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21.
5, 12-Diazadibenz[a,h]anthracene ( 20 ) was synthesized in 21% overall yield for seven steps. Salient features of the synthesis include the initial, one-step conversion of trans, trans-1,4-bis-(β-nitrovinyl)benzene into 2,2″-dinitro-p-terphenyl by Diels-Alder condensation plus elimination, monocyclization of the derived 2,2″-diformylamino-p-terphenyl to give 8-(2-amino-1-phenyl)-phenanthridine ( 10 ) in the presence of fortified polyphosphoric acid, and accomplishment of a second cyclization step only after reduction of the heteroring in 10 (by means of diisobutyl-aluminum hydride) plus formylation. The 6-methyl and 6,13-dimethyl derivatives of 20 were prepared similarly. 相似文献
22.
L. H. Klemm Lee Lam Bryon Severns Sandip K. Sur 《Journal of heterocyclic chemistry》1990,27(7):1969-1972
Treatment of phenanthro[4,5-bcd]thiophene ( 2 ) with acetyl chloride and aluminum chloride in nitrobenzene gives acetylation of positions ortho and para to the heteroatomic sulfur atom. In separate experiments, mixtures of 1- and 3-acetyl (50% yield, ratio 1.9:1) or of 1,5-, 1,7-, and 3,5-diacetyl (79% yield, ratio 3:1:1) derivatives were obtained. Isolated as isomerically pure products were the 1-acetyl and the 1,5-diacetyl compounds, as well as the oximes of the 1- and 3-acetyl derivatives. Comparison of these results is made with those reported for nitration of 2 , which also occurs ortho and para to the sulfur atom, and with nitration and acetylation of pyrene (the benzolog of 2 ) which substitutes in the corresponding positions. 相似文献
23.
The kinetics of solvolysis of the title compound (QAc) in undried DMSO-d6 to give 4-(1-ethoxycarbonyl-1-cyano)methylquinoline (QH) and HOAc at ambient temperature were investigated by 1H nmr spectrometry. With a limited excess of water the solvolysis follows a three-step process of $ {\rm QAc} + {\rm H}_2 {\rm O}\mathop \to \limits^{k_1} {\rm QH} + {\rm HOAc}, $ , and $ {\rm Ac}_{\rm 2} {\rm O} + {\rm H}_2 {\rm O}\mathop \to \limits^{k_3} {\rm 2\,HOAc}, $ where k2 > k1 and k3 < k1. Addition of pyridine-d5 to the reaction mixture markedly catalyzes the overall solvolysis, while addition of CF3CO2D to the reaction mixture simplifies the kinetics to pseudo first-order in [QAc] with k = 4.3 × 10?3 min?1. 相似文献
24.
Treatment of thieno[2,3-b]pyridine (1a) with n-butyllithium in hexane-tetramethylethylene-diamine at ?70° plus subsequent addition of dimethylformamide produced 2-formyl-Ia (66%). Halogen-metal exchange between 3-bromothieno[2,3-b]pyridine and n-butyllithium was effected in ether at ?70. Further reaction of the 3-lithio-Ia intermediate with a variety of carbonyl compounds gave 3-substituted thieno[2,3-b]pyridines bearing formyl (77%), acetyl, benzoyl, chloroacetyl, ethoxycarbonyl, N-phenylcarbamyl, and diphenyl hydroxymethyl groups. Common characteristics of these derivatives in pmr and mass spectra are noted. 相似文献
25.
Mixtures of diblock co-oligomers of tri-O-methylated and unmodified cello-oligosaccharides have been found to be amphiphilic, as reported before. In order to clarify
their accurate amphiphilic property, diblock co-oligomers of tri-O-methylated and unmodified cello-oligosaccharides with monodispersity, methyl β-d-glucopyranosyl-(1→4)-2,3,6–tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6–tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-d-glucopyranoside (1, pentamer), methyl β-d-glucopyranosyl-(1→4)- β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-d-glucopyranoside (2, hexamer), and methyl β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1→4)- 2,3,6-tri-O-methyl-d-glucopyranoside (3, trimer) were synthesized independently. These compounds had higher surface activities compared to the mixture of diblock
co-oligomers of tri-O-methylated and unmodified cello-oligosaccharides and commercially available methylcellulose (MC) SM-4. This paper describes
the methods of synthesis of these compounds, and the influence of amphiphilic character on their surface activity. A new class
of carbohydrate-based nonionic surfactant without long alkyl chain was discovered. 相似文献
26.
To avoid changes in the original As species distribution in natural water after sampling, a method of immediate separation
of As(V) by anion exchange at the sampling site was developed. The procedure consists of two steps. The total concentration
of arsenic is determined in one part of the water sample acidified on site. Another part of the water samples is pressed through
a column filled with an anion exchanger. The As(III) species that is not redox-stable remains in the effluent of the sorbents
column and can be analyzed with conventional methods after stabilization by addition of conc. HNO3. As(V) is sorbed by the exchanger material. The As(V) concentration can be calculated as the difference between Assol and As(III), neglecting very low contents of methylated species.
Oxidation of Fe(II) by air followed by co-precipitation of arsenic with iron hydroxide was applied in field experiments to
minimize the As concentration in seepage and mining water. 相似文献
27.
The Bernthsen reaction between N-1-naphthyl-2-naphthylamine and 2-methylbutanoic acid and its anhydride at 200–230° for seven hours gives a low yield of 12- or 13-s-butyldibenz[a,h]acridine, instead of the expected 14-isomer. The parent molecule dibenz[a,h]acridine results from the same reaction conducted at 270° for thirteen hours. It is suggested that alkyl migration may have occurred in some other cases where the Bernthsen reaction was reported to yield 14-alkyldibenz[a,h]acridines. 相似文献
28.
29.
L. H. Klemm Susan Johnstone Sandip K. Sur Daniel R. Muchiri 《Journal of heterocyclic chemistry》1989,26(5):1277-1281
Three compounds, thieno[3,2-b]pyridine 4-oxide, 7-nitrothieno[3,2-b]pyridine 4-oxide ( 1 c), and 6-cyano-thieno[2,3-b]pyridine, undergo nitration by means of a mixture of nitric and sulfuric acids to yield 3,7-dinitro-thieno[3,2-b]pyridine (3%), 3,7-dinitrothieno[3,2-b]pyridine 4-oxide ( 1d ) (26%), and 6-carbamoyl-5-nitrothieno[2,3-b]pyridine ( 6b ) (11%), respectively. Structures of the products were ascertained by spectral means, notably infrared, 1H nmr, and 13C nmr. It is proposed that 1d exists (at least in part) as a tricyclic structure and that 6b may result from an intramolecular mechanism of nitration. An attempt to de-N-oxygenate 1c with excess triphenylphosphine removes more than one oxygen atom per molecule (as triphenylphosphine oxide) without producing an identified thienopyridine product. 相似文献
30.
Daniel Ayuk Mbi Egbe Eckhard Birckner Elisabeth Klemm 《Journal of polymer science. Part A, Polymer chemistry》2002,40(15):2670-2679
Luminophoric dialdehyde 1,4‐bis[4‐formylphenylethynyl‐(2,5‐dioctadecyloxyphenyl)‐buta‐1,3‐diyne] ( 4 ) enables the synthesis of diyne‐containing hybrid polyphenyleneethynylene/poly(p‐phenylenevinylene) polymer poly[1,4‐phenylene‐ethynylene‐1,4‐(2,5‐dioctadecyloxy)phenylene‐butadi‐1,3‐ynylene‐1,4‐(2,5‐dioctadecyloxy)phenylene‐ethynylene‐1,4‐phenylene‐ethene‐1,2‐diyl‐1,4‐(2,5‐dioctadecyloxy)phenylene‐ethene‐1,2‐diyl] ( 7 ) with a well‐defined general structure (? Ph? C?C? Ar? C?C? C?C? Ar? C?C? Ph? CH?CH? Ar? CH?CH? )n, which was confirmed by NMR and infrared spectroscopy. The highly luminescent material is thermostable, soluble in usual organic solvents through the grafting of octadecyloxy side groups, and can be processed into transparent films. With the aim to investigate the effect of ? C?C? C?C? in the photophysical behavior of 7 , a comparison of the photophysics of monomers 3 [1,4‐bis(4‐formylphenylethynyl)‐2,5‐dioctadecyloxybenzene] and 4 and subsequently of their respective polymers 6 and 7 has been carried out. Similar photophysical behaviors for 6 (poly[1,4‐phenylenethynylene‐1,4‐(2,5‐dioctadecyloxyphenylene)ethene‐1,2‐diyl]) and 7 were observed in dilute CHCl3 solution as a result of an identical chromophore system responsible for the absorption (λa = 448 nm) and emission (λf = 490 nm) in both compounds. The increased planarization and enhanced rigidity of the conjugated backbone in the solid state at room temperature as well as in frozen dilute tetrahydrofuran solution at 77 K cause the bathochromic shift of the absorption and emission spectra. The large octadecyloxy side chains obviously limit strong π‐π interchain interactions in the solid films, which explains the high fluorescence quantum yields of 35 and 52% obtained for 6 and 7 , respectively. The energetically arduous migration of the π electron through the diyne units not only requires a higher threshold voltage for the detection of photoconductivity in 7 but could possibly limit radiationless deactivation channels of the exciton, which explains the approximate 20% fluorescence quantum yields difference between 6 and 7 in the solid state. The electron‐withdrawing effect of the triple bonds confer both 6 and 7 with a good electron‐accepting property (Eox = 1.39 V vs Ag/AgCl) if used in light‐emitting diode devices. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2670–2679, 2002 相似文献