全文获取类型
收费全文 | 203篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
化学 | 161篇 |
晶体学 | 1篇 |
力学 | 8篇 |
数学 | 11篇 |
物理学 | 30篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 6篇 |
2017年 | 2篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 9篇 |
2013年 | 6篇 |
2012年 | 19篇 |
2011年 | 17篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 15篇 |
2007年 | 21篇 |
2006年 | 11篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 9篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1996年 | 6篇 |
1988年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有211条查询结果,搜索用时 46 毫秒
161.
Three-dimensional periodic structures have many applications in acoustics and their properties are strongly related to structural details. Here we demonstrate through simulations the ability to tune the phononic band gaps of 3D periodic elastomeric structures using deformation. The elastomeric nature of the material makes the transformation of the band gaps a reversible and repeatable process, providing avenues for the design of tunable 3D phononic crystals such as sonic switches. 相似文献
162.
Nadiège Nomède-Martyr Elodie Disa Katia Guérin Pierre Bonnet Marc Dubois 《Comptes Rendus Chimie》2018,21(8):791-799
Beneficial effects of fluorination on the stability of carbon nanofibre (CNF) dispersion in organic solvents as a function of time are evidenced. Because of their excellent friction properties, fluorinated CNFs (CF0.85) can be used as nanoparticles of tribo-active phase in lubrication; however, they have to be added into a matrix. We have shown that mixtures of CF0.85 are more stable than CNF solutions. Investigations by ultraviolet–visible spectroscopy have been carried out 2 h after sonication and after an ageing of 4 months. Hansen solubility theory was used, and after ageing, tribological and Raman spectroscopy experiments showed no significant modification of physicochemical properties of the CF0.85. 相似文献
163.
Walter Baratta Prof. Giorgio Chelucci Dr. Santo Magnolia Dr. Katia Siega Dr. Pierluigi Rigo Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(3):726-732
Chiral pincer ruthenium complexes of formula [RuCl(CNN)(Josiphos)] ( 2 – 7 ; Josiphos=1‐[1‐(dicyclohexylphosphano)ethyl]‐2‐(diarylphosphano)ferrocene) have been prepared by treating [RuCl2(PPh3)3] with (S,R)‐Josiphos diphosphanes and 1‐substituted‐1‐(6‐arylpyridin‐2‐yl)methanamines (HCNN; substituent=H ( 1 a ), Me ( 1 b ), and tBu ( 1 c )) with NEt3. By using 1 b and 1 c as a racemic mixture, complexes 4 – 7 were obtained through a diastereoselective synthesis promoted by acetic acid. These pincer complexes, which display correctly matched chiral PP and CNN ligands, are remarkably active catalysts for the asymmetric reduction of alkyl aryl ketones in basic alcohol media by both transfer hydrogenation (TH) and hydrogenation (HY), achieving enantioselectivities of up to 99 %. In 2‐propanol, the enantioselective TH of ketones was accomplished by using a catalyst loading as low as 0.002 mol % and afforded a turnover frequency (TOF) of 105–106 h?1 (60 and 82 °C). In methanol/ethanol mixtures, the CNN pincer complexes catalyzed the asymmetric HY of ketones with H2 (5 atm) at 0.01 mol % relative to the complex with a TOF of ≈104 h?1 at 40 °C. 相似文献
164.
Katia Snégaroff Dr. Jean‐Martial L'Helgoual'ch Dr. Ghenia Bentabed‐Ababsa Dr. Tan Tai Nguyen Floris Chevallier Dr. Mitsuhiro Yonehara Masanobu Uchiyama Prof. Aïcha Derdour Prof. Florence Mongin Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(39):10280-10290
In situ mixtures of CdCl2?TMEDA (0.5 equiv; TMEDA=N,N,N′,N′‐tetramethylethylenediamine) or InCl3 (0.33 equiv) with [Li(tmp)] (tmp=2,2,6,6‐tetramethylpiperidino; 1.5 or 1.3 equiv, respectively) were compared with the previously described mixture of ZnCl2?TMEDA (0.5 equiv) and [Li(tmp)] (1.5 equiv) for their ability to deprotonate anisole, benzothiazole, and pyrimidine. [(tmp)3CdLi] proved to be the best base when used in tetrahydrofuran at room temperature, as demonstrated by subsequent trapping with iodine. The Cd–Li base then proved suitable for the metalation of a large range of aromatics including benzenes bearing reactive functional groups (CONEt2, CO2Me, CN, COPh) or heavy halogens (Br, I), and heterocycles (from the furan, thiophene, pyrrole, oxazole, thiazole, pyridine, and diazine series). Five‐membered heterocycles benefiting from doubly activated positions were similarly dideprotonated at room temperature. The aromatic lithium cadmates thus obtained were involved in palladium‐catalyzed cross‐coupling reactions or simply quenched with acid chlorides. 相似文献
165.
Katia A.G. Azevedo Marta C. Gadotti Luiz A.C. Ladeira 《Nonlinear Analysis: Theory, Methods & Applications》2007
We discuss the existence of periodic solutions to a system of differential equations with distributed delay which shows a certain type of symmetry. For this, such solutions are related to the solutions of a system of second-order ordinary differential equations. 相似文献
166.
We propose and demonstrate a novel method for the elimination of arbitrary frequency chirp from short optical pulses. The technique is based on the combination of two cascaded second-order nonlinearities in two individual periodically poled lithium niobate waveguides. The proposed scheme operates independently of the spectral phase characteristics of the input pulse, producing a near-transform-limited output. 相似文献
167.
Diego Antonioli Michele Laus Katia Sparnacci Simone Deregibus Valerj Kapeliouchko Giovanna Palamone Tiziana Poggio Giampaolo Zuccheri Rosita Passeri 《Macromolecular Symposia》2010,296(1):197-202
The thermal and dynamic-mechanical characteristics of three PTFE/PMMA nanoparticle samples are described. The shell forming PMMA, once isolated from the PTFE cores, exhibits a lower thermal stability than the PMMA component in the corresponding nanocomposite under both thermal and oxidative degradation conditions thus indicating a definite, though moderate, thermal reinforcement due to the morphology of the nanocomposites. An increase in the thermal stability under nitrogen atmosphere was observed as the PTFE amount increases. However under air, no difference is observed in the various systems. These observations suggest that only a physical shield can be exerted by the PTFE cores to the PMMA matrix possibly due to a weak interface between PTFE and the PMMA. This hypothesis is also substantiated by the DMA analysis. 相似文献
168.
Angelini Flavio Colaneri Katia Herzel Stefano Nicolosi Marco 《Computational Management Science》2021,18(4):539-561
Computational Management Science - We study the optimal asset allocation problem for a fund manager whose compensation depends on the performance of her portfolio with respect to a benchmark. The... 相似文献
169.
Microwave‐Assisted Synthesis and Physicochemical Characterization of Tetrafuranylporphyrin‐Grafted Reduced‐Graphene Oxide
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Federica Bosca Dr. Laura Orio Dr. Silvia Tagliapietra Dr. Ingrid Corazzari Dr. Francesco Turci Dr. Katia Martina Dr. Linda Pastero Prof. Giancarlo Cravotto Dr. Alessandro Barge 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(5):1608-1613
This work describes the design of a modified porphyrin that bears four furan rings linked by 1,2‐bis‐(2‐aminoethoxy)ethane spacers. This unit is a well‐suited scaffold for a Diels–Alder reaction with commercial reduced‐graphene oxide, which is also described in this paper. A new hybrid material is obtained, thanks to efficient grafting under microwave irradiation, and fully characterized in terms of structure (UV, TGA, Raman) and morphology (HR‐TEM and AFM). Potential applications in photo‐ and sonodynamic therapy are envisaged. 相似文献
170.