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Paolo Linda Cynthia Ebert Mara Lovrecich Fulvio Rubessa 《Journal of heterocyclic chemistry》1984,21(1):271-272
The hydroxide ion catalyzed hydrolysis of indole-1-carboxamide and indole-1-(N,N-dimethyl)carboxamide has been studied in water at 60.0° and [OH−] concentration between 0.3--2.4N. The rate constants of formation of the tetrahedral intermediate are strongly increased by N-substitution with a heteroaromatic ring in comparison with simple amides. Carbamazepine, (5H-dibenz[b,f]azepine)-5-carboxamide, a potent anticonvulsant drug, is particularly stable under these conditions. 相似文献
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Alessandro Cagnina Sandro Campestrini Fulvio Di Furia Patrizia Ghiotti 《Journal of molecular catalysis. A, Chemical》1998,130(3):751-231
As reported in previous papers, the oxidation of ethylbenzene with Ph4PHSO5 catalyzed by Mn(TMP)Cl in the presence of nitrogen bases in 1,2-dichloroethane homogeneous solution affords fair yields (up to 80%) of oxygenated products. Acetophenone is the major product together with minor amounts of 1-phenylethanol ([ketone]/[alcohol]6). In this paper we report further observations concerning this system. In particular we find that a similar products distribution is observed when soluble Co(II) or Fe(II) species, i.e. acetylacetonate derivatives, are used instead of the manganese porphyrin. On the other hand for these compounds, which are catalysts of radical reactions, the product distribution is determined by a remarkably larger reactivity of the alcohol initially formed compared with that of the alkane (kR–OH/kR–H200). The product distribution for the Mn(TMP)Cl catalysis cannot be rationalized on the same basis. Direct experiments show that the reactivity of the two substrates is similar (kR–OH/kR–H2–6) thus suggesting that a mechanism different from the simple radical hydrogen atom abstraction is taking place. The dependence of the chemioselectivity of hydrocarbon oxidation on the nature of the manganese porphyrin employed and of a number of additives indicates that the product distribution is mainly determined by the relevance of the association of the alcohol intermediate to the catalyst prior to the second oxidation step leading to ketone. Two different rho Hammett's values are obtained for ethylbenzenes oxidation depending on the method employed for the measurement of reaction rates, i.e. by separate or by competitive experiments thus providing further mechanistic information on the association of the substrates to the oxo-species. 相似文献
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A short-time synthesis of SBA-15 is reported by using two different silica sources, sodium metasilicate (Na2SiO3(9)H2O) and tetraethyl orthosilicate (TEOS). The SBA-15 samples obtained from both silica sources were highly ordered as evidenced by SAXS spectra showing five reflection peaks characteristic for p6mm symmetry group. While the surface areas of these samples were similar, the pore volume of the sample prepared from TEOS was slightly larger than that from sodium metasilicate. However, the latter exhibited higher microporosity and thicker pore walls. It was shown that a significant reduction of time of the self-assembly step from 24 to 2 h had no detrimental influence on the quality of SBA-15 materials. 相似文献
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The rates of reaction of t-BuOOK, t-BuOK, n-BuOOK, and p-MeC6H4OKwith p-nitrophenyl diphenylphosphinate 1 and with p-nitrophenyl benzoate 2 have been measured in toluene both in the absence and in the presence of crown polyether dicyclohexyl-18-crown-6 3a . The rates of nucleophilic displacementon 1 by HOO?, t-BuOO?, and some “nonalpha” oxyanions in water have also been determined. Solvent transfer from water to toluene results in increasing the nucleophilic reactivity of the t-butyl hydroperoxide anion. Rate ratios QQa are given which allow one to estimate the enhanced reactivity of t-BuOO? (an α-nucleophile) compared to oxygen nucleophiles of comparable base strength toward 1 and 2 . These are for substrate 1 , Qα (water) ? 6.5 and Qα (toluene) ? 2.7; for substrate 2 , Qα (water) ? 5.5 and Qα (toluene) ? 5. The hypothesis is advanced that solvation is not a major factor in determining the α-effect of the t-butylhydroperoxide anion. 相似文献
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Cacace F de Petris G Rosi M Troiani A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(24):5684-5693
Mass spectrometric techniques have been utilized in conjunction with theoretical methods to detect and characterize new species formed upon ionization of gaseous mixtures containing ozone and an NOx oxide. NO5+ as well as isomeric NO4+ and NO3+ ions have been identified. Moreover, utilization of neutralization reionization mass spectrometry (NRMS) has provided strong evidence for, if not a conclusive demonstration of, the existence of a new NO3 isomer, in addition to the long-known trigonal radical, as a gaseous species with a lifetime in excess of approximately 1 microsecond. 相似文献