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排序方式: 共有127条查询结果,搜索用时 46 毫秒
41.
Chaitanya Ittamalla Saikrishna Chintha Dr. Nagaraju Medishetti Dr. Jagadeesh Babu Nanubolu Dr. Krishnaiah Atmakur 《European journal of organic chemistry》2023,26(22):e202300357
Synthesis of title compounds were accomplished by a reaction of vinyl malononitriles and arylidene pyrazolones catalyzed by base. This protocol proceeds via Michael addition followed by intramolecular cyclization leading to the formation of two new C−C bonds. Further the same reaction was also conducted with α,α-dicyano olefins and vinyl malononitriles to furnish 1,6-dihydro biphenyl compounds. Simple reaction conditions, high yields and compatibility are the advantages of this protocol. 相似文献
42.
A simple and rapid reversed-phase liquid chromatography (LC) method with photodiode array (PDA) and electrospray ionization (ESI)-mass spectrometry (MS) as detectors was developed and validated to separate, identify, and quantitate the related substances of Doxazosin mesylate (DXZN) for monitoring the reactions involved during process development. The high-performance liquid chromatography profiles of related-substances of DXZN are used as fingerprints to follow the procedures used in the manufacturing units. The separation is accomplished on an Inertsil ODS-3 column with acetonitrile-ammonium acetate (10 mM, pH 4.0) as the mobile phase, using a gradient elution mode and monitoring the eluents by a photodiode array detector at 265 nm at ambient temperature. LC-ESI-MS-MS is used to identify the additional impurities formed during the synthesis. The identified impurities were synthesized and characterized by UV, Fourier transform-IR, 1H NMR, and MS data. The detection limits for the impurities are 0.74 - 4.14 x 10(-9) g, and the method is found to be suitable not only for the monitoring of synthetic reactions, but also for quality assurance of DXZN in bulk drugs and formulations. 相似文献
43.
44.
Dr. Karre Nagaraju Dr. Dongshun Ni Prof. Dr. Dawei Ma 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22223-22226
Kopsinitarines A–E are complex octacyclic caged Kopsia alkaloids with strained cage skeletons and a unique cyclic hemiaminal bridge that makes total synthesis challenging. Herein, we disclose the first total synthesis of kopsinitarine E. The key synthetic features include a SmI2-mediated radical cascade cyclization and a subsequent semi-pinacol rearrangement to install the key carbocyclic skeleton, a chemoselective hydrosilyl amide reduction to construct the hemiaminal ether bridge, and an intramolecular Mannich reaction to establish the highly strained cage system. 相似文献
45.
P. V. Raja Shekar D. Nagaraju V. Ganesh K. Kishan Rao 《Crystal Research and Technology》2009,44(6):652-656
Single crystals of Sr(NO3)2, Ba(NO3)2 and Pb(NO3)2 are grown from their aqueous solutions at a constant temperature of 35 °C by slow evaporation technique. Crystals of size 8 to 10 mm along one edge are obtained in a period of 10 days. Chemical etching technique has been employed to study the dislocations in these crystals. The dislocations are randomly distributed and the dislocation density is about 104 to 105 /cm2. Microhardness studies are made on as–grown (111) faces of these crystals upto a load of 100 g. The hardness of the crystals increases with an increase in load and thereafter it becomes independent of the applied load. These results are discussed on the basis of reverse indentation size effect. Meyer index number n for these crystals is estimated at both low and high load regions. An analysis of hardness data of these crystals as well as some other cubic crystals like alums and alkali halates are discussed using Gilman–Chin parameter Hv/C44, where Hv is the microhardness and C44 is the shear constant. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
46.
An isocratic reversed-phase high-performance liquid chromatographic method has been developed for separation and simultaneous determination of COX-2 inhibitors, viz., celecoxib, rofecoxib, valdecoxib, nimesulide and nabumetone, using 4-chloro-2-nitroaniline as internal standard. Good chromatographic separation was achieved using a reversed-phase Inertsil C(18) column with mobile phase consisting of methanol and 0.05% aqueous glacial acetic acid (68:32 v/v) using photodiode array (PDA) detector at 230 nm. It was validated with respect to accuracy, precision, linearity, limit of detection and quantification. The linearity range was found to be 1.0--20 microg/mL and the percentage recoveries were between 97.55 and 100.14. The method is suitable not only for the estimation of active ingredients in pharmaceutical dosage forms but also in vitro estimations in human plasma. It is simple, rapid, selective and capable of detecting and determining COX-2 inhibitors with a detection limit of 0.127--1.040 microg/mL simultaneously. 相似文献
47.
Murthy JN Nagaraju M Sastry GM Rao AR Sastry GN 《Journal of computer-aided molecular design》2005,19(12):857-870
Summary This study sheds new light on the role of acidic residues present in the active site cavity of human aromatase. Eight acidic
residues (E129, D222, E245, E302, D309, E379, D380 and D476) lining the cavity are identified and studied using comparative
modeling, docking, molecular dynamics as well as statistical techniques. The structural environment of these acidic residues
is studied to assess the stability of the corresponding carboxylate anions. Results indicate that the environment of the residues
E245, E302 and D222 is most suitable for carboxylate ion formation in the uncomplexed form. However, the stability of D309,
D222 and D476 anions is seen to increase on complexation to steroidal substrates. In particular, the interaction between D309
and T310, which assists proton transfer, is found to be formed following androgen/nor-androgen complexation. The residue D309
is found to be clamped in the presence of substrate which is not observed in the case of the other residues although they
exhibit changes in properties following substrate binding. Information entropic analysis indicates that the residues D309,
D222 and D476 have more conformational flexibility compared to E302 and E245 prior to substrate binding. Interaction similar
to that between D476 and D309, which is expected to assist androgen aromatization, is proposed between E302 and E245. The
inhibition of aromatase activity by 4-hydroxy androstenedione (formestane) is attributed to a critical hydrogen bond formation
between the hydroxy moiety and T310/D309 as well as the large distance from D476. The results corroborate well with earlier
site directed mutagenesis studies. 相似文献
48.
Jeshma Kovvuri Burri Nagaraju C. Ganesh Kumar K. Sirisha Cheemalamarri Chandrasekhar Abdullah Alarifi Ahmed Kamal 《Journal of Saudi Chemical Society》2018,22(6):665-677
Catalyst-free one-pot CN and CC bond formation is described as a simple and ecofriendly method for the synthesis of pyrazole-aniline linked coumarin derivatives. Employing this protocol, a series of derivatives were synthesized in good to excellent yields and tested against different bacterial strains as well as fungal strains. Most of the compounds exhibited potential antimicrobial activity against both Gram-positive and Gram-negative bacterial strains. Among them, the compounds 4b, 4e, 4?h, 4i and 4?k exhibited promising activity on all the tested bacterial strains with values ranging between 1.9 and 7.8?µg/mL. In addition, these compounds were tested against various fungal strains and were found to exhibit potential antifungal activity. Fascinatingly, among the tested derivatives, the compounds 4e, 4?h and 4i were found to be equipotent to miconazole (positive control) against some of the tested fungal strains. Moreover, these compounds showed promising bactericidal, Candida-cidal and biofilm inhibition activities. Further, mechanistic study was carried out with the most active derivative 4i indicated that these compounds inhibit the ergosterol biosynthesis pathway. 相似文献
49.
A Convenient and Facile Hantzsch Synthesis of Aryl Imidazo[1,2‐b]Isoxazolyl‐N‐aryl Thiazol Amines
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E. Rajanarendar K. Thirupathaiah S. Ramakrishna D. Nagaraju 《Journal of heterocyclic chemistry》2016,53(6):1983-1989
The Hantzsch synthesis of novel aryl imidazo[1,2‐b]isoxazolyl‐N‐aryl thiazol amines 5 analogues were described. Reaction of 3‐aminoisoxazole 1 with substituted phenacyl bromides 2 in dry ethanol afforded the corresponding 6‐methyl‐3‐arylimidazo[1,2‐b]isoxazoles 3 in good yields. Compounds 3 on reaction with chloroacetyl chloride in 1,4‐dioxane furnished the corresponding 2‐chloro‐1‐(6‐methyl‐3‐arylimidazo[1,2‐b]isoxazol‐2‐yl)ethanones 4 . Compounds 4 on heating with N‐aryl thioureas in an oil bath underwent cyclization to afford the title compounds viz., imidazo[1,2‐b]isoxazolyl‐N‐aryl thiazol amines 5 in moderate to good yields by Hantzsch synthesis. 相似文献
50.
Nagaraju Mupparapu Narsaiah Battini Satyanarayana Battula Shahnawaz Khan Dr. Ram A. Vishwakarma Dr. Qazi Naveed Ahmed 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2954-2960
Given the attractive ability of iminium ions to functionalize molecules directly at ostensibly unreactive positions, the reactivity of iminium ions, in which an α CH2 group is replaced by C?O was explored. Background studies on the ability of such iminium cations to promote reactions via an iminium‐catalyzed or iminium‐equivalent pathway are apparently unavailable. Previously, tandem cross‐coupling reactions were reported, in which an iminium ion undergoes nucleophilic 1,2‐addition to give a putative three‐component intermediate that abstracts a proton in situ and undergoes self‐deamination followed by unprecedented DMSO/aerobic oxidation to generate α‐ketoamides. However, later it was observed that iminium ions can generate valuable α‐ketoamides through simple aerobic oxidation. In all reactions, iminium ions were generated in situ by reaction of 2‐oxoaldehydes with secondary amines. 相似文献