全文获取类型
收费全文 | 126篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
化学 | 109篇 |
力学 | 2篇 |
数学 | 15篇 |
物理学 | 12篇 |
出版年
2021年 | 1篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 15篇 |
2011年 | 9篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 16篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1986年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有138条查询结果,搜索用时 15 毫秒
41.
Nieto-Oberhuber C Muñoz MP López S Jiménez-Núñez E Nevado C Herrero-Gómez E Raducan M Echavarren AM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(6):1677-1693
Gold(I) complexes are the most active catalysts for alkoxy- or hydroxycyclization and for skeletal rearrangement reactions of 1,6-enynes. Intramolecular alkoxycyclizations also proceed efficiently in the presence of gold(I) catalysts. The first examples of the skeletal rearrangement of enynes by the endocyclic cyclization pathway are also documented. Iron(III) is also able to catalyze exo and endo skeletal rearrangements of 1,6-enynes, although the scope of this transformation is more limited. The gold(I)-catalyzed endocyclic cyclization proceeds by a mechanism different from those followed in the presence of PdII, HgII, or RhI catalysts. 相似文献
42.
C. Arribas Rosa M. Masegosa C. Salom E. Arévalo S. G. Prolongo Margarita G. Prolongo 《Journal of Thermal Analysis and Calorimetry》2006,86(3):693-698
Diglycidyl ether of bisfenol-A (DGEBA)/polybenzyl methacrylate (PBzMA)
blends cured with 4,4’-diaminodiphenylmethane (DDM) were studied. Miscibility,
phase separation, cure kinetics and morphology were investigated through differential
scanning calorimetry (DSC) and scanning electron microscopy (SEM). Non-reactive
DGEBA/PBzMA blends are miscible over the whole composition range. The addition
of PBzMA to the reactive (DGEBA+DDM) mixture slows down the curing rate, although
the reaction mechanism remains autocatalytic. On curing, initially miscible
(DGEBA+DDM)/PBzMA blends phase separate, arising two glass transition temperatures
that correspond to a PBzMA-rich phase and to epoxy network. Cured epoxy/PBzMA
blends present different morphologies as a function of the PBzMA content. 相似文献
43.
Dauphin Y Cuif JP Salomé M Susini J Williams CT 《Analytical and bioanalytical chemistry》2006,386(6):1761-1771
The microstructure and composition of the layers of two giant avian eggshells were investigated using a combination of scanning
electron microscopy, electron probe microanalyses, and X-ray absorption near-edge structure spectroscopy (XANES). The two
species have some similarities and differences in their microstructure and composition; the composition is not homogeneous
throughout the eggshell thickness. XANES studies show that sulfur is associated with amino acids in the inner organic membranes,
whereas in the mineralised layers the sulfur is mainly associated with sulfated polysaccharides. These results are similar
to those obtained on chicken eggshells, and confirm the active role of sulfated acidic polysaccharides in biomineralisation
processes of carbonate skeletons. 相似文献
44.
Roux S Garcia B Bridot JL Salomé M Marquette C Lemelle L Gillet P Blum L Perriat P Tillement O 《Langmuir : the ACS journal of surfaces and colloids》2005,21(6):2526-2536
The use of gold nanoparticles as biological probes requires the improvement of colloidal stability. Dihydrolipoic acid (DHLA), a dithiol obtained by the reduction of thioctic acid, appears therefore very attractive for the stabilization and the further functionalization of gold nanoparticles because DHLA is characterized by a carboxylic acid group and two thiol functions. The ionizable carboxylic acid groups ensure, for pH > or = 8, the water solubility of DHLA-capped gold (Au@DHLA) nanoparticles, prepared by the Brust protocol, and the stability of the resulting colloid by electrostatic repulsions. Moreover almost all DHLA, adsorbed onto gold, adopts a conformation allowing their immobilization by both sulfur ends. It is proved by sulfur K-edge X-ray absorption near edge structure spectroscopy, which appears as an appropriate tool for determining the chemical form of sulfur atoms present in the organic monolayer. Such a grafting renders the DHLA monolayers more resistant to displacement by dithiothreitol than mercaptoundecanoic acid monolayers. The presence of DHLA on gold particles allows their functionalization by the electroluminescent luminol through amine coupling reactions assisted by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide. As a luminol-functionalized particle is nine times as bright as a single luminol molecule, the use of the particles as a biological probe with a lower threshold of detection is envisaged. 相似文献
45.
Ybert C Nadal F Salomé R Argoul F Bourdieu L 《The European physical journal. E, Soft matter》2005,16(3):259-266
We report on the experimental characterisation of electrically induced flows at the micrometer scale through Fluorescence Correlation Spectroscopy (FCS) measurements. We stress the potential of FCS as a useful characterisation technique in microfluidics devices for transport properties cartography. The experimental results obtained in a model situation are in agreement with previous calculations (F. Nadal, F. Argoul, P. Kestener, B. Pouligny, C. Ybert, A. Ajdari, Eur. Phys. J. E 9, 387 (2002)) predicting the structure and electric-field dependency of the induced flow. Additionally, the present study evidences a complex behaviour of the probe nanobeads under electric field whose precise understanding might prove relevant for situations where nano-objects interact with an external electric field. 相似文献
46.
Amador-Bedolla C Salomón-Ferrer R Lester WA Vázquez-Martínez JA Aspuru-Guzik A 《The Journal of chemical physics》2007,126(20):204308
Electrophilic amination is an appealing synthetic strategy to construct carbon-nitrogen bonds. The authors explore the use of the quantum Monte Carlo method and a proposed variant of the electron pair localization function--the electron pair localization function density--as a measure of the nucleophilicity of nitrogen lone pairs as a possible screening procedure for electrophilic reagents. 相似文献
47.
Blends of a linear unsaturated polyester (LUP, commercially named Al100) with poly(?-caprolactone) (PCL) of different molecular weights have been studied. The miscibility and crystallinity have been analyzed through FT-IR spectroscopy, differential scanning calorimetry (DSC) and environmental scanning electronic microscopy (ESEM). All the blends were subjected to the same heat treatment consisting of crystallizing during 45 min at constant temperature (10, 20, 30 or 40 °C). The glass transition temperature, Tg, and fusion temperature, Tfus, have been determined in the whole composition range for each blend. The Tg-composition dependence and the high degree of crystallinity detected at intermediate blend compositions denote an anomalous behaviour that could indicate the lack of homogeneity (phase separation) in the different blends studied. The ESEM measurements confirm the lack of homogeneity of the amorphous region in blends with high content of LUP. The results have been discussed as a function of the crystallization temperature and the molecular weight of PCL. 相似文献
48.
Salomé Machado A. A. Martins V. C. A. Plepis A. M. G. 《Journal of Thermal Analysis and Calorimetry》2002,67(2):491-498
Collagen:chitosan blends in 1:1 ratio were prepared and characterized by Fourier transform infrared spectroscopy, thermal
(DSC, TG) and rheological studies. Apparently each material maintains its behavior and addition of chitosan does not denature
collagen fibers. The rheological behavior showed that adding chitosan to collagen causes a decrease of storage modulus (G’),viscous
loss modulus (G”) and apparent viscosity when measured as a function of frequency. Both anionic and native collagen presented
more solid-like behavior than fluid-like viscoelastic behavior. Collagen:chitosan blends exhibits a more fluid-like viscoelastic
behavior.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
49.
Delgado S Gallego A Castillo O Zamora F 《Dalton transactions (Cambridge, England : 2003)》2011,40(4):847-852
An unprecedented in situ multiple bond cleavage of S-S, S-C(sp(2)) and C-N in the pyrimidinedisulfide (pym(2)S(2)) ligand is observed by the reaction of CuCl(2)·2H(2)O with this ligand under solvothermal and solvothermal-microwave conditions. In this process the formation of the compound [Cu(II)(μ-Cl)(Cl)L](2), where L represents the new ligand (L = 2-(pyrimidin-2-ylamino)-1,3-thiazole-4-carbaldehyde), is observed. This ligand has been further isolated and X-ray characterized. The similar reaction carried out under solvothermal-microwave conditions gives, in addition to the latter compound, the complex {9·[Cu(pym(2)S(3))(μ-Cl)(Cl)](2)·[Cu(pym(2)S(2))(μ-Cl)(Cl)](2)}. Coordination of a pyrimidinetrisulfide ligand (pym(2)S(3)) is reported for the first time. This work represents an illustrative example of the novel synthetic perspectives attainable via solvothermal-microwave procedures. 相似文献
50.
M. Sc. Niklas Felix König Dr. Abdelaziz Al Ouahabi Dr. Salomé Poyer Prof. Laurence Charles Dr. Jean-François Lutz 《Angewandte Chemie (International ed. in English)》2017,56(25):7297-7301
A three-step post-polymerization modification method was developed for the design of digitally encoded poly(phosphodiester)s with controllable side groups. Sequence-defined precursors were synthesized, either manually on polystyrene resins or automatically on controlled pore glass supports, using two phosphoramidite monomers containing either terminal alkynes or triisopropylsilyl (TIPS) protected alkyne side groups. Afterwards, these polymers were modified by stepwise copper-catalyzed azide–alkyne cycloaddition (CuAAC). The terminal alkynes were first reacted with a model azide compound, and after removal of the TIPS groups, the remaining alkynes were reacted with another organic azide. This simple method allows for quantitative side-chain modification, thus opening up interesting avenues for the preparation of a wide variety of digital polymers. 相似文献