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排序方式: 共有146条查询结果,搜索用时 468 毫秒
31.
Muhammad Nazrul Islam Burak Aksu Mehmet Güncü Markus Gallei Metin Tulu Tarik Eren 《Journal of polymer science. Part A, Polymer chemistry》2020,58(6):872-884
Bacterial infection is a global problem, especially resistance acquired by bacteria against to antibiotics; there is urgent need for the development of antibiotics. Here, we proposed dendron-grafted polymers via ring opening metathesis polymerization (ROMP) featuring different with tailored hydrophobicity/hydrophilicity and cationic charges. Dendritic oxanorbornene derivatives were synthesized having two and six carbon linkers and their corresponding random and block copolymers were prepared having pendant pyridinium salt moieties via ROMP. In total, 12 different water-soluble dendronized cationic polymers featuring hexyl pyridinium moieties were prepared and investigated. Six carbon linker possessing triple charge density and hexyl pyridinium functionality each repeating unit copolymers exhibited high antibacterial activity against Gram-positive bacteria (S. aureus). However, all the polymers were inactive against Gram-negative bacteria (E. coli). Most of the copolymers are non-hemolytic (>HC 50 = 1,000 μg/ml). It was also observed that, there is no significant effect between block copolymers and random copolymers keeping hydrophobicity and cationic charge density constant. Zeta potential was measured to investigate the mechanism in solution via the interaction of polymers with S. aureus, while scanning electron microscope (SEM) measurements image confirms damage of the bacterial cell wall after implementation of biocidal polymer. 相似文献
32.
Olivier Duclaux Tarik Chafik Hicham Zaitan Jean Louis Gass Daniel Bianchi 《Reaction Kinetics and Catalysis Letters》2002,76(1):19-26
Oxidation of benzene into CO2 in air has been studied in the temperature range of 300-673 K on supported metal oxides and on 0.7% Pt/Al2O3, in the absence and in the presence of several Volatile Organic Compounds (VOCs). On the metal oxides, the deep oxidation of benzene is strongly inhibited in presence of VOCs and O-containing VOCs lead to more toxic VOCs (i.e: acetaldehyde). 相似文献
33.
Dr. Mei Ding Dr. Anne K. Hickey Dr. Maren Pink Prof. Joshua Telser Prof. David L. Tierney Martin Amoza Mathieu Rouzières Tarik J. Ozumerzifon Wesley A. Hoffert Prof. Matthew P. Shores Prof. Eliseo Ruiz Dr. Rodolphe Clérac Prof. Jeremy M. Smith 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(45):10625-10632
The single-molecule magnet (SMM) properties of a series of ferrocenium complexes, [Fe(η5-C5R5)2]+ (R=Me, Bn), are reported. In the presence of an applied dc field, the slow dynamics of the magnetization in [Fe(η5-C5Me5)2]BArF are revealed. Multireference quantum mechanical calculations show a large energy difference between the ground and first excited states, excluding the commonly invoked, thermally activated (Orbach-like) mechanism of relaxation. In contrast, a detailed analysis of the relaxation time highlights that both direct and Raman processes are responsible for the SMM properties. Similarly, the bulky ferrocenium complexes, [Fe(η5-C5Bn5)2]BF4 and [Fe(η5-C5Bn5)2]PF6, also exhibit magnetization slow dynamics, however an additional relaxation process is clearly detected for these analogous systems. 相似文献
34.
Reda M. Abdel‐Rahman Mohamed S. T. Makki Tarik E. Ali Magdy A. Ibrahim 《Journal of heterocyclic chemistry》2015,52(6):1595-1607
The synthesis and chemical behavior of 3‐functionalized 5,6‐diphenyl‐1,2,4‐triazines towards some electrophilic and nucleophilic reagents are reviewed. The synthesis, unique features, and medicinal, pharmacological, and biological significance of these constituents are also reported. 相似文献
35.
Noha M. Hassanin Tarik E. Ali Hafez M. El-Shaaer 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):651-655
AbstractNovel 2-sulfido-2,3-dihydro-4H-chromeno[2,3-d][1,3,2]diazaphosphinines are obtained in a simple one-pot procedure via treatment of 2-imino-2H-chromene-3-carboxamide with various phosphorus sulfides. Possible reaction mechanisms are proposed. The structure of the obtained products is confirmed by elemental analyses and spectral tools. 相似文献
36.
Valsesia A Colpo P Meziani T Lisboa P Lejeune M Rossi F 《Langmuir : the ACS journal of surfaces and colloids》2006,22(4):1763-1767
This work presents an original and straightforward technique for antibody immobilization onto a surface, keeping the antibody in a biologically reactive configuration. Self-assembly of molecular monolayers and plasma-based colloidal lithography were combined to create chemical nanopatterns on the surface of a biosensing device. This technique was employed to create an array of 100 nm wide motifs having a hexagonal 2-D crystalline structure, characterized by COOH-terminated nanospots in a CH3-terminated matrix. The quality control of the chemical nanopattern was carried out by combining atomic force microscopy, ellipsometry, and contact angle measurements. Enzyme-linked immunosorbent assay experiments were set up showing that the COOH/CH3 nanopatterned surface constrains the immobilization of the antibodies in a biologically reactive configuration, thus significantly improving the device performances as compared to those of more conventional nonpatterned COOH-terminated or CH3-terminated surfaces. 相似文献
37.
38.
Matrab T Yassar A Viau G Chakroune N Fievet F Lacaze PC 《Journal of colloid and interface science》2006,296(1):95-101
Monodisperse ruthenium nanoparticles functionalized by electroactive oligothiophenes have been prepared and characterized. Using TEM, UV-visible and FTIR we established that the organization of these nanoparticles into nanospheres can be directly controlled via modulation of the pi-pi interaction between the organic components adsorbed on the surface. This finding also shows that the self-assembled nanoheterostructures may be switched from monodisperse nanoparticles to ordered nanospheres by tuning the pH. 相似文献
39.
Mass spectrometric studies of non-covalent compounds: why supramolecular chemistry in the gas phase?
Supramolecular chemistry has progressed quite a long way in recent decades. The examination of non-covalent bonds became the focus of research once the paradigm that the observed properties of a molecule are due to the molecule itself was revised, and researchers became aware of the often quite significant influence of the environment. Mass spectrometry and gas-phase chemistry are ideally suited to study the intrinsic properties of a molecule or a complex without interfering effects from the environment, such as solvation and the effects of counterions present in solution. A comparison of data from the gas phase, i.e. the intrinsic properties, with results from condensed phase, i.e. the properties influenced by the surroundings of the molecule, can consequently contribute significantly to the understanding of non-covalent bonds. This review provides insight into the often-underestimated power of mass spectrometry for the investigation of supramolecules. Through example studies, several aspects are discussed, including determination of structure in solution and the gas phase, ion mobility studies to reveal the formation of zwitterionic structures, stereochemical issues, analysis of reactivity of supramolecular compounds in the condensed and in the gas phase, and the determination of thermochemical data. 相似文献
40.
T. Kousksou A. Jamil S. Gibout Y. Zeraouli 《Journal of Thermal Analysis and Calorimetry》2009,96(3):841-852
This paper presents some results obtained by Differential Scanning Calorimetry (DSC) for characterizing the phase transition
within an emulsion. The dispersed substances are either hexadecane, octadecane, water or binary solution. A non-equilibrium
model taking into account the inter-phase heat transfer between the emulsifying medium and the dispersed droplet is proposed
and explains the main experimental features. 相似文献