全文获取类型
收费全文 | 1148篇 |
免费 | 53篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 10篇 |
综合类 | 3篇 |
化学工业 | 280篇 |
金属工艺 | 17篇 |
机械仪表 | 14篇 |
建筑科学 | 66篇 |
矿业工程 | 1篇 |
能源动力 | 19篇 |
轻工业 | 110篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 103篇 |
一般工业技术 | 197篇 |
冶金工业 | 179篇 |
原子能技术 | 6篇 |
自动化技术 | 191篇 |
出版年
2023年 | 4篇 |
2022年 | 16篇 |
2021年 | 36篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 26篇 |
2016年 | 25篇 |
2015年 | 32篇 |
2014年 | 48篇 |
2013年 | 89篇 |
2012年 | 59篇 |
2011年 | 82篇 |
2010年 | 60篇 |
2009年 | 59篇 |
2008年 | 67篇 |
2007年 | 63篇 |
2006年 | 53篇 |
2005年 | 25篇 |
2004年 | 38篇 |
2003年 | 37篇 |
2002年 | 32篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 20篇 |
1998年 | 19篇 |
1997年 | 8篇 |
1996年 | 20篇 |
1995年 | 17篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1975年 | 10篇 |
1973年 | 3篇 |
1961年 | 3篇 |
1956年 | 3篇 |
排序方式: 共有1204条查询结果,搜索用时 15 毫秒
31.
Laurence Feldmeyer Kristine Heidemeyer Nikhil Yawalkar 《International journal of molecular sciences》2016,17(8)
Acute generalized exanthematous pustulosis (AGEP) is a severe, usually drug-related reaction, characterized by an acute onset of mainly small non-follicular pustules on an erythematous base and spontaneous resolution usually within two weeks. Systemic involvement occurs in about 20% of cases. The course is mostly benign, and only in rare cases complications lead to life-threatening situations. Recent studies highlight the importance of genetic variations in interleukin-36 receptor antagonist gene (IL-36RN) in the pathogenesis of this disease. The physiopathology of AGEP remains unclear, but an involvement of innate and acquired immune cells together with resident cells (keratinocytes), which recruit and activate neutrophils via production of cytokines/chemokines such as IL-17, IL-36, granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor alpha (TNFα) and chemokine (C-X-C motif) ligand 8 (CXCL8)/IL-8, has been postulated. Treatment is based on the removal of the causative drug, supportive care, infection prevention and use of potent topical or systemic steroids. 相似文献
32.
33.
Although previous works have shown the marked influence of thiourea as an organic additive in electrolyte bulk on copper electrodeposition, a variety of mechanisms could be responsible. The present paper concerns the effect of a thiourea layer adsorbed prior to copper electrodeposition. First evidence of a monolayer on platinum substrate was revealed by X-ray photoelectron spectroscopy. Two different times (15 h and 1 min) for platinum immersion were tested, and it was observed that, even for short times, thiourea is chemisorbed on the surface. Then, effects of thiourea adsorption on copper underpotential deposition (UPD) and overpotential deposition (OPD) processes on polycrystalline platinum were investigated by polarisation curves, atomic force microscopy and X-ray photoelectrons. Thiourea monolayer increases the copper UPD process: in fact the current density of UPD cathodic peak is higher in the presence of thiourea on the platinum surface. However no modifications were observed on the AFM images and on the XPS spectra. For the copper OPD process, the presence of thiourea monolayer inhibits copper deposition: the current density of OPD cathodic peak is lower whatever the immersion time of the platinum substrate in the thiourea solution. Moreover, XPS spectra show that the presence of thiourea modified the oxidation state of the copper coating, as an oxide film is formed more quickly on the surface of the coating. 相似文献
34.
Laurence Lucchese Christopher M. Liauw Norman S. Allen Michele Edge Frank Thompson Robert S. Whitehouse 《Polymer Bulletin》2000,44(2):187-194
Summary Microwave dielectric loss spectroscopy (MDS) has shown remarkable potential as a tool for the observation of changes in elastomer network structure within the interphase region of natural rubber/ carbon black composites. During crosslinking (non elemental sulphur system) the dielectric loss progressively increased. However, during ageing at high temperature the dielectric loss decreased. Parallel studies on the unfilled matrix yielded no such variation in dielectric loss. It was therefore concluded that the changes in microwave responses were related to the development of the interphase during curing and its subsequent destruction during ageing. The microwave response was related to the composite mechanical properties as a function of ageing time. The effect of stabiliser was also investigated. Received: 13 September 1999/Revised version: 7 February 2000/Accepted: 10 February 2000 相似文献
35.
Solid state characterization of poly(L‐lysine)hydrobromide was obtained via differential scanning calorimetry, thermogravimetric analysis, optical microscopy and infrared spectroscopy. The glass transition temperature of poly(L‐lysine)hydrobromide is 178°C. This thermal transition has not been reported previously. Poly(L‐lysine)'s Tg decreases when complexes are produced with the following divalent transition metal chlorides; cobalt chloride hexahydrate, nickel chloride hexahydrate, copper chloride dihydrate and anhydrous zinc chloride. At 10 mol% salt, nickel, chloride decreases Tg by 45°C, and the general trend is Ni2+Co2+Zn2+Cu2+. The depression of poly(L‐lysine)'s Tg correlates well with ligand field stabilization energies for pseudo‐octahedral and pseudo‐tetrahedral dn complexes (n = 7, 8, 10) from the 1st row of the d‐block. However, d9 copper(II) complexes cannot be included in this empirical correlation. Infrared spectroscopic evidence suggests that Co2+, Ni2+ and Zn2+ coordinate to the carbonyl oxygen in the main chain of the polymer. When transition metal ions coordinate to C? O, the network of hydrogen bonded amide groups is disrupted, which lowers the glass transition. The amide I region of the infrared spectrum reveals a hydrogen bonded C? O stretch @ 1655 cm?1 that is characteristic of poly(α‐amino acid) random coil conformations, and a metal‐ligand coordinated C? O stretch @ 1625 cm?1 in complexes with divalent cobalt, nickel and zinc. The amide II region of the infrared spectrum near 1550 cm?1 is also sensitive to the formation of coordination complexes with these d‐block metal chlorides. 相似文献
36.
Emma L. Bradley Laurence Castle Andrew P. Damant Sue M. Jickells Mark R. Philo 《Journal of Coatings Technology and Research》2010,7(4):477-483
Glass–fiber-reinforced plastic (GRP) vats are used widely for the storage of foodstuffs and potable water. As the inner surfaces
deteriorate during decades of use, they need to be repaired. The unsaturated polyester resins that are used for recoating
are crosslinked with styrene which can cause taint and odor problems. This article describes some coating parameters that
affect the content of residual styrene and its subsequent migration. The influences of cure temperature and duration, along
with the effect of washing with warm detergent solution, were investigated. Cured specimens were tested for their residual
styrene content and for styrene migration into the food simulants, distilled water, 3% acetic acid, and 15% ethanol. The dominant
factor in reducing the amount of residual styrene is the temperature. The resin self-heats as it cures, typically up to 50°C.
Thus, any further lowering of the styrene content requires a higher cure temperature than this. A 3-h cure at 80°C reduced
both the residual content and the migration levels by about 100-fold. At lower cure temperatures, the heating effect of washing
at 60°C is more important than the washing effect of the detergent. When less catalyst was used the residual styrene levels
rose dramatically, from 70 to 360 to 1300 mg/kg for the normal dose, half and quarter the normal dose, respectively. There
was a linear relationship between residual content in the GRP and the migration levels. This correlation could be used for
monitoring the quality of vats repaired in situ, using styrene-based coating resins. 相似文献
37.
JosA. Castillo Christine Gurard‐Hlaine Mariana Gutirrez Xavier Garrabou Martine Sancelme Melanie Schürmann Tomoyuki Inoue Virgil Hlaine Franck Charmantray Thierry Gefflaut Laurence Hecquet Jesús Joglar Pere Claps GeorgA. Sprenger Marielle Lemaire 《Advanced Synthesis \u0026amp; Catalysis》2010,352(6):1039-1046
A mutant of D ‐fructose‐6‐phosphate aldolase (FSA) of Escherichia coli, FSA A129S, with improved catalytic efficiency towards dihydroxyacetone (DHA), the donor substrate in aldol addition reactions, was explored for synthetic applications. The kcat/KM value for DHA was 17‐fold higher with FSA A129S than that with FSA wild type (FSA wt). On the other hand, for hydroxyacetone as donor substrate FSA A129S was found to be 3.5‐fold less efficient than FSA wt. Furthermore, FSA A129S also accepted glycolaldehyde (GA) as donor substrate with 3.3‐fold lower affinity than FSA wt. This differential selectivity of both FSA wt and FSA A129S for GA makes them complementary biocatalysts allowing a control over donor and acceptor roles, which is particularly useful in carboligation multi‐step cascade synthesis of polyhydroxylated complex compounds. Production of the mutant protein was also improved for its convenient use in synthesis. Several carbohydrates and nitrocyclitols were efficiently prepared, demonstrating the versatile potential of FSA A129S as biocatalyst in organic synthesis. 相似文献
38.
Jethro Akroyd Alastair J. Smith Laurence R. McGlashan Markus Kraft 《Chemical engineering science》2010,65(6):1915-1924
This paper investigates a mean reaction rate closure for turbulent reacting flows called the Direct Quadrature Method of Moments using the Interaction by Exchange with the Mean micromixing model (DQMoM-IEM). The method was first introduced for reacting flows by Fox (Computational Models for Turbulent Reacting Flows, Cambridge University Press, 2003). We present a systematic study that considers several important new aspects of the method. In particular we introduce a new analytic expression for the DQMoM-IEM source terms. We present a rigourous numerical investigation and discuss problems of boundedness and singularity in detail. We introduce a filter function to overcome these issues in the general case and present analytic integrals for special cases of specific terms. We extend the methodology to take advantage of these developments and show details of the implementation in a commercial computational fluid dynamics (CFD) code. We present an extensive set of numerical experiments and validation. The method is proven for a problem known from the literature which includes an isothermal dimerisation process. Experimental and transported probability density function (PDF) data compare reasonably well. The method is discussed critically and areas for further research are suggested to make the method more practical. 相似文献
39.
Bataillou Léa Martinelli Laure Desgranges Clara Bosonnet Sophie Ginestar Kevin Miserque Frédéric Wouters Yves Latu-Romain Laurence Pugliara Alessandro Proietti Arnaud Monceau Daniel 《Oxidation of Metals》2020,93(3-4):329-353
Oxidation of Metals - The oxidation of a Ni–30Cr alloy at 700 °C in impure argon was studied in order to provide new elements of understanding on chromia scale growth in low... 相似文献
40.
Laurence Fouilland Mohamed El Mansori 《Journal of Materials Processing Technology》2013,213(2):201-213
The present paper investigates the brittle–ductile transition (BDT) of the primary shear zone during cutting of spheroidal graphite (SG) iron in the austenitization temperature range (around 1000 °C). The experimental tests were performed using a cutting test bench in the cutting speed range of 0.8–1.6 m s?1. The cut surfaces were studied using optical microscopy and scanning electron microscope (SEM) analysis techniques. The obtained results revealed either consequent deep fractured regions governed by a brittle-cracking regime (BCR) or a crack-free cut surface governed by a ductile-shear regime (DSR) with large plastic deformations.When cutting data were discussed with respect to the influences of cutting parameters and obtained cut surface, the correlation is significantly rich. Both cut surface integrity, cutting force curves and metallographic results show a BDT indicating a change in the dominating hot cutting process mechanism. Such a transition is associated with the dynamic recrystallization promoting strain softening and hot cutting by ductile shearing. 相似文献