程 | 3篇 |
无线电 | 13篇 |
一般工业技术 | 18篇 |
冶金工业 | 5篇 |
原子能技术 | 1篇 |
自动化技术 | 28篇 |
出版年
2023年 | 5篇 |
2022年 | 17篇 |
2021年 | 12篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 13篇 |
2014年 | 10篇 |
2013年 | 7篇 |
2012年 | 9篇 |
2011年 | 12篇 |
2010年 | 13篇 |
2009年 | 9篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有165条查询结果,搜索用时 15 毫秒
111.
Maria Kourti Danai Liaropoulou Maria Paschou Ioanna Giagklisi Maria Paschalidi Evangelia Petani Panagiota Papazafiri 《International journal of molecular sciences》2022,23(3)
The two crucial cellular insults that take place during cerebral ischemia are the loss of oxygen and loss of glucose, which can both activate a cascade of events leading to neuronal death. In addition, the toxic overactivation of neuronal excitatory receptors, leading to Ca2+ overload, may contribute to ischemic neuronal injury. Brain ischemia can be simulated in vitro by oxygen/glucose deprivation, which can be reversible by the re-establishment of physiological conditions. Accordingly, we examined the effects of glucose deprivation on the PI3K/Akt survival signaling pathway and its crosstalk with HIF-1α and Ca2+ homeostasis in SH-SY5Y human neuroblastoma cells. It was found that glucose withdrawal decreased HIF-1α protein levels even in the presence of the ischemia-mimicking CoCl2. On the contrary, and despite neuronal death, we identified a strong activation of the master pro-survival kinase Akt, a finding that was also confirmed by the increased phosphorylation of GSK3, a direct target of p-Akt. Remarkably, the elevated Ca2+ influx recorded was found to promptly trigger the activation of Akt, while a re-addition of glucose resulted in rapid restoration of both Ca2+ entry and p-Akt levels, highlighting the plasticity of neurons to respond to ischemic challenges and the important role of glucose homeostasis for multiple neurological disorders. 相似文献
112.
A fundamental investigation of the electrolytic deposition of copper from concentrated aqueous ammoniacal solutions has been carried out based on the thermodynamic analysis of the system Cu–NH3–H2O. The speciation of copper vs. pH and redox potential was modeled in high ionic strength solutions, in which the activity coefficients of the system species were estimated according to the Modified Bromley's Methodology. The electrochemical behavior of the redox system Cu(0)/Cu(I)/Cu(II) in concentrated aqueous ammoniacal solutions was studied at pH = 9.5 and the cathodic reactions in these solutions were determined. It was found that metallic copper was formed under strongly reductive redox conditions, while under mildly reductive to mildly oxidative conditions the cuprous di-ammine complex species dominate. Under highly oxidative conditions the cupric tetra-ammine complex species predominated. According to the theory and results, the cathodic deposition of copper from concentrated aqueous ammoniacal solutions proceeds in a two-step reduction mechanism. The cupric ammine species are first reduced to cuprous di-ammine, which in turn is reduced to metallic copper. The electrochemical experiments revealed that copper deposition over time follows a sigmoid-type curve, verifying the two-step mechanism. The main feature of these sigmoid curves was the presence of an induction period with negligible copper deposition, followed by an acceleration period where the copper deposition rate gradually increased. By increasing the applied cell voltage, the induction period was significantly reduced or disappeared. 相似文献
113.
Orphanoudakis Theofanis Perissakis Stylianos Pramataris Kostas Nikolaou Nikos Zervos Nick Steck Matthias Baumhof Christoph Verkest Diederik Ykman-Couvreur Chantal Doumenis Gregory Karoubalis Fotis Theologitou Ioanna Reisis Dionysios Konstantoulakis George Vogiatzis Nikos 《Telecommunication Systems》2003,23(3-4):351-367
In multimedia applications, the stringent requirements for balancing transmission capacity, flexible service provisioning
and cost reduction lead the manufactures to provide highly integrated System-on Chip (SoC) solutions. This paper analyzes
the application of high-bandwidth-networking SoCs to improve on the cost efficiency of multimedia service distribution in
home networks. We present a case study, where we utilize the inherent protocol processing capabilities and high bandwidth
interfaces of a modern network processor, scaled down to match the performance targets and low cost requirements of the home
networking environment. An efficient, low cost Residential Gateway architecture results by mapping the home services onto
the processing and memory blocks of this SoC.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
114.
Dunlosky John; Domoto Peter K.; Wang Mei-Ling; Ishikawa Takayoshi; Roberson Ioanna; Nelson Thomas O.; Ramsay Douglas S. 《Canadian Metallurgical Quarterly》1998,6(1):77
Many hypotheses have been proposed to account for the effects of nitrous oxide on memory, with one emerging possibility being that it has a global effect on memory-related functioning. This possibility was explored by examining the effects of nitrous oxide on memory performance and on the accuracy of people's judgments about their memory performance. Participants inhaled 30% nitrous oxide or a placebo gas while items were studied and while judgments were made about the likelihood of recall for each item. Next, all participants inhaled the placebo during paired-associate recall. Although administration of nitrous oxide during study impaired recall, it did not affect the predictive accuracy of the metacognitive judgments. These results provide pharmacological evidence for a distinction between memory and metamemory. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
115.
Dusan Mihajlovic Dragana Vucevic Ioanna Chinou Miodrag Colic 《European Food Research and Technology》2014,238(5):881-887
Royal jelly (RJ) fatty acids have recently been shown to possess various pharmacological and biological activities. In this work, we studied the immunomodulatory effects of 10-hydroxy-trans-2-decenoic acid (10-HDA) and 3,10-dihydroxy-decanoic acid (3,10-DDA), isolated from RJ, using a model of phytohaemagglutinin-activated human peripheral blood mononuclear cells (PBMCs). We showed that higher concentrations (500 μM) of both fatty acids inhibited the proliferation of PBMCs, and the process was followed by a decrease in the production of interleukin-2 (IL-2). 10-HDA at the concentration of 500 μM inhibited the production of IL-1β and tumor necrosis factor-α by stimulated PBMCs, whereas the same dose of 3,10-DDA had no effect on the levels of these cytokines. Regarding T helper (Th) cytokine profile, higher concentration of 10-HDA, in contrast to the lower one (50 μM), inhibited both Th1 and Th2 response, whereas Th17 response was not significantly modulated, as judged by the levels of interferon-γ, IL-5 and IL-17A in culture supernatants, respectively. Lower concentration of 3,10-DDA stimulated Th1 and Th17 responses and inhibited IL-10 production, whereas the higher dose augmented the Th2 response. In conclusion, our results showed a significant, dose-dependent, immunomodulatory effect of RJ fatty acids in vitro, which was also associated with their structure. 相似文献
116.
Mortars are among the first building materials used in constructions, even from prehistoric times (8th millennium BC). Their study reveals a great source of information regarding the evolution of their technological characteristics and application techniques, the availability and exploitation of raw materials, as well the wider socio-economic aspects of each era. The aim of this paper is to comparatively evaluate the analysis results from approximately 1,000 structural mortar samples taken from various monuments and historic buildings of Greece, dated from the Hellenistic period, until the beginning of the 20th century. The analysis focused in the determination of their physico-mechanical and chemical properties, such as porosity, apparent specific gravity, mechanical strength, aggregates type and granulometry and chemical composition. Through the results' evaluation, significant remarks can be made upon the evolution of the raw materials used (binding system, aggregates, additives), as well as regarding the final properties of historic structural mortars. It is concluded that hydrated lime was the main binding agent used for a long-lasting period of 2.5 millenniums, while mixed type binding systems based on lime and natural pozzolan were systematically used for producing durable mortars, resistant to humidity. In any case, it seems that ancient masons were fully aware of the significant role of mortars in constructions and were capable of exploiting the available raw materials and application techniques to the maximum. 相似文献
117.
Lühl L Mantouvalou I Malzer W Schaumann I Vogt C Hahn O Kanngiesser B 《Analytical chemistry》2012,84(4):1907-1914
A new approach for chemical speciation in stratified systems using 3D Micro-XAFS spectroscopy is developed by combining 3D Micro X-ray Fluorescence Spectroscopy (3D Micro-XRF) and conventional X-ray Absorption Fine Structure Spectroscopy (XAFS). A prominent field of application is stratified materials within which depth-resolved chemical speciation is required. Measurements are collected in fluorescence mode which in general lead to distorted spectra due to absorption effects. Developing a reliable reconstruction algorithm for obtaining undistorted spectra for superficial and in-depth layers is proposed and validated. The developed algorithm calculates the attenuation coefficients of the analyte for the successive layers facilitating a new spectroscopic tool for three-dimensionally resolved nondestructive chemical speciation. 相似文献
118.
One of the most critical issues in introducing Wireless LAN (WLAN) real-time and delay sensitive applications, such as Voice
over IP (VoIP), is guaranteeing IP service continuation during inter-subnet Basic Service Set (BSS) transitions. Even though
WLANs offer very high channel bandwidth, they exhibit long network-layer handoff latency. This is a restraining factor for
mobile clients using interactive multimedia applications such as VoIP or video streaming. In a previous work, we presented
a novel fast and efficient IP mobility solution, called “IP-IAPP”, which offers constant IP connectivity to the 802.11 mobile
users and successfully preserves their ongoing sessions, even during subnet handoffs (fast recovery of active connections).
It is an 802.11-dependent IP mobility solution, which accelerates the network reconfiguration phase after subnet handoffs
and significantly reduces the IP handoff latency. It restores L3 connectivity almost simultaneously to the L2 connectivity
after a subnet handoff, due to a zero-delay movement detection method. As a result, even the most demanding next generation
WLAN applications such as Voice over WLAN (VoWLAN) suffer insignificant disruption. In this paper we present an improved version
of the IP-IAPP mobility mechanism (new optimized protocol procedures). Certain extensions have also been incorporated to the
initial proposal, for the provision of more advanced services: (a) secure inter-AP IP-IAPP communications, (b) zero patching
on the clients s/w, and (c) support of clients which use a dynamic IP address. Performance measurements out of further and
more complex testing verify that the proposed method outperforms other existing mobility solutions, and still introduces the
lesser imperative amendments to the existing 802.11 wireless LAN framework.
Ioanna F. Samprakou received her B. Eng in Computer Engineering and Informatics in 2000 and her MSc. in the same area in 2003 from the University
of Patras, Greece. She is currently a Ph.D canditate at the University of Patras. She has joined Atmel SA in 2002, where she
is a Senior Wireless System Eng at the System Concept and Design group. She specializes in wireless technologies, and mobile
communications, and holds a patent in the field of IP mobility. She has led teams in developing wireless 802.11 products such
as Wi-Fi APs, STAs, and VoIP phones. Previously she has worked for the Research & Academic Computer & Technology Institute
of Patras (RACTI) as an R&D computer engineer. She is a member of the Technical Chamber of Greece.
Christos J. Bouras obtained his Diploma and PhD from the Computer Science and Engineering Department of Patras University (Greece). He is currently
an Associate Professor in the above department. Also he is a scientific advisor of Research Unit 6 in Research Academic Computer
Technology Institute (CTI), Patras, Greece. His research interests include Analysis of Performance of Networking and Computer
Systems, Computer Networks and Protocols, Telematics and New Services, QoS and Pricing for Networks and Services, e – learning,
Networked Virtual Environments and WWW Issues. He has extended professional experience in Design and Analysis of Networks,
Protocols, Telematics and New Services. He has published 200 papers in various well-known refereed conferences and journals.
He is a co-author of 7 books in Greek. He has been a PC member and referee in various international journals and conferences.
He has participated in R&D projects such as RACE, ESPRIT, TELEMATICS, EDUCATIONAL MULTIMEDIA, ISPO, EMPLOYMENT, ADAPT, STRIDE,
EUROFORM, IST, GROWTH and others. Also he is member of, experts in the Greek Research and Technology Network (GRNET), Advisory
Committee Member to the World Wide Web Consortium (W3C), IEEE Learning Technology Task Force, IEEE Technical Community for
Services Computing WG 3.3 Research on Education Applications of Information Technologies and W 6.4 Internet Applications Engineering
of IFIP, Task Force for Broadband Access in Greece, ACM, IEEE, EDEN, AACE and New York Academy of Sciences.
Theodore E. Karoubalis. received his B. Eng in Computer Engineering and Informatics in 1992 and his Ph.D. in the same area in 1996 from the University
of Patras, Greece. He has joined ATMEL Hellas SA at 1998. Since 1998 he is the Manager of PSLi software dpt. and since 2002
he is the manager of System and Concepts dpt. His interests include systems on chip, embedded applications, wireless systems
etc. He is a member of IEEE and the Technical Chamber of Greece. 相似文献
119.
A primary challenge in unsupervised clustering using mixture models is the selection of a family of basis distributions flexible enough to succinctly represent the distributions of the target subpopulations. In this paper we introduce a new family of Gaussian Well distributions (GWDs) for clustering applications where the target subpopulations are characterized by hollow [hyper-]elliptical structures. We develop the primary theory pertaining to the GWD, including mixtures of GWDs, selection of prior distributions, and computationally efficient inference strategies using Markov chain Monte Carlo. We demonstrate the utility of our approach, as compared to standard Gaussian mixture methods on a synthetic dataset, and exemplify its applicability on an example from immunofluorescence imaging, emphasizing the improved interpretability and parsimony of the GWD-based model. 相似文献
120.