全文获取类型
收费全文 | 622篇 |
免费 | 59篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 258篇 |
金属工艺 | 5篇 |
机械仪表 | 17篇 |
建筑科学 | 17篇 |
矿业工程 | 1篇 |
能源动力 | 18篇 |
轻工业 | 183篇 |
水利工程 | 2篇 |
无线电 | 22篇 |
一般工业技术 | 58篇 |
冶金工业 | 11篇 |
原子能技术 | 11篇 |
自动化技术 | 75篇 |
出版年
2024年 | 3篇 |
2023年 | 9篇 |
2022年 | 54篇 |
2021年 | 78篇 |
2020年 | 22篇 |
2019年 | 19篇 |
2018年 | 26篇 |
2017年 | 27篇 |
2016年 | 31篇 |
2015年 | 23篇 |
2014年 | 29篇 |
2013年 | 41篇 |
2012年 | 38篇 |
2011年 | 39篇 |
2010年 | 39篇 |
2009年 | 28篇 |
2008年 | 33篇 |
2007年 | 25篇 |
2006年 | 17篇 |
2005年 | 13篇 |
2004年 | 15篇 |
2003年 | 17篇 |
2002年 | 14篇 |
2001年 | 5篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
排序方式: 共有682条查询结果,搜索用时 31 毫秒
171.
Recent research has shown that the longitudinal control of platoons of vehicles is appropriate to improve the traffic capacity of road networks while maintaining the safety distance between vehicles. This paper investigates the possibility of reducing the number of accidents involving pedestrians or other vulnerable road users (VRUs), like cyclists and motorcyclists, by providing the control systems of the vehicles of the platoon with some collision detection and avoidance capabilities. The control system proposed in this paper allows to maintain a desired distance from the preceeding vehicle, and, as a novelty with respect to other proposals, to avoid the collision with VRUs present on the road. The proposed control scheme is realized by means of a supervisor, which makes the decision on which is the appropriate current control mode for each controlled vehicle, and manages the switches among low-level controllers. The adopted control technique is the so-called sliding mode control methodology, which is particularly suitable to deal with the uncertainties and disturbances typical of automotive applications. 相似文献
172.
Spectral cytopathology (SCP) is a novel approach for disease diagnosis that utilizes infrared spectroscopy to interrogate the biochemical components of cellular samples and multivariate statistical methods, such as principal component analysis, to analyze and diagnose spectra. SCP has taken vast strides in its application for disease diagnosis over the past decade; however, fixation-induced changes and sample handling methods are still not systematically understood. Conversely, fixation and staining methods in conventional cytopathology, typically involving protocols to maintain the morphology of cells, have been documented and widely accepted for nearly a century. For SCP, fixation procedures must preserve the biochemical composition of samples so that spectral changes significant to disease diagnosis are not masked. We report efforts to study the effects of fixation protocols commonly used in traditional cytopathology and SCP, including fixed and unfixed methods applied to exfoliated oral (buccal) mucosa cells. Data suggest that the length of time in fixative and duration of sample storage via desiccation contribute to minor spectral changes where spectra are nearly superimposable. These findings illustrate that changes influenced by fixation are negligible in comparison to changes induced by disease. 相似文献
173.
Daniela Alesiani Antonella Canini Brigida DAbrosca Marina DellaGreca Antonio Fiorentino Claudio Mastellone Pietro Monaco Severina Pacifico 《Food chemistry》2010,118(2):199-207
Fifty-nine secondary metabolites have been isolated from Cydonia vulgaris peels and characterised on the basis of their spectroscopic features. Among them, five metabolites, 3β-(18-hydroxylinoleoyl)-28-hydroxyurs-12-ene (12), 3β-linoleoylurs-12-en-28-oic acid (15), 3β-oleoyl-24-hydroxy-24-ethylcholesta-5,28(29)-diene (24), tiglic acid 1-O-β-d-glucopyranoside (35), and 6,9-dihydroxymegastigmasta-5,7-dien-3-one 9-O-β-d-gentiobioside (46), have been isolated and elucidated for the first time. All of the compounds were tested for their radical-scavenging and antioxidant activities by measuring their capacity to scavenge the 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical, and anion superoxide radical and to induce the reduction of Mo(VI) to Mo(V). The antiproliferative activity of all the most abundant compounds by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) bioassay on murine B16-F1 melanoma cells has been also assessed. 相似文献
174.
Paola Parente Yanicet Ortega Begoña Savoini Miguel A. Monge Antonella Tucci Leonardo Esposito Begoña Ferrari A. Javier Sanchez-Herencia 《Journal of the European Ceramic Society》2012,32(16):3989-3993
Microstructural characterization of stress states of alumina layers subjected to residual compressive stresses was performed by positron annihilation spectroscopy (PAS). Al2O3–t-ZrO2 three layered samples were appropriately designed and processed by sequential slip casting with symmetric structure. The zirconia contents inside the core layer were selected in order to generate compressive stresses of variable intensity in the outer Al2O3 layers. PAS results highlighted a correlation between positron annihilation parameters and microstructural changes related to the generation of residual stresses. 相似文献
175.
Alessia Mongelli Veronica Barbi Michela Gottardi Zamperla Sandra Atlante Luana Forleo Marialisa Nesta Massimo Massetti Alfredo Pontecorvi Simona Nanni Antonella Farsetti Oronzo Catalano Maurizio Bussotti Laura Adelaide Dalla Vecchia Tiziana Bachetti Fabio Martelli Maria Teresa La Rovere Carlo Gaetano 《International journal of molecular sciences》2021,22(11)
The SARS-CoV-2 infection determines the COVID-19 syndrome characterized, in the worst cases, by severe respiratory distress, pulmonary and cardiac fibrosis, inflammatory cytokine release, and immunosuppression. This condition has led to the death of about 2.15% of the total infected world population so far. Among survivors, the presence of the so-called persistent post-COVID-19 syndrome (PPCS) is a common finding. In COVID-19 survivors, PPCS presents one or more symptoms: fatigue, dyspnea, memory loss, sleep disorders, and difficulty concentrating. In this study, a cohort of 117 COVID-19 survivors (post-COVID-19) and 144 non-infected volunteers (COVID-19-free) was analyzed using pyrosequencing of defined CpG islands previously identified as suitable for biological age determination. The results show a consistent biological age increase in the post-COVID-19 population, determining a DeltaAge acceleration of 10.45 ± 7.29 years (+5.25 years above the range of normality) compared with 3.68 ± 8.17 years for the COVID-19-free population (p < 0.0001). A significant telomere shortening parallels this finding in the post-COVID-19 cohort compared with COVID-19-free subjects (p < 0.0001). Additionally, ACE2 expression was decreased in post-COVID-19 patients, compared with the COVID-19-free population, while DPP-4 did not change. In light of these observations, we hypothesize that some epigenetic alterations are associated with the post-COVID-19 condition, particularly in younger patients (< 60 years). 相似文献
176.
Antonella De Leonardis Luciano Pizzella Vincenzo Macciola 《European Journal of Lipid Science and Technology》2008,110(10):941-948
The antioxidant effects on cod liver oil (CLO) of chlorogenic acid (CGA) and its metabolites, caffeic acid (CA) and quinic acid (QA), were investigated. All three chemicals were separately added to CLO at a concentration range of 0.001–0.080 wt‐% and tested by Rancimat. CA was the best antioxidant; its antioxidant effect was directly proportional to the dose added, but only within the concentration range of 0.005–0.050 wt‐%. QA did not show any effect on CLO oxidation, while CGA revealed itself as a weak antioxidant. Cytotoxicity was also evaluated by using murine 3T6 fibroblasts treated for 24 h with CGA, CA and QA at a concentration range of 0.1–5.0 mM. QA did not have an influence on cell proliferation, while CGA and CA showed a significant anti‐proliferative activity already at a concentration of 0.1 mM. Finally, compounds similar to the standard 8‐iso prostaglandin F2α, called CLO‐“isoprostanes”‐like compounds, were isolated. At high temperature (100 and 110 °C) CLO‐“isoprostanes‐like” compounds did not show a relevant pro‐oxidant action on the refined olive oil to which they were added in variable amounts. On the contrary, the CLO‐“isoprostanes”‐like compounds significantly decreased the antioxidant effectiveness of CA. Indeed, at a CLO‐“isoprostanes‐like” compound dose of 300 µg, the antioxidant effectiveness of CA was halved. 相似文献
177.
Alessandro Paolini Antonella Baldassarre Ilaria Del Gaudio Andrea Masotti 《International journal of molecular sciences》2015,16(8):19631-19644
In this review we reported and discussed the structural features of the ATP-Binding Cassette (ABC) transporter ABCA3 and how the use of bioinformatics tools could help researchers to obtain a reliable structural model of this important transporter. In fact, a model of ABCA3 is still lacking and no crystallographic structures (of the transporter or of its orthologues) are available. With the advent of next generation sequencing, many disease-causing mutations have been discovered and many more will be found in the future. In the last few years, ABCA3 mutations have been reported to have important pediatric implications. Thus, clinicians need a reliable structure to locate relevant mutations of this transporter and make genotype/phenotype correlations of patients affected by ABCA3-related diseases. In conclusion, we strongly believe that the model preliminarily generated by these novel bioinformatics tools could be the starting point to obtain more refined models of the ABCA3 transporter. 相似文献
178.
179.
Dr. Antonella Virgilio Prof. Veronica Esposito Dr. Giuseppe Citarella Prof. Luciano Mayol Prof. Aldo Galeone 《Chembiochem : a European journal of chemical biology》2012,13(15):2219-2224
Several anti‐HIV aptamers adopt DNA quadruplex structures. Among these, “Hotoda's aptamer” (base sequence TGGGAG) was one of the first to be discovered. Although it has been the topic of some recent research, no detailed structural investigations have been reported. Here we report structural investigations on this aptamer and analogues with related sequences, by using UV, CD, and NMR spectroscopy as well as electrophoretic techniques. The addition of a 3′‐end thymine has allowed us to obtain a single, investigable quadruplex structure. Data clearly point to the presence of an A‐tetrad. Furthermore, the effects of the incorporation of an 8‐methyl‐2′‐deoxyguanosine at the 5′‐end of the G‐run were investigated. 相似文献
180.
Antonella Santone 《Acta Informatica》2002,38(8):531-564
When verifying concurrent systems, described by transition systems, state explosion is one of the most serious problems: systems are often described by transition systems with a prohibitive number of states.
The primary cause of this problem is the parallel composition of interacting processes. In the recent years, compositional
techniques have been developed to attack the state explosion problem. These techniques are based on dividing the verification
task into simpler tasks, exploiting the natural decomposition of complex systems into processes. In this paper we present
a formula-based compositional approach that allows us to deduce a property of a parallel composition of processes by checking
it only on a component process. The approach can be automated and it is completely transparent to the user.
Received: 17 May 2001 / 27 February 2002 相似文献