全文获取类型
收费全文 | 813篇 |
免费 | 30篇 |
专业分类
电工技术 | 4篇 |
综合类 | 1篇 |
化学工业 | 209篇 |
金属工艺 | 18篇 |
机械仪表 | 9篇 |
建筑科学 | 26篇 |
矿业工程 | 5篇 |
能源动力 | 23篇 |
轻工业 | 176篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 48篇 |
一般工业技术 | 104篇 |
冶金工业 | 98篇 |
原子能技术 | 13篇 |
自动化技术 | 101篇 |
出版年
2023年 | 7篇 |
2022年 | 14篇 |
2021年 | 32篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 15篇 |
2017年 | 21篇 |
2016年 | 27篇 |
2015年 | 17篇 |
2014年 | 17篇 |
2013年 | 50篇 |
2012年 | 59篇 |
2011年 | 51篇 |
2010年 | 49篇 |
2009年 | 45篇 |
2008年 | 37篇 |
2007年 | 45篇 |
2006年 | 38篇 |
2005年 | 21篇 |
2004年 | 30篇 |
2003年 | 25篇 |
2002年 | 24篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 18篇 |
1997年 | 10篇 |
1996年 | 14篇 |
1995年 | 10篇 |
1994年 | 22篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1970年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有843条查询结果,搜索用时 0 毫秒
21.
Sylvie Lartigue Korinek Jacques Castaing 《Journal of the American Ceramic Society》2003,86(4):566-573
The microstructure of polycrystalline alumina deformed under hydrostatic pressure and at low temperature is investigated by transmission electron microscopy. Deformation occurs mainly by prism plane slip and rhombohedral twinning. Introduction of hydrogen leads to a significant decrease in the yield stress. In large grain size alumina deformed with hydrogen, accommodation of twinning involves dislocation reactions in the twin boundary and in the grains rather than by cracking. Prism plane dislocations decompose into basal dislocations by cross slip probably due to a decrease of Peierls stress for basal slip in the presence of hydrogen. 相似文献
22.
Sylvie Boileau 《Polymer》2003,44(21):6449-6455
Telechelic, hydroxyalkyl terminated polydimethylsiloxanes were obtained under mild conditions via hydrosilylation of allyl alcohol or ethylene glycol monoallyl ether by oligomeric αω-hydride terminated polydimethylsiloxanes, with the use of a platinum catalyst. They were subsequently modified in a phase transfer catalyzed reaction by propargyl bromide, to give telechelic polysiloxanes terminated by acetylenic groups. The synthetic pathway is described and the characterization of the obtained products is presented. 相似文献
23.
Effect of GABA,a Bacterial Metabolite,on Pseudomonas fluorescens Surface Properties and Cytotoxicity
Audrey Dagorn Annelise Chapalain Lily Mijouin Mélanie Hillion Cécile Duclairoir-Poc Sylvie Chevalier Laure Taupin Nicole Orange Marc G. J. Feuilloley 《International journal of molecular sciences》2013,14(6):12186-12204
Different bacterial species and, particularly Pseudomonas fluorescens, can produce gamma-aminobutyric acid (GABA) and express GABA-binding proteins. In this study, we investigated the effect of GABA on the virulence and biofilm formation activity of different strains of P. fluorescens. Exposure of a psychotropic strain of P. fluorescens (MF37) to GABA (10−5 M) increased its necrotic-like activity on eukaryotic (glial) cells, but reduced its apoptotic effect. Conversely, muscimol and bicuculline, the selective agonist and antagonist of eukaryote GABAA receptors, respectively, were ineffective. P. fluorescens MF37 did not produce biosurfactants, and its caseinase, esterase, amylase, hemolytic activity or pyoverdine productions were unchanged. In contrast, the effect of GABA was associated to rearrangements of the lipopolysaccharide (LPS) structure, particularly in the lipid A region. The surface hydrophobicity of MF37 was marginally modified, and GABA reduced its biofilm formation activity on PVC, but not on glass, although the initial adhesion was increased. Five other P. fluorescens strains were studied, and only one, MFP05, a strain isolated from human skin, showed structural differences of biofilm maturation after exposure to GABA. These results reveal that GABA can regulate the LPS structure and cytotoxicity of P. fluorescens, but that this property is specific to some strains. 相似文献
24.
Initial Molecular Recognition Steps of McjA Precursor during Microcin J25 Lasso Peptide Maturation 下载免费PDF全文
Dr. Nadine Assrir Dr. Anna Pavelkova Régine Dazzoni Dr. Rémi Ducasse Dr. Nelly Morellet Dr. Eric Guittet Prof. Sylvie Rebuffat Dr. Séverine Zirah Dr. Yanyan Li Dr. Ewen Lescop 《Chembiochem : a European journal of chemical biology》2016,17(19):1851-1858
Microcin J25 (MccJ25) has emerged as an excellent model to understand the maturation of ribosomal precursor peptides into the entangled lasso fold. MccJ25 biosynthesis relies on the post‐translational modification of the precursor McjA by the ATP‐dependent protease McjB and the lactam synthetase McjC. Here, using NMR spectroscopy, we showed that McjA is an intrinsically disordered protein without detectable conformational preference, which emphasizes the active role of the maturation machinery on the three‐dimensional folding of MccJ25. We further showed that the N‐terminal region of the leader peptide is involved in interaction with both maturation enzymes and identified a predominant interaction of V43–S55 in the core McjA sequence with McjC. Moreover, we demonstrated that residues K23–Q34 in the N‐terminal McjA leader peptide tend to adopt a helical conformation in the presence of membrane mimics, implying a role in directing McjA to the membrane in the vicinity of the lasso synthetase/export machinery. These data provide valuable insights into the initial molecular recognition steps in the MccJ25 maturation process. 相似文献
25.
Sirine ChehaidiVincent Salles Sylvie FoucaudAlexandre Maitre Paul Goursat 《Journal of the European Ceramic Society》2011,31(6):1113-1122
We performed pyrolysis of SiCNAlH and SiCNYOH nanopowder precursors under a reactive atmosphere (Ar/NH3/H2) with various compositions of ammonia (NH3) and dihydrogen (H2) to diminish C content, which is deleterious for thermal stability and sintering of the powders. This paper continues a previous work on the fabrication of an Si3N4/SiC composite without free C by studying the effect of H2 on the C/N atomic ratio of the powder. We studied the influence of the nature of the gaseous mixture (Ar/NH3/H2) on the powder composition. Elemental analysis showed that the introduction of H2 in the pyrolysis atmosphere limited the decomposition of NH3 and allowed for control of the C/N ratio. This behaviour can be explained by the structural evolution observed by 29Si NMR spectrometry but also by Fourier transform infrared and Raman spectroscopy. An Si3N4/SiC composite, with traces of free C, was obtained after post-pyrolysis heat treatment of the powders synthesized with 10 wt.% of H2 and 25 wt.% NH3. 相似文献
26.
Self-assembled monolayers (SAMs) of organic molecules are of exceptional technological importance since they represent a convenient, flexible, and simple system for tuning the chemical and physical properties of surfaces. The fine control of surface properties is directly dependent on the structure of mixed SAMs which is difficult to characterize at the nanoscale with usual techniques such as scanning probe microscopies. In this study, we report on a general method to investigate at the nanoscale the structure of molecular patterns which consist in SAMs of two components. Iron oxide nanoparticles (NPs) have been used as probing agents to study indirectly the structure of mixed SAMs. Mixed SAMs were prepared by the replacement of mercaptododecane (MDD) adsorbed by mercaptoundecanoic acid (MUA) molecules on gold substrates. Therefore, the SAM surface displays both chelating carboxylic terminal groups and non-chelating methylene terminal groups. As NPs have been previously demonstrated to specifically interact with carboxylic acid groups, the increasing density in NPs was correlated with the evolution of the COOH/CH(3) terminal groups ratio. Therefore the structure of mixed SAMs was studied indirectly as well as the kinetic of the replacement reaction and its mechanism. With this aim, we took advantage of the SPR properties of the gold substrate and of the high refractive index of iron oxide nanoparticles to follow their assembling on mixed SAMs as a time resolved study. The high sensitivity and tuning of the SPR signal over a wide range of wavelengths are correlated with the NP density. Furthermore, SEM combined with image analysis has allowed studying the replacement rate of MDD by MUA in SAMs. We took also advantages of the magnetic properties of NPs to evaluate qualitatively the replacement of thiol molecules. 相似文献
27.
Nawel Achir Caroline Pénicaud Sylvie Avallone Philippe Bohuon 《Journal of the American Oil Chemists' Society》2011,88(12):2035-2045
The aim of this study was to gain further insight into β-carotene thermal degradation in oils. Multiresponse modeling was
applied to experimental high-performance liquid chromatography–diode array detection (HPLC–DAD) data (trans-, 13-cis-, and 9-cis-β-carotene concentrations) during the heat treatments (120–180 °C) of two β-carotene-enriched oils, i.e., palm olein and
copra. The test of different reaction schemes showed that β-carotene isomerization reactions were dominant and reversible.
The resulting cis isomers and trans-β-carotene simultaneously underwent oxidation and cleavage reactions at the same rate constant. From the kinetic analysis,
it appeared that—contrary to oxidation and cleavage reactions—isomerization rate constants did not follow the Arrhenius law.
However, the isomerization equilibrium constant increased with temperature, favoring isomer production, particularly 9-cis-β-carotene. Its production was shown to be concomitant with oxidation and cleavage reactions, indicating that 9-cis-β-carotene could be a good degradation indicator during oil storage or processing. 相似文献
28.
The miscibility of poly(methylmethacrylate) (PMMA) and (trifluoroethyl methacrylic ester-MMA) copolymers (MMA-MATRIFE) with poly(vinylidene fluoride) (PVDF) and VDF copolymers was studied by differential scanning calorimetry (DSC) as a function of the fluorinated copolymer crystallinity and fluoroalkyl methacrylic ester content in the methacrylic copolymer. Miscibility limits were found identical whatever be the blend preparation technique, although solution mixing induced some polymer fractionation, thus giving slightly higher blend glass transition temperature. The miscibility domain widths are reduced when using MMA-MATRIFE copolymers as compared to PMMA-containing blends and miscibility limits are dependent on the MATRIFE content in the methacrylic copolymer. Moreover, PVDF or VDF copolymer melting enthalpy decrease is associated to a partial dissolution of the semi-crystalline polymer in PMMA or MMA-MATRIFE copolymer above the total miscibility limit. The evolution of dynamic moduli as a function of blends composition confirms the miscibility limits determined by DSC. The Flory-Huggins interaction parameters were determined through the melting point depression analysis and compared to correlate the intensity of inter- or intra-molecular interactions between the polymers to the postulated ‘acidity’ of hydrogen atoms in various VDF-containing polymers. The interaction parameter χ12 increases with the fluoroalkyl methacrylic ester content, corresponding to a prevalence of intra-molecular on inter-molecular interactions in these blends. Similarly, PVDF offers higher χ12 values as compared to VDF-TFE or particularly to VDF-TrFE copolymers. These results highlight the importance of the nature of fluorinated polymers and of the inter- or intra-molecular character of dipolar interactions on both, copolymer miscibility and interaction parameter values. 相似文献
29.
Nicolas Illy Sylvie Boileau Mitchell A. Winnik Jacques Penelle Valessa Barbier 《Polymer》2012,53(4):903-912
A novel type of clickable polymers with a very high local density of allyl side groups was developed. These polymers were obtained by the anionic ring-opening (co)polymerization of diallyl cyclopropane-1,1-dicarboxylate using as an initiating system a protic precursor whose acid–base reaction with the t-BuP4 phosphazene base generated the initiator in situ. The obtained polymers display geminated allyl groups on every third carbon alongside the macromolecular backbone. Homopolymers as well as block and statistical copolymers have been synthesized, with controlled molecular weights and narrow molecular weight distributions. The coupling of mercaptans with the allyl CC double bonds has been investigated both thermally and photochemically, with the influence of the type of initiation on the efficiency of the polymer modification being discussed in comparison with other “clickable” systems. Further functionalization by several thiols was performed, leading to a range of functional poly(cyclopropane-1,1-dicarboxylate)s. 相似文献
30.
Thioether Analogues of Disulfide‐Bridged Cyclic Peptides Targeting Death Receptor 5: Conformational Analysis,Dimerisation and Consequences for Receptor Activation 下载免费PDF全文
Dr. Karolina Pulka‐Ziach Dr. Valeria Pavet Neila Chekkat Dr. Karine Estieu‐Gionnet Roman Rohac Dr. Marie‐Charlotte Lechner Dr. Cristian R. Smulski Dr. Gabrielle Zeder‐Lutz Dr. Danièle Altschuh Dr. Hinrich Gronemeyer Prof. Dr. Sylvie Fournel Dr. Benoit Odaert Dr. Gilles Guichard 《Chembiochem : a European journal of chemical biology》2015,16(2):293-301
Cyclic peptides containing redox‐stable thioether bridges might provide a useful alternative to disulfide‐bridged bioactive peptides. We report the effect of replacing the disulfide bridge with a lanthionine linkage in a 16‐mer cyclic peptide that binds to death receptor 5 (DR5, TRAIL‐R2). Upon covalent oligomerisation, the disulfide‐bridged peptide has previously shown similar behaviour to that of TNF‐related apoptosis inducing ligand (TRAIL), by selectively triggering the DR5 cell death pathway. The structural and biological properties of the DR5‐binding peptide and its desulfurised analogue were compared. Surface plasmon resonance (SPR) data suggest that these peptides bind DR5 with comparable affinities. The same holds true for dimeric versions of these peptides: the thioether is able to induce DR5‐mediated apoptosis of BJAB lymphoma and tumorigenic BJELR cells, albeit to a slightly lower extent compared to its disulfide homologue. NMR analysis revealed subtle variation in the conformations of the two peptides and suggests that the thioether peptide is slightly less folded than its disulfide homologue. These observations could account for the different capability of the two dimers to cluster DR5 receptors on the cell surface and to trigger apoptosis. Nevertheless, our results suggest that the thioether peptide is a potential candidate for evaluation in animal models. 相似文献