全文获取类型
收费全文 | 91篇 |
免费 | 1篇 |
专业分类
化学 | 36篇 |
数学 | 5篇 |
物理学 | 51篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 4篇 |
2012年 | 10篇 |
2011年 | 2篇 |
2010年 | 4篇 |
2009年 | 8篇 |
2008年 | 4篇 |
2007年 | 7篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 1篇 |
2002年 | 1篇 |
1998年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1985年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1972年 | 1篇 |
1930年 | 2篇 |
排序方式: 共有92条查询结果,搜索用时 31 毫秒
1.
Photodynamic Therapy Efficacy Enhanced by Dynamics: The Role of Charge Transfer and Photostability in the Selection of Photosensitizers
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)
Prof. Luis G. Arnaut Prof. Mariette M. Pereira Dr. Janusz M. Dąbrowski Elsa F. F. Silva Dr. Fábio A. Schaberle Dr. Artur R. Abreu Luís B. Rocha Dr. Madalina M. Barsan Prof. Krystyna Urbańska Prof. Grażyna Stochel Prof. Christopher M. A. Brett 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(18):5346-5357
Progress in the photodynamic therapy (PDT) of cancer should benefit from a rationale to predict the most efficient of a series of photosensitizers that strongly absorb light in the phototherapeutic window (650–800 nm) and efficiently generate reactive oxygen species (ROS=singlet oxygen and oxygen‐centered radicals). We show that the ratios between the triplet photosensitizer–O2 interaction rate constant (kD) and the photosensitizer decomposition rate constant (kd), kD/kd, determine the relative photodynamic activities of photosensitizers against various cancer cells. The same efficacy trend is observed in vivo with DBA/2 mice bearing S91 melanoma tumors. The PDT efficacy intimately depends on the dynamics of photosensitizer–oxygen interactions: charge transfer to molecular oxygen with generation of both singlet oxygen and superoxide ion (high kD) must be tempered by photostability (low kd). These properties depend on the oxidation potential of the photosensitizer and are suitably combined in a new fluorinated sulfonamide bacteriochlorin, motivated by the rationale. 相似文献
2.
Alexandre P. Felgueiras Fbio M. S. Rodrigues Rui M. B. Carrilho Pedro F. Cruz Vitor H. Rodrigues Tams Kgl Lszl Kollr Mariette M. Pereira 《Molecules (Basel, Switzerland)》2022,27(6)
Four stereoisomeric monoether derivatives, based on axially chiral (R)- or (S)-BINOL bearing a chiral (+)- or (−)-neomenthyloxy group were synthesised and fully characterised by NMR spectroscopy and X-ray crystallography. The respective tris-monophosphites were thereof prepared and fully characterised. The coordination ability of the new bulky phosphites with Rh(CO)2(acac), was attested by 31P NMR, which presented a doublet in the range of δ = 120 ppm, with a 1J(103Rh-31P) coupling constant of 290 Hz. The new tris-binaphthyl phosphite ligands were further characterised by DFT computational methods, which allowed us to calculate an electronic (CEP) parameter of 2083.2 cm−1 and an extremely large cone angle of 345°, decreasing to 265° upon coordination with a metal atom. Furthermore, the monophosphites were applied as ligands in rhodium-catalysed hydroformylation of styrene, leading to complete conversions in 4 h, 100% chemoselectivity for aldehydes and up to 98% iso-regioselectivity. The Rh(I)/phosphite catalytic system was also highly active and selective in the hydroformylation of disubstituted olefins, including (E)-prop-1-en-1-ylbenzene and prop-1-en-2-ylbenzene. 相似文献
3.
Grimault S Lucas T Quellec S Mariette F 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,170(1):79-87
MRI thermometry methods are usually based on the temperature dependence of the proton resonance frequency. Unfortunately, these methods are very sensitive to the phase drift induced by the instability of the scanner which prevents any temperature mapping over long periods of time. A general method based on 3D spatial modelling of the phase drift as a function of time is presented. The MRI temperature measurements were validated on gel samples with uniform and constant temperature and with a linear temperature gradient. In the case of uniform temperature conditions, correction of the phase drift proved to be essential when long periods of acquisition were required, as bias could reach values of up to 200 degrees C in its absence. The temperature uncertainty measured by MRI was 1.2 degrees C in average over 290 min. This accuracy is coherent with the requirements for food applications especially when thermocouples are useless. 相似文献
4.
Ana R. Almeida Rui M.B. Carrilho Andreia F. Peixoto Artur R. Abreu Artur Silva Mariette M. Pereira 《Tetrahedron》2017,73(17):2389-2395
Different families of new amino compounds were efficiently synthesized, through optimized sequential processes, involving rhodium catalyzed hydroformylation as the key step. The selection of appropriate hydroformylation catalytic systems and reaction conditions allowed obtaining aldehydes derived from several n-alkyl olefins, cholest-4-ene and 3-vinyl-1H-indole, which were subsequently transformed, in one-pot, in to α-amino acids via hydroformylation/Strecker reaction, and in to tertiary amines via hydroaminomethylation, with excellent yields. 相似文献
5.
Triangulations in CGAL 总被引:7,自引:0,他引:7
Jean-Daniel Boissonnat Olivier Devillers Sylvain Pion Monique Teillaud Mariette Yvinec 《Computational Geometry》2002,22(1-3):5-19
This paper presents the main algorithmic and design choices that have been made to implement triangulations in the computational geometry algorithms library
. 相似文献
6.
Tomato pericarp tissue was studied by low-field nuclear magnetic resonance (NMR) relaxometry. Two kinds of experiments were
performed to investigate the correlation between multi-exponential NMR relaxation and the subcellular compartments. The longitudinal
(T
1) versus transverse (T
2) relaxation times were first measured on fresh samples and then the transverse relaxation time was measured on samples exposed
to water stress. Four signal components were found in all experiments. The results showed that all signal components corresponded
to the water in different cell compartments, and that no signal from non-exchangeable protons was present. Moreover, we demonstrated
that NMR relaxation is suitable for the continuous monitoring of water rebalancing between subcellular compartments of plant
tissues. 相似文献
7.
L. Besombes Y. Lger L. Maingault D. Ferrand J. Cibert H. Mariette 《Physica E: Low-dimensional Systems and Nanostructures》2006,35(2):300
The magnetic state of a single magnetic ion (Mn2+) embedded in an individual quantum dot is optically probed using micro-spectroscopy. The fine structure of a confined exciton in the exchange field of a single Mn2+ ion (S=) is analyzed in detail. The exciton–Mn2+ exchange interaction shifts the energy of the exciton depending on the Mn2+ spin component and six emission lines are observed at zero magnetic field. The emission spectra of individual quantum dots containing a single magnetic Mn atom differ strongly from dot to dot. The differences are explained by the influence of the system geometry, specifically the in-plane asymmetry of the quantum dot and the position of the Mn atom. Depending on both these parameters, one has different characteristic emission features which either reveal or hide the spin state of the magnetic atom. The observed behavior in both zero field and under magnetic field can be explained quantitatively by the interplay between the exciton–Mn2+ exchange interaction (dependent on the Mn position) and the anisotropic part of the electron–hole exchange interaction (related to the asymmetry of the quantum dot). 相似文献
8.
Hans Adriaensen Maja Musse Stéphane Quellec Alexandre Vignaud Mireille Cambert François Mariette 《Magnetic resonance imaging》2013
The transverse relaxation signal from vegetal cells can be described by multi-exponential behaviour, reflecting different water compartments. This multi-exponential relaxation is rarely measured by conventional MRI imaging protocols; mono-exponential relaxation times are measured instead, thus limiting information about of the microstructure and water status in vegetal cells. In this study, an optimised multiple spin echo (MSE) MRI sequence was evaluated for assessment of multi-exponential transverse relaxation in fruit tissues. The sequence was designed for the acquisition of a maximum of 512 echoes. Non-selective refocusing RF pulses were used in combination with balanced crusher gradients for elimination of spurious echoes. The study was performed on a bi-compartmental phantom with known T2 values and on apple and tomato fruit. T2 decays measured in the phantom and fruit were analysed using bi- and tri-exponential fits, respectively. The MRI results were compared with low field non-spatially resolved NMR measurements performed on the same samples. 相似文献
9.
A. A. Titov E. T. Kulatov Yu. A. Uspenskii V. V. Tugushev H. Mariette J. Cibert 《Bulletin of the Lebedev Physics Institute》2008,35(2):57-62
The X-ray K spectra of Mn absorption were used for Mn ion distribution in (Ga, Mn)N. According to the performed calculations, two threshold lines were observed in the K spectra of (Ga, Mn)N crystals with uniform Mn ion distribution. If Mn ions form chains, these two threshold lines merge into one broad line. 相似文献
10.
Paola Fermo Eleonora Delnevo Marina Lasagni Silvia Polla Mariette de Vos 《Microchemical Journal》2008,88(2):150-159
In the present paper chemical characterization has been carried out on 67 shards of archaeological pottery from Dougga (North Tunisia). The analysed shards, dated to the Byzantine period (VI–VII century A.D.), belong to the three ceramic classes African Red Slip Ware, Dougga Ware and African cooking Ware. Fourteen elements have been determined by both atomic emission spectroscopy with flame as source (AES) and by using an inductively coupled plasma source (ICP-OES). The data acquired have been treated by statistical techniques in order to define grouping for the examined shards. Both unsupervised and supervised methods have been employed in order to define groups of different pottery shards. As a comparison, some samples (control group) coming from Southern Tunisia have been examined. All the statistical methods employed have evidenced how the control group, as concerns the chemical composition, is clearly distinguishable from Ain Wassel samples which are highly homogeneous. In fact because of the compositional homogeneity of the Northern Tunisia productions, it is quite difficult to establish a good classification and distribution of the samples in well defined cluster. Nevertheless supervised analysis has evidenced how, among the three classes, the African cooking Ware is the more distinguishable one confirming the archaeologists' hypothesis that Dougga Ware is an imitation of African Red Slip Ware. 相似文献