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Phosphorylation of ddC and 3TC was efficiently performed on soluble poly(ethylene glycol) support. The corresponding 5'-monophosphate derivatives were obtained by oxidation of the support bound 5'-H-phosphonate intermediates. Then, di- and triphosphorylations were carried out using a carbonyldiimidazole activation step followed by nucleophilic substitution with suitable phosphate salts. Trivalent phosphorus chemistry appeared as a good alternative for monophosphate synthesis of acid-sensitive 2',3'-dideoxynucleosides. 相似文献
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Suzanne Burling Dr. L. Jonas L. Häller Dr. Elena Mas‐Marzá Dr. Aitor Moreno Stuart A. Macgregor Prof. Mary F. Mahon Dr. Paul S. Pregosin Prof. Dr. Michael K. Whittlesey Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(41):10912-10923
The five‐coordinate ruthenium N‐heterocyclic carbene (NHC) hydrido complexes [Ru(IiPr2Me2)4H][BArF4] ( 1 ; IiPr2Me2=1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene; ArF=3,5‐(CF3)2C6H3), [Ru(IEt2Me2)4H][BArF4] ( 2 ; IEt2Me2=1,3‐diethyl‐4,5‐dimethylimidazol‐2‐ylidene) and [Ru(IMe4)4H][BArF4] ( 3 ; IMe4=1,3,4,5‐tetramethylimidazol‐2‐ylidene) have been synthesised following reaction of [Ru(PPh3)3HCl] with 4–8 equivalents of the free carbenes at ambient temperature. Complexes 1 – 3 have been structurally characterised and show square pyramidal geometries with apical hydride ligands. In both dichloromethane or pyridine solution, 1 and 2 display very low frequency hydride signals at about δ ?41. The tetramethyl carbene complex 3 exhibits a similar chemical shift in toluene, but shows a higher frequency signal in acetonitrile arising from the solvent adduct [Ru(IMe4)4(MeCN)H][BArF4], 4 . The reactivity of 1 – 3 towards H2 and N2 depends on the size of the N‐substituent of the NHC ligand. Thus, 1 is unreactive towards both gases, 2 reacts with both H2 and N2 only at low temperature and incompletely, while 3 affords [Ru(IMe4)4(η2‐H2)H][BArF4] ( 7 ) and [Ru(IMe4)4(N2)H][BArF4] ( 8 ) in quantitative yield at room temperature. CO shows no selectivity, reacting with 1 – 3 to give [Ru(NHC)4(CO)H][BArF4] ( 9 – 11 ). Addition of O2 to solutions of 2 and 3 leads to rapid oxidation, from which the RuIII species [Ru(NHC)4(OH)2][BArF4] and the RuIV oxo chlorido complex [Ru(IEt2Me2)4(O)Cl][BArF4] were isolated. DFT calculations reproduce the greater ability of 3 to bind small molecules and show relative binding strengths that follow the trend CO ? O2 > N2 > H2. 相似文献
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John J. Orlando Geoffrey S. Tyndall Eric C. Apel Daniel D. Riemer Suzanne E. Paulson 《国际化学动力学杂志》2003,35(8):334-353
Rate coefficients and/or mechanistic information are provided for the reaction of Cl‐atoms with a number of unsaturated species, including isoprene, methacrolein ( MACR ), methyl vinyl ketone ( MVK ), 1,3‐butadiene, trans‐2‐butene, and 1‐butene. The following Cl‐atom rate coefficients were obtained at 298 K near 1 atm total pressure: k(isoprene) = (4.3 ± 0.6) × 10?10cm3 molecule?1 s?1 (independent of pressure from 6.2 to 760 Torr); k( MVK ) = (2.2 ± 0.3) × 10?10 cm3 molecule?1 s?1; k( MACR ) = (2.4 ± 0.3) × 10?10 cm3 molecule?1 s?1; k(trans‐2‐butene) = (4.0 ± 0.5) × 10?10 cm3 molecule?1 s?1; k(1‐butene) = (3.0 ± 0.4) × 10?10 cm3 molecule?1 s?1. Products observed in the Cl‐atom‐initiated oxidation of the unsaturated species at 298 K in 1 atm air are as follows (with % molar yields in parentheses): CH2O (9.5 ± 1.0%), HCOCl (5.1 ± 0.7%), and 1‐chloro‐3‐methyl‐3‐buten‐2‐one (CMBO, not quantified) from isoprene; chloroacetaldehyde (75 ± 8%), CO2 (58 ± 5%), CH2O (47 ± 7%), CH3OH (8%), HCOCl (7 ± 1%), and peracetic acid (6%) from MVK ; CO (52 ± 4%), chloroacetone (42 ± 5%), CO2 (23 ± 2%), CH2O (18 ± 2%), and HCOCl (5%) from MACR ; CH2O (7 ± 1%), HCOCl (3%), acrolein (≈3%), and 4‐chlorocrotonaldehyde (CCA, not quantified) from 1,3‐butadiene; CH3CHO (22 ± 3%), CO2 (13 ± 2%), 3‐chloro‐2‐butanone (13 ± 4%), CH2O (7.6 ± 1.1%), and CH3OH (1.8 ± 0.6%) from trans‐2‐butene; and chloroacetaldehyde (20 ± 3%), CH2O (7 ± 1%), CO2 (4 ± 1%), and HCOCl (4 ± 1%) from 1‐butene. Product yields from both trans‐2‐butene and 1‐butene were found to be O2‐dependent. In the case of trans‐2‐butene, the observed O2‐dependence is the result of a competition between unimolecular decomposition of the CH3CH(Cl)? CH(O?)? CH3 radical and its reaction with O2, with kdecomp/kO2 = (1.6 ± 0.4) × 1019 molecule cm?3. The activation energy for decomposition is estimated at 11.5 ± 1.5 kcal mol?1. The variation of the product yields with O2 in the case of 1‐butene results from similar competitive reaction pathways for the two β‐chlorobutoxy radicals involved in the oxidation, ClCH2CH(O?)CH2CH3 and ?OCH2CHClCH2CH3. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 334–353, 2003 相似文献
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1-Fluoro-2-pyridone has been used to fluorinata selectively enamines and Grignard reagents under mild conditions. 相似文献
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Abstract— The isolation of a mutant, strain PM-9, of Rhodopseudonionus spheroides with an abnormal complement of carotenoid pigments is described.
PM-9 accumulates phytoene, phytofluene, ζ-carotene and neurosporene. Semi-aerobic cultures form more ζ-carotene and neurosporene relative to total carotenoids than do photo-synthetic cultures.
PM-9 is killed on exposure to light and oxygen.
By making use of the effect of oxygen on the nature of the carotenoids in PM-9, we have shown that these pigments do not directly influence the in vivo spectrum of bacteriochlorophyll.
Diphenylamine inhibits the synthesis of coloured carotenoids in Rhodopseudonionos gelatinosa but does not change the bacteriochlorophyll spectrum. 相似文献
PM-9 accumulates phytoene, phytofluene, ζ-carotene and neurosporene. Semi-aerobic cultures form more ζ-carotene and neurosporene relative to total carotenoids than do photo-synthetic cultures.
PM-9 is killed on exposure to light and oxygen.
By making use of the effect of oxygen on the nature of the carotenoids in PM-9, we have shown that these pigments do not directly influence the in vivo spectrum of bacteriochlorophyll.
Diphenylamine inhibits the synthesis of coloured carotenoids in Rhodopseudonionos gelatinosa but does not change the bacteriochlorophyll spectrum. 相似文献