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排序方式: 共有508条查询结果,搜索用时 15 毫秒
31.
Jetti RK Thallapally PK Nangia A Lam CK Mak TC 《Chemical communications (Cambridge, England)》2002,(9):952-953
The title molecule forms a honeycomb network of molecular and nitro-trimer synthons with guest species included in the hexagonal voids. 相似文献
32.
[structure: see text] Crystal engineering of an organic ladder can be achieved with a T-shaped molecule, 4,4-bis(4'-hydroxyphenyl)-1-cyclohexanol, having three hydroxyl functionalities that can form O-H...O hydrogen-bonded helices. The topology of this network structure finds a parallel in three-connected coordination polymers. 相似文献
33.
Craig F Ferris Tara Stolberg Praveen Kulkarni Murali Murugavel Robert Blanchard D Caroline Blanchard Marcelo Febo Mathew Brevard Neal G Simon 《BMC neuroscience》2008,9(1):111
Background
With the advent of functional magnetic resonance imaging (fMRI) in awake animals it is possible to resolve patterns of neuronal activity across the entire brain with high spatial and temporal resolution. Synchronized changes in neuronal activity across multiple brain areas can be viewed as functional neuroanatomical circuits coordinating the thoughts, memories and emotions for particular behaviors. To this end, fMRI in conscious rats combined with 3D computational analysis was used to identifying the putative distributed neural circuit involved in aggressive motivation and how this circuit is affected by drugs that block aggressive behavior. 相似文献34.
Abhishek Verma Swati Nagpal Praveen K. Pandey P. K. Bhatnagar P. C. Mathur 《Journal of nanoparticle research》2007,9(6):1125-1131
Quantum Dots of CdS
x
Se1−x
embedded in borosilicate glass matrix have been grown using Double-Step annealing method. Optical characterization of the
quantum dots has been done through the combinative analysis of optical absorption and photoluminescence spectroscopy at room
temperature. Decreasing trend of photoluminescence intensity with aging has been observed and is attributed to trap elimination.
The changes in particle size, size distribution, number of quantum dots, volume fraction, trap related phenomenon and Gibbs
free energy of quantum dots, has been explained on the basis of the diffusion-controlled growth process, which continues with
passage of time. For a typical case, it was found that after 24 months of aging, the average radii increased from 3.05 to
3.12 nm with the increase in number of quantum dots by 190% and the size-dispersion decreased from 10.8% to 9.9%. For this
sample, the initial size range of the quantum dots was 2.85 to 3.18 nm. After that no significant change was found in these
parameters for the next 12 months. This shows that the system attains almost a stable nature after 24 months of aging. It
was also observed that the size-dispersion in quantum dots reduces with the increase in annealing duration, but at the cost
of quantum confinement effect. Therefore, a trade off optimization has to be done between the size-dispersion and the quantum
confinement. 相似文献
35.
36.
C. Praveen 《Tetrahedron》2008,64(10):2369-2374
Pyridinium chlorochromate (PCC) supported on silica gel effects the oxidative cyclization of structurally diverse thiophenolic and phenolic Schiff's bases, thereby providing an efficient and convenient method for the synthesis of a library of 2-arylbenzothiazoles and 2-arylbenzoxazoles. 相似文献
37.
Lalit Giri Arun Kumar Jugran Amit Bahukhandi Praveen Dhyani Indra D. Bhatt Ranbeer Singh Rawal Shyamal Kumar Nandi Uppeandra Dhar 《Applied biochemistry and biotechnology》2017,181(1):267-282
Habenaria edgeworthii Hook. f. ex Collett is an important terrestrial orchid used in different Ayurvedic formulations. In the present study, variations among morphological, phytochemical and molecular markers were assessed. A significant difference was observed among populations using morphological traits. Inter-simple sequence repeat (ISSR) data revealed lower genetic diversity at population level (He = 0.207) as compared to species level (He = 0.334). Analysis of molecular variance (AMOVA) indicates 74 % variation among populations and 26 % within population. Tuber extracts showed significantly (p < 0.05) higher total phenolics and flavonoids among the populations. Antioxidant activity determined by 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays exhibited considerable antioxidant potential. Furthermore, the associations between molecular and morphological and phytochemical attributes were studied using multiple regression analysis (MRA). Several ISSR fragments were associated with some morphological and phytochemical traits. These ISSR fragments can be useful for breeding programme of the species when no other genetic information, such as linkage maps and quantitative trait loci, is available. 相似文献
38.
Synthesis and photophysical studies of a simple and efficient dansyl-styrylquinoline conjugate (DansSQ) which shows excellent selectivity toward Fe2+ over other transition metal ions including Fe3+ are described. The fluorescent emission of DansSQ at 450 nm was enhanced upon addition of Fe2+ in the presence of common interfering metal ions in background. These studies suggest that DansSQ could be used as fluorescent sensor for Fe2+. 相似文献
39.
Choorikkat Ranjith K.K. Vijayan Vakayil K. Praveen N.S. Saleesh Kumar 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(5):1610-1616
In the present work an array of novel substituted 2H-chromen-2-one (coumarin) derivatives has been subjected to photophysical analysis. Though the influence of the electron-donating groups such as amino, substituted amino, hydroxyl, alkoxy groups, etc. at position 7 of the coumarin ring system has been extensively studied, the luminescent properties of the coumarin moieties with an acetoxy substituent have not been explored. Herein it is attempted to study the variation of fluorescence behavior of substituted coumarin derivatives with change of nature and position of the substituents on the 2H-chromen-2-one skeleton. Effect of a methyl substituent at position 4 which imposes abnormal photophysical behavior to the chromenone unit has also been briefly described. 相似文献
40.
Molly Megraw Praveen Sethupathy Kiranmai Gumireddy Shane T. Jensen Qihong Huang Artemis G. Hatzigeorgiou 《Theoretical chemistry accounts》2010,125(3-6):593-598
In this study, we investigate whether miRNAs located within “host” protein-coding genes may regulate the expression of their host genes. We find that 43 of 174 miRNAs encoded within RefSeq genes are predicted to target their host genes. Statistical analysis of this phenomenon suggests that gene auto-regulation via miRNAs may be under positive selective pressure. Our analysis also indicates that several of the 43 miRNAs have a much lower expectation of targeting their host genes by chance than others. Among these examples, we identify miR-128b:ARPP-21 (cyclic AMP-regulated phosphoprotein, 21 kD) as a case in which both the miRNA and the target site are also evolutionarily conserved. We provide experimental support for this miRNA:target interaction via reporter silencing assays, and present evidence that this isoform-specific gene auto-regulation has been preserved in vertebrate species in order to prevent detrimental consequences of ARPP-21 over-expression in brain. 相似文献