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121.
Putikam Raghunath Yun‐Min Lee Shang‐Ying Wu Jong‐Shinn Wu Ming‐Chang Lin 《International journal of quantum chemistry》2013,113(12):1735-1746
Hydrogen atoms and SiHx (x = 1–3) radicals coexist during the chemical vapor deposition (CVD) of hydrogenated amorphous silicon (a‐Si:H) thin films for Si‐solar cell fabrication, a technology necessitated recently by the need for energy and material conservation. The kinetics and mechanisms for H‐atom reactions with SiHx radicals and the thermal decomposition of their intermediates have been investigated by using a high high‐level ab initio molecular‐orbital CCSD (Coupled Cluster with Single and Double)(T)/CBS (complete basis set extrapolation) method. These reactions occurring primarily by association producing excited intermediates, 1SiH2, 3SiH2, SiH3, and SiH4, with no intrinsic barriers were computed to have 75.6, 55.0, 68.5, and 90.2 kcal/mol association energies for x = 1–3, respectively, based on the computed heats of formation of these radicals. The excited intermediates can further fragment by H2 elimination with 62.5, 44.3, 47.5, and 56.7 kcal/mol barriers giving 1Si, 3Si, SiH, and 1SiH2 from the above respective intermediates. The predicted heats of reaction and enthalpies of formation of the radicals at 0 K, including the latter evaluated by the isodesmic reactions, SiHx + CH4 = SiH4 + CHx, are in good agreement with available experimental data within reported errors. Furthermore, the rate constants for the forward and unimolecular reactions have been predicted with tunneling corrections using transition state theory (for direct abstraction) and variational Rice–Ramsperger–Kassel–Marcus theory (for association/decomposition) by solving the master equation covering the P,T‐conditions commonly employed used in industrial CVD processes. The predicted results compare well experimental and/or computational data available in the literature. © 2013 Wiley Periodicals, Inc. 相似文献
122.
Michael P. Hughes Katie D. Rosenthal Raghunath R. Dasari Benjamin R. Luginbuhl Brett Yurash Seth R. Marder Thuc‐Quyen Nguyen 《Advanced functional materials》2019,29(29)
Increasing the dielectric constant of organic photovoltaic materials to reduce recombination rates has long been pursued, however, material modification often results in the modification of multiple device characteristics, making system comparison difficult. In this study, a fullerene derivative with an increased blend dielectric constant is examined by the addition of a triethylene glycol appendage to the fullerene (TEG‐PCBM). Density functional theory calculations show a small change to the permanent dipole moment between TEG‐PCBM and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC60BM) resulting in similar solubility, morphology, and device performance. TEG‐PCBM is blended with donors P3HT and PTB7‐Th and a comparable performance to PC60BM is found. This model system shows the rarely reported characteristic of an increase in the dielectric constant while leaving its other properties unaltered. Looking at light intensity effects on open‐circuit voltage (Voc), short‐circuit current (Jsc), and fill factor (FF) along with exciton dissociation efficiency, it is observed that when switching to the TEG‐ modified fullerene derivative, geminate recombination is not reduced, and Shockley–Read–Hall recombination is increased. While triethlyene glycol appendages may prove to be ineffective in improving recombination through increased dielectric constant, an approach for studying recombination in future high dielectric systems is provided. 相似文献
123.
The Use of Pinner Type Reaction for the Synthesis of New Indeno[2,1‐c]pyridine‐4‐carbonitrile Derivatives
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Prashant S. Nikam Shivaraj P. Patil Shrikant B. Kanawade Sachin A. Gangurde Meenakshi Rathi Raghunath B. Toche 《Journal of heterocyclic chemistry》2015,52(1):150-155
An efficient and convenient route was developed for the synthesis of new pyridinecarbonitrile derivatives by using the Pinner type of reaction. The 2‐((E)‐2‐((dimethylamino)methylene)‐1,2‐dihydro‐5,6‐dimethoxyinden‐3‐ylidene) malononitrile 2 was reacted in the presence of dry HCl gas to yield 3‐chloro‐6,7‐dimethoxy‐9H‐indeno[2,1‐c]pyridine‐4‐carbonitrile ( 3 ) in good yield. The SNAr reaction on compound 3 with various nucleophiles yielded 3‐substituted pyridinecarbonitriles 4 , 5 , 6 , 7 , 8 , 9 in moderate to good yield. 相似文献
124.
Kanamycin, a broad-spectrum antituberculosis antibiotic, was coupled to three different collagen substrates using l-ethyl-3-(3-dimethylaminopropyl)carbodiirnide, glutaraldehyde, and periodiate-oxidized kanamycin possessing aldehyde functional groups. Kanamycin-treated collagen fibers have exhibited marked differences in their chemical contraction and relaxation, swelling, and shrinkage-temperature behavior compared to untreated collagen fibers. In an in vitro study, a release of 26% of the bound kanamycin from collagen-kanamycin complex was noticed. 相似文献
125.
New 3-(heteroaryl)aminocoumarin derivatives were synthesized from 3-aminocoumarin, applying optimized Buchwald-Hartwig amination conditions using Palladium acetate, Cesium carbonate, and BINAP in 1,4-dioxane employing elevated temperature conditions and under an argon atmosphere. The target heteroarylaminocoumarin derivatives were obtained in moderate to good yields ranging from 56% to 98%. The procedure described could be widely employed for the preparation of new heterocyclic compounds when one of the core moieties is coumarin and has the potential to be active drug candidates. 相似文献
126.
127.
Benzylic/allylic alcohols are converted via site-selective C(sp2)–C(sp3) cleavage to value-added nitrogenous motifs, viz., anilines and/or nitriles as well as N-heterocycles, utilizing commercial hydroxylamine-O-sulfonic acid (HOSA) and Et3N in an operationally simple, one-pot process. Notably, cyclic benzylic/allylic alcohols undergo bis-functionalization with attendant increases in architectural complexity and step-economy.Benzylic/allylic alcohols are converted via site-selective C(sp2)–C(sp3) cleavage to value-added nitrogenous motifs, viz., anilines and/or nitriles as well as N-heterocycles, utilizing commercial hydroxylamine-O-sulfonic acid (HOSA) and Et3N in an operationally simple, one-pot process. 相似文献
128.
129.
Numerical solutions are often inaccurate because conventional co-ordinate systems do not represent the complex physical boundaries accurately. In the present work, the numerical solution of linear shallow water wave equations has been obtained by transforming the physical domain into a rectangular computational domain using elliptic differential operators. This work is part of a programme to develop three-dimensional body-fit grid systems for environmental flows. Solutions have been obtained for a cylindrical container and also a parabolic container. The initial conditions chosen are the ones for which analytical solutions exist. The numerical solutions compare well with analytical solutions. 相似文献
130.
S. Selvasekarapandian N. M. Manikandan R. Sivakumar V. Meenakshinundaram V.M. Raghunath 《Journal of Radioanalytical and Nuclear Chemistry》2002,252(2):429-435
The systematic study of background radiation and the distribution of radionuclides in the environment of Nilgiris biosphere in South India, have been carried out with an objective of establishing reliable baseline data on the background radiation level of the region. Soil samples have been collected at various places of Kotagiri taluk in Nilgiris biosphere and are analyzed for radioactivity measurements of primordial radionuclides by 3"×3" NaI(TI) gamma-ray spectrometer. It is observed that the average activity of 232Th series, 238U series and 40K in soil samples is found to be 102 Bq.kg–1, 41 Bq.kg–1 and 229 Bq.kg–1, respectively which contributes to a total gamma-dose of 86 nGy.h–1. Results of this systematic investigation establish the existence of wide range of variation in 232Th series, 238U series and 40K activities, which may be attributable to the existence of wide variety of lithological compounds in the zone under study. The ambient gamma-radiation dose measured is found to vary from 91 to 193 nGy.h–1 with a mean of 142.8 nGy.h–1. The measured ambient gamma-dose is more than 50% of the dose calculated from soil activities, which is due to the higher cosmic ray contribution to the total dose in the environment. The data is compared with different places around the world and the results are discussed in this paper 相似文献