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961.
The extraction of ion-pairs of monovalent anions (chloride, bromide, iodide, perchlorate, benzenesulfonate, naphthalenesulfonate and octanesulfonate ions) with pararosaniline, crystal violet, ethyl violet and methylene blue cations is described. The extraction constants (Kex) for these ion-pairs between an aqueous phase and several organic phases (1,2-dichloroethane, chloroform, o-dichlorobenzene, chlorobenzene, benzene and toluene) were determined. The values of log Kex for ion-pairs with ethyl violet were on average about 2.7 times larger than those of crystal violet, which were in turn about 6 times larger than those for pararosaniline. The order of the extractability of ion-pairs was 1,2-dichloroethane > chloroform > o-dichlorobenzene > chlorobenzene > benzene > toluene, and the differences of the log Kex between two successive solvents averaged 0.4, 1.9, 2.1, 2.6 and 0.8, respectively. Ethyl violet and crystal violet are useful extraction-spectrophotometric reagents for iodide, perchlorate and alkyl or arylsulfonate ions. 相似文献
962.
963.
964.
Microbial degradation of a tetramethylarsonium salt during incubation at 25°C was investigated under both aerobic and anaerobic conditions. Two media (1/5 ZoBell 2216E and inorganic salt medium), added with the sediments or suspended substances as the sources of the microorganisms, were used. Degradation of the tetramethylarsonium salt occurred only in the ZoBell medium: under anaerobic conditions, trimethylarsine oxide and dimethylarsinic acid were derived with the sediments, and dimethylarsinic acid with the suspended substances, the salt degrading more rapidly with the former than with the latter. Small amounts of two metabolites, trimethylarsine oxide and inorganic arsenic(V), was also derived in the aerobically incubated ZoBell medium added with the suspended substances. This result means that the tetramethylarsonium salt is degraded to inorganic arsenic, which is the starting material for arsenic circulation in marine ecosystems, via trimethylarsine oxide and dimethylarsinic acid. 相似文献
965.
The 1,3-dipolar cycloaddition reactivity and regioselectivity of methyleneadamantane 1, ethyl adamantylideneacetate 7a, adamantylideneacetonitrile 7b and ω-methoxymethyleneadamantane 7c with substituted benzonitrile oxides 3a-i were calculated by CNDO/2 method using the perturbation equation derived by Klopman and Salem. The calculation predicted an exclusive formation of adamantan - 2 - spiro - 5' - 3' - aryl - Δ2' - isooxazoline 4a-i in the reactions of 1, 7a and 7b with 3a-i, and a formation of 67–69:33-31 mixture of 4a-i and isomeric 5a-i in the reaction of 7c with 3a-i. The predicted exclusive formation of 4a-i were experimentally observed in the reactions of 1,7a and 7b with 3a-i generated from 2a-i with Et3N or thermally, but the reaction of 7c with 3a did not afford the corresponding adducts. A considerably higher reactivity of CN triple bond than CC double bond was observed in the reaction of 7b with 3a and 1,2,4-oxadiazole derivative 11 was obtained as the major product. 相似文献
966.
967.
Ken'Ichi Hanaoka Hideki Yamamoto Keishiro Kawashima Shoji Tagawa Toshikazu Kaise 《应用有机金属化学》1988,2(4):371-376
Arsenic compounds were extracted with chloroform/methanol/water from tissues of marine animals (four carnivores, five herbivores, five plankton feeders). The extracts were purified by cation and anion exchange chromatography. Arsenobetaine [(CH3)3As+CH2COO?], dimethylarsinic acid [(CH3)2AsOOH], trimethylarsine oxide [(CH3)3AsO] and arsenite, arsenate, and methylarsonic acid [(CH3)AsO(OH)2] as a group with the same retention time were identified by high-pressure liquid chromatography. Arsenic was determined in the collected fractions by graphite furnace atomic absorption spectrometry. Arsenobetaine found in all the animals was almost always the most abundant arsenic compound in the extracts. These results show that arsenobetaine is present in marine animals independently of their feeding habits and trophic levels. Arsenobetaine-containing growth media (ZoBell 2216E; solution of inorganic salts) were mixed with coastal marine sediments as the source of microorganisms. Arsenobetaine was converted in both media to trimethylarsine oxide and trimethylarsine oxide was converted to arsenite, arsenate or methylarsonic acid but not to dimethylarsinic acid. The conversion rates in the inorganic medium were faster than in the ZoBell medium. Two dominant bacterial strains isolated from the inorganic medium and identified as members of the Vibro–Aeromonas group were incapable of degrading arsenobetaine. 相似文献
968.
Hiroshi Mukai Shoji Miyazaki Shigeo Umetani Sorin Kihara Masakazu Matsui 《Analytica chimica acta》1989
The synergic liquid/liquid extraction of lithium and sodium with 4-acyl-5-pyrazolones having bulky substituents and tri-n-octylphosphine oxide (TOPO) is described. The maximum percentage extraction and the separation of lithium and sodium were improved by introducing bulky substituents. Quantitative extraction (? 99% ) of lithium could be achieved by adduct formation with TOPO, which enhanced the extraction much more than did triphenylphosphine oxide. The extraction decreased in the solvent order cyclohexane ? benzene ? chloroform, which is the general trend in synergic extractions. 相似文献
969.
Shoji Ishibashi Norio Terada Masayuki Hirabayashi Hideo Ihara 《Hyperfine Interactions》1994,84(1):115-120
We have calculated distributions and lifetimes of positrons in the infinite-layer compound SrCuO2 and those trapped at possible point defects therein. In the delocalized state, positrons show their density maxima at interstitial sites in the Sr planes and have a significant overlap also with Cu and O atoms. The corresponding positron lifetime is 149 ps. It has been revealed that the Sr vacancy strongly localizes positrons with the binding energy of 2.8 eV and the lifetime of 238 ps, while the O vacancy does not trap positrons. Calculations are also performed on related materials Sr2Cu4O6 and Sr4Cu6O10, which are characterized by one-dimensional networks of edge-sharing CuO4 squares. Positrons are predominantly distributed between these networks in these materials and their corresponding lifetimes are 170–171 ps. 相似文献
970.
Takeshi Asai Shichio Kawai Ryo Nagai Shoji Mochizuki 《Journal of Physics and Chemistry of Solids》1984,45(2):173-179
From 1H and 7LiNMR relaxation times T1, T2 and T1ρ in Li5NI2 and the solid solution Li5NI2?0.77LiOH, the diffusive motion of the Li+ ion was studied to make clear the role of the OH? ion in improving the Li+ ionic conduction. At temperatures as low as 140 K, each Li+ ion jumps among four available positions. Its activation energies are 9.26 and 11.8 kJ mol?1 for Li5NI2 and Li5NI2?0.77LiOH, respectively. Diffusive motion was observed in T2 and T1ρ above 240 K. The mode of the cation distribution and the diffusion mechanism are not affected by the presence of the OH? anion. The most noticeable fact is that the OH? ion is substituted selectively for the N3? ion that is the nearest neighbour of the Li+ ion. This selective substitution increases the concentration of the Li+ vacancy most effectively up to 4.2% of the total Li positions. At the same time it diminishes the strong attractive force of the N3? anion binding the Li+ ion to the position, and thus the activation energy. For the diffusion, an anomalously low attempt frequency of 3̃ × 109Hz was obtained from T1ρ, while the normal value of 4.8 × 1012Hz was obtained from the ionic conductivity. The large discrepancy was attributed to the collective nature of the Li+ diffusive motion. 相似文献