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排序方式: 共有98条查询结果,搜索用时 0 毫秒
1.
Jun-tao Chang Joerg Evers Marian O. Scully M. Suhail Zubairy 《量子光学学报》2006,12(B08):77-77
We propose a scheme to obtain the distance of two identical atoms placed inside the standing wave field by monitoring the collective resonance fluorescence spectrum emitted by the two particles. We find three different parameter ranges, depending on the distance of the atoms as compared to the transition wavelength. For large interparticle distances, dipole-dipole coupling is negligible, and the main system evolution arises from the interaction with the standing wave field. In the small-distance limit, the dynamics is dominated by the dipole-dipole interaction. Finally, in the intermediate region, a rich interplay of the various couplings arises, which however is lifted for strong driving laser fields. The present measurement procedure allows us to distinguish the three cases. In each of the cases, we show how to determine the distance of the two particles and their respective positions relative to the nodes of the standing wave field with fractional-wavelength precision. 相似文献
2.
A series of new platinum(II) and platinum(IV) complexes of the type [PtII(HMI)2X] (where HMI=hexamethyleneimine, X=dichloro, sulfato, 1,1-cyclobutanedicarboxylato [CBDCA], oxalato, methylmalonato, or tatronato) and [PtIV(HMI)2Y2Cl2] (where Y=hydroxo, acetato, or chloro) were synthesized and characterized by infrared (IR) spectroscopy, 13C and 195Pt nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Among the complexes synthesized, [PtII(hexamethyleneimine)2(1,1-cyclobutanedicarboxylato)]·H2O was examined by single-crystal X-ray diffraction. The slightly distorted square planar coordination environment of the platinum metal includes the amino group of the hexamethyleneimine (HMI) molecule and the oxygen atoms of the carboxylato ligand. The cyclobutanedicarboxylic acid (CBDCA) molecule adopts six-member chelating rings with platinum. Hydrogen bonding plays an important part in holding the crystal lattice together. 相似文献
3.
R. Dylewicz A. Z. Khokhar R. Wasielewski P. Mazur F. Rahman 《Applied physics. B, Lasers and optics》2012,107(2):393-399
We describe the fabrication and characterization of a randomly etched gallium nitride (GaN) surface for enhancing light extraction from light-emitting diodes. Our technique uses silica spheres as nano-targets in a sputter-etch process and produces a fine-grained surface with features around 35 nm. The textured surface layer acts as a graded refractive index layer with antireflection properties. Measurements show that photoluminescence intensity from such treated surfaces on a GaN LED wafer increases 2.2?times over that from pristine surfaces. These findings are also supported by computer modelling studies described here. 相似文献
4.
Navkiran Kaur Mansimran Khokhar Vaibhav Jain P. V. Bharatam Rajat Sandhir Rupinder Tewari 《Applied biochemistry and biotechnology》2013,171(2):417-436
Emergence of the multidrug-resistant pathogens has rendered the current therapies ineffective thereby, resulting in the need for new drugs and drug targets. The accumulating protein sequence data has initiated a drift from classical drug discovery protocols to structure-based drug designing. In the present study, in silico subtractive genomics approach was implemented to find a set of potential drug targets present in an opportunist bacterial pathogen, Acinetobacter baumannii (A. baumannii). Out of the 43 targets identified, further studies for protein model building and lead-inhibitor identification were carried out on two cell-essential targets, MurA and MurB enzymes (of A. baumannii designated as MurAAb and MurBAb) involved in the peptidoglycan biosynthesis pathway of bacteria. The homology model built for each of them was further refined and validated using various available programs like PROCHECK, Errat, ProSA energy plots, etc. Compounds showing activity against MurA and MurB enzymes of other organisms were collected from the literature and were docked into the active site of MurAAb and MurBAb enzymes. Three inhibitors namely, T6361, carbidopa, and aesculin, showed maximum Glide score, hydrogen bonding interactions with the key amino acid residues of both the enzymes and acceptable ADME properties. Furthermore, molecular dynamics simulation studies on MurAAb–T6361 and MurBAb–T6361 complexes suggested that the ligand has a high binding affinity with both the enzymes and the hydrogen bonding with the key residues were stable in the dynamic condition also. Therefore, these ligands have been propsed as dual inhibitors and promising lead compounds for the drug design against MurAAb and MurBAb enzymes. 相似文献
5.
Muhammad Rafique Nayyar H. Mirjat Aamir M. Soomro Suhail Khokhar Yong Shuai 《Physics letters. A》2018,382(16):1108-1119
First-principles calculations were performed to investigate the structural, electronic, magnetic and optical properties of nitrogen (N) and magnesium (Mg) atom co-doped graphene systems. We observed that, N and Mg atom co-doping in graphene, introduces half-metallic properties in the electronic structure of graphene, introduces ferromagnetism behavior along with new trends in optical properties of graphene. Doping site and concentration of N and Mg atoms in graphene was changed and resulting effects of these changes on aforementioned properties were investigated. Through density of states plots we observed that, Mg atom sp orbitals mainly induced magnetic moments in graphene. It was revealed that, N/Mg atoms substitution in graphene introduces a red shift in absorption spectrum towards visible range and a finite absorption coefficient quantity value in 0 to 3 eV and 7 to 11 eV energy intervals is also produced, that is unavailable for absorption spectrum of intrinsic graphene. Moreover, N/Mg atoms co-doping produces increment in the reflectivity parameter of graphene in low lying energy region, while producing diminishing behavior in the higher energy range. These results offer a possibility to tune electronic, magnetic and optical characteristics of graphene sufficiently for utilization in graphene based spintronic and optoelectronic devices. 相似文献
6.
Imran Ali Mohd Suhail Mohammad Nadeem Lone Zeid A. Alothman Abdulrahman Alwarthan 《液相色谱法及相关技术杂志》2016,39(9):435-444
It is a continuous chase of researchers to separate chiral racemates due to their dominance in the pharmaceutical industry, agrochemicals, and food additives. There are many analytical techniques which have been used to resolve one chiral center racemates, but, little the literature report is scanty for the resolution of multiple stereogenic center racemates. Therefore, in this article the efforts were made to describe the enantiomeric resolution of multiple stereogenic center racemates by different modalities of chromatography. The various modalities discussed are high-performance liquid chromatography, capillary electrophoretic chromatography, miceller electrokinetic chromatography, supercritical fluid chromatography, nanoliquid chromatography, and gas chromatography. Besides, the attempts have also been made to discuss the future challenges and prospectives of the enantiomeric resolution of multichiral racemates. 相似文献
7.
The kinetic study of in-situ eopolymerization of aniline with o- and p-methylaniline by ammonium persulfate (APS) has been carried out. UV-vis spectroscopic method was used to investigate the course of copolymerization. Structural characterization was studied by PT-IR spectral analysis. The electronic spectra of the copolymers poly(aniline-co-p-toluidine) and poly(aniline-co-o- toluidine) show blue shift. The shift has been observed in the bands corresponding to π→π^* transition as well as in the exciton transition. The increase in absorbance recorded during the reaction for different concentration of aniline, o- and p-toluidine at various intervals of time of polymerization reaction indicates a growth in the polymer formation. The resulting first-order rate constant was used to calculate the rate of copolymer formation using the rate equation -d[A]/dt = kc^n. 相似文献
8.
9.
Mohd. Sajid Ali Mohd. Suhail Goutam Ghosh Mohammad Kamil Kabir-ud-Din 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,350(1-3):51-56
The interaction between bis(hexadecyldimethylammonium)hexane dibromide (16-6-16), bis(tetradecyldimethylammonium)hexane dibromide (14-6-14), their conventional counterparts cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB) with polyvinylpyrrolidone (PVP) was investigated using the conductivity technique. The results show that gemini surfactants interact strongly with PVP as compared to conventional surfactants. The results also reveal that the surfactants with shorter hydrocarbon chain interact weakly as those of longer hydrocarbon chain. The interactions of 16-6-16 and 14-6-14 and their conventional counterparts with PVP were also studied using dynamic light scattering (DLS) measurements. We have also highlighted the effect of surfactant–polymer interactions on the dispersion force in the solution. Critical aggregation concentration (cac) and critical micelle concentration (cmc) were obtained using the conductivity data. The degrees of micelle ionization and free energies associated with aggregation, micellization, and transfer have also been evaluated and discussed. 相似文献
10.
Filipa Silva Dr. Shaista S. Khokhar Danielle M. Williams Dr. Robert Saunders Dr. Gareth J. S. Evans Michael Graz Prof. Dr. Thomas Wirth 《Angewandte Chemie (International ed. in English)》2018,57(38):12290-12293
We describe a short total synthesis of ajoene, a major biologically active constituent of garlic. The instability of allicin as the only other known alternative starting material has led to the development of a reliable procedure for the synthesis of ajoene from simple building blocks that is also suitable for upscale operations. 相似文献