全文获取类型
收费全文 | 83篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 58篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 16篇 |
物理学 | 9篇 |
出版年
2023年 | 1篇 |
2019年 | 2篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2012年 | 9篇 |
2011年 | 1篇 |
2009年 | 7篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1976年 | 1篇 |
1938年 | 1篇 |
1933年 | 1篇 |
1929年 | 1篇 |
1928年 | 2篇 |
1926年 | 1篇 |
1915年 | 2篇 |
1913年 | 2篇 |
排序方式: 共有86条查询结果,搜索用时 78 毫秒
31.
Keyes TE Evrard B Vos JG Brady C McGarvey JJ Jayaweera P 《Dalton transactions (Cambridge, England : 2003)》2004,(15):2341-2346
A novel dinuclear ruthenium(II) complex bridged by dianionic bridge 3-(2-phenol)-5-(pyridin-2-yl)-1,2,4-triazole in which the ruthenium metal atoms are bound through N,N coordination to the pyridine and triazole and O,N coordination to the triazole and phenolate is described. The electrochemical, spectroscopic and photophysical behaviour of the dimer is compared with its associated N,N- and O,N-coordinated mononuclear complexes. The mixed valence complex was prepared electrochemically and a weak inter-valence charge transfer transition is observed which from Hush theory provides an electronic coupling matrix element of 666 cm(-1), suggesting the complex is weakly coupled and valence trapped. In its native state the dinuclear compound is essentially non-emissive but upon the oxidation of the O,N moiety luminescence from the complex is reversibly switched on at 0.3 V and reversibly switched off by application of 1.3 or 0 V. To our knowledge this is the first report of a luminescent mixed valence ruthenium complex. 相似文献
32.
Dr. Philippe Pierrat Dr. Gilles Laverny Dr. Gaëlle Creusat Dr. Patrick Wehrung Dr. Jean‐Marc Strub Dr. Alain VanDorsselaer Prof. Françoise Pons Dr. Guy Zuber Dr. Luc Lebeau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(7):2344-2355
One of the potential benefits of drug delivery systems in medicine is the creation of nanoparticle‐based vectors that deliver a therapeutic cargo in sufficient quantity to a target site to enable a selective effect, width of the therapeutic window depending on the toxicity of the vector and the cargo. In this work, we intended to improve the siRNA delivery efficiency of a new kind of nucleic acid carrier, which is the result of the conjugation of the membrane phospholipid 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) to the membrane‐active species Triton X‐100 (TX100). We hypothesized that by improving the biodegradability the cytotoxicity of the conjugate might by reduced, whereas its original transfection potential would be tentatively preserved. DOPC was conjugated to Triton X‐100 through spacers displaying various resistance to chemical hydrolysis and enzyme degradation. The results obtained through in vitro siRNA delivery experiments showed that the initial phosphoester bond can be replaced with a phospho(alkyl)enecarbonate group with no loss in the transfection activity, whereas the associated cytotoxicity was significantly decreased, as assessed by metabolic activity and membrane integrity measurements. The toxicity of the conjugates incorporating a phospho(alkyl)enesuccinnate moiety proved even lower but was clearly balanced with a reduction of the siRNA delivery efficiency. Hydrolytic stability and intracellular degradation of the conjugates were investigated by NMR spectroscopy and mass spectrometry. A general trend was that the more readily degraded conjugates were those with the lower toxicity. Otherwise, the phospho(alkyl)enecarbonate conjugates revealed some hemolytic activity, whereas the parent phosphoester did not. The reason why these conjugates behave differently with respect to hemolysis might be a consequence of unusual fusogenic properties and probably reflects the difference in the stability of the conjugates in the intracellular environment. 相似文献
33.
We consider a linear system of thermoelasticity in a compact, C
infin, n-dimensional connected Riemannian manifold. This system consists of a wave equation coupled to a heat equation. When the boundary
of the manifold is non‐empty, Dirichlet boundary conditions are considered. We study the controllability properties of this
system when the control acts in the hyperbolic equation (and not in the parabolic one) and has its support restricted to an
open subset of the manifold. We show that, if the control time and the support of the control satisfy the geometric control
condition for the wave equation, this system of thermoelasticity is null-controllable. More precisely, any finite‐energy solution
can be driven to zero at the control time. An analogous result is proved when the control acts on the parabolic equation.
Finally, when the manifold has no boundary, the null‐controllability of the linear system of three‐dimensional thermoelastic
ity is proved.
(Accepted June 13, 1996) 相似文献
34.
The synthesis of phospholipids 1 n– 3 n, rationally designed for two-dimensional crystallization of progesterone and estradiol receptors, is reported. The structure of these lipids provides them with essential properties such as fluidity and stability when spread into monolayers at the air/H2O interface, affinity for the protein to be crystallized, and accessibility of the ligand under the lipid monolayer. 相似文献
35.
Emmanuel Klein Stéphane Mons Alain Valleix Charles Mioskowski Luc Lebeau 《The Journal of organic chemistry》2002,67(1):146-153
Dinucleoside polyphosphates are ubiquitous compounds tightly involved in the regulation of a number of key biological processes. Hydrolysis-resistant analogues of Ap(3)A and Gp(3)G, two important members of that family of nucleotides, have been synthesized. P(1),P(2):P(2),P(3)-Bis-methylene diadenosine and diguanosine triphosphates were prepared from O,O-dialkyl methaneselenophosphonates using an original methodology. Whereas the 2-fold addition of the methanephosphonate anion to the activated phosphorus species cannot be performed, multiple condensation of lithiated methaneselenophosphonate with electrophilic trivalent phosphorus compounds is revealed to be very effective. A one-pot condensation/esterification/oxidation sequence involving O,O-dialkyl methaneselenophosphonates provides a highly efficient route to the PCH(2)PCH(2)P backbone. This new development in selenophosphonate chemistry offers a great potential for further regioselective functionalization of polyphosphate mimics. 相似文献
36.
Benedicte Rønne Kristensen Assoc. Prof. Christian Marcus Pedersen 《European journal of organic chemistry》2023,26(16):e202300213
A self-promoted glycosylation method for the stereoselective formation of β-glucosides from a substrate library of glycosyl trichloroacetimidate glycosyl donors and glycosyl acceptors is presented. The simple two-component reaction takes place at elevated temperatures, without the addition of any additives or catalysts. After a simple basic workup, N-glycosides were obtained in good yields and with high β-selectivity and hence this method allows for easy access to glycoconjugates under very mild conditions. The influences of neighboring group participation and substituents, in both the glycosyl donor and acceptor, were studied. Kinetic data were obtained from in situ IR and these were used for a Hammett study. A connection between the pKa of the acceptor and reaction rate was found and new mechanistic insight in self-promoted glycosylations gained. 相似文献
37.
The interest in organic-inorganic hybrids as materials for optics and photonics started more than 25 years ago and since then has known a continuous and strong growth. The high versatility of sol-gel processing offers a wide range of possibilities to design tailor-made materials in terms of structure, texture, functionality, properties and shape modelling. From the first hybrid material with optical functional properties that has been obtained by incorporation of an organic dye in a silica matrix, the research in the field has quickly evolved towards more sophisticated systems, such as multifunctional and/or multicomponent materials, nanoscale and self-assembled hybrids and devices for integrated optics. In the present critical review, we have focused our attention on three main research areas: passive and active optical hybrid sol-gel materials, and integrated optics. This is far from exhaustive but enough to give an overview of the huge potential of these materials in photonics and optics (254 references). 相似文献
38.
Natalya A. Vodolazkaya Christelle Despas Bénédicte Lebeau Claire Marichal Alain Walcarius 《Journal of Sol-Gel Science and Technology》2012,63(3):587-594
New hybrid organic–inorganic materials exhibiting ordered mesoporous structures have been synthesized by co-condensation of tetraethoxysilane and various alkyltrimethoxysilanes with increasing length of the hydrocarbon chain (propyl, octyl, hexadecyl), in water–ethanol solution containing ammonia, in the presence of a cationic surfactant (cetyltrimethylammonium bromide) as templating agent. The obtained hybrid materials were characterized by using several physico-chemical techniques, such as X-ray diffraction, N2 adsorption, 29Si MAS NMR, SEM and elemental analysis. It was shown that the direct synthesis procedure allows obtaining ordered hybrid mesoporous silica with various contents of organic functions, from 5 to 20 %. Moreover, increasing the chain length of the organic group, from propyl to octyl and hexadecyl leads to a change of the pore structure from hexagonal p6mm MCM-41 type architecture to cubic Ia3d MCM-48 type mesostructure. 相似文献
39.
M Hessien P Léone M Suchaud B Lebeau H Nouali Y Guari E Prouzet 《Chemical communications (Cambridge, England)》2012,48(80):10022-10024
PIC (Phase Inversion Composition) O-W nanoemulsions was used as a template for the synthesis of Hierarchical Porous Silica (HPS), and the oil phase of the nanoemulsion was used as a nanoreactor for the preparation of magnetic gamma-Fe(2)O(3) nanoparticles, confined within the silica matrix. 相似文献
40.
G. Lebeau 《Inventiones Mathematicae》1989,95(2):277-323
Résumé Nous étudions le phénomène d'intéraction des singularités pour les équations des ondes non-linéaires. Nous traitons en particulier l'apparition générique de caustiques en dimension 2-d'espace. 相似文献