全文获取类型
收费全文 | 463篇 |
免费 | 21篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 131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 | 17篇 |
2021年 | 29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484条查询结果,搜索用时 15 毫秒
471.
Vittorio Pace Laura Castoldi Wolfgang Holzer 《Advanced Synthesis \u0026amp; Catalysis》2014,356(8):1761-1766
Chloromethyllithium carbenoid has been chemoselectively added to cyclic enones (5‐, 6‐ and 7‐membered systems, including two natural products) to provide chloromethyl allylic alcohols. Under the optimized reaction conditions neither concomitant (n+1) homologation nor conjugate addition or Simmons–Smith‐like cyclopropanation takes place. The presence of LiBr is estimated to play a dual role, namely as a carbenoid stabilizer and mild Lewis acid activator of the CO group. Notably, the mesomeric effect caused by β‐heteroatom‐containing substituents promotes the attack of the reagent at the most activated position.
472.
Marianna Mastromatteo Amalia Conte Michele Faccia Matteo Alessandro Del Nobile Angelo Vittorio Zambrini 《Journal of dairy science》2014
In this work, the effect of active coating on the shelf life of low-moisture Mozzarella cheese packaged in air and modified atmosphere (MAP) was studied. The active coating was based on sodium alginate (2%, wt/vol) and potassium sorbate (1%, wt/vol). The MAP was made up of 75% CO2 and 25% N2 (MAP1), 25% CO2 and 75% N2 (MAP2), or 50% CO2 and 50% N2 (MAP3). The product quality decay was assessed by monitoring microbiological and sensory changes during storage at 4, 8, and 14°C. Results showed that the combination of active coating and MAP was able to improve the preservation of low-moisture Mozzarella cheese. Specifically, the shelf life increased up to 160 d for samples stored at 4°C, and 40 and 11 d for those at 8 and 14°C, respectively. A faster quality decay for untreated samples packaged in air was observed. In particular, the Pseudomonas spp. growth and the appearance of molds were responsible for product unacceptability. The combination of active coating and MAP represents a strategic solution to prolong the shelf life of low-moisture Mozzarella cheese and to ensure the safety of the product under thermal abuse conditions. 相似文献
473.
Capozzi V Ladero V Beneduce L Fernández M Alvarez MA Benoit B Laurent B Grieco F Spano G 《Food microbiology》2011,28(3):434-439
Enterococcus faecium strains were isolated from red wines undergoing malolactic fermentation and identified by comparison of their 16S rDNA gene sequences with those included in the GenEMBL Databases. The tyrosine decarboxylase gene was identified in all the strains analysed by PCR using gene-specific primers and the ability to produce tyramine in a synthetic media was analysed by RP-HPLC. Survival of an E. faecium strain was also evaluated in microvinification assays using two different musts with different ethanol concentrations (10% and 12% (v/v)). Tyramine production was monitored during the vinification trials. Our results suggest that E. faecium strains isolated from wine are able to produce tyramine and tolerate wine conditions following a pre-acidic stress. 相似文献
474.
Margaret Ottaviano Emilio Francesco Giunta Pasquale Rescigno Ricardo Pereira Mestre Laura Marandino Marianna Tortora Vittorio Riccio Sara Parola Milena Casula Panagiotis Paliogiannis Antonio Cossu Ursula Maria Vogl Davide Bosso Mario Rosanova Brunello Mazzola Bruno Daniele Giuseppe Palmieri Giovannella Palmieri 《International journal of molecular sciences》2021,22(13)
The cure rate of germ cell tumours (GCTs) has significantly increased from the late 1970s since the introduction of cisplatin-based therapy, which to date remains the milestone for GCTs treatment. The exquisite cisplatin sensitivity has been mainly explained by the over-expression in GCTs of wild-type TP53 protein and the lack of TP53 somatic mutations; however, several other mechanisms seem to be involved, many of which remain still elusive. The findings about the role of TP53 in platinum-sensitivity and resistance, as well as the reported evidence of second cancers (SCs) in GCT patients treated only with surgery, suggesting a spectrum of cancer predisposing syndromes, highlight the need for a deepened understanding of the role of TP53 in GCTs. In the following report we explore the complex role of TP53 in GCTs cisplatin-sensitivity and resistance mechanisms, passing through several recent genomic studies, as well as its role in GCT patients with SCs, going through our experience of Center of reference for both GCTs and cancer predisposing syndromes. 相似文献
475.
We introduce two new natural decision problems, denoted as ? RATIONAL NASH and ? IRRATIONAL NASH, pertinent to the rationality and irrationality, respectively, of Nash equilibria for (finite) strategic games. These problems ask, given a strategic game, whether or not it admits (i) a rational Nash equilibrium where all probabilities are rational numbers, and (ii) an irrational Nash equilibrium where at least one probability is irrational, respectively. We are interested here in the complexities of ? RATIONAL NASH and ? IRRATIONAL NASH. Towards this end, we study two other decision problems, denoted as NASH-EQUIVALENCE and NASH-REDUCTION, pertinent to some mutual properties of the sets of Nash equilibria of two given strategic games with the same number of players. The problem NASH-EQUIVALENCE asks whether or not the two sets of Nash equilibria coincide; we identify a restriction of its complementary problem that witnesses ? RATIONAL NASH. The problem NASH-REDUCTION asks whether or not there is a so called Nash reduction: a suitable map between corresponding strategy sets of players that yields a Nash equilibrium of the former game from a Nash equilibrium of the latter game; we identify a restriction of NASH-REDUCTION that witnesses ? IRRATIONAL NASH. As our main result, we provide two distinct reductions to simultaneously show that (i) NASH-EQUIVALENCE is co- $\mathcal{NP}$ -hard and ? RATIONAL NASH is $\mathcal{NP}$ -hard, and (ii) NASH-REDUCTION and ? IRRATIONAL NASH are both $\mathcal{NP}$ -hard, respectively. The reductions significantly extend techniques previously employed by Conitzer and Sandholm (Proceedings of the 18th Joint Conference on Artificial Intelligence, pp. 765–771, 2003; Games Econ. Behav. 63(2), 621–641, 2008). 相似文献
476.
Giuseppe Pepe Maria Cotugno Federico Marracino Susy Giova Luca Capocci Maurizio Forte Rosita Stanzione Franca Bianchi Simona Marchitti Alba Di Pardo Sebastiano Sciarretta Speranza Rubattu Vittorio Maglione 《International journal of molecular sciences》2021,22(7)
Alterations in the metabolism of sphingolipids, a class of biologically active molecules in cell membranes with direct effect on vascular homeostasis, are increasingly recognized as important determinant in different vascular disorders. However, it is not clear whether sphingolipids are implicated in the pathogenesis of hypertension-related cerebrovascular and renal damage. In this study, we evaluated the existence of possible abnormalities related to the sphingolipid metabolism in the brain and kidneys of two well validated spontaneously hypertensive rat strains, the stroke-prone (SHRSP) and the stroke-resistant (SHRSR) models, as compared to the normotensive Wistar Kyoto (WKY) rat strain. Our results showed a global alteration in the metabolism of sphingolipids in both cerebral and renal tissues of both hypertensive strains as compared to the normotensive rat. However, few defects, such as reduced expression of enzymes involved in the metabolism/catabolism of sphingosine-1-phosphate and in the de novo biosynthetic pathways, were exclusively detected in the SHRSP. Although further studies are necessary to fully understand the significance of these findings, they suggest that defects in specific lipid molecules and/or their related metabolic pathways may likely contribute to the pathogenesis of hypertensive target organ damage and may eventually serve as future therapeutic targets to reduce the vascular consequences of hypertension. 相似文献
477.
Massimo Mariello Luca Fachechi Francesco Guido Massimo De Vittorio 《Advanced functional materials》2021,31(27):2101047
Flexible electronics based on piezoelectric/triboelectric devices is an attractive technology for human sensing. Their hybridization overcomes the limitations of single components, resulting in compliant skin sensors with enhanced performances and applicability. Such hybrid devices are typically based on wide-area scarcely durable polymers or lead-containing piezoelectric materials; they are often not biocompatible and poorly skin-adaptable, lacking in multifunctionality. In this work, a novel compliant, conformal hybrid piezoelectric-triboelectric ultra-thin wearable sensor made of biocompatible materials is reported. The device is in contact with skin through an ultra-soft patch covered on both sides by a thin friction parylene film. Its working principle is unprecedently based on three simultaneous, complementary and mutually enhancing effects: piezoelectric, skin-contact-actuation, and piezo-tribo hybrid contact. The device can detect, with high sensitivity and wide measurement range, both the impulsiveness of sudden motions and the slower micro-friction phenomena due to skin deformations, ensuring a stable and repeatable identification of bio-signals typical of body movements. The device multifunctionality is shown for identifying gait walking, distinguishing hand gestures with a 5-sensor system on the hand back, and monitoring human joints motions (neck, wrist, elbow, knee, ankle). The assessed energy harvesting capabilities demonstrate the suitability for fabrication of more complex self-powered sensing systems. 相似文献
478.
Umair Aftab Aneela Tahira Alessandro Gradone Vittorio Morandi Muhammad Ishaq Abro Muhammad Moazam Baloch Adeel Liaquat Bhatti Ayman Nafady Alberto Vomiero Zafar Hussain Ibupoto 《International Journal of Hydrogen Energy》2021,46(13):9110-9122
For an active hydrogen gas generation through water dissociation, the sluggish oxygen evolution reaction (OER) kinetics due to large overpotential is a main hindrance. Herein, a simple approach is used to produce composite material based on TiO2/Co3O4 for efficient OER and overpotential is linearly reduced with increasing amount of TiO2. The scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) investigations reveal the wire like morphology of composite materials, formed by the self-assembly of nanoparticles. The titania nanoparticles were homogenously distributed on the larger Co3O4 nanoparticles. The powder x-ray diffraction revealed a tetragonal phase of TiO2 and the cubic phase of Co3O4 in the composite materials. Composite samples with increasing TiO2 content were obtained (18%, 33%, 41% and 65% wt.). Among the composites, cobalt oxide-titanium oxide with the highest TiO2 content (CT-20) possesses the lowest overpotential for OER with a Tafel slope of 60 mV dec?1 and an exchange current density of 2.98 × 10?3A/cm2. The CT-20 is highly durable for 45 h at different current densities of 10, 20 and 30 mA/cm2. Electrochemical impedance spectroscopy (EIS) confirmed the fast charge transport for the CT-20 sample, which potentially accelerated the OER kinetics. These results based on a two-step methodology for the synthesis of TiO2/Co3O4 material can be useful and interesting for various energy storage and energy conversion systems. 相似文献
479.
Alessandra Mingione Francesca Pivari Nicoletta Plotegher Michele Dei Cas Aida Zulueta Tommaso Bocci Marco Trinchera Elisabetta Albi Vittorio Maglione Anna Caretti Luigi Bubacco Rita Paroni Daniele Bottai Riccardo Ghidoni Paola Signorelli 《International journal of molecular sciences》2021,22(12)
Parkinson’s disease (PD) is a proteinopathy associated with the aggregation of α-synuclein and the formation of lipid–protein cellular inclusions, named Lewy bodies (LBs). LB formation results in impaired neurotransmitter release and uptake, which involve membrane traffic and require lipid synthesis and metabolism. Lipids, particularly ceramides, are accumulated in postmortem PD brains and altered in the plasma of PD patients. Autophagy is impaired in PD, reducing the ability of neurons to clear protein aggregates, thus worsening stress conditions and inducing neuronal death. The inhibition of ceramide synthesis by myriocin (Myr) in SH-SY5Y neuronal cells treated with preformed α-synuclein fibrils reduced intracellular aggregates, favoring their sequestration into lysosomes. This was associated with TFEB activation, increased expression of TFEB and LAMP2, and the cytosolic accumulation of LC3II, indicating that Myr promotes autophagy. Myr significantly reduces the fibril-related production of inflammatory mediators and lipid peroxidation and activates NRF2, which is downregulated in PD. Finally, Myr enhances the expression of genes that control neurotransmitter transport (SNARE complex, VMAT2, and DAT), whose progressive deficiency occurs in PD neurodegeneration. The present study suggests that counteracting the accumulation of inflammatory lipids could represent a possible therapeutic strategy for PD. 相似文献
480.
Simona Damiano Giuliana La Rosa Concetta Sozio Gina Cavaliere Giovanna Trinchese Maddalena Raia Roberto Patern Maria Pina Mollica Vittorio Enrico Avvedimento Mariarosaria Santillo 《International journal of molecular sciences》2021,22(5)
Inside the adult CNS, oligodendrocyte progenitor cells (OPCS) are able to proliferate, migrate and differentiate into mature oligodendrocytes (OLs) which are responsible for the production of myelin sheet and energy supply for neurons. Moreover, in demyelinating diseases, OPCs are recruited to the lesion areas where they undergo differentiation and myelin synthesis. Serotonin (5-hydroxytryptamine, 5-HT) is involved in OLs’ development and myelination, but so far the molecular mechanisms involved or the effects of 5-HT on mitochondria function have not yet been well documented. Our data show that 5-HT inhibits migration and proliferation committing cells toward differentiation in an immortalized human oligodendrocyte precursor cell line, M03-13. Migration blockage is mediated by reactive oxygen species (ROS) generation since antioxidants, such as Vit C and Cu-Zn superoxide dismutase, prevent the inhibitory effects of 5-HT on cell migration. 5-HT inhibits OPC migration and proliferation and increases OL phenotypic markers myelin basic protein (MBP) and Olig-2 via protein kinase C (PKC) activation since the inhibitor of PKC, bis-indolyl-maleimide (BIM), counteracts 5-HT effects. NOX inhibitors as well, reverse the effects of 5-HT, indicating that 5-HT influences the maturation process of OPCs by NOX-dependent ROS production. Finally, 5-HT increases mitochondria function and antioxidant activity. The identification of the molecular mechanisms underlying the effects of 5-HT on maturation and energy metabolism of OPCs could pave the way for the development of new treatments for autoimmune demyelinating diseases such as Multiple Sclerosis where oligodendrocytes are the primary target of immune attack. 相似文献