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991.
Microwave-assisted extraction using 1 M KOH/methanol (alkaline-MAE) in combination with solid-phase extraction treatment was developed and applied to polycyclic aromatic hydrocarbons (PAHs) in a sediment sample. Although various conditions were examined (100 or 150 °C for 10 or 30 min), comparable concentrations of PAHs to those obtained by conventional extraction with 1 M KOH/methanol at 70 °C for 4 h were obtained, even at 100 °C for 10 min. The concentrations obtained by using MeOH at 150 °C for 30 min without KOH were lower (by 1.3-37%) than those obtained by alkaline-MAE at 150 °C for 30 min. Since the developed technique can introduce higher concentration of benzo[ghi]perylene relative to those using pressurized liquid extraction (toluene, 150 °C, 15 MPa, 10 min, two cycles), the developed alkaline-MAE is a effective technique. 相似文献
992.
E. B. Melnikova M. M. Elchaninov A. A. Milov B. S. Lukyanov 《Chemistry of Heterocyclic Compounds》2008,44(9):1070-1076
The electrophilic reactions (nitration, bromination, hydroxymethylation, formylation, acylation) and radical substitution
reactions (nitration, arylation) of 2-(2-furyl)benzothiazole have been studied. It was found that all of the reactions occur
at position 5 of the furan ring. Only nitration in PPA gave the 5',6-dinitro derivative. Quantum-chemical calculation data
for the electron density distribution in the neutral and protonated 2-(2-furyl)benzothiazole molecules are given.
Dedicated to Boris Aleksandrovich Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1331–1338, September, 2008. 相似文献
993.
S. V. Chepyshev Yu. N. Chepysheva A. B. Ryabitskii A. V. Prosyanik 《Chemistry of Heterocyclic Compounds》2008,44(5):523-529
In vinyl nucleophilic substitution (SN
vin) with the hydrochlorides or 4-toluenesulfonates of primary arylamines 1-alkyl-3-alkylaminopyrrole-2,5-diones form the corresponding
1-alkyl-3-arylaminopyrrole-2,5-diones, which are also produced in situ from the corresponding arylaminofumarates and primary
alkylamines.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 668–675, May, 2008. 相似文献
994.
995.
Jiadong Chen Yulu Zhang Prof. Dr. Shengbiao Tang Prof. Dr. Ying Shao Prof. Dr. Jiangtao Sun 《European journal of organic chemistry》2023,26(32):e202300605
One-step process for the preparation of a 1,3-dienyl-5-ester motif from readily available substrate remains a challenging work in organic synthesis. We herein report the first example of C5-regioselective esterification of unactivated dienyl alcohols, using free carboxylic acids as nucleophiles under mild conditions, providing a series of 1,3-dienyl-5-ester compounds in excellent regioselectivity and E-selectivity. 相似文献
996.
Yanpeng Liu Dr. Houzong Yao Dr. Man-Kit Tse Shu Chen Dr. Shek-Man Yiu Prof. Dr. Guangyu Zhu 《欧洲无机化学杂志》2023,26(3):e202200763
Platinum-based complexes are among the most widely utilized cancer therapeutics. Current Pt(II) drugs face some challenges including toxicity and drug resistance. To solve these issues, great efforts have been devoted to developing nonclassical platinum complexes, such as Pt(IV) prodrugs, that act via mechanisms distinct from those of the approved drugs. Compared with active Pt(II) counterparts, Pt(IV) complexes are relatively inert. Although direct interactions between Pt(IV) complexes and nucleotides have been reported, the reaction is slow due to the kinetic inertness of Pt(IV) complexes. Herein, we design and synthesize a Pt(IV) monotrifluoromethyl complex, in which the chloride ligand that is trans to trifluoromethyl ligand is reactive. The Pt(IV) monotrifluoromethyl complex is very stable in water but displays high reactivity towards various substrates including buffer components and 5’-dGMP. The study of reaction mechanism reveals that this Pt(IV) complex reacts with phosphate via SN2 nucleophilic substitution pathway, which is different from Pt(II) drugs. The Pt(IV) monotrifluoromethyl complex is cytotoxic in human ovarian cancer cells. Our work reports an example of a reactive organometallic Pt(IV) complex that can directly interact with nucleophiles and implies its potential as an anticancer agent. 相似文献
997.
Dmytro I. Sierov Illia V. Dzhulai Kateryna I. Siryk Kostiantyn V. Shvydenko Tetiana I. Shvydenko Prof. Dr. Kostiantyn Nazarenko Prof. Dr. Aleksandr Kostyuk Oleksandr S. Liashuk Prof. Dr. Oleksandr O. Grygorenko 《European journal of organic chemistry》2023,26(34):e202300538
A systematic study on the SnAr reaction of halogenated fluoropyridines and (hetero)aliphatic nitrile anions as an approach to the synthesis of functionalized pyridines bearing a (cyclo)alkyl or saturated heterocyclic substituent by is described. The scope of the method was demonstrated on a wide range of (hetero)aliphatic nitriles (including three- to six-membered cycloalkane derivatives and N-, O-, S-containing saturated heterocycles) and all isomeric halogenated 2-and 4-fluoropyridines. High chemo- and regioselectivity (i. e., exclusive substitution of the fluorine atom), as well as excellent scalability of the proposed reaction sequence were demonstrated (up to 450 g for the arylation step or up to 77 g of cycloalkylpyridine over two steps in a single run). The utility of the synthesized products was illustrated in the additional functional group transformations resulting in synthetically valuable pyridine-containing building blocks. 相似文献
998.
Computational studies have often been carried out on hydrogen-terminated nanographenes (NGs). These structures are, however, far from those deduced from experimental observations, which have suggested armchair edges with two carboxy groups on the edges as dominant. We conducted computational studies on NGs consisting of C42, C60, C78, C96, C142, and C174 carbon atoms with hydrogen, carboxy, and N-methyl imide-terminated armchair edges. DFT calculations inform distorted basal planes and similar HOMO-LUMO gaps, indicating that the edge oxidation and functionalization do not very influence the electronic structure. Comparison of observed UV-vis spectra of carboxy- and N-octadecyl chain terminated NGs with calculated spectra of model NGs informs the contribution of π-π* transitions on the basal plane to the absorptions in the visible region. A dimeric structure of NG and octadecyl-installed NG demonstrate that both the distorted basal planes and the steric contacts among the functional groups widen the surface-to-surface distance thereby allowing the invasion of solvent molecules between the surfaces. This picture is consistent with the improved solubility of edge-modified NGs. 相似文献
999.
Ugo Jacovella Corentin Rossi Claire Romanzin Christian Alcaraz Roland Thissen 《Chemphyschem》2023,24(2):e202200474
Structural rearrangements in ions are essential for understanding the composition and evolution of energetic and chemically active environments. This study explores the interconversion routes for simple polycyclic aromatic hydrocarbons, namely naphthalene and azulene radical cations (C10H8+), by combining mass spectrometry and vacuum ultraviolet tunable synchrotron radiation through the chemical monitoring technique. Products of ion-molecule reactions are used to probe C10H8+ structures that are formed as a function of their internal energies. Isomerisation from azulene radical cation towards naphthalene radical cation in a timescale faster than 80 μs was monitored, whereas no reverse isomerisation was observed in the same time window. When energising C10H8+ with more than 6 eV, the reactivity of C10H8+ unveils the formation of a new isomeric group with a contrasted reactivity compared with naphthalene and azulene cations. We tentatively assigned these structures to phenylvinylacetylene cations. 相似文献
1000.
Synthesis of Multiply Substituted Polycyclic Aromatic Hydrocarbons by Iridium‐Catalyzed Annulation of Ring‐Fused Benzocyclobutenol with Alkyne through C−C Bond Cleavage
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Jiajia Yu Hong Yan Prof. Dr. Chen Zhu 《Angewandte Chemie (International ed. in English)》2016,55(3):1143-1146
The first iridium‐catalyzed intermolecular cyclization between alkynes and ring‐fused benzocyclobutenols (RBCB) through C?C bond cleavage is described. A variety of elusive polycyclic aromatic hydrocarbons (PAHs) with multiple substituents are obtained in good yields under mild conditions. This procedure provides a unique and expeditious tool for the synthesis of PAHs. 相似文献