全文获取类型
收费全文 | 51篇 |
免费 | 6篇 |
专业分类
化学 | 50篇 |
晶体学 | 6篇 |
数学 | 1篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2005年 | 6篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有57条查询结果,搜索用时 15 毫秒
41.
[reaction: see text] Synthesis of mono meso-free modified corroles by a [3+1] methodology is reported. 相似文献
42.
43.
Venkatraman S Kumar R Sankar J Chandrashekar TK Sendhil K Vijayan C Kelling A Senge MO 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(6):1423-1432
Ferrocenyl macrocyclic conjugates involving 22 pi oxasmaragdyrins and 18 pi oxacorroles have been synthesized and characterized. The direct covalent linkage of the ferrocenyl moiety to the meso position of the macrocycle is achieved by simple oxidative coupling of appropriate precursors with trifluoroacetic acid as catalyst. The electronic coupling between the ferrocenyl moiety and the macrocyclic pi system is apparent from: a) the red shifts (293-718 cm(-1)) of the Soret and Q-bands in the electronic absorption spectra of ferrocenyl conjugates; b) the shift of oxidation potentials (50-130 mV) of both the ferrocene and the corrole rings to the positive potentials; and c) considerable shortening of the C-C bond which connects the ferrocene and the meso-carbon atom of the macrocycle. The single-crystal X-ray structure of oxasmaragdyrin-ferrocene conjugate 9 reveals the planarity of the 22 pi skeleton with very small deviations of the meso-carbon atoms. The meso-ferrocenyl substituent has a small dihedral angle of 38 degrees, making way for mixing of the molecular orbitals of the ferrocene and the macrocycle. However, the other two meso substituents are almost perpendicular to the mean plane, defined by the three meso carbon atoms. Classical C-H...O and nonclassical C-H...pi interactions lead to a two-dimensional supramolecular network. Ferrocene-smaragdyrin conjugate 9 bonds to a chloride ion in the protonated form and a rhodium(i) ion in the free base form. Nonlinear optical measurements reveal a larger nonlinear refractive index (-5.83 x 10(-8)cm(2)W(-1)) and figure of merit (2.28 x 10(-8)cm(3)W(-1)) for the rhodium smaragdyrin-ferrocene conjugate 19 than for the others, suggesting its possible application in optical devices. 相似文献
44.
S. Senthilkumaar K. Porkodi R. Vidyalakshmi 《Journal of photochemistry and photobiology. A, Chemistry》2005,170(3):225-232
Nanocrstalline pure anatase titania were prepared by sol–gel process at room temperature followed by ultrasonication (Ti–US). The photocatalytic activity of Ti–US has been evaluated by the degradation of textile dye, Methylene Blue in presence and absence of common inorganic salts (NO3−, C2O42−, SO42−, citrate). It was observed that, in presence of anions, the degradation of the dye increases significantly. The influence of the presence of H2O2 on the degradation rate was studied. The dependence of photodegradation of the dye rates on various parameters such as dye concentration, photocatalyst concentration and pH were also investigated. The photodegradation rate follows first order kinetics. H2O2 and UV light have a negligible effect in absence of Ti–US catalyst. The relative photonic efficiency of the system is reported using phenol as a standard organic compound. 相似文献
45.
Rath H Sankar J Prabhuraja V Chandrashekar TK Nag A Goswami D 《Journal of the American Chemical Society》2005,127(33):11608-11609
The third-order nonlinear optical response through measurement of two-photon absorption cross-sections (TPACS) for aromatic core-modified expanded porphyrin analogues by a femtosecond open aperture Z-scan method is reported. The values reported here are among the largest known so far in the literature for any organic molecules. 相似文献
46.
Sureshan Muthusamy Rajamanikandan Sundarraj Srimari Srikanth Prabhu Dhamodharan Jeyakanthan Jeyaraman Saraboji Kadhirvel 《Structural chemistry》2022,33(3):935-947
Structural Chemistry - Lymphatic filariasis (LF) is one among the leading neglected diseases caused by mosquitoe-borne parasite Wuchereria bancrofti to humans. Though drugs are available for the... 相似文献
47.
A. Nallini K. Saraboji M. N. Ponnuswamy M. Venkatraj R. Jeyaraman 《Crystal Research and Technology》2005,40(6):622-626
Adducing structural analogies between the two fused systems, N1, N5‐Dibenzoyltetrahydro‐4‐methyl‐1,5‐benzodiazepin‐2‐one, C24H20N2O3 (DBTBO CCDC 200341) and Tetrahydro‐4‐methyl‐1,5‐benzodiazepin‐2‐one, C10H12 N2O (TBO CCDC 200342) helps to find the pharmacological differences from the view point of variant hetero atom substitutions in the hetero cycle. Both the diazepines crystallized in identical monoclinic space group P21/n with a = 14.1134(1) Å, b = 9.2444(1) Å, c = 16.3812(1) Å; β = 107.11(1)º, V = 2042.7(3) Å3 for DBTBO and a = 9.3363(7) Å, b = 10.4895(8) Å, c = 9.9852(7) Å, β = 91.314(1)º, V = 977.62(1) Å3 for TBO, respectively. The two structures were solved by direct methods and refined by full‐matrix least‐squares procedure to final R‐values of R1 = 0.0575(DBTBO) and R1 = 0.0984(TBO). Structural differences include non‐identical boat conformations of these seven‐membered rings and the different non‐bonding interactions in the benzodiazepine pair. 相似文献
48.
Biju Basumatary Dr. R. V. Ramana Reddy Rahul Prof. Dr. Jeyaraman Sankar 《Angewandte Chemie (International ed. in English)》2018,57(18):5052-5056
An expanded porphyrinoid has been obtained by a simple ring expansion from a contracted porphyrinoid, namely corrole. Spectroscopic, structural, and computational investigations reveal peculiar π‐conjugation and geometry. The effect of extended π‐conjugation is evident from perturbed redox behavior and photophysical properties. Owing to the strong diatropic ring current of the corrole and cross‐conjugation, the molecule exhibits a non‐aromatic nature for the expanded π‐circuit, as evident from NMR studies. 相似文献
49.
Periasamy Devi Jeyaraman Selvaraj Nirmalram Packianathan Thomas Muthiah 《Journal of chemical crystallography》2011,41(11):1624-1629
Abstract
Two nearly isostructural pseudopolymorphic forms of pyrimethaminium terephthalate have been synthesized and their supramolecular architectures analyzed. In both the crystals, the protonated pyrimethamine (PMN) cation interacts with the carboxylate anion via N–H···O hydrogen bonds to form the robust R22(8) motif. The centrosymmetrically (N–H···N) paired PMN cations are bridged on either sides by interaction of the solvent molecules with the amino groups (N–H···O) of PMN cations. The combination of two R22(8) motifs formed between the PMN cations and PMN cation solvent, leads to the formation of the complementary DADA (D = hydrogen bonded donor, A = hydrogen bonded acceptor) array of quadruple hydrogen bonds. The solvent molecule further interacts with the corresponding anion via O–H···O hydrogen bonds. Moreover, both the solvates exhibit several edge to face stacking interactions. They have in common, two C–H···π interactions; one between the symmetry related cations and other between the cation and anion. The molecular packing of the ethanol solvate is further strengthened by C–H···O and C–H···π interaction between the solvent and the ions. 相似文献50.
N. Sukumar M. N. Ponnuswamy J. C. Thenmozhiyal R. Jeyaraman 《Journal of chemical crystallography》1995,25(4):177-179
The structure of the title compound, DTMP (C15H17NS2O), has been investigated in solution and in the solid state by IR, NMR and X-ray methods. The crystal structure was solved by direct methods and refined by least-squares procedures to anR-factor of 0.073. The piperidine ring adopts achair conformation. The methyl and thioenyl rings are in theequatorial position. The angle between the best plane of the piperidine ring and the thioenyl rings A and B are 88.1(1)° and 89.5(1)°, respectively.DCB contribution No. 846 相似文献