全文获取类型
收费全文 | 201篇 |
免费 | 1篇 |
专业分类
化学 | 133篇 |
晶体学 | 9篇 |
力学 | 2篇 |
数学 | 19篇 |
物理学 | 39篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 12篇 |
2012年 | 14篇 |
2011年 | 14篇 |
2010年 | 12篇 |
2009年 | 9篇 |
2008年 | 23篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 6篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 7篇 |
1981年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有202条查询结果,搜索用时 390 毫秒
41.
Souvik Guha Ibrahim Yussif El-Deeb Shalini Yadav Ranajit Das Dr. Kshatresh Dutta Dubey Mousumi Baruah Dr. Ludovic Gremaud Prof. Dr. Subhabrata Sen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(63):e202202405
Herein we have reported the discovery of a pentacyclic building block comprised of fused indole-quinoline and piperidinone from the natural product perophoramidine as a formidable anticancer agent. The compounds were synthesized in six steps where the key steps involved a blue LED mediated intramolecular cyclopropanation of the indole intermediates and concomitant reduction of the associated aryl nitro moiety to nitroso in the molecule. Cytotoxicity screening of the compounds against an array of cancer cells that is, MCF7, HCT116 and A549 demonstrated 0.6 to 9 μM IC50s by few of the compounds. γH2AX immunofluorescence assay of the two most potent molecules from the phenotypic screening with anti-γ-H2AX Alexa Fluor 488 antibody revealed extensive DNA damage of the A549 cells which indicated probable PARP inhibition (similar to Perophoramidine). Through molecular docking and molecular dynamic (MD) simulation studies the binding efficiency of our compounds with poly(ADP-ribose)polymerase 1 (PARP 1) enzyme was determined. Chemiluminescent PARP Assay with Histone-coated strips indicated that the most active compounds from the phenotypic screening induced PARP-1 inhibition with IC50s of 1.3→1.5 μM. 相似文献
42.
Using certain representations for Eisenstein series, we uniformly derive several Ramanujan-type series for 1/π. 相似文献
43.
The quantum speed of evolution for the phase covariant map is investigated. This involves absorption, emission, and dephasing processes. The maps under various combinations of the above processes are considered to investigate the effect of phase covariant maps on quantum speed limit time. For absorption-free phase covariant maps, combinations of dissipative and CP-(in)divisible (non)-Markovian dephasing noises are considered. The role of coherence-mixedness balance on the speed limit time is checked in the presence of both vacuum and finite temperature effects. The rate at which Holevo's information changes and the action quantum speed of evolution for specific cases of the phase covariant map are also investigated. 相似文献
44.
D. Suresh Babu W. Marjit Singh Dipjyoti Kalita Jubaraj B. Baruah 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(1):486-489
The quinonic compound 3-hydroxy-4-(1-(2,4-dihydroxyphenyl)-2-hydroxy-2,2-diphenylethylidene)cyclohexa-2,5-dienone (I) is synthesised by the reaction of benzil with 1,3-dihydroxybenzene in basic medium. Solution of this compound shows visibly distinct colour differences in different solvents. From the different absorption maxima of the compound in visible spectra it can be used as an excellent analytical reagent to screen different solvents. 相似文献
45.
Baruah M Qin W Flors C Hofkens J Vallée RA Beljonne D Van der Auweraer M De Borggraeve WM Boens N 《The journal of physical chemistry. A》2006,110(18):5998-6009
Steady-state and time-resolved fluorescence techniques have been used to study the photophysical properties of the fluorescent BODIPY-derived dye 3-{2-[4-(dimethylamino)phenyl]ethenyl}-4,4-difluoro-8-(4-methoxyphenyl)-1,5,7-trimethyl-3a,4a-diaza-4-bora-s-indacene. This compound has been synthesized via a microwave-assisted condensation of p-N,N-dimethylaminobenzaldehyde with the appropriate 1,3,5,7-tetramethyl substituted borondipyrromethene unit. The fluorescence properties of the dye are strongly solvent dependent: increasing the solvent polarity leads to lower fluorescence quantum yields and lifetimes, and the wavelength of maximum fluorescence emission shifts to the red. The Catalán solvent scales are found to be the most suitable for describing the solvatochromic shifts of the fluorescence emission. These are dominated by polarity/polarizability effects, as confirmed by quantum-chemical calculations performed in the dielectric continuum approximation. Fluorescence decay profiles of the dye can be described by a single-exponential fit in most solvents investigated, while two decay times are found in alcohols. The dye undergoes a reversible protonation-deprotonation reaction in the acidic pH range with a pK(a) of 2.25 in acetonitrile solution. Fluorimetric titrations as a function of pH produce fluorescence emission enhancements at lower pH. The fluorescence excitation spectra show a hypsochromic shift from 600 nm for the neutral amine to 553 nm for the ammonium form, so that ratiometric measurements can be used to determine pK(a). 相似文献
46.
47.
The authors show that certain theta function identities of Schroeter and Ramanujan imply elegant partition identities. 相似文献
48.
Nirmal Misra Mohendra Roy Dambarudhar Mohanta Kishor Kumar Baruah Amarjyoti Choudhury 《Central European Journal of Physics》2008,6(1):109-115
ZnO:Mn semiconductor quantum dots were prepared by solution casting led microemulsion route. Quantum dots of average size
∼2 nm were noticed in transmission electron micrographs. The present work highlights colour change phenomena (photochromic
effect) of quantum dots while subjected to photon illumination. The magneto-optic measurements e.g. magnetic field (H) vs angle of rotation (θ) show step like behavior and is ascribed to the quantum confinement effect of diluted magnetic ZnO:Mn nanostructures. Further,
underlying mechanism responsible for exhibiting photochromism and magneto-optic effects are also discussed.
相似文献
49.
Azlactone 3a reacted with furan-2-aldehyde and thiophene-2-aldehyde imines to give corresponding 3-amido-β-lactams in good yields. 相似文献
50.
BODIPY-based hydroxyaryl derivatives as fluorescent pH probes 总被引:3,自引:0,他引:3
Baruah M Qin W Basarić N De Borggraeve WM Boens N 《The Journal of organic chemistry》2005,70(10):4152-4157
[structures: see text] Seven new 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyes with phenolic or naphtholic subunits on position 8 and with substituents having different electron driving forces on positions 3 and 5 were synthesized. Their absorption and steady-state fluorescence properties were investigated as a function of solvent. The novel compounds, with the exception of 4,4-difluoro-8-(4-hydroxyphenyl)-3,5-bis-(4-methoxyphenyl)-4-bora-3a,4a-diaza-s-indacene, are characterized by absorption maxima in the range 493-515 nm and small (400-600 cm(-1)) Stokes shifts. The exceptional dye has absorption maxima in the 570-580 nm region and fluorescence emission maxima around 610-620 nm, depending on the solvent. In aqueous solution, the dyes show a large fluorescent enhancement upon increasing the acidity of the solution. They can be used in aqueous solution as fluorescent pH probes excitable with visible light, with pKa values ranging from 7.5 to 9.3, depending on the substitution pattern on positions 3, 5, and 8. 相似文献