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11.
Noble metals are well-known to afford highly active, selective and durable catalysts, and have thus been at the core of the development of greener processes. In recent years, however, growing concerns about their scarcity, cost and toxicity has triggered research efforts towards the development of earth-abundant catalysts. In this Current Opinion, recent examples of the use in catalysis of pure earth-abundant metals, earth-abundant metals with minute quantities of noble metals, or earth-abundant metals activated by light are presented. This highlight article showcases the current trends in sustainable organic transformations, catalyzed by nanomaterials. 相似文献
12.
B. Madhu Babu Pramod B. ThakurN. Nageswara Rao G. Santosh KumarH.M. Meshram 《Tetrahedron letters》2014
A rapid, efficient, and convenient synthesis of functionalized triarylmethane is described by the Friedel–Crafts alkylation of methoxybenzenes with a variety of aldehydes in the presence of BF3·OEt2. The generality of the method is demonstrated by screening a variety of di- or tri-substituted arenes as well as substituted aromatic, heteroaromatic, and aliphatic aldehydes. (−)-Tatarinoid C is synthesized in a single step following the same protocol. 相似文献
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N. Pongali Sathya Prabu M. L. N. Madhu Mohan 《Journal of Thermal Analysis and Calorimetry》2013,113(2):811-820
Novel homologous series of supramolecular hydrogen bonded liquid crystals have been investigated. Hydrogen bonds are formed between p-n octyloxy benzoic acid and various p-n alkyloxy benzoic acids whose carbon chain length varied from pentyl to dodecyl. These complexes are characterized by Fourier transform infrared spectroscopy, polarizing optical microscopy (POM), and differential scanning calorimetry (DSC). Phase diagram is constructed from POM and DSC data. The order of the phase transitions is determined by Navard and Cox ratio (N R). Characteristic phases like nematic, smectic C, and smectic F are identified. A new smectic ordering observed in this series is investigated by constructing phase diagram obtained from two binary mixtures of the present homologs. Inter-digitation of lamellar layers is observed to be one of the reasons for the occurrence of new smectic ordering. Optical tilt angle in smectic C phase is fitted to a power law. The magnitude of exponent of the power law is found to concur with the Mean Field theory predicted value. 相似文献
16.
Chilakapati Venkata Vishnu Vardhan Sajal Ghosh Subramaniam Nagaraj Raghavachary Sridharan Thiagarajan Gnanasekaran 《Journal of Thermal Analysis and Calorimetry》2013,112(1):127-131
A study of binary, CaBr2–CaHBr system was carried out by differential thermal analysis (DTA), covering the composition range from 100 % CaBr2 to 100 % CaHBr between room temperature and 800 °C. From DTA results, the contour of solidus and liquidus temperatures with composition is plotted and the phase diagram of CaBr2–CaHBr system is constructed. The system shows an eutectic reaction at 576 °C and the eutectic composition is 79.6 mol% CaBr2. Co-existing phases in different phase fields are characterized by X-ray diffraction analysis. 相似文献
17.
Fault tree analysis (FTA) is a promising quantitative technique for risk analysis in chemical process industries (CPIs). In FTA, a certain sequence of basic events (causes) leads to one specific Top event (critical event of interest). However, the conventional fault tree analysis has the limitations of staticity and uncertainty. The staticity in conventional FTA arises due to its inability to accommodate time-dependent characteristics of the process system. Whereas uncertainty primarily lies in the failure probability data of basic events. This paper proposes an innovative methodology that uses a time-dependent covariate model to update the failure probability values of major contributing basic events in FTA. A novel subclass of the family of phase-type distributions is used to model the covariates corresponding to the basic events. The newly developed methodology is applied for a case study in a chlorine manufacturing facility to estimate the chlorine release probability. The blockage in the pipeline was identified as the significant reason for chlorine release from expert opinion and sensitivity analysis. The results of the proposed model of FTA are compared with that of conventional FTA. 相似文献
18.
Madhu Kumar Reddy Kandula Mohan Gundluru Bakthavatchala Reddy Nemallapudi Sravya Gundala Peddanna Kotha Grigory V. Zyryanov Sridevi Chadive Suresh Reddy Cirandur 《Journal of heterocyclic chemistry》2021,58(1):172-181
A novel series of piperazine-1,2,3-triazole bearing dimethyl(((2-(4-((1H-1,2,3-triazole-4-yl)methyl)piperazin-1-yl)ethylamino)(2-hydroxyaryl)methyl)phosphonate derivatives have been prepared via copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) (Click Reaction) and Schiff base reactions. The synthesized compounds were confirmed by spectral characterization (1H, 13C and 31P NMR, and mass). The title compounds were evaluated for in vitro alpha glucosidase enzyme inhibition and in vitro antioxidant activity using DPPH and H2O2 methods. 相似文献
19.
Anil Kumar Gunthanakkala Madhu Sekhar Mangali Padmavathi Venkatapuram Padmaja Adivireddy 《Journal of heterocyclic chemistry》2020,57(12):4164-4174
A new class of bis(arylsulfonylmethylazolyl)pyridines and bis(arylaminosulfonylmethyl-azolyl)pyridines were synthesized from the synthetic intermediates methyl arylsulfonylacetic acid hydrazide and methyl arylaminosulfonylacetic acid hydrazide adopting a green methodology-ultrasonication. All the synthesized compounds were resulted in higher yield and in shorter reaction times. The spectral parameters such as IR, 1H NMR, 13C NMR, mass and microanalyzes were used to determine the structures of all the synthesized compounds and were assayed for antioxidant activity. The bis(arylaminosulfonylmethylazolyl)pyridines showed higher radical scavenging activity than the bis(arylsulfonylmethylazolyl)pyridines. Besides, unsubstituted, and methyl substituted compounds exhibited greater activity. Among all the tested compounds 8b and 11b were identified as potential antioxidants. 相似文献
20.
Prof. Dr. Klaus Banert Dr. Madhu Chityala Dr. Marcus Korb 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(28):6158-6164
Although the chemistry of elusive tricyanomethane (cyanoform) has been studied during a period of more than 150 years, this compound has very rarely been utilized in the synthesis or modification of heterocycles. Three-membered heterocycles, such as epoxides, thiirane, aziridines, or 2H-azirines, are now treated with tricyanomethane, which is generated in situ by heating azidomethylidene-malonodinitrile in tetrahydrofuran at 45 °C or by adding sulfuric acid to potassium tricyanomethanide. This leads to ring expansion with formation of 2-(dicyanomethylidene)oxazolidine derivatives or creation of the corresponding thiazolidine, imidazolidine, or imidazoline compounds and opens up a new access to these push–pull-substituted olefinic products. The regio- and stereochemistry of the ring-enlargement processes are discussed, and the proposed reaction mechanisms were confirmed by using 15N-labeled substrates. It turns out that different mechanisms are operating; however, tricyanomethanide is always acting as a nitrogen-centered nucleophile, which is quite unusual if compared to other reactions of this species. 相似文献