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排序方式: 共有84条查询结果,搜索用时 375 毫秒
1.
A. Abras A. A. G. Campos A. V. de Carvalho L. O. Ladeira 《Applied Physics A: Materials Science & Processing》1986,41(3):185-189
Iron-boride layers on low-carbon steel were produced by thermochemical diffusion process. The surface interaction products: Fe2B, FeB, FeBx (x>1) and a solid solution of iron in boron were identified by surface Mössbauer spectroscopy (CEMS and XMS). Samples of original and boronized steel were subjected to corrosion process by immersion in HCl (0.1 N) solution for 150 h. While the steel sample was strongly corroded, none corrosion product was found on the boronized sample surface. However, significant changes in relative percentages of the various iron boride phases were detected. Also, samples of original and boronized steel were subjected to oxidation process by heat-treatment in air at 300°C for 8 h and 500°C for 4 h. At 300°C, while bulk Fe3O4 and -Fe2O3 were formed on the steel surface, none iron oxide was detected on the boronized surface. At 500° C, while only pure bulk -Fe2O3 was detected on the steel surface, a particle size distribution of-Fe2O3, with particle size of about 100 Å, was probably formed on the boronized surface, as evidenced by CEMS. 相似文献
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Enhanced π‐Backdonation from Gold(I): Isolation of Original Carbonyl and Carbene Complexes
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Dr. Maximilian Joost Dr. Laura Estévez Sonia Mallet‐Ladeira Dr. Karinne Miqueu Dr. Abderrahmane Amgoune Dr. Didier Bourissou 《Angewandte Chemie (International ed. in English)》2014,53(52):14512-14516
The specific electronic properties of bent o‐carborane diphosphine gold(I) fragments were exploited to obtain the first classical carbonyl complex of gold [(DPCb)AuCO]+ (ν(CO)=2143 cm?1) and the diphenylcarbene complex [(DPCb)Au(CPh2)]+, which is stabilized by the gold fragment rather than the carbene substituents. These two complexes were characterized by spectroscopic and crystallographic means. The [(DPCb)Au]+ fragment plays a major role in their stability, as substantiated by DFT calculations. The bending induced by the diphosphine ligand substantially enhances π‐backdonation and thereby allows the isolation of carbonyl and carbene complexes featuring significant π‐bond character. 相似文献
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The protected ceramide: N‐((2S,3S,4R)‐3,4‐bis(benzyloxy)‐1‐hydroxyoctadecan‐2‐yl)tetracosanamide, was attempted to introduce a triflate as a leaving group followed by a nucleophilic substitution with azido group in one‐pot manner. Unexpectedly, the oxazole ring formed via a thermodynamically favored intramolecular cyclization was opened to generate the original ceramide by triflic acid. In addition, the residual acid promoted a formylation of the primary hydroxy group in DMF. 相似文献
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A Bis‐Sulfonyl O,C,O Aryl Pincer Ligand and its Tin(II) Complex: Synthesis,Structural Studies,and DFT Calculations
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Mohammad El Ezzi Romaric Lenk Dr. David Madec Dr. Jean‐Marc Sotiropoulos Sonia Mallet‐Ladeira Dr. Annie Castel 《Angewandte Chemie (International ed. in English)》2015,54(3):805-808
The efficiency of the deprotonated aryl bis‐sulfone [2,6‐{(p‐tolyl)SO2}2C6H3]? as an O,C,O‐coordinating pincer‐type ligand was described. The bis‐sulfone precursor was synthesized using a straightforward palladium‐catalyzed cross‐coupling reaction. As a result of directed ortho metalation (DoM) through sulfonyl groups, a selective lithiation of the aryl group was achieved and the corresponding carbanion was isolated and its structure determined by single‐crystal X‐ray diffraction analysis. A heteroleptic tin(II) complex has been prepared by a nucleophilic substitution reaction. Crystallographic analysis and DFT calculations indicate that the bis‐sulfonyl moiety acts as a new O,C,O‐coordinating pincer‐type ligand with intramolecular S?O coordination to a tin(II) center. The cis form with the two nonbonded oxygen atoms of the sulfonyl groups on the same side is preferentially obtained. 相似文献
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Geagea R Ladeira S Mazières S Destarac M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(13):3718-3725
Molybdenum and chromium pentacarbonyldiphenylphosphinocarbodithioate complexes have been prepared in a one‐pot reaction from the corresponding metallocarbonyldiphenylphosphine. The complexes have been characterised by IR, 1H, 31P and 13C NMR spectroscopies and by mass spectrometry. The solid‐state structures of [Cr(CO)5{PPh2CS2CH(Ph)CH3}] ( 1 ) and [Mo(CO)5{PPh2CS2CH(Ph)CH3}] ( 2 ) are reported. Compounds 1 and 2 are isostructural and crystallise in the triclinic P$\bar 1Molybdenum and chromium pentacarbonyldiphenylphosphinocarbodithioate complexes have been prepared in a one-pot reaction from the corresponding metallocarbonyldiphenylphosphine. The complexes have been characterised by IR, (1)H, (31)P and (13)C?NMR spectroscopies and by mass spectrometry. The solid-state structures of [Cr(CO)(5){PPh(2)CS(2)CH(Ph)CH(3)}] (1) and [Mo(CO)(5){PPh(2)CS(2)CH(Ph)CH(3)}] (2) are reported. Compounds 1 and 2 are isostructural and crystallise in the triclinic P1 space group. These new organometallic compounds are highly efficient reversible chain-transfer agents for reversible addition-fragmentation chain-transfer (RAFT) polymerisation of styrene (St) and n-butyl acrylate (nBA), with controlled number-average molar mass values and narrow dispersities (<1.2). The controlled character of the polymerisation was further exemplified by the synthesis of St and nBA diblock copolymers. 相似文献
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Frontispiece: Dative Au→Al Interactions: Crystallographic Characterization and Computational Analysis
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