全文获取类型
收费全文 | 195篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 170篇 |
晶体学 | 2篇 |
力学 | 4篇 |
数学 | 7篇 |
物理学 | 19篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 8篇 |
2013年 | 6篇 |
2012年 | 10篇 |
2011年 | 11篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 11篇 |
2007年 | 14篇 |
2006年 | 13篇 |
2005年 | 18篇 |
2004年 | 11篇 |
2003年 | 9篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 10篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有202条查询结果,搜索用时 15 毫秒
81.
Mazzaglia A Angelini N Darcy R Donohue R Lombardo D Micali N Sciortino MT Villari V Scolaro LM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(23):5762-5769
The entanglement process between water-soluble 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine and the amphiphilic cyclodextrin (CD) heptakis(2-omega-amino-O-oligo(ethylene oxide)-6-hexylthio)-beta-CD and the occurrence of various species at different porphyrin:CD ratios were studied by a combination of UV/Vis absorption, fluorescence anisotropy, time-resolved fluorescence, resonance light scattering, and circular dichroism. The effect of the entanglement process on the mean vesicle diameter was investigated over a wide concentration range by quasielastic light-scattering techniques. The experimental results indicate that the presence of porphyrins in this colloidal system promotes some structural rearrangements, essentially driven by charge interaction, which are responsible for a sensitive change of vesicle dimensions. In the range of porphyrin:CD molar ratios between 1:10 and 1:50, the porphyrin is solubilized in monomeric form (tau(1)=11.5 ns) and photosensitizes the production of singlet oxygen ((1)O(2)). At the same molar ratio the ability of this amphiphilic cyclodextrin to transport porphyrins into tumor cells indicates specificity at the nuclear-compartment level. These findings may be of potential interest for the of development agents for photodynamic therapy of tumors. 相似文献
82.
Mirror‐Image Packing Provides a Molecular Basis for the Nanomolar Equipotency of Enantiomers of an Experimental Herbicide
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Claudine Bisson Dr. K. Linda Britton Dr. Svetlana E. Sedelnikova H. Fiona Rodgers Dr. Thomas C. Eadsforth Dr. Russell C. Viner Dr. Tim R. Hawkes Dr. Patrick J. Baker Prof. David W. Rice 《Angewandte Chemie (International ed. in English)》2016,55(43):13485-13489
Programs of drug discovery generally exploit one enantiomer of a chiral compound for lead development following the principle that enantiomer recognition is central to biological specificity. However, chiral promiscuity has been identified for a number of enzyme families, which have shown that mirror‐image packing can enable opposite enantiomers to be accommodated in an enzyme's active site. Reported here is a series of crystallographic studies of complexes between an enzyme and a potent experimental herbicide whose chiral center forms an essential part of the inhibitor pharmacophore. Initial studies with a racemate at 1.85 Å resolution failed to identify the chirality of the bound inhibitor, however, by extending the resolution to 1.1 Å and by analyzing high‐resolution complexes with the enantiopure compounds, we determined that both enantiomers make equivalent pseudosymmetric interactions in the active site, thus mimicking an achiral reaction intermediate. 相似文献
83.
Pignolet C Filiâtre C Foissy A 《Langmuir : the ACS journal of surfaces and colloids》2008,24(18):10181-10186
This study demonstrates the influence of a cationic surfactant on colloidal particle electrodeposition (migration and adhesion). Three cetyltrimethylammonium salts (CTA+) with various counterions (bromide, chloride, and hydrogenosulphate) were studied. Particle transport toward the electrode was driven by the electrophoretic force. Once particles reached the electrode, a wide variety of behaviors were observed, depending on surfactant concentration and counterions: particles would stick permanently or slide along the electrode surface, remain or detach upon potential switching, act as nuclei for aggregate growth, or produce a homogeneous particle film. The experimental results also demonstrate the specific influence of surfactant counterions on the deposited film morphology. 相似文献
84.
Gaie-Levrel F Gutlé C Jochims HW Rühl E Schwell M 《The journal of physical chemistry. A》2008,112(23):5138-5151
Photoionization mass spectrometry (PIMS) has been used to study the dissociative ionization of three anthropogenic atmospheric aerosol precursors (o-xylene, 2-methylstyrene, indene) and five of their main atmospheric degradation products (o-tolualdehyde, 2-methylphenol, o-toluic acid, phthalic acid, and phthaldialdehyde). Ionization and fragment appearance energies have been experimentally determined in the 7-15 eV photon energy regime. Moreover, intensive ab inito quantum chemical calculations have been performed to compute the first ionization energies and heats of formation of these compounds (including also phthalic anhydride). Several methods have been used, and the theoretical results are compared to the experimental values with the aim to find the best method to predict thermochemical data for similar molecules. The vacuum-UV fragmentation pathways following photoionization are discussed. The results of this work are important with respect to the analytical chemistry of these compounds since their basic gas phase ion energetics data are mostly unknown. They will help in interpreting real-time mass spectrometric measurements used for the study of organic aerosol formation in smog chambers and in the real atmosphere. 相似文献
85.
The effect of adding various kinds of acids HX (X = Cl, Br, I, CF(3)COO, CF(3)SO(3), TFPB ((3,5-(CF(3))(2)C(6)H(3))(4)B) to isomeric tetra(2-pyridyl)porphyrin, tetra(3-pyridyl)porphyrin, and tetra(4-pyridyl)porphyrin (TpyP(2), TpyP(3), and TpyP(4)) in dichloromethane solution has been investigated through the combined use of UV/vis absorption, fluorescence emission, and resonance light scattering (RLS) techniques. The experimental evidence points to a marked dependence of the protonation and aggregation behavior on the nature of both acids and porphyrins. In general, three different trends can be recognized: (i) formation of a fully protonated species, followed by aggregation; (ii) formation of a tetraprotonated species, which aggregates and, on further addition of acid, disaggregates; and (iii) protonation of the four pyridyl moieties, leading to a tetraprotonated ion pair, in the unique case of the bulky TFPB(-) anion. In all cases, the protonated species and the resulting aggregates exhibit spectroscopic features that are markedly influenced by the nature of the counteranions. A model for J-aggregation has been proposed on the basis of an interplay of hydrogen bonding, electrostatic interactions, and dispersive interactions. Kinetic control of the aggregation process allows for a fine-tuning of the spectroscopic properties of the final aggregated species. 相似文献
86.
Parent M Mongin O Kamada K Katan C Blanchard-Desce M 《Chemical communications (Cambridge, England)》2005,(15):2029-2031
New multipolar derivatives built from triazole moieties that combine full transparency and strong TPA in the visible region as well as fully tuneable fluorescence have been designed; such chromophores open a new route for optical limiting. 相似文献
87.
88.
Zaina Ibrahim Mohamed Allaoui Estelle le Gall Dr. Arnaud Fihey Rodrigo Plaza-Pedroche Dr. Claudine Katan Prof. Françoise Robin-le Guen Prof. Julián Rodríguez-López Dr. Sylvain Achelle 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(36):8153-8161
The photophysical properties of a series of conjugated push–pull (iso)quinolines were studied. The compounds were synthesized by well-established and straightforward methodologies. The materials exhibited not only emission solvatochromism in a variety of nonpolar solvents, but also tunable halochromism. Some of the compounds remained moderately luminescent after protonation and had a red emissive form, which was used to obtain white-light emission, both in solution and in thin films, by controlled protonation of the initially blue–green-emitting materials. This methodology has potential applications in the fabrication of white organic light-emitting diodes with two forms of a single emitter in equilibrium. 相似文献
89.
90.
Aurore De Rache Dr. Iva Kejnovská Prof. Michaela Vorlíčková Prof. Claudine Buess‐Herman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(14):4392-4400
Aptamer‐based biosensors offer promising perspectives for high performance, specific detection of proteins. The thrombin binding aptamer (TBA) is a G‐quadruplex‐forming DNA sequence, which is frequently elongated at one end to increase its analytical performances in a biosensor configuration. Herein, we investigate how the elongation of TBA at its 5′ end affects its structure and stability. Circular dichroism spectroscopy shows that TBA folds in an antiparallel G‐quadruplex conformation with all studied cations (Ba2+, Ca2+, K+, Mg2+, Na+, NH4+, Sr2+ and the [Ru(NH3)6]2+/3+ redox marker) whereas other structures are adopted by the elongated aptamers in the presence of some of these cations. The stability of each structure is evaluated on the basis of UV spectroscopy melting curves. Thermal difference spectra confirm the quadruplex character of all conformations. The elongated sequences can adopt a parallel or an antiparallel structure, depending on the nature of the cation; this can potentially confer an ion‐sensitive switch behavior. This switch property is demonstrated with the frequently employed redox complex [Ru(NH3)6]3+, which induces the parallel conformation at very low concentrations (10 equiv per strand). The addition of large amounts of K+ reverts the conformation to the antiparallel form, and opens interesting perspectives for electrochemical biosensing or redox‐active responsive devices. 相似文献