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排序方式: 共有127条查询结果,搜索用时 15 毫秒
31.
Dr. Franck Bertorelle Dr. K. David Wegner Martina Perić Bakulić Hussein Fakhouri Clothilde Comby-Zerbino Dr. Amin Sagar Dr. Pau Bernadó Dr. Ute Resch-Genger Prof. Vlasta Bonačić-Koutecký Dr. Xavier Le Guével Dr. Rodolphe Antoine 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(39):e202200570
Atomically precise gold nanoclusters are a fascinating class of nanomaterials that exhibit molecule-like properties and have outstanding photoluminescence (PL). Their ultrasmall size, molecular chemistry, and biocompatibility make them extremely appealing for selective biomolecule labeling in investigations of biological mechanisms at the cellular and anatomical levels. In this work, we report a simple route to incorporate a preformed Au25 nanocluster into a model bovine serum albumin (BSA) protein. A new approach combining small-angle X-ray scattering and molecular modeling provides a clear localization of a single Au25 within the protein to a cysteine residue on the gold nanocluster surface. Attaching Au25 to BSA strikingly modifies the PL properties with enhancement and a redshift in the second near-infrared (NIR-II) window. This study paves the way to conrol the design of selective sensitive probes in biomolecules through a ligand-based strategy to enable the optical detection of biomolecules in a cellular environment by live imaging. 相似文献
32.
Laser ablation generation of clusters from As‐Te mixtures,As‐Te glass nano‐layers and from Au‐As‐Te nano‐composites. Quadrupole ion trap time‐of‐flight mass spectrometry
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33.
Fuji T Suzuki Y Horio T Suzuki T Mitrić R Werner U Bonačić-Koutecký V 《The Journal of chemical physics》2010,133(23):234303
Ultrafast photodynamics of furan has been studied by time-resolved photoelectron imaging (TRPEI) spectroscopy with an unprecedented time resolution of 22 fs. The simulation of the time-dependent photoelectron kinetic energy distribution (PKED) has been performed with ab initio nonadiabatic dynamics "on the fly" in the frame of time-dependent density functional theory. Based on the agreement between experimental and theoretical time-dependent photoelectron signal intensity as well as on PKED, precise time scales of ultrafast internal conversion from S(2) over S(1) to the ground state S(0) of furan have been revealed for the first time. Upon initial excitation of the S(2) state which has π-π* character, a nonadiabatic transition to the S(1) state occurs within 10 fs. Subsequent dynamics invokes the excitation of the C-O stretching and C-O-C out of plane vibrations which lead to the internal conversion to the ground state after 60 fs. Thus, we demonstrate that the TRPEI combined with high level nonadiabatic dynamics calculations provide fundamental insight into ultrafast photodynamics of chemically and biologically relevant chromophores. 相似文献
34.
Compounds derived from different N,N′-carbonyl-bis-(l-amino acids) and their methyl and benzyl esters were synthesized and characterized by elemental analysis, infrared and nuclear magnetic resonance. The amino acids used were valine, leucine, phenylglycine and phenylalanine. All compounds revealed complex thermal behaviour as proved by differential scanning calorimetry, X-ray powder diffractometry and optical birefringence observation by polarizing microscope. Above isotropization temperature N,N′-carbonyl-bis-(l-amino acids) decomposed. The number and kinds of thermal phase transitions of investigated esters vary from a simple phase transition and melting to a complex polymorphism, and strongly depends on molecular structure. One to four phase transitions have been observed upon heating. Phase transition temperatures showed considerable variation with choice of the supstituent on symmetric carbons and therminal carboxylic groups. The results are discussed in terms of the architecture of investigated molecules that hinder mesomorphism. 相似文献
35.
Schäfer-Bung B Bonacić-Koutecký V Sauer F Weber SM Wöste L Lindinger A 《The Journal of chemical physics》2006,125(21):214310
We present a joint theoretical and experimental study of the maximization of the isotopomer ratio (23)Na(39)K(23)Na(41)K using tailored phase-only as well as amplitude and phase modulated femtosecond laser fields obtained in the framework of optimal control theory and closed loop learning (CLL) technique. A good agreement between theoretically and experimentally optimized pulse shapes is achieved which allows to assign the optimized processes directly to the pulse shapes obtained by the experimental isotopomer selective CLL approach. By analyzing the dynamics induced by the optimized pulses we show that the mechanism involving the dephasing of the wave packets between the isotopomers (23)Na (39)K and (23)Na (41)K on the first excited state is responsible for high isotope selective ionization. Amplitude and phase modulated pulses, moreover, allow to establish the connection between the spectral components of the pulse and corresponding occupied vibronic states. It will be also shown that the leading features of the theoretically shaped pulses are independent from the initial conditions. Since the underlying processes can be assigned to the individual features of the shaped pulses, we show that optimal control can be used as a tool for analysis. 相似文献
36.
Let G be a 2-dimensional connected, compact Abelian group and s be a positive integer. We prove that a classification of s-sheeted covering maps over G is reduced to a classification of s-index torsionfree supergroups of the Pontrjagin dual . Using group theoretic results from earlier paper we demonstrate its consequences. We also prove that for a connected compact group Y:
- (1)
- Every finite-sheeted covering map from a connected space over Y is equivalent to a covering homomorphism from a compact, connected group.
- (2)
- If two finite-sheeted covering homomorphisms over Y are equivalent, then they are equivalent as topological homomorphisms.
37.
L. Javier Hernández Paricio Vlasta Matijevi? 《Journal of Pure and Applied Algebra》2010,214(3):281-296
It is well known that for a connected locally path-connected semi-locally 1-connected space X, there exists a bi-unique correspondence between the pointed d-fold connected coverings and the transitive representations of the fundamental group of X in the symmetric group Σd of degree d.The classification problem becomes more difficult if X is a more general space, particularly if X is not locally connected. In attempt to solve the problem for general spaces, several notions of coverings have been introduced, for example, those given by Lubkin or by Fox. On the other hand, different notions of ‘fundamental group’ have appeared in the mathematical literature, for instance, the Brown-Grossman-Quigley fundamental group, the ?ech-Borsuk fundamental group, the Steenrod-Quigley fundamental group, the fundamental profinite group or the fundamental localic group.The main result of this paper determines different ‘fundamental groups’ that can be used to classify pointed finite sheeted connected coverings of a given space X depending on topological properties of X. 相似文献
38.
Malgorzata Witko Vlasta Bona
I-Koutecký 《International journal of quantum chemistry》1986,29(5):1535-1554
Potential energy curves for the lowest singlet and triplet states of Me + C2H4, Me+ + C2H4, MeO, MeO + C2H4, and (MeO + C2H4)+ systems for Me = Be, Mg, and Zn have been determined employing PP-MRD-CI or an all electron MRD-CI procedure. A binding interaction in the ground state has been found for oxides, all cation systems, and the BeO + C2H4 system. In the cases of MgO + C2H4 and ZnO + C2H4, only low lying excited states exhibit attractive interactions. Among three oxides considered, BeO is less pronounced biradically than MgO and ZnO. In order to obtain a binding interaction between an oxide and the olefin in the ground state, the p orbital of the metal must be sufficiently involved in binding. 相似文献
39.
This feasibility study deals with the use of preparative capillary isotachophoresis (CITP), operating in a discontinuous fractionation mode, to the separations and isolations of glycoforms of recombinant human erythropoietin (rhEPO). The preparative CITP separations were monitored by capillary zone electrophoresis (CZE) with a hydrodynamically closed separation unit. Such a CZE system, suppressing fluctuations of the migration data linked with fluctuations of EOF and hydrodynamic flow, made possible to evaluate and compare the preparative CITP separations performed within a longer time frame. Preparative CITP, carried out in the separation unit with coupled columns of enhanced sample loadability, separating 100 microg of rhEPO in a run lasting ca. 30 min, gave the production rate higher than 55 ng/s for the rhEPO glycoforms. The preparative separations included valve isolations of the glycoforms from the ITP stack into four or six fractions. Such numbers of the fractions corresponded to typical numbers of the major glycoform peaks as resolved in CZE of rhEPO. With respect to close effective mobilities of the glycoforms and a multicomponent nature of rhEPO, the fractions contained mixtures of glycoforms with the dominant glycoforms enriched 10-100-fold, relative to the original rhEPO sample. 相似文献
40.