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991.
The effects of fluorination on the conformational landscape of adrenergic neurotransmitters is exemplified trough the conformation analysis of 2‐(2‐F‐phenyl)ethanamine (2FPEA) carried out by microwave spectroscopy and quantum chemical calculations. Five different conformers of the nine possible stable ones for 2FPEA are observed by molecular‐beam Fourier‐transform microwave spectroscopy. Their unambiguous identification is possible by comparing the experimental rotational constants and the quadrupole coupling constants with those obtained by quantum chemical calculations carried out at the MP2/6‐311++G(d,p) level of theory. The relative abundances of the conformers in the jet are estimated from the relative intensities in the observed spectra. A qualitative agreement between experimental and theoretical energies was found, and the remaining deviations are explained by population transfer taking place during the adiabatic expansion. The energy landscape, which also takes the interconversion barriers between the conformers into consideration, is thus characterized completely by the strong interplay of quantum chemical methods and precise experimental data. Significant changes in energy and structure of the 2FPEA conformers are found compared to those obtained for the prototype molecule 2‐phenylethanamine (PEA). 相似文献
992.
JJ Rodríguez K Filipiak M Maslyk J Ciepielski S Demkowicz S de Pascual-Teresa S Martín-Santamaría B de Pascual-Teresa A Ramos 《Organic & biomolecular chemistry》2012,10(36):7334-7346
Based on the benzo[b]naphtho[1,2-d]furan and benzo[b]naphtho[1,2-d]thiophene frameworks, a series of ligands with different basic side chains (BSCs) has been synthesized and pharmacologically evaluated. Also, their binding modes have been modelled using docking techniques. It was found that the introduction of a BSC in these systems brings about a decrease of affinity for both estrogen receptors α and β in an in vitro competitive binding assay. However, two full antagonists of the estrogen receptor β ( and ) have been discovered, with potency in the low micromolar concentration in a cell-based luciferase reporter assay, and completely devoid of activity against the α receptor at the same concentration range. Differences in the ERα/ERβ binding modes have also been rationalized with the help of molecular modelling techniques. This interesting functional profile could be used to elucidate the physiological role of each ER subtype. 相似文献
993.
994.
A series of acetone-sensitized photodecarboxylation reactions involving phthalimides have been investigated using conventional and microphotochemistry. Both, intra- and intermolecular transformations were compared. In all cases examined, the reactions performed in microreactors were superior in terms of conversions or isolated yields. These findings unambiguously prove the advantage of microphotochemistry over conventional photochemical techniques. 相似文献
995.
González-Rodríguez MV Dopico-García MS Noguerol-Cal R Carballeira-Amarelo T López-Vilariño JM Fernández-Martínez G 《Journal of separation science》2010,33(22):3595-3603
This article investigates the applicability of HPLC-UV, ultra performance LC-evaporative light-scattering detection (UPLC-ELSD), HPLC-ESI(+)-MS and HPLC-hybrid linear ion trap (LTQ) Orbitrap MS for the analysis of different non-ionic antistatic additives, Span 20, Span 60, Span 65, Span 80, Span 85 (sorbitan fatty acid esters), Atmer 129 (glycerol fatty acid ester) and Atmer 163 (ethoxylated alkylamine). Several alkyl chain length or different degrees of esterification of polyol derivatives can be present in commercial mixtures of these polymer additives. Therefore, their identification and quantification is complicated. Qualitative composition of the studied compounds was analysed by MS. HPLC-UV, UPLC-ELSD and HPLC-LTQ Orbitrap MS methods were applied to the quantitative determination of the different Spans, Atmer 129 and Atmer 163, respectively. Quality parameters of these methods were established and no derivatization was necessary. 相似文献
996.
Vincent Belluau Elfrun Ratzke Sonia Gallagher Michael Oelgemöller 《Tetrahedron letters》2010,51(36):4738-6535
Photoadditions of phenylacetates to phthalimide in pH 7 buffer solution give the corresponding benzylated-hydroxyphthalimidines in moderate to high yields of up to 94%. In a micro-structured reactor, higher conversions and purities are achieved. With branched phenylacetates, photoaddition affords diastereoisomeric mixtures with low to moderate de values. Subsequent acid-catalyzed dehydration furnishes the corresponding 3-arylmethyleneisoindolin-1-ones in good to excellent yields and with high E-selectivities. Irradiation of the parent 3-phenylmethyleneisoindolin-1-one under oxidative conditions only leads to cis/trans-isomerization. 相似文献
997.
Photoreactions involving N,N-dimethylated α-amino acid salts and N-methylphthalimide are dominated by photoreduction and acetone trapping. Only, N-phenyl glycinate underwent photodecarboxylative addition in a moderate yield of 30%. In contrast, N-acylated α-amino acid salts readily gave addition products in fair to high yields of 20-95%. Comparison experiments with N,N-dimethylacetamide and amino-/amido-containing phthalimides revealed the origin of the crucial electron-transfer step and the reactivity order NR3 » ? RCONR2 was established. 相似文献
998.
Pauline Gualco Dr. Maxime Mercy Sonia Ladeira Dr. Yannick Coppel Dr. Laurent Maron Dr. Abderrahmane Amgoune Dr. Didier Bourissou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(35):10808-10817
Coordination of ambiphilic diphosphine–silane ligands [o‐(iPr2P)C6H4]2Si(R)F (R=F, Ph, Me) to AuCl affords pentacoordinate neutral silicon compounds in which the metal atom acts as a Lewis base. X‐ray diffraction analyses, NMR spectroscopy, and DFT calculations substantiate the presence of Au→Si interactions in these complexes, which result in trigonal‐bipyramidal geometries around silicon. The presence of a single electron‐withdrawing fluorine atom is sufficient to observe coordination of the silane as a σ‐acceptor ligand, provided it is positioned trans to gold. The nature of the second substituent at silicon (R=F, Ph, Me) has very little influence on the magnitude of the Au→Si interaction, in marked contrast to N→Si adducts. According to variable‐temperature and 2D EXSY NMR experiments, the apical/equatorial positions around silicon exchange in the slow regime of the NMR timescale. The two forms, with the fluorine atom in trans or cis position to gold, were characterized spectroscopically and the activation barrier for their interconversion was estimated. The bonding and relative stability of the two isomeric structures were assessed by DFT calculations. 相似文献
999.
Sonia Rueda 《代数通讯》2013,41(3):1127-1152
Abstract Consider the algebra R = ?[A,B,H] subject to relations where and . We study these algebras for different f and ç. We study highest weight modules and finite dimensional simple modules. We introduce the categories p with p ≥ 1, with an interesting decomposition in categories p I and p II . We also consider the BGG-category and develop new techniques towards the study of . 相似文献
1000.
Nicolas Andruskiewitsch Sonia natale Nicolas Andruskiewitsch sonia natale 《代数通讯》2013,41(10):3239-3254
In this paper we discuss the structure of some product G =AB of nilpotent subgroups A and B. In particular we prove that if G is a minimax soluble group or a finitely generated linear group and if it does not have non-trivial periodic normal subgroups, then G is metanilpotent. 相似文献