全文获取类型
收费全文 | 76篇 |
免费 | 4篇 |
专业分类
化学 | 45篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 3篇 |
物理学 | 27篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 10篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 7篇 |
2007年 | 2篇 |
2006年 | 5篇 |
2005年 | 1篇 |
2003年 | 1篇 |
2002年 | 1篇 |
1997年 | 2篇 |
1993年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有80条查询结果,搜索用时 15 毫秒
1.
Savita Verma Deepak M. Maher Samadhan S. Nagane Bhausaheb V. Tawade Prakash P. Wadgaonkar 《Journal of polymer science. Part A, Polymer chemistry》2019,57(5):588-597
New aromatic (co)polyesters containing pendant propargyloxy groups were synthesized by phase transfer‐catalyzed interfacial polycondensation of 5‐(propargyloxy)isophthaloyl chloride (P‐IPC) and various compositions of P‐IPC and isophthaloyl chloride with bisphenol A. FTIR and NMR spectroscopic data, respectively, revealed successful incorporation of pendant propargyloxy groups into (co)polyesters and formation of (co)polyesters with desired compositions. (Co)polyesters exhibited good solubility in common organic solvents such as chloroform, dichloromethane, and tetrahydrofuran and could be cast into transparent, flexible, and tough films from chloroform solution. Inherent viscosities and number average molecular weights of (co)polyesters were in the range 0.77–1.33 dL/g and 43,600–118,000 g/mol, respectively, indicating the achievement of reasonably high‐molecular weights. The 10% weight loss temperatures of (co)polyesters were in the range 390–420 °C, demonstrating their good thermal stability. (Co)polyesters exhibited Tg in the range 146–170 °C and Tg values decreased with increase in mol % incorporation of P‐IPC. The study of non‐isothermal curing by DSC indicated thermal crosslinking of (co)polyesters via propargyloxy groups. The utility of pendant propargyloxy group was demonstrated by post‐modification of the selected copolyester with 1‐(4‐azidobutyl)pyrene, 9‐(azidomethyl)anthracene, and azido‐terminated poly(ethyleneglycol) monomethyl ether via copper(I)‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction. FTIR and 1H NMR spectra confirmed that click reaction was quantitative. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 588–597 相似文献
2.
Quantum dot infrared photodetectors can be coupled with micro‐structured filters to create narrowband sensors. Guided‐mode resonance filters based on a high‐index dielectric slab can exhibit bandpass characteristics that are suitable for monolithic integration with focal‐plane arrays. Here, patterned Ge filters were integrated with InGaAs/GaAs quantum dot detectors to linearly tune their 77 K photoresponse peaks from 5.6 µm to 6.2 µm. The dark current was not influenced by these filters but the ability to narrow the photoresponse linewidth was limited by substrate scattering, which is often encountered with front‐side illumination architectures. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
3.
X. M. Wen L. V. Dao P. Hannaford S. Mokkapati H. H. Tan C. Jagadish 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(1):65-70
We investigate the electron dynamics of p-type modulation doped and undoped
InGaAs/GaAs quantum dots using up-conversion photoluminescence at low
temperature and room temperature. The rise time of the p-doped sample is
significantly shorter than that of the undoped at low temperature. With
increasing to room temperature the undoped sample exhibits a decreased rise
time whilst that of the doped sample does not change. A relaxation mechanism
of electron-hole scattering is proposed in which the doped quantum dots
exhibit an enhanced and temperature independent relaxation due to excess
built-in holes in the valence band of the quantum dots. In contrast, the
rise time of the undoped quantum dots decreases significantly at room
temperature due to the large availability of holes in the ground state of
the valence band. Furthermore, modulation p-doping results in a shorter
lifetime due to the presence of excess defects. 相似文献
4.
The discovery of magnetic superconductors has posed the problem of the coexistence of two kinds of orders (magnetic and superconducting) in some temperature intervals in these systems. New microscopic mechanisms developed by us to explain the coexistence and reentrant behaviour are reported. The mechanism for antiferromagnetic superconductors which shows enhancement of superconductivity below the magnetic transition is found relevant for rare-earth systems having less than half-filled f-atomic shells. The theory will be compared with the experimental results of SmRh4B4 system. A phenomenological treatment based on a generalized Ginzburg-Landau approach will also be presented to explain the anomalous behaviour of the second critical field in some antiferromagnetic superconductors. These magnetic superconductors provide two kinds of Bose fields, namely, phonons and magnons which interact with each other and also with the conduction electrons. Theoretical studies of the effects of the excitations of these modes on superconducting pairing and magnetic ordering in these systems will be discussed. 相似文献
5.
Thermal post-buckling paths of homogeneous, isotropic, square plate configurations resting on elastic foundation (Winkler type) subjected to biaxial compressive thermal loads are expressed as simple closed-form solutions by using the Rayleigh–Ritz method based on coupled displacement fields. Geometric non-linearity of von-Karman type is considered. The in-plane displacement field variations used in the formulation of Rayleigh–Ritz method are derived by using the governing in-plane static differential equations of the plate which in turn simplifies the difficulty of assuming an in-plane displacement field variations of the square plate. Accuracy and robustness of the proposed closed-form solutions are demonstrated by using the non-linear finite element formulation results which are obtained from an equilibrium path approach. 相似文献
6.
Rahul D. Shingte Deepshikha Chatterjee Bhausaheb V. Tawade Bharat Shrimant 《高分子科学杂志,A辑:纯化学与应用化学》2019,56(2):136-145
Three bisphenols containing cardo perhydrocumyl cyclohexylidene group, namely; 1,1-bis(4-hydroxyphenyl)-4-perhydrocumylcyclohexane, 1,1-bis(4-hydroxy-3-methylphenyl)-4-perhydrocumylcyclohexane and 1,1-bis(4-hydroxy-3,5-dimethylphenyl)-4-perhydrocumylcyclohexane were synthesized starting from p-cumyl phenol. Each of these bisphenols was polycondensed with both terephthaloyl chloride and isophthaloyl chloride by phase transfer-catalyzed interfacial polymerization to obtain a series of new aromatic polyesters. Inherent viscosities and number average molecular weights of polyesters were in the range 0.51-0.64 dL/g and 17390-41430?g/mol, respectively which indicated the formation of reasonably high molecular weight polymers. The detailed NMR studies revealed that axial and equatorial identity of the phenyl rings of bisphenols was retained in polyesters resulting in constitutional isomerism. Polyesters containing perhydrocumyl cyclohexylidene groups showed excellent solubility in organic solvents viz, chloroform, dichloromethane, 1,1,2,2-tetrachloroethane and tetrahydrofuran. The self-standing films of polyesters could be cast from their chloroform solution. The 10% weight loss temperatures and glass transition temperatures of polyesters were in the range 453–485?°C and 201–267?°C, respectively demonstrating their excellent thermal characteristics. The gas permeability study of polyesters was carried out for He, H2 and N2 by variable-volume method. An improvement in permeability and decrease in selectivity was observed due to symmetric methyl substituents while reverse trend was observed in case of polyesters with asymmetric methyl substituents. 相似文献
7.
Jagadish Babu Vemula 《Journal of Turbulence》2017,18(7):653-687
Shock waves in high-speed flows can drastically alter the nature of Reynolds stresses in a turbulent flow. We study the canonical interaction of homogeneous isotropic turbulence passing through a normal shock, where the shock wave generates significant anisotropy of Reynolds stresses. Existing Reynolds stress models are applied to this canonical problem to predict the amplification of the stream-wise and transverse normal Reynolds stresses across the shock wave. In particular, the efficacy of the different models for the rapid pressure–strain correlation is evaluated by comparing the results with available direct numerical simulation (DNS) data. The model predictions are found to be grossly inaccurate, especially at high-Mach numbers. We propose physics-based improvement to the Reynolds stress-transport equation in the form of shock-unsteadiness effect and enstrophy amplification for turbulent dissipation rate . The resulting model is found to capture the essential physics of Reynolds stress amplification, and match DNS data for a range of Mach numbers. Numerical error encountered at shock waves are also analysed and the model equations are cast in conservative form to obtain physically consistent results with successive grid refinement. Finally, the proposed model for canonical shock-turbulence interaction is generalised to multi-dimensional flows with shock of arbitrary orientation. 相似文献
8.
Jagadish C. Sircar Thomas Capiris Stephen J. Kesten 《Journal of heterocyclic chemistry》1981,18(1):117-121
Reactions of 2H-3,1-benzoxazine-2,4-(1H)dione (isatoic anhydride) (1) with anions of 1,4-dihydro-5H-pyrazol-5-ones (2) gave pyrazolo[5,1-6]quinazolin-9-ones (3) via the nucleophilic attack of the anion 2b rather than 2a. However, in the case of 5-methoxyisatoic anhydride ( 10c) , both products 3e and 11c were obtained. A new synthetic method of preparation of 5-(alkylthio)-2-aminobenzoic acids (18) was described. These acids (18) were used to synthesize a series of substituted pyrazolo[5,1-b]quinazolin-9-ones (3) . 相似文献
9.
Bhagyashri B. Kamble Tawade Anita K. Kamble Pravin Padavi Mukesh N. Sharma Kiran Kumar K. Ajalkar Balu D. Tayade Shivaji N. 《Russian Journal of Electrochemistry》2020,56(9):766-774
Russian Journal of Electrochemistry - A micro-bricks shaped tungsten oxide (WO3) was prepared by hydrothermal method. The prepared material was characterized by field emission scanning electron... 相似文献
10.
Jagadish B Brickert-Albrecht GL Nichol GS Mash EA Raghunand N 《Tetrahedron letters》2011,52(17):2058-2061
1,4,7-Tris(tert-butoxycarbonylmethyl)-1,4,7,10-tetraazacyclododecane is widely used as an intermediate in the preparation of medically important DO3A and DOTA metal chelators. Despite its commercial availability and importance, the literature describing the preparation and properties of the free base is limited and sometimes unclear. We present herein an efficient synthesis of the hydrobromide salt of 1,4,7-tris(tert-butoxycarbonylmethyl)-1,4,7,10-tetraazacyclododecane, characterize this compound spectroscopically and by X-ray crystallographic analysis, describe its simple conversion to the corresponding free base, characterize this compound spectroscopically and by X-ray crystallographic analysis, and make observations on the reactivity of this interesting and useful compound. 相似文献