全文获取类型
收费全文 | 148篇 |
免费 | 4篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 1篇 |
综合类 | 2篇 |
化学工业 | 28篇 |
金属工艺 | 12篇 |
机械仪表 | 1篇 |
建筑科学 | 2篇 |
能源动力 | 7篇 |
轻工业 | 13篇 |
水利工程 | 1篇 |
石油天然气 | 13篇 |
无线电 | 19篇 |
一般工业技术 | 16篇 |
冶金工业 | 22篇 |
自动化技术 | 18篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 12篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 6篇 |
2013年 | 10篇 |
2012年 | 5篇 |
2011年 | 11篇 |
2010年 | 8篇 |
2009年 | 5篇 |
2008年 | 5篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有155条查询结果,搜索用时 15 毫秒
81.
82.
83.
Fabrizio Sarasini Jacopo Tirill Gianluca Maffei Antonio Zuorro Roberto Lavecchia Francesca Luzi Debora Puglia Luigi Torre Abdelhak Maghchiche 《Polymer Engineering and Science》2019,59(12):2418-2428
This work investigates the morphology, the thermal, and mechanical properties of technical fibers extracted from the Ampelodesmos mauritanicus (Diss) grass using a process that combines mechanical, mild chemical, and enzymatic steps. The structure and the thermal stability of Diss fibers make them suitable as a reinforcing filler in polymer composites, which was assessed by manufacturing biocomposites with improved stiffness and a tensile strength not degraded by Diss fibers when compared to those of a commodity polymer and a biodegradable one, namely polypropylene and poly(lactic acid). This work confirms that enzyme mixtures obtained from commercially available products of relatively low cost can represent a simple and environmentally friendly means to extract less common natural fibers. POLYM. ENG. SCI., 59:2418–2428, 2019. © 2019 Society of Plastics Engineers 相似文献
84.
Oliva R Falcigno L D'Auria G Dettin M Scarinci C Pasquato A Di Bello C Paolillo L 《Chembiochem : a European journal of chemical biology》2003,4(8):727-733
Proteolytic activation of the HIV-1 envelope glycoprotein gp160 is selectively performed by the proprotein convertase furin at the C-terminus of the sequence R508-E-K-R511 (site 1), in spite of the presence of another consensus sequence, Lys500-Ala-Lys-Arg503 (site 2). On the basis of the solution structural analysis of the synthetic peptide p498, spanning the gp160 sequence Pro498-Gly516, we previously suggested a possible role of an N-terminal helix in regulating the exposure and accessibility of the gp160 physiological cleavage site, enclosed in a loop. Here we report on the activity and conformation of the 23-residue peptide h-REKR, designed to exhibit a large N-terminal helix, followed by the gp160 native sequence, Arg508-Gly516. h-REKR is digested by furin with high efficiency, comparable to the full native p498. Circular dichroism analyses, in mixtures from pure water to 98 % trifluoroethanol, outline a significant content of helical structure in the peptide conformation. The molecular model obtained from NMR data collected in trifluoroethanol/water, by means of DYANA and AMBER simulations, indeed has helical structure on a large N-terminal segment. Such a long helix does not seem to affect the loop conformation of the C-terminal site 1-containing sequence, which exhibits the same proton chemical shifts already observed for the full native p498. 相似文献
85.
Livio Sacchi 《Architectural Design》2007,77(3):20-25
For 30 years, Renzo Piano has been producing distinguished buildings and delighting the world with his innovation and sensitivity. Here, Livio Sacchi attempts to tease out some of the reasons behind Piano's sustained success. Having gained an almost unparalleled international profile during the last couple of decades, a period that has been notoriously difficult for Italian architects, Piano's career has an almost mythic quality. It boasts one of the most unlikely competition wins of all time that ceded one of the most prestigious sites in the world, the Centre Pompidou in Paris, to two completely unknown architects in their late 20s. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
86.
Serena Notartomaso Nico Antenucci Francesca Liberatore Giada Mascio Stefano Vito Boccadamo Pompili Joan Font Mariarosaria Scioli Livio Luongo Antonietta Arcella Roberto Gradini Amadeu Llebaria Ferdinando Nicoletti 《International journal of molecular sciences》2022,23(14)
Breakthrough cancer pain (BTcP) refers to a sudden and transient exacerbation of pain, which develops in patients treated with opioid analgesics. Fast-onset analgesia is required for the treatment of BTcP. Light-activated drugs offer a novel potential strategy for the rapid control of pain without the typical adverse effects of systemic analgesic drugs. mGlu5 metabotropic glutamate receptor antagonists display potent analgesic activity, and light-induced activation of one of these compounds (JF-NP-26) in the thalamus was found to induce analgesia in models of inflammatory and neuropathic pain. We used an established mouse model of BTcP based on the injection of cancer cells into the femur, followed, 16 days later, by systemic administration of morphine. BTcP was induced by injection of endothelin-1 (ET-1) into the tumor, 20 min after morphine administration. Mice were implanted with optic fibers delivering light in the visible spectrum (405 nm) in the thalamus or prelimbic cortex to locally activate systemically injected JF-NP-26. Light delivery in the thalamus caused rapid and substantial analgesia, and this effect was specific because light delivery in the prelimbic cortex did not relieve BTcP. This finding lays the groundwork for the use of optopharmacology in the treatment of BTcP. 相似文献
87.
Berg M Luzi S Trang PT Viet PH Giger W Stüben D 《Environmental science & technology》2006,40(17):5567-5573
Arsenic removal efficiencies of 43 household sand filters were studied in rural areas of the Red River Delta in Vietnam. Simultaneously, raw groundwater from the same households and additional 31 tubewells was sampled to investigate arsenic coprecipitation with hydrous ferric iron from solution, i.e., without contact to sand surfaces. From the groundwaters containing 10-382 microg/L As, < 0.1-48 mg/L Fe, < 0.01-3.7 mg/L P, and 0.05-3.3 mg/L Mn, similar average removal rates of 80% and 76% were found for the sand filter and coprecipitation experiments, respectively. The filtering process requires only a few minutes. Removal efficiencies of Fe, phosphate, and Mn were > 99%, 90%, and 71%, respectively. The concentration of dissolved iron in groundwater was the decisive factor for the removal of arsenic. Residual arsenic levels below 50 microg/L were achieved by 90% of the studied sand filters, and 40% were even below 10 microg/L. Fe/As ratios of > or = 50 or > or = 250 were required to ensure arsenic removal to levels below 50 or 10 microg/L, respectively. Phosphate concentrations > 2.5 mg P/L slightly hampered the sand filter and coprecipitation efficiencies. Interestingly, the overall arsenic elimination was higher than predicted from model calculations based on sorption constants determined from coprecipitation experiments with artificial groundwater. This observation is assumed to result from As(lll) oxidation involving Mn, microorganisms, and possibly dissolved organic matter present in the natural groundwaters. Clear evidence of lowered arsenic burden for people consuming sand-filtered water is demonstrated from hair analyses. The investigated sand filters proved to operate fast and robust for a broad range of groundwater composition and are thus also a viable option for mitigation in other arsenic affected regions. An estimation conducted for Bangladesh indicates that a median residual level of 25 microg/L arsenic could be reached in 84% of the polluted groundwater. The easily observable removal of iron from the pumped water makes the effect of a sand filter immediately recognizable even to people who are not aware of the arsenic problem. 相似文献
88.
The aim of this paper is to present the preliminary experimental analysis results carried out on the commercial internal combustion engine set in a CHP (combined heat and power) mode, fueled by renewable hydrogen and methane mixtures. The hydrogen is produced by an alkaline electrolyser fed by a 5.8 kWp grid connected PV (photovoltaic) plant. The acceptance test conducted with hydrogen percentages ranging from 0%-10% has been carried out at partial load: 45 kW~l instead of the full power of 60 kWe~. In order to evaluate the CHP energy consumption and environmental performance (NOx and CO), the analysis was conducted for 240 h, using a portable flue gas analyser and two mass flow meters for hydrogen and methane. Without engine parameters optimization--relative equivalence ratio (2) and spark advance--increasing hydrogen addition rate, a slight enhancement in electrical efficiency occurs. Furthermore, due to the engine control system and lower blends LHV (lower heating value), the methane consumption decreases disproportionately to the hydrogen amount in the mixture. Finally, referring to standard operating condition, the environmental results show that using enrichment of 10%, running the engine with 18 degrees spark advance and 2 of 1.4, CO and NOx emissions are reduced by 6.3% and 27% respectively. 相似文献
89.
Elsner M Haderlein SB Kellerhals T Luzi S Zwank L Angst W Schwarzenbach RP 《Environmental science & technology》2004,38(7):2058-2066
Natural attenuation processes of chlorinated solvents in soils and groundwaters are increasingly considered as options to manage contaminated sites. Under anoxic conditions, reactions with ferrous iron sorbed at iron(hyro)xides may dominate the overall transformation of carbon tetrachloride (CCl4) and other chlorinated aliphatic hydrocarbons. We investigated mechanisms and product formation of CCl4 reduction by Fe(II) sorbed to goethite, which may lead to completely dehalogenated products or to chloroform (CHCl3), a toxic product which is fairly persistent under anoxic conditions. A simultaneous transfer of two electrons and cleavage of two C-Cl bonds of CCl4 would completely circumvent chloroform production. To distinguish between initial one- or two-bond cleavage, 13C-isotope fractionation of CCl4 was studied for reactions with Fe(II)/ goethite (isotopic enrichment factor epsilon = -26.5% percent per thousand) and with model systems for one C-Cl bond cleavage and either single-electron transfer (Fe(II) porphyrin, epsilon = -26.1 percent per thousand) or partial two-electron transfer (polysulfide, epsilon = -22.2 percent per thousand). These epsilon values differ significantlyfrom calculations for simultaneous cleavage of two C-Cl bonds (epsilon approximately equal to -50 percent per thousand), indicating that only one C-Cl bond is broken in the critical first step of the reaction. At pH 7, reduction of CCl4 by Fe(II)/ goethite produced approximately 33% CHCl3, 20% carbon monoxide (CO), and up to 40% formate (HCOO-). Addition of 2-propanol-d8 resulted in 33% CDCl3 and only 4% CO, indicating that both products were generated from trichloromethyl radicals (*CCl3), chloroform by reaction with hydrogen radical donors and CO by an alternative pathway likely to involve surface-bound intermediates. Hydrolysis of CO to HCOO-was surface-catalyzed by goethite butwastoo slow to account for the measured formate concentrations. Chloroform yields slightly increased with pH at constant Fe(II) sorption density, suggesting that pH-dependent surface processes direct product branching ratios. Surface-stabilized intermediates may thus facilitate abiotic mineralization of CCl4, whereas the presence of H radical donors, such as natural organic matter, enhances formation of toxic CHCl3. 相似文献
90.
This paper focuses on the study of glasses using models of thermodynamic and transport properties (e.g. heat capacity, viscosity and liquid fragility) for various alloys in comparison with organic and inorganic substances. The work attempts to identify possible correlations and trends in these properties which can relate to indicators of melt fragility for metallic glasses. The ratio of the specific heat integral between selected temperatures gives only a rough indication of the fragility behaviour. More insight is gained by considering the thermodynamic fragility index derived from the potential energy landscape model having either a hyperbolic or Gaussian distribution of energy minima. The Wang–Angell–Richert correlation holds for some metallic glasses. Deviations from it help in identifying hidden transitions in the liquid state. 相似文献