全文获取类型
收费全文 | 99篇 |
免费 | 1篇 |
专业分类
化学 | 75篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 15篇 |
物理学 | 5篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 6篇 |
2012年 | 5篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 3篇 |
2007年 | 8篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1993年 | 1篇 |
1985年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有100条查询结果,搜索用时 15 毫秒
61.
The viscoelasticity of thermotropic liquid crystalline polymers: effects of the chemical composition
In this work, the rheological properties of the wholly aromatic random copolyester HBA/HNA (60/40), the commercial copolyesteramide Vectra B950, and the semiflexible commercial copolyester Rodrun 3000, PET/HBA 40/60, were investigated. All the thermotropic liquid crystalline polymers (TLCPs) show linear viscoelastic behavior at small strain amplitudes. The strain sweep experiments have clearly indicated that the onset for non linearity significantly decreases as the applied frequency increases in all the TLCPs here studied, independent of chemical composition and flexibility. In the case of the Vectra B950, a strain-hardening effect occurred at a strain of about 40% for all the applied frequencies. The frequency behavior showed that the HBA/HNA 60/40 TLCP is characterized by the leveling off of G′ and by a dominant elastic behavior at low frequencies. The inclusion of the flexible PET determines the disappearance of the plateau value for G′ with a viscous response at low frequencies.Paper presented at the Annual Meeting of the European Society of Rheology, Grenoble, April 2005. 相似文献
62.
de Siqueira Geisa Liandra de Andrade da Silveira Ana Claudia Lazzarotto Simone Rosa da Silveira de Godoy Rossana Catie Bueno Schnitzler Egon Lazzarotto Marcelo 《Journal of Thermal Analysis and Calorimetry》2019,135(2):1269-1283
Journal of Thermal Analysis and Calorimetry - The effect of compressor speed, initial refrigerant charge and volume concentrations of SiO2/PAG nanolubricant on the performance of automotive... 相似文献
63.
Giuliana Ferrante Rossana Rossi Giovanna Cilluffo Dario Di Silvestre Andrea Brambilla Antonella De Palma Chiara Villa Velia Malizia Rosalia Gagliardo Yvan Torrente Giovanni Corsello Giovanni Viegi Pierluigi Mauri Stefania La Grutta 《Molecules (Basel, Switzerland)》2021,26(5)
Urine proteomic applications in children suggested their potential in discriminating between healthy subjects from those with respiratory diseases. The aim of the current study was to combine protein fractionation, by urinary extracellular vesicle isolation, and proteomics analysis in order to establish whether different patterns of respiratory impedance in healthy preschoolers can be characterized from a protein fingerprint. Twenty-one 3–5-yr-old healthy children, representative of 66 recruited subjects, were selected: 12 late preterm (LP) and 9 full-term (T) born. Children underwent measurement of respiratory impedance through Forced Oscillation Technique (FOT) and no significant differences between LP and T were found. Unbiased clustering, based on proteomic signatures, stratified three groups of children (A, B, C) with significantly different patterns of respiratory impedance, which was slightly worse in group A than in groups B and C. Six proteins (Tripeptidyl peptidase I (TPP1), Cubilin (CUBN), SerpinA4, SerpinF1, Thy-1 membrane glycoprotein (THY1) and Angiopoietin-related protein 2 (ANGPTL2)) were identified in order to type the membership of subjects to the three groups. The differential levels of the six proteins in groups A, B and C suggest that proteomic-based profiles of urinary fractionated exosomes could represent a link between respiratory impedance and underlying biological profiles in healthy preschool children. 相似文献
64.
Interproximation methods for surfaces can be used to construct a smooth surface interpolating some data points and passing through specified regions. In this paper we study the use of mixed splines, that is smoothing splines with additional interpolation constraints, to solve the interproximation problem for surfaces in the case of scattered data. The solution is obtained by solving a linear system whose structure can be improved by using “bell-shaped” thin plate splines. 相似文献
65.
Federica Guarra Alessio Terenzi Christine Pirker Rossana Passannante Dina Baier Ennio Zangrando Vanessa Gómez-Vallejo Tarita Biver Chiara Gabbiani Walter Berger Jordi Llop Luca Salassa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(39):17278-17284
AuIII complexes with N-heterocyclic carbene (NHC) ligands have shown remarkable potential as anticancer agents, yet their fate in vivo has not been thoroughly examined and understood. Reported herein is the synthesis of new AuIII-NHC complexes by direct oxidation with radioactive [124I]I2 as a valuable strategy to monitor the in vivo biodistribution of this class of compounds using positron emission tomography (PET). While in vitro analyses provide direct evidence for the importance of AuIII-to-AuI reduction to achieve full anticancer activity, in vivo studies reveal that a fraction of the AuIII-NHC prodrug is not immediately reduced after administration but able to reach the major organs before metabolic activation. 相似文献
66.
In this paper a workforce model is studied from both a theoretical and an algorithmic point of view. In the considered hierarchical model workforce units can be substituted by higher qualified ones; external workforce can also be hired to cover low qualified jobs. An exact recursive solution algorithm is proposed to solve the problems and its efficiency is improved by means of cut conditions and discrete convexity properties. Finally, the results of a computational test are provided. 相似文献
67.
Milián L Estellés R Abarca B Ballesteros R Sanz MJ Blázquez MA 《Chemical & pharmaceutical bulletin》2004,52(6):696-699
Four phenanthrene and one aporphine alkaloids semi-synthesized from boldine were evaluated for their inhibitory effect on reactive oxygen species (ROS) generation. ROS generation by neutrophils stimulated with N-formyl-methionyl-leucyl-phenylalanine was inhibited in a concentration dependent manner. Alkaloids exerted similar inhibitory effect in the hypoxanthine-xanthine oxidase system than in stimulated neutrophils, which could be attributed to a direct ROS scavenging activity. None of the alkaloids assayed had any effect on xanthine oxidase activity. Therefore the synthesized alkaloids might constitute an alternative therapy in inflammation disorders in which ROS generation is involved. 相似文献
68.
Rossana Bonnaccorsi Eolo Scrocco Jacopo Tomasi Alberte Pullman 《Theoretical chemistry accounts》1975,36(4):339-344
The ab initio isopotential map of guanine is given and compared to that of adenine. It shows that in contrast to the situation in adenine, the most basic site of guanine is N7 with a secondary potential minimum at O6. These results as well as those concerning the secondary out-of-plane attractive regions over the NH2 group and C8 H bonds of the two molecules are discussed in connection with the available experimental knowledge concerning the bonding of alkylating carcinogens and mutagens. 相似文献
69.
Elisabetta Alberico Ilenia Nieddu Rossana Taras Serafino Gladiali 《Helvetica chimica acta》2006,89(8):1716-1729
A range of α,β‐unsaturated acids and esters have been selectively reduced to the corresponding saturated acid derivatives by hydrogen transfer. As the reducing agent, formic acid was used in the presence of RhI complexes formed with the powerful chiral ligand Ph‐binepine ( 1 ), an axially chiral binaphthalene‐type monodentate P‐donor ligand. Very high stereoselectivities (up to 97% ee) were obtained in the case of itaconic acid ( 2a ). 相似文献
70.
The stability of an equilibrium point of a dynamical system is determined by the position in the complex plane of the so-called characteristic values of the linearization around the equilibrium. This work presents an approach for the computation of characteristic values of partial differential equations of evolution involving time delay, based on a coupled pseudospectral-spectral method. Convergence of computed values is of infinite order with respect to the pseudospectral discretization and of finite order with respect to the spectral one. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献